Condenser June 2017 by Editor, IIAR

THE OFFICIAL MAGAZINE OF THE AMMONIA REFRIGERATION INDUSTRY n JUNE 2017

The Internet of

REFRIGERATION Networked Equipment Aims to Improve Safety, Operations

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JUNE 2017

CO ND E N SE R S TA FF Publisher

David Rule

Editor-In-Chief Andrea Collins Creative Director Bill Ellis V.P. Marketing and Sales Eileen McKeown V.P. and Technical Director Eric Smith Staff Writers Mindy Long Rob Duca

COV E R STORY

As demand grows for the remote monitoring of all types of equipment – driven largely by the need to safeguard consumers and food, manage energy use, and provide a consistent, effective maintenance program – a large, connected ecosystem of refrigeration infrastructure is taking shape.

International Institute of Ammonia Refrigeration 1001 North Fairfax Street, Suite 503 Alexandria, VA 22314 www.iiar.org Phone: 703-312-4200 Fax: 703-312-0065

ALSO:

11 P ackaged

Components Promise Flexibility, Lower Install Costs

4 Chairman’s Message 6 President’s Message 15 Case Study 17 IIAR Members Honored with

Awards from Accelerate America

19 21 www.iiar.org

IIAR Remembers George Yoksas

23 24 28

Recommended Practices

30 37

Government Relations

ARF News

RETA, IIAR Develop CO2 Training Materials Technical Paper

Energy Efficiency A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

chairman’s MESSAGE BY WALTER TEETER

e’re kicking off a new year and setting new agendas, and even though I’m well into my term as your IIAR Chairman, I’d like to take this opportunity to welcome everyone – new and renewing members alike. We’ve just wrapped up our annual agenda-setting session and meeting of the Board of Directors, and I’m happy

membership renewal effort - and extend special thanks and appreciation to all who contributed their time and financial support to this year’s event. If you didn’t already realize that we’re in the midst of IIAR membership renewal season, the success of our most recent conference – which surpassed expectations – is a great reminder of how essential IIAR membership is to the leadership of our industry.

Resolving some of the most complex scenarios we are facing will depend on the ability of IIAR’s membership to come together and continue to develop the resources and communicate the potential of new technologies at our industry’s central event. to report that IIAR is embarking on several ambitious goals this year as your staff is busier than ever completing products and projects that move us closer to our strategic vision. This year’s Industrial Refrigeration Conference was our first major step in that direction, and I’m very pleased to report that the event again saw recordbreaking numbers of attendees and exhibitors, and added important alliances through developing relationships with the regulatory community. IIAR’s 2017 show was one of our best conferences yet, and that is always due to the hard work and contributions of IIAR’s membership. It’s appropriate to take a minute – as we begin our 4

This year, we looked at many of the challenges facing our business environment, talked about the regulatory landscape, and examined the technology and best practices we’ll need to meet growing demand from so many new – and traditional – sectors. Resolving some of the most complex scenarios we are facing will depend on the ability of IIAR’s membership to come together and continue to develop the resources and communicate the potential of new technologies at our industry’s central event. I’d like to take this opportunity to call not only for your renewed membership, but also for your increased participation and leadership in IIAR’s committees and

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

development of conference technical papers. Whether you get involved as a committee member or tech paper author, or in any other way, your involvement is what moves us forward. Our publications are second to none, addressing new trends and introducing new technologies, and you, as an IIAR member have the opportunity to contribute to them directly. You also have an opportunity, as a member, to expand your interaction with your peers, and influence the policies, codes and standards that shape the way we do business. Our committees span all of these areas and beyond, and they all depend on your help and support in some form. To that end, we’ll be focused once more on the work of our committees this year, especially in the regulatory arena, where we’ve continued to build relationships on behalf of our industry, carrying the torch on initiatives with the Department of Homeland Security, EPA, OSHA and many other government organizations. And we’re continuing to grow as a resource for the educational and training materials that make our industry safe and enable the use of new natural refrigeration technologies. I encourage you to turn to Dave Rule’s President’s Message in this issue to read about the exciting developments around our new education program – starting with the success of the IIAR-2 training course. The Academy of Natural Refrigerants is one of our most exciting new initiatives. However you decide to get involved this year, I’m hoping you’ll see this IIAR membership renewal season a little differently, as a chance to dive in to the work of your organization. We’re growing like never before, and I’m looking forward to working with you all in the year ahead. www.iiar.org

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

president’s MESSAGE BY DAVE RULE

t’s the beginning of the summer and that means it’s time for one of IIAR’s most important activities – leading membership renewals. And while this may seem like a routine activity we all work hard to complete every year, I’d like to take the opportunity in my column this month to point out that, as an IIAR member, this is one of the most important contributions you can make to the success of our industry. The call for renewals is much more than an invitation to continue your membership. It’s an invitation to support the growth and expansion of new initiatives, programs and goals, and to support the expansion of our industry in general. We’re focused on membership and committee work that will address the trends that are already shaping our future as a technical community. And your staff and dedicated Board of Directors are looking ahead to take stock of where we are now, and where we’re headed. New technologies like low charge systems, greater adoption of CO2, and other developments are taking natural refrigerants in new directions, and IIAR is keeping pace. One of the most promising new programs you’ve heard me talk about is our Academy of Natural Refrigerants. The IIAR-2 initial class was a great success, the second round of new classes are now available online for members to complete their course work remotely, and we’re looking forward to expanding this functionality in the year ahead. This remote training platform is an important new way IIAR is providing members essential access to IIAR member benefits – and I’m looking

forward to expanding this functionality in the year ahead. We’ll continue to carry forward the IIAR-2 classes and exams and we’ll begin work on the Board of Directorsled initiative to create similar classes and exams for IIAR Standards 4, 5, and 8 as well as a PSM/ RMP introduction course. We’ll release course work in September for the IIAR 4, 5 and 8 Standards, and an introduction course for Process Safety Management and Risk Management will begin in November. The PSM and RMP module will be the first of several PSM/RMP course modules that will be offered by both IIAR and the University of Wisconsin to provide a comprehensive certificate for PSM/RMP professionals working in our industry. Our expansive educational program is being designed for the long term – to provide members with educational choices to meet their business and professional development requirements, and I hope you, as an IIAR member, will find value in it for years to come. We’re also expanding our education program with the continued development of new materials for our monthly series of education webinars for IIAR members. I hope you’ll take advantage of this great member resource – to expand your knowledge base, and just get new perspective on day-to-day operational issues in the year ahead. As I mentioned in my last column, IIAR’s advocacy and outreach efforts are growing like never before, and I’m pleased to report that recent meetings with OSHA, EPA and DHS have been a success, especially where our new education initiatives and broader effort to inform the regulatory community are concerned.

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

I’d also like to touch on our upcoming Natural Refrigerants Conference & Expo, which is slated for the Broadmoor Hotel in Colorado Springs, CO next March. We are expanding our technical program this year to include more Tech Paper sessions, Workshops and Panels designed to address the expanded opportunities for natural refrigerants in both the industrial and commercial market sectors. And we’ve recently confirmed the venue for our popular Monday night event, which will be held at the U.S. Olympic Training Center. The evening will include a tour of the facility with several Olympic demonstrations including gymnastics, wrestling and target shooting. This will be a rare opportunity to see how Olympic athletes train and, as always, a great chance for conference attendees to network with members of all sectors of our industry. This is an exciting time to be a member of IIAR, and these member benefits, programs and projects are opportunities to make our industry more dynamic and effective than ever before. Our success as an IIAR member community is directly related to your membership renewal, and, of course, the dedication and hard work of the many volunteer members serving on the various technical committees, executive committee and the board of directors. As a member, you are IIAR’s most valuable resource. I’m looking forward to working with the IIAR community this year to achieve all of our goals, and I invite everyone to renew your membership, and get involved in helping us fulfill the important mission of our organization. www.iiar.org

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

150 Years of Cool Innovations

Installed the first unit cooler in a butcher shop in Milwaukee. Provided pack ice machines for steam ships moving food stuffs to the troops in Europe Developed the VMC 440 reciprocating compressor – still considered the industry standard. Introduced the VSS 601 single-screw compressor Vilter continues to innovate with the introduction of the VSMC configurable compressor EXCLUSIVE FEATURES INCLUDE: · Dual port liquid injection · No oil pump required for most applications · Locally mounted pressure transducers and temperature sensors

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The Internet of

REFRIGERATION Networked Equipment Aims to Improve Safety, Operations

he Internet of Things — an increasingly massive network of electronically connected systems, devices and people that enables cross-platform data sharing — is creating a large, connected ecosystem across many industries, including refrigeration. “There is continuing growth in remote monitoring with all types of refrigeration equipment, driven largely by the need to safeguard consumers and food, manage energy use, and provide a consistent, effective maintenance program,” said Dean Landeche, vice president of marketing for Emerson Commercial & Residential Solutions, a technology and engineering services provider based in St. Louis. Retail groceries have long recognized the importance of connected refrigeration systems, and have high adoption rates of connected devices, Landeche said. Previously, the primary focus was operating alerts and

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alarms to indicate problems. “Now, with more points of connection, more sophisticated data from embedded sensor and controllers and advanced analytics capabilities in the 'big data' world, the focus has changed to creating more insights that drive specific decisions and actions,” he explained. Landeche said he is seeing much more interest and use of information to prompt action in advance, based on opportunities and trends identified in data patterns rather than reacting to failure modes and alerts. “Applied at the system, site and enterprise levels, those types of insight-driven actions have huge implications for cost-saving, labor productivity, maintenance improvement, food safety and more,” he said. Tristam Coffin, director of sustainability and facilities for retail grocer Whole Foods, said there is value in having information housed in one location. “You can’t manage what you don’t measure. You want to be able to measure systems and compare them so you can manage loads properly and have

access to troubleshoot, make changes or make adjustments so the system is operating appropriately,” he said. Coffin said Whole Foods is constantly looking for new solutions, and has remote control over the refrigeration systems and other major HVAC systems. However, Coffin said he hasn’t found a single solution. “The main obstacle we’re running into is one, equipment and two, whether that equipment is open protocol so we can integrate other software systems to take an enterprise approach. We’re in the discovery process right now,” he said. Coffin said systems haven’t evolved much in the last 10 years, but he is starting to see a shift. “We’re seeing a little bit of fusion of technology with the Internet of Things and softwareas-a-service technology becoming available. That is exciting,” he said, adding that the challenge is making them all communicate with each other. “We have a lot of things but we don’t have them all dialed in and connected with each other.”

COV E R

story

Through remote monitoring, equipment owners and their service providers can often detect problems as they emerge rather than after-the-fact in an emergency breakdown. “Major food safety risk and food loss is often avoided, and system operation can be maintained through proactive efforts,” Landeche said. “We’re also seeing more adoption of remote monitoring for refrigerant leak detection, where advanced data can often identify small leaks up to 30 days prior to discovery by leak detectors.”

for complex and costly project-style work. “Today’s smarter systems are making it easier, faster and highly reliable to implement equipment monitoring and performance processes,” Landeche said. With more embedded electronics, self-diagnosing systems, automated data processing and easy access to wireless networks, many start-up challenges and operational difficulties have been minimized, Landeche said. For many organizations considering remote monitoring, network security

“Major food safety risk and food loss is often avoided, and system operation can be maintained through proactive efforts,” Landeche said. “We’re also seeing more adoption of remote monitoring for refrigerant leak detection, where advanced data can often identify small leaks up to 30 days prior to discovery by leak detectors.” – Dean Landeche, vice president of marketing for Emerson Commercial & Residential Solutions

Colmac Coil’s heat exchangers include sensors that talk to a central computer system in a facility. “We’re reporting things like temperatures, pressures, different operating conditions of the machinery that indicate to the central computer system timeliness of maintenance, proper operation or failure modes,” said Bruce Nelson, president of Colmac Coil. “Not only does it allow companies to do more preventative maintenance, but also anticipate failures and make adjustments before things fail. It also offers opportunities for increased efficiency of operation.” Landeche said he is also seeing simplification of the actual insights tools, meaning that users can often use software more easily than before rather than relying on expert third-parties 10

remains a concern, as a few wellpublicized security breaches have been linked to access through IoT systems. “These concerns generally can be resolved through proven, managed security processes, effective firewall systems, separate operating networks, or even full outsourcing of IoT system functions to keep equipment and operational functions totally separated from customer records and financial data,” Landeche said. A wider array of embedded sensors provides more points of data to internal controllers. In turn, those controllers have more onboard functionality for automated operations, more storage capacity for data, and onboard communications capabilities that can often exchange information in a direct-to-cloud environment.

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

For example, Emerson’s CoreSense technology unlocks advanced diagnostics, protection and communication in Copeland compressors. With in-depth system information, technicians can make faster, more accurate decisions resulting in improved compressor performance and reliability. Based on user interest and contractor support, CoreSense availability has been extended as a basic component on many of Copeland’s Scroll compressors. Rob Seitz, owner of Kolbi Pipe Marker Co., said he is seeing an increase in the number of companies requesting QR codes. With QR codes, each piece of equipment would have its own code and anyone with a smart device can scan the code and view standard operating procedures for that equipment, preventative maintenance schedules, prior maintenance work and other pertinent information on their smart phone or portable device. Kolbi can print the codes on five different substrates. “We’re getting a lot of questions and opportunities about QR codes. Contractors and the individual owners are coming to us asking if we can do this. Because of our digital printing equipment and capabilities, we’re able to say we can,” he said. “The information is accessible. It is powerful and everybody can have it,” Seitz said, adding that the technology allows for the accumulation of information and makes it instantly accessible right at a piece of equipment as well as online. Coffin of Whole Foods said he believes that as technology evolves and the industry moves into natural refrigerants there will be even more opportunity for visibility from a safety perspective. “I think it is important that technology continues to evolve and provide visibility for energy management and load-side management of the systems that are being employed in any given facility,” he said. People expect to have visibility into whatever they may be managing at their fingertips and Coffin expects customer demand will only increase. “It started with email on your phone, now you can be 3,000 miles away from a facility but dial in and see exactly how it is operating,” he said. www.iiar.org

Packaged Components Promise Flexibility, Lower Install Costs

ackage systems are providing turn-key solutions for those within the refrigeration industry, and some manufacturers are turning to packaged components within those systems, which can cut down on the number of parts in use and make maintenance easier.

“Years ago, everything was basically custom, but today you’re seeing lots of people packaging equipment and some of that has packaged components. Look at a valve. It used to be you had to buy six to eight components for a valve group. The manufacturers have gotten that down to a convenient assembly.” –Bob Czarnecki, chairman of the IIAR standards committee and a retired refrigeration program manager at Campbell Soup Co.

“Years ago, everything was basically custom, but today you’re seeing lots of people packaging equipment and some of that has packaged components,” said Bob Czarnecki, chairman of the IIAR standards committee and a retired refrigeration program manwww.iiar.org

ager at Campbell Soup Co. “Look at a valve. It used to be you had to buy six to eight components for a valve group. The manufacturers have gotten that down to a convenient assembly.”

For example, some coils include valves and controllers. “You’re seeing other people do that as well,” Czarnecki said. “People are doing this mainly because the customers like it.”

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The World’s largest meeting dedicated to Natural Refrigeration MARCH 18–21 • COLORADO SPRINGS, CO

Exhibitor Registration Begins: • August 2017 for prior year sponsors • September 2017 for prior year exhibitors • October 2017 for all other IIAR conference exhibitors For more information about the 2018 IIAR Natural Refrigeration Conference & Expo or to find out how you can become a sponsor visit www.iiar.org/event.

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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Bruce Nelson, president of Colmac Coil, said Colmac is always looking for ways to add value to the customer. “As a heat-exchanger manufacturer, we are increasingly offering our customers control valves and controls that are incorporated into the heat exchangers themselves,” he said, adding that the company is also looking for ways to make systems more intelligent.

Danish equipment manufacturer Danfoss has taken a modular approach across its entire platform, including its valves, which creates a more compact and effective way of installing the valve station. “It is a natural fit for a package system, which has much more space constraints,” said Terry Chapp, North American business development manager for Danfoss.

“The end user is looking for something that is more complete that isn’t this custom thing they have to take care of. They’re looking for more flexibility and lower install costs and equipment that takes up less space. –Bob Czarnecki, chairman of the IIAR standards committee and a retired refrigeration program manager at Campbell Soup Co.

Colmac Coil’s Advanced Direct Expansion evaporator technology now uses more specific control valves that are more sophisticated than the traditional hand expansion valve. “There is a digital controller that monitors the evaporator performance and controls the expansion valve appropriately and reports what it is doing to the facility control system,” Nelson said. When Emerson Commercial & Residential Solutions, St. Louis, Mo., creates a package with the screw compressor, they also provide the motor to go with it. “We put this together and sell this compression package to a designbuild contractor or an OEM and they would add that to part of their larger architecture,” said Andre Patenaude, director of CO2 business development for Emerson Climate Technologies. Generally, Emerson will approach an OEM or a design-build contractor and explain that the company has electronic controllers that can be packaged up or married to the electronic expansion valve controls or the CO2 control. www.iiar.org

SIMPLIFIED MAINTENANCE

Maintenance is part of any refrigeration system. “Any piece of rotating equipment like a compressor or a fan or a pump has a normal maintenance schedule,” Nelson said. “All rotating equipment has a defined lifetime and even parts that don’t move like coils and condensers, have other maintenance issues that have to be addressed.” However, the modular approach makes repairs easier, Chapp said. “Historically when you had different components, you have to isolate them and pump down the refrigerant,” Chapp said. “With the valve station, there is much smaller internal volume and there is not as much liquid or gas to pump down and it is very easy to isolate which part has to be worked on.” Once it is pumped down, Chapp said, changing the module is as easy as removing four bolts, pulling out the module and replacing it. Patenaude said package systems use semi-hermetic compressors. Because

they are not fully hermetic, they can be serviced and repaired. “More and more techs today don’t spend as much time repairing. They tend to want to replace a component,” he said. Being able to easily swap out components could be beneficial given the aging workforce within the industrial refrigeration industry. “The ability to spend the time learning and mentoring in today’s environment is substantially reduced. You have to make it easier on the technician and the modular design makes it easy,” Chapp said. “If a guy can pull four bolts and replace it, it is easier to find someone properly trained to complete the work.” Depending on the system, the initial cost of packaged components could be higher, but Chapp said insulation costs could decrease because there is no need to create vapor barriers for every little piece. “You’re putting one piece on,” he said. Pump manufacturer Grundfos of Downers Grove, Ill., uses a variety of package components within its systems, including electrical panels, heat exchangers, control cabinets and variable frequency drives, said Doug Bolinger, national sales manager, industrial refrigeration for Grundfos. THE FUTURE OF PACKAGE SYSTEMS

Bolinger said package systems have several benefits, including being a onestop shop and coming with a complete package warranty. It also allows one manufacturer to handle order intake and complete an entire system, as well as provide technical support and service support going forward. Regulations related to the handling of ammonia in a facility are typically triggered by the amount of ammonia in a facility. “Package systems reduce regulatory burdens by reducing the ammonia charge in each of the systems. There is also some interest in package systems as a way to reduce installation time,” Nelson said. “The end user is looking for something that is more complete that isn’t this custom thing they have to take care of. They’re looking for more flexibility and lower install costs and equipment that takes up less space,” Czarnecki said.

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

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| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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hen a large food distribution facility was faced with major issues resulting from evaporator and condenser coils coated with dust, dirt, and production debris, it turned to EcoClear in Georgia and its deepcleaning system. The facility was looking to improve air flow, increase dehumidification, improve energy savings and reduce maintenance cost through a deep cleaning of the coils.

supply air temperatures and overall increase energy usage.” Simply put, properly cleaned evaporator coils will prevent food contamination, improve air flow and reduce operating costs. “We had an area that needed more air flow,” the food distribution facility’s refrigeration manager said. “The evaporator coils had frosted up. Initially, we had a mechanic clean them and we thought it was thoroughly done, but we couldn’t see deep enough into the coils.”

The process involves self-contained pressure-washing rigs that are designed to deliver a high volume of water hot enough for sanitation. (While being treated, units are taken off-line for a limited amount of time.) The technique employed is more important than the amount of pressure in order to avoid flattening the coil fins, causing a further reduction in the coil heat-transfer performance, and unknowingly pushing dirt deeper into the coil due to a lack of water volume. Coils with a layer of dust the thickness of a dime lose up to 21 percent in efficiency, because the coat of dust insulates the surfaces, thus reducing the cooling capacity. As reported by Tony Lundell, IIAR assistant technical director, in Condenser in June 2014, dirty evaporator coils “increase discharge head pressures, reduce compressor capacities, increase delivered www.iiar.org

CAS

Cleaner Coils Boost Cooling Capacity

D TU

coil heat-transfer performance, and unknowingly pushing dirt deeper into the coil due to a lack of water volume. Three employees worked on two five-foot-long evaporator coils, removing the fans from on top of the coils, removing the side panels, and then using biodegradable soaps and high-volume pressure washers to penetrate deep into the coils. “With a clean coil, the temperature drop across the coil is typically 10 to 15 degrees. This company had a threedegree drop, which meant 50 percent less air flow. That costs around $5,000 per unit in energy efficiency annually,” said Brian Hindt, EcoClear owner. That translates for a company that has 20 units to as much as $100,000 in energy savings. The company’s deep-cleaning system improved heat transfer and air flow, allowing the facility to reduce running time and maintain temperature. “It takes longer for the cleaning, about one full day, but it’s the right way to do it,” the facility’s refrigeration manager said. “They put some pressure on the coils and they got them clean. Just looking at the coil I can see more humidity being picked up out of the air, more condensation falling off the coils into the drain pans, and the coils definitely aren’t freezing. I can also tell that the air flow has increased.” EcoClear uses a proprietary software to estimate the cost savings produced by their complete cleaning and coatings. The cost of this process is typically covered in four to six months. “If you have a totally clean system you will reduce the running time on your compressor, and therefore reduce

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

the frequency of oil changes. You’re also not blowing foreign matter, which stops production and results in wasted product,” Hindt said. Following the deep cleaning, a proprietary disinfectant was applied that kills listeria, salmonella, E. coli to a log reduction of six. The company said its disinfectant is a registered EPA and NSF product. The unique blend provides many advantages to current market chemicals, including the ability to be applied in unconditioned space, is food-safe with no wipedown required, and does not have any VOCs. A specialized GreenScreen coating is then applied to the unit, which is onehalf to one micron thick. The GreenScreen protective coating is a photocatalyst of nanocrystals that acts as a “wetting agent” to help water run off in sheets, instead of typical beading that leaves spots. The coating forms a thin water film, which easily runs off, taking dirt, oils and contaminants with it. With less spotting, easier dirt release and oil removal, reduction in cleaning costs and faster evaporation, the coating provides superior heat transfer by inducing film flow and evaporation. Essentially, the coating prevents the surface from growing bacteria and does not allow anything to stick to it. Therefore, the coils will remain cleaner longer, which makes for easier future cleanings. The coating lasts, on average, one to two years. The deep cleaning resulted in an eight-degree temperature drop across the coil and increased air flow from 7,500 to 13,900 cubic feet per minute in one coil, and from 8,100 to 14,000 cfm in the second coil. In addition, the post-coil dry-bulb split went from five to 9.8 degrees in the first coil, for a 70 percent improvement, and from 4.8 to 10.7 degrees in the second coil, for a 100 percent improvement. “After the cleaning, we’re using less horsepower and fewer kilowatt hours to run the coil,” the refrigeration manager said. “The unit runs 40 percent less than before. This has made a big difference. We are able to maintain temperature much more easily.” 16

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IIAR Members Honored with Awards from Accelerate America

ccelerate America magazine honored five IIAR member companies for their work in advancing natural refrigerant adoption in North America as part of its second annual awards program. The awards were presented in June during the ATMOsphere America conference in San Diego The magazine, which is produced by shecco America, presented best-insector awards to: Whole Foods Market in the food retail, category; United States Cold Storage in the industrial category; and Nestlé in the foodservice category. Hillphoenix received the Innovation of the Year award for its AdvansorFlex transcritical carbon dioxide modular refrigeration system designed for small-format stores. “Congratulations are in order for all of these companies,” said IIAR

www.iiar.org

President Dave Rule. “Their leadership in this industry — developing and engineering new methods of using natural refrigerants to replace HFCs — and their support of IIAR and Atmosphere America is having a real, positive environmental impact.” Whole Foods has been a leader in natural refrigerants, including CO2 and ammonia. The food retailer has transcritical CO2 systems at several locations and is testing ammonia-CO2. The company says its Whole Foods Market store in Santa Clara, California, has the most environmentallyadvanced grocery retail refrigeration system in the U.S. US Cold Storage provides temperature-controlled warehousing and transportation at 39 facilities across the country. In 2015, US Cold Storage installed its first ammonia-carbon dioxide refrigeration system and one of the first

in the industrial refrigeration industry. Hillphoenix, a provider of environmentally sustainable refrigeration systems, has created the AdvansorFlex CO2 refrigeration system as part of its evolving Advansor CO2 platform. The latest offering is designed to bring HFC-free refrigeration to small and medium-sized retailers. The Person of the Year award was presented to Paul Anderson, senior director of engineering for Target, which has installed propane stand-alone display cases in more than 580 stores. “Paul Anderson has been a leader at Target, first in making CO2 cascade systems a prototype for new stores, and then by installing propane cases on a national scale.” Anderson has been with Target since 2007. He also held positions with Eaton Corp., Taylor Industries and John Deer.

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

A DX ÂŽ Te c h n o l o g y f o r l o w c h a r g e a m m o n i a e v a p o r a t o r s : I n h e r e n t l y s a fe r t e c h n o l o g y | L e s s e x p e n s i v e to i n s t a l l E xc e l l e n t e v a p o r a to r p e r f o r m a n c e | R e d u c e d r e g u l a to r y r e q u i r e m e n t s

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| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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IIAR Remembers George Yoksas

eorge Yoksas was a long-time federal safety regulator, but he hated when red tape got in the way of solving issues. “He wanted to find solutions. He would say, ‘How can we make this work and have a meaningful impact?’ ” said Doug Reindl, a professor in the University of Wisconsin departments of Engineering Professional Development and Mechanical Engineering, and a founding director of the Industrial Refrigeration Consortium. “He was willing to think differently than someone who might look at a standard or regulation and say ‘It says this.’ He thought about what made sense.”

to transplant knowledge of ammonia refrigeration technologies into the agency through a web-delivered training program designed specifically for OSHA compliance personnel. “He worked his way up from a bootson-the-ground position to various management roles,” said Reindl, who taught a process safety management course with Yoksas at Wisconsin for 20 years. “He was familiar with OSHA standards and regulations, and he knew how to apply them. He was very involved when PSM was rolled out in 1992. “I knew immediately I was blessed when I had the opportunity to work with George. His passion and commitment to improving workplace safety was endless and inspiring. He was a master of both the subject matter he taught and

“I knew immediately I was blessed when I had the opportunity to work with George. His passion and commitment to improving workplace safety was endless and inspiring. He was a master of both the subject matter he taught and in the delivery of his message.” – Doug Reindl, professor in the University of Wisconsin departments of Engineering

Professional Development and Mechanical Engineering, and a founding director of the Industrial Refrigeration Consortium

Yoksas, who died at age 66 on June 5 in Darien, Ill., spent more than 40 years with the U.S. Occupational Safety and Health Administration, working in the safety and health field. He started with OSHA in 1975 as a safety specialist compliance officer and went on to serve as the area director in the Milwaukee office and as a Process Safety Management specialist for Region V. His duties included overseeing implementation of the PSM standard throughout the six states that make up OSHA Region V. He was one of OSHA’s leading experts on PSM and was closely involved in its application in ammonia refrigerated facilities. He was instrumental in working with IIAR www.iiar.org

in the delivery of his message.” Dave Rule, president of IIAR, remembers Yoksas as a compliance officer who was zealous about improving safety. “He was always very involved in making comments and suggestions on how we could improve our standards,” he said. “But he was always very reasonable. Some inspectors can be quick to make a citation of a little substance, but George didn’t approach it that way. He approached things logically, always for the best interest of the industry in trying to make things safe.” Yoksas worked closely with IIAR in the search to improve safety standards. “He was very appreciative of the work that the IIAR was doing and he

always wanted to be involved to help us in developing our standards,” Rule said. “He was very supportive of what we were doing. Besides being an allaround good guy, it was really nice to work with somebody who had the best interests of our industry at his core.” Yoksas took the time to learn about the ammonia refrigeration industry, Reindl said. “He wasn’t afraid to get involved in a specialized industry and learn more about the technology so that he could help end users be in compliance and also educate people in his own agency as to how they should look at that industry,” he said. “He learned a lot about ammonia refrigeration and was able to help people in OSHA understand that technology. Yoksas played a major role in OSHA’s creation of the Office of Chemical Process Safety Enforcement initiatives. “He recognized that ammonia is a specialized knowledge, and he was a key resource in helping field people understand how the technology works and how the standards should apply to that technology,” Reindl said. He was also a gifted instructor and presenter, Reindl said. “He was very engaging, people really liked his style. He had a little humor in there, all these things you wouldn’t think of from a so-called ‘stodgy regulator.’ He was very dynamic, and his depth of knowledge was wide and deep,” he said. Yoksas, a respected advisor and a mentor to many in the industry, regularly taught PSM-related courses at the OSHA Training Institute, and at the time of his passing he was a staff member with OSHA’s Office of Chemical Process Safety. Tributes posted to his online obituary detailed his many contributions to safety and how he impacted those in the industry. “He believed in safety, he enforced safety and he taught safety to all who would listen. He did all of this with a smile and with dignity,” one tribute read. “He will continue to save lives and make workplaces safer through all the compliance officers he has taught and assisted with PSM cases,” read another. Yoksas leaves his wife, Diana; two sons, Clay and Adam Yoksas; a sister, Dena (Jack) Kempf; and many nieces and nephews.

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

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| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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the CMP “reverse flow” by-pass line is necessary to manage liquid vaporization through the flow circuit. The CMP internal motor heat induction is more than five times that of the corresponding MDP magnetic drive coupling. Continuous-duty recirculation pumps (vs. intermittent transfer) represent a more significant impact on energy consumption. Motor full-loadamp ratings are one indication. However, the heat rise through a pump’s internal flow and cooling circuit is the primary determining factor. There are four heat induction sources common to both MDP and CMP systems: pump hydraulic efficiency and internal recirculation, which varies with operating point and pump efficiency; eddy current losses, factored by speed, grade of alloy and thickness; motor efficiency; and internal bushing friction, factored by speed. Heat induction sources unique to CMP include motor stator winding heat and motor armature/rotor slippage. Magnetic-drive pumps utilize standardized motors that are accessible without decommissioning and evacuating the pump of ammonia. Thus, the MDP pump and motor offer the ability for field repair. Lower operating speeds provide stable NPSH (Net Positive Suction Head), without flow restrictive inducers, with lower wear coefficients, and extended pump life cycles. “When operating a CMP at 3,600 rpm, NPSHa (Net Positive Suction Head Available) can be marginal [between the system suction head pressure and the pump’s Net Positive Suction Head Required],” Warrender said. “Operating with marginal NPSHa can affect pump life and potentially lead to vaporization and cavitation within the pump.” Operating at higher speeds may compromise the liquid film on the wearing surfaces. Compressed gases such as NH3 and CO2 have low viscosity and specific heat values, and can vaporize through the pump lubrication and cooling circuit, increasing wear on the shaft sleeves, journal and thrust-bearing surfaces. Additionally,

eal-less magnetic pumps, or mag-drive pumps, have become the preferred option for a variety of conditions in the ammonia refrigeration industry, mainly because they take the heat generated by the pump's electric motor out of the cooling process. Sealless magnetic-drive pumps (MDP) are equipped with totally enclosed fan-cooled (TEFC) motors, offering versatility for a variety of conditions in ammonia and carbon-dioxide refrigeration processes. Because the MDP avoids adding motor heat to the system's cooling load, the result can be significant energy savings. The other type of sealless pump is a cannedmotor pump (CMP), which is totally enclosed liquid-cooled (TELC). “The electrical motor on our magdrive pump is fan-cooled by ambient air temperature, so we’ve removed the internal motor heat from a cooling process,” says Joe Warrender, general manager of Warrender, Ltd, which has specialized in manufacturing sealless magnetic pumps for more than 30 years. “That is the primary source of heat, and adds to the overall heat load. Canned motor pumps must cool the electric motor windings with process liquid,” he said. “Another source of heat is the resistance to the magnetic field through static metallic barriers, with MDP rear casing or CMP isolation shell,” Warrender said. “As opposed to CMP’s electromagnetic field, the MDP has a permanent magnetic field in the drive coupling. Magnetic hysteresis losses from either type of field is reduced exponentially by lowering the rotational speeds.” A MDP rear casing with twice the wall thickness of a CMP, operating at 1,800 rpm, has comparable magnetic energy losses or resistance as the canned motor shell with the same metallurgy, operating at 3,600 rpm. Therefore, both canned-motor pumps and magnetic pumps generate eddy currents. However, the heat load of TELC canned-motor pump windings is based on motor stator heat, independent of pump speed. For example,

Sealless Pumps Reap Energy Savings

EFFICIE

bearing-wear coefficients drop exponentially with speed. CMP internal motor windings continue heating the liquid even after the pump stops. That means it may be necessary to operate continuously to avoid vapor-locking the pump, thus consuming excess energy. “We’ve developed a sealless transfer pump that will overcome the pressure in the highpressure receiver and transfer directly from a control pressure receiver or lower pressure vessel,” Warrender said. Ammonia transfer pumps have long caused issues for conventional pumps due to the risks of extremely low NPSH, potential entrained vapor and frequent on/off cycling. Pump life is severely diminished with low NPSH, while on/off cycling can lead to flashing and vapor locking. Steep pump performance curves, with higher rise to shut-off, accommodates varying head conditions for improved reliability. The rise to shutoff is the determined operating point before flow ceases and the pump is damaged – in other words, how much head pressure is generated before the pump reaches a shut-off condition. “NH3 vapor pressure and corresponding head conditions can vary with ambient temperature,” Warrender said. “Our mag-drive transfer pumps can generate very high head pressure that compensates for variations in discharge heads due to temperature fluctuation. We have two-stage and three-stage pumps. The three-stage pump can deliver liquid from the sidewalk to the sky deck of the John Hancock Tower in Chicago, which is 1,100 feet up.”

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

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| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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1. Understand the numerous codes and regulations associated with natural refrigerants.

Although ammonia is an outstanding solution for meat and poultry plants, dairies and packaged food manufacturers, partly because the system can be flexible and run at a different temperatures, operators should be prepared for greater regulatory oversight, including increased paperwork and documentation. They will be required to adhere to local building, mechanical and fire codes, and IIAR’s suite of standards (IIAR-2, 4, 5, 6, & 7). Federal guidelines will also require Process Safety Management and Risk Management programs for plants operating with 10,000 pounds or more of ammonia, and an Ammonia Refrigeration Managment program when operating below that figure. www.iiar.org

ith production of HCFC refrigerants ending in less than three years, food and beverage manufacturers who currently rely on R-22 are faced with some difficult choices. Although facilities can continue to use recycled, reclaimed or stockpiled R-22 past Jan. 1, 2020, there will come a time when the shift to lower global-warming-potential synthetic refrigerants or natural refrigerants, such as ammonia, is unavoidable. “Nobody really knows how fast the supply of R-22 will run out once production is stopped,” said Jim Adler, P.E. department manager of Refrigeration Engineering at Hixson Architecture & Engineering. “It could be five or 10 years, but you will run out of inventory eventually. This is a risk that facility owners must consider.” Adler listed five things operators should know when making the transition from R-22 to a natural refrigerant. Adler recently presented a Food Plant of the Future webinar titled, “Beyond R-22: Refrigeration Solutions for Tomorrow.”

M O C

MEN

R-22: Five Things to Know 2. Audit existing equipment.

Operators must understand what changes will be needed to the system and the equipment. Start with an equipment/system audit to document what type of systems and what materials of construction are presently used. Most HCFC systems are copper-based and are incompatible with ammonia, which requires carbon steel, stainless steel or aluminum. “You can’t just merge the two systems together,” Adler said. Some field-erected R-22 systems may be able to be converted to ammonia but seals, gaskets, control valves, and relief valves may need to be changed. In addition, it will be necessary to check the pressure ratings of the components to verify that they are suitable for an ammonia system. “The audit should be done by a professional, not your maintenance person,” Adler said. “That person needs to understand the implication of switching to a natural refrigerant so they know where to look to collect the data.” 3. Consider the cost.

Ammonia will be more expensive, at least at the outset. “You’re looking at welded steel pipe, which is more expensive, as well as more robust system components than some of the commercial-grade systems you can get with R-22,” Adler said. “Going natural isn’t the lowest first-cost option.” 4. Pay attention to training.

Employees must be fully trained on how to operate the system, on maintenance and on how to respond to a leak before the system is operational. Unlike R-22, ammonia is self-alarming and there is usually a zero-tolerance attitude regarding an ammonia leak. Operators must have an emergency response plan in place and a working relationship with local first responders. Adler said several things can be done to reduce the risks and the regulatory burden required for ammonia

ACTICE

systems. “You can design a lowcharge system that utilizes a secondary refrigerant like glycol or use a low-charge package system currently offered by several manufacturers. Work with your design professional to make the best choice.” 5. Think long term.

Ammonia typically operates at a lower kilowatt per ton, so it’s an energy saver. And it probably won’t be delisted by the EPA. “Ammonia is zero ODP and zero GWP and has been around and successfully used for over 100 years: It’s not going to be phased out,” Adler said. He emphasized that operators won’t be making the switch alone. There are many highly trained professionals in the ammonia refrigeration industry who are available to help make the transition from R-22. “The IIAR is there for support, along with a competent group of professional engineers, contractors, and safety pros who can help you get there,” Adler added. “In the end, it’s a matter of determining what meets your goals and what is best for your company,” Adler said. “Find out your leakage rates, how much R-22 you’re currently buying and how much you’re using. If you’re buying 25 to 30 percent each year, you have a problem. If you’re buying five to ten percent, you have a pretty tight system and maybe you can reclaim and reuse R-22 or have some stockpiled. Ultimately, though, that R-22 is going to be used up. We just don’t know how long it will take.”

A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

ARF

news

ARF to Create Industry Insulation Standards and Quality Control Guidelines While insulation is a critical element within refrigeration systems, there currently is no industry standard for installation or quality control of the installation, a gap that the Ammonia Refrigeration Foundation plans to address with a new research project. “Cold insulation systems are very finicky about how they are installed. Just like a cold beer on a hot humid day on your deck, water wants to condense from the air onto cold

“Cold insulation systems are very finicky about how they are installed. Just like a cold beer on a hot humid day on your deck, water wants to condense from the air onto cold surfaces.” – Jim Young, technical director for ITW Insulation Systems surfaces,” said Jim Young, technical director for ITW Insulation Systems. “Water is the enemy of insulation as it can cause corrosion, reduce the insulating ability, and even damage the insulation system. The key to a cold-pipe insulation system is designing it to keep water out. That is a tough thing to do, but it can be done with proper insulation system design and installation.” Because insulation is so critical, the Ammonia Refrigeration Foundation research project seeks to create instal24

lation guidelines for industrial refrigeration systems and a quality-assurance procedure for installation, which will help improve safety, economics, insulation system longevity, and process control. The project will focus on cold pipe, tank, and equipment insulation.

Dave Rule, president of the International Institute of Ammonia Refrigeration, said the insulation project was determined to be of importance to all IIAR members and there was interest in identifying the types of insulation systems that have worked best.

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| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

ARF

news

He said members are interested in which insulation is the most effective, particularly in protecting pipes from corrosion. They also want to know the most effective installation practices. “That has always been an ongoing concern. It is an important concern in running a plant, maintaining the system and making appropriate decisions when modifying a system,” Rule said. “When building a new system, it will help engineers make good, safe decisions on how to build their systems and

facturers have good installation guidelines, the industry lacks a good way of monitoring or controlling the installation of the insulation system,” he said. What’s more, best practices vary from contractor to contractor, Teale explained. Most insulation is done by insulation contractors, and Young said the guidelines will provide information to help companies monitor installation and be sure it is done following industry standards. Teale said that although manufac-

“The public will benefit from having insulation systems that provide safer, longer-lasting, and more energy-efficient system installations,” Teale said. “If the installation guidelines and quality assurance procedures are implemented at some future date, it will provide authorities having jurisdiction, inspectors and compliance officials criteria for inspections and approval of insulation systems.” – Eric Teale, director refrigeration engineering/food and beverage sales, Corval Group, Inc. install them for maximum service life.” Eric Teale, director refrigeration engineering/food and beverage sales for Corval Group Inc., said installation guidelines will allow all parties involved with installing insulation systems to speak a common language and have the same expectations for the finished product. Currently, insulation manufacturers offer proprietary guidelines, but those don’t provide the objectivity that an industry association can offer, Young said. “We realized that even if we as manu26

turers have created guidelines for how their specific products are to be used, they are not comprehensive on how to install the entirety of an insulation system. He added that the project is needed because end users, specifiers, inspectors and insulation contractors are left to rely on guidelines and procedures produced by insulation system material manufacturers. “These guidelines and procedures are often not specific to refrigeration systems and in certain instances are outdated or apply only for hot piping

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

systems where the heat flux is in the opposite direction as compared to refrigeration systems,” he said. The guidelines and procedures currently available are also incomplete in how they address such things as insulation joints, vapor retarder/barrier joints and insulation systems, Teale said. “It is at these joints and terminations that the insulation system is most susceptible to failures due to expansion and contraction forces and mechanical damage,” he said. “One of the end results is that the insulation thickness is increased by specifiers to decrease the heat flux into the insulation system giving false hope that this will prevent joints from failing and allowing moisture infiltration into the insulation system.” Teale said insulation systems installed in accordance with the industry guidelines arising from this research will increase their longevity and performance. He said there will also be economic benefits due to facility owners, specifiers, material manufacturers and contractors not having to produce their own installation guidelines and quality-assurance procedures. “The public will benefit from having insulation systems that provide safer, longer-lasting, and more energyefficient system installations,” Teale said. “If the installation guidelines and quality assurance procedures are implemented at some future date, it will provide authorities having jurisdiction, inspectors and compliance officials criteria for inspections and approval of insulation systems.” IIAR and the Ammonia Refrigeration Foundation have been looking at the project for several years, and it was funded in late 2016. Young solicited project monitoring subcommittee members during the spring IIAR meeting and said he expects to begin holding meetings this summer. Young said the project will take two to three years to complete, and it will focus on compiling data and interviewing industry experts. “This is a bit of an unusual project in that it won’t include any experimentation,” Young said. www.iiar.org

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

RETA, IIAR Develop CO2 Training Materials As hydrofluorocarbons and hydrochlorofluorocarbons are being phased out, there is a growing emphasis on natural refrigerants. To help improve safety and educate those within the industry, IIAR and the Refrigerating Engineers and Technicians Association are working to create safety standards and develop educational materials

skilled technicians and operators will increase. This need can be somewhat filled by on-the-job training, but additional methods will be needed to fully address the job opportunities,” said Jim Price, education manager for RETA. “Those with training and certifications will be best prepared to take advantage of the opportunities.”

Dave Rule, president of IIAR, said ammonia and carbon dioxide are the most common natural refrigerants being used, and he is seeing more ammonia and CO2 being used together in cascade systems. “Because of that and because new technology has brought different types of equipment designs, both ammonia and CO2 are able to be used in places they wouldn’t have been before,” he explained.

Price said it will take about one year to produce the training materials, and RETA is halfway through the process. He anticipates multiple paths of study, including selfstudy, traditional brick-and-mortar classroom learning,

As a result, Rule said he is seeing an increased need for safety standards and technical training related to CO2. IIAR is addressing safety and is in the process of developing new standards. “We want to make sure the engineering and safety designs are correct, adequate and introduced to the industry in a timely manner. We also need to ensure the technicians and the engineers have the appropriate safety standards,” Rule said. IIAR offers a CO2 handbook and is in the process of updating it to make it more current, Rule said. “All of this surrounds the emphasis on natural refrigerants being used more prevalently,” he said. The Refrigerating Engineers and Technicians Association is developing new training materials jointly with members of the North American Sustainable Refrigeration Council on both commercial and industrial applications of CO2 as a refrigerant. “As CO2 becomes more accepted in both the commercial and industrial markets, the need for trained and 28

Although the common principles of refrigeration apply to CO2, there are some important differences that need to be understood. seminars and online learning. He said multiple certification opportunities will be available. “The paths may include general CO2 studies, commercial systems, industrial system and combined studies,” Price said, adding that the details of the study paths and certifications will be presented once the study material is closer to completion. Although the common principles of refrigeration apply to CO2, there are some important differences that need to be understood. “Pressures are different, much higher than we are used to seeing in typical ammonia refrigeration systems. New terms that are not familiar to us have to be learned and understood such as triple point, critical point, and transcritical,” Price said. In addition, simple tasks, such as system charging, system pump downs to opening the system, may have to be relearned. “In many ways RETA and IIAR are working together to address the more common use of CO2,” Rule said.

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

Trump Administration Advances Regulatory Reform

government

resident Trump made regulatory reform a priority during the campaign and pledged to provide industry relief from overly burdensome regulations.Since President Trump took office, he has initiated a number of actions to advance regulatory reform that will impact the industrial refrigeration industry.

RELATIONS BY LOWELL RANDEL, IIAR GOVERNMENT RELATIONS DIRECTOR

one new regulation issued, at least two prior regulations must be identified for elimination.The new policy applies to “major” regulations that have at least a $100 million annual impact. The order also calls for the reduction in costs of regulations and places a cap of zero dollars on new regulations for the remainder of fiscal year 2017. Any new incremental costs associated with

cies will be measured on their success in following the new policies. REGULATORY REFORM AND RMP FINAL RULE

The Environmental Protection Agency (EPA) completed it multi-year effort to revise the Risk Management Program (RMP) regulation with the publication of a Final Rule on Friday, January 13, 2017, just one week before President

INITIAL “FREEZE” ON REGULATIONS

On January 20th, White House Chief of Staff Reince Priebus issued a memo directing agencies to freeze activity on late term Obama regulations.The Memorandum asked departments and agencies to: • Send no regulations to the Federal Register until a department or agency head appointed or designated by the President after noon on January 20, 2017, reviews and approves the regulation. • For regulations that have been sent to the Federal Register, but not yet published, immediately withdraw them (subject to the exceptions described above and consistent with Federal Register procedures). • For regulations that have been published in the Federal Register but have not taken effect, temporarily postpone their effective date for 60 days for the purpose of reviewing questions of fact, law, and policy (and possible further review). • Regulations subject to statutory or judicial deadlines are excluded. EXECUTIVE ORDER 13771

On January 30, 2017, President Donald Trump signed an Executive Order entitled “Reducing Regulation and Controlling Regulatory Costs.” The action addresses a promise he made on the campaign trail to curtail the impact of federal regulations. The Executive Order institutes a policy that for every 30

Beginning in fiscal year 2018, each agency will be given a set budget for regulatory expenses. Agencies will be required to identify budget offsets for any regulation that is estimated to have increased costs in that fiscal year. new regulations in 2017 must be offset with the elimination of existing regulatory costs. Beginning in fiscal year 2018, each agency will be given a set budget for regulatory expenses. Agencies will be required to identify budget offsets for any regulation that is estimated to have increased costs in that fiscal year. EXECUTIVE ORDER 13777

President Trump followed his first Executive Order on regulatory reform with a second order that provides additional details on the process by which agencies should review regulations.Executive Order 13777 directs each agency to name a Regulatory Reform Officer and a Regulatory Reform Task Force. The task forces will identify outdated, unnecessary and ineffective regulations. Initial reports are due 90 days from the issuance of the order.The order includes an accountability mechanism, so agen-

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

Trump took office.The original effective date of the Final Rule was March 14, 2017.However, the Trump Administration put a “freeze” on all regulations finalized at the end of the Obama Administration.This included a delay of the RMP rule until March 21, 2017. In late February, a petition was filed by industry with EPA requesting a further delay in the effective date of the regulation.Administrator Scott Pruitt moved quickly to extend the effective date by an additional 90 days, to June 19, 2017. Pruitt also published a Proposed Rule that would make the effective date February 19, 2019. IIAR helped lead a coalition of industry groups in submitting comments supporting the delay until February 2019.The extended delay will give the new policy officials within the Trump Administration time to consider the www.iiar.org

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We take great pride in associating with these companies. We very much appreciate the fact they are a part of our organization, and we are honored they aspire to represent Frick Industrial Refrigeration. Our product is only as good as the people who design it, build it and install it. It’s not all about the machinery, it’s about the dedicated people who make and install our renowned equipment. Frick, the heart of industrial refrigeration for over 125 years. Buy with confidence, specify Frick.

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government

RELATIONS Trump Administration Advances Regulatory Reform

concerns that have been raised regarding the Final Rule and evaluate potential improvements to the regulation.The comment period for the Proposed Rule closed on May 19, 2017.EPA will now review the comments received and move forward with drafting a Final Rule regarding the revised effective date. IMPACTS ON OSHA AND DOL REGULATIONS

OSHA began the process of considering changes to the Process Safety Management (PSM) regulation during the Obama Administration, similar to EPA’s efforts to change RMP.OSHA’s rulemaking process generally takes longer that EPA, and the agency was not able to get to the Proposed Rule stage before the change in administrations.As a result, it is very unlikely that OSHA will advance its rulemaking efforts on PSM for the foreseeable future. In addition to halting rulemaking efforts on PSM, the Trump Administration has also taken action to stop or delay other OSHA regulations finalized late in the Obama Administration.On May 17, 2017, OSHA announced that it intends to extend the initial date by which certain employers are required to electronically submit their injury and illness logs.The Recordkeeping Rule currently requires certain employers to submit the information from their completed 2016 Form 300A to OSHA electronically by July 1, 2017. The extent of the delay is not known at this time, but the move signals that the new Administration shares some of the concerns raised by industry about the public posting of injury and illness logs. On May 23, 2017, the Department of Labor (DOL) sent a new proposed rulemaking to the White House Office of Management and Budget that would rescind the Obama administration’s persuader rule. The persuader rule altered the advice exemption under the Labor Management Reporting and Disclosure Act, effectively interfering with both employers’ access to legal advice on labor matters and attorney-client privilege.The new policy would effectively discourage employers from engaging with attorneys and other experts during the course of a union campaign.The 32

rule was permanently enjoined by a U.S. District Court in November 2016.The Trump Labor Department has decided not to appeal the ruling and is moving forward with rescinding the regulation. The Trump Administration has moved to officially withdraw a letter of interpretation issued by the Obama Administration In 2013 that granted union representatives permission to accompany OSHA inspectors on walk around

George W. Bush Administration.Congress has passed, and President Trump has signed, 14 CRA resolutions in 2017. Once such effort addressed an OSHA regulation known as the Volks Rule. The regulationthat would extend to five years the explicit six-month statute of limitations on recordkeeping violations in the Occupational Safety and Health (OSH) Act.The new policy was counter to the underlying statutory authority

The new policy direction should prove helpful in mitigating the impact of late term Obama regulations and slow the development of new regulatory burdens that may impact the industrial refrigeration industry. IIAR will continue to actively engage with new policy officials and like-minded industry partners as regulatory reform efforts move forward. inspections at non-union workplaces.The LOI was in response to a request from organized labor to change the original policy that stated employee representatives “shall be” employees of the employer unless third parties could provide specific expertise such as language interpretation or technical expertise.The LOI expanded this to include union representatives as identified by employees. The Trump Administration’s withdrawal came as part of a settlement arising from an industry challenge to the LOI. Congress has also been active in addressing regulations finalized late in the Obama Administration.The Congressional Review Act (CRA) give Congress the authority to disapprove of regulations within 60 legislative days of becoming final.Until 2017, the CRA was only used successfully once, to stop an OSHA ergonomics rule at the beginning of the

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

and went against multiple appeals court rulings on OSHA’s statute of limitations on recordkeeping violations.Congress successfully utilized the Congressional Review Act to disapprove of the regulation and President Trump signed the resolution into law. SUMMARY

President Trump’s actions to reform the regulatory process and walk back certain Obama regulations signal a significant shift in the regulatory climate. The new policy direction should prove helpful in mitigating the impact of late term Obama regulations and slow the development of new regulatory burdens that may impact the industrial refrigeration industry.IIAR will continue to actively engage with new policy officials and like-minded industry partners as regulatory reform efforts move forward. www.iiar.org

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

RENEW YOUR IIAR MEMBERSHIP TODAY! The strength of our organization lies in the intellectual leadership and collective voice of its members. As an active technical society, your participation is at the core of our work, and your role as a representative of this industry has never been more important. We encourage everyone to participate in IIAR on our various committees: CO2 | CODE | COMPLIANCE GUIDELINES | EDUCATION | GOVERNMENT RELATIONS INTERNATIONAL | MARKETING | PIPING | RESEARCH | SAFETY | STANDARDS If you would like to join an IIAR committee please email us at info@iiar.org and reference the committee of your choice. Great things are accomplished through the dedication of our members with regard to IIAR committee work. IIAR is committed to our mission to provide advocacy, education and standards for the benefit of the global community in the safe and sustainable design, installation and operation of ammonia and other natural refrigerant systems.

WHAT’S ON THE HORIZON … In the 2017 – 2018 member year IIAR will continue its work with the introduction of IIAR Standards 6 and 9 leading the way. Take a look at What’s on the Horizon for IIAR: • The online Learning Management System – Allows access to IIAR’s Academy of Natural Refrigeration education programs, IIAR videos, webinars, and IIAR major publications. • Updates to the Ammonia Refrigeration Manual – With a new Ammonia Refrigeration Manual for low charge systems • Development of online resources addressing the unique challenges that End Users face • Expansion of our international presence – Including the development of the Spanish Language website • The Completion of Series 1 – Basic Ammonia Refrigeration – Module 9: Vessels (Video & Workbook) • New Certificate Program – IIAR Standards 4/5/8 • Update to Piping Handbook • Update to CO2 Handbook

WHEN YOU BELONG TO THE IIAR COMMUNITY…

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

YOUR www.iiar.org

Log on to www.iiar.org with your username and password, click My IIAR, then click the Renew Now button. IIAR MEMBER BENEFITS IIAR eLibrary, Member App and Online Resources The most comprehensive on-line resource of ammonia and natural refrigeration technical publications at your fingertips! • Free online access to IIAR Bulletins • Free online access to IIAR Standards • Free online access to the Ammonia Data Book • And, Free online access to more than 400 Technical Papers. IIAR Publications Discounts IIAR members receive significant discounts on popular industry publications: • Ammonia Refrigeration Piping Handbook • Process Safety Management and Risk Management Program Guidelines • Carbon Dioxide Industrial Refrigeration Handbook • IIAR Safety and Training Videos, and more… IIAR Communications The Condenser, a quarterly magazine and the IIAR Connect, delivered digitally each month contain: • Technical Updates and New Industry Information • Regulatory Issues and Code & Standards Revisions • IIAR and Other Association News

IIAR Conference Registration & Exhibitor Discounts • The IIAR annual conference attracts over 1,700 industry professionals worldwide – Only IIAR members receive a discounted conference rate on attendance • The IIAR conference offers career and professional development through technical presentations and workshop participation. IIAR On-Line Membership Directory & Member App • IIAR members can connect and network with industry professionals throughout the world. IIAR Education Programs • Discounted prices on IIAR Certificate Courses • Access to the Academy of Natural Refrigerants learning resources • Access to monthly IIAR Member Webinars

Download the IIAR App at the Google Play Store or the Apple App Store. Access your member benefits at the touch of your fingertip…

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

From fundamentals of design to startup and operation as it applies to industrial applications, the all new CO2 HANDBOOK is a must-have technical resource for industrial refrigeration professionals worldwide.

Order your copy today at www.iiar.org 36

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

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PARALLEL OPERATION OF SCREW COMPRESSOR PACKS B. PIJNENBURG AND J. RITMANN BITZER KÜHLMASCHINENBAU GMBH, JENS JUULS VEJ 16, 8260 VIBY J. AARHUS, DK E-MAIL: BAS.PIJNENBURG@BITZER.DE, JOHN.RITMANN@BITZER.DE

ABSTRACT Ammonia screw compressor packs utilizing parallel operation of two or three smaller industrial NH3 screw compressors offer the optimum way to fulfill maximum part load efficiency, increased redundancy, and other highly desirable features in the industrial refrigeration industry. Optimized parallel operation can secure continuous operation and can in most applications be configured to improve overall operating economy. New compressors have been developed to meet requirements for flexibility in operation and have intelligent controls. The intelligent control system must focus on all external demands and strive toOperation offer always theCompressor lowest possible Parallel of Screw Packs absorbed power, including future scenarios with conParallel Operation of Screw Compressor Packs nection to smart grid. This paper builds on and includes most of the results of an earlier investigation to of Screw Compressor Packs showParallel how toOperation implement a series of compressor packs following basically the results of these findings.

Introduction Introduction Introduction Ammonia Ammonia compressor compressor packs packs are are typically typically equipped equipped with with one one or or more more compressors. compressors. Figure 1 shows an example of a two-compressor pack. The compressors can Ammonia compressor packsofare typically equipped with one or more compressors. Figure 1 shows an example a two-compressor pack. The compressors can be be equipped with variable speed drive (VSD). A study about parallel operation of Figure 1 shows an example of drive a two-compressor pack. Theparallel compressors can of bescrew equipped with variable speed (VSD). A study about operation screw compressors for industrial ammonia refrigeration describes the optimum way of equipped with speed drive (VSD). A study about parallel operation compressors forvariable industrial ammonia refrigeration describes the optimum wayofofscrew configuring packs with multiple compressors (Pijnenburg and Ritmann 2015). The compressors for industrial ammonia refrigeration describesand theRitmann optimum2015). way of configuring packs with multiple compressors (Pijnenburg The findings from this study define the overall design criteria for highest possible partconfiguring packs compressors (Pijnenburg andhighest Ritmann 2015).partThe findings from this with studymultiple define the overall design criteria for possible load efficiency over a wide range of capacity. The first part of this article analyzes findings from this define theofoverall design forofhighest possible partload efficiency overstudy a wide range capacity. The criteria first part this article analyzes that study, including different methods capacity method load same efficiency over a wide the range of capacity. Theof part ofregulation, this articlethe analyzes that same study, including the different methods offirst capacity regulation, the method for evaluating total efficiency, and the comparison between different numbers of that same study, including theand different methods ofbetween capacitydifferent regulation, the method for evaluating total efficiency, the comparison numbers of parallel operating compressors. for evaluating totalcompressors. efficiency, and the comparison between different numbers of parallel operating parallel operating compressors. Maintaining Maintaining high high efficiency efficiency is is one one of of the the most most important important criteria criteria for for industrial industrial refrigeration customers. Operational safety and reliability are other important Maintaining efficiency is one of safety the most forimportant industrial criteria refrigeration high customers. Operational andimportant reliability criteria are other criteria that emphasize the need for a certain amount of redundancy. Often the customers’ refrigeration customers. andofreliability are other criteria that emphasize the needOperational for a certainsafety amount redundancy. Oftenimportant the customers’ products or output from processes are far more expensive than the additional cost that emphasize the from need processes for a certain redundancy. the customers’ products or output areamount far moreofexpensive thanOften the additional cost of securing proper back-up of their cooling system. Packs with multiple compressors products or proper output back-up from processes far more expensive than multiple the additional cost of securing of theirare cooling system. Packs with compressors offer high redundancy, in terms of having more smaller compressors and drive of securing proper back-up of their coolingmore system. Packs with multiple offer high redundancy, in terms of having smaller compressors andcompressors drive systems, thereby ensuring that the unit can continue to deliver cooling capacity, offer highthereby redundancy, in terms of having smaller compressors and drive even systems, ensuring that the unit canmore continue to deliver cooling capacity, even during planned service or unforeseen repair in case of failures. Naturally, maximum systems, therebyservice ensuring that the unitrepair can continue deliver cooling capacity, even during planned or unforeseen in case oftofailures. Naturally, maximum up-time and stops have in industrial during planned service unintended or unforeseen repair in high case priority of failures. Naturally, maximum up-time and minimum minimum unintended stops have high priority in the the industrial refrigeration system. This paper describes some of these requested redundancy up-time and minimum unintended stops have priority in the industrial refrigeration system. This paper describes somehigh of these requested redundancy features. refrigeration system. This paper describes some of these requested redundancy features. features. A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER A A dedicated dedicated control control system system is is needed needed to to fully fully utilize utilize the the advantage advantage of of parallel parallel operation, both regarding efficiency and redundancy. The control system shall ensure

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during planned service or unforeseen repair in case of failures. Naturally, maximum up-time and minimum unintended stops have high priority in the industrial PARALLEL OPERATION OF SCREW PACKSsome of these requested redundancy refrigeration system. This COMPRESSOR paper describes features. 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX

A dedicated control system is needed to fully utilize the advantage of parallel 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX operation, both regarding efficiency and redundancy. The control system shall ensure 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX maximum efficiency and reliability, when& operating inside and even 2017 IIARoperational Natural Refrigeration Equipment San Antonio, TX absorbed power, including the future abilityConference to respondHeavy to smart gridsExpo, or variations of outside the compressor application limits, into the whole to capacity range.orThe control of absorbed power, including the future ability respond smart grids variations the electricity pricing during night and day. system must focus onduring all external demands, yetrespond strive totooffer thegrids lowest possible of the electricity pricing night andability day. to absorbed power, including the future smart or variations absorbed power, including the future the electricity pricing during night andability day. to respond to smart grids or variations of absorbed power, including the future ability to respond to smart grids or variations of the electricity pricing during night and day. the electricity pricing during night and day. | | |Technical Paper #3 | |

Figure 1. Example of a screw compressor package with two compressors. Figure 1. Example of a screw compressor package with two compressors. Figure 1. Example of a screw compressor package with two compressors. Figure 1. Example of a screw compressor package with two compressors. Common Methods Requirements Capacity Figure 1. Example of a screwand compressor package with for two compressors.

Control Systems Common Methods and Requirements for Capacity Control Systems Common Methods and Requirements for Capacity Control Systems Different methods exist to control the capacity of a compressor system. The quality of Different methods exist and to control the capacity for of a Capacity compressorControl system. The quality of Common Methods Requirements Systems the capacityMethods control systems be measured with different parameters: Common and can Requirements for Capacity Control Systems the capacity controlexist systems can be measured different parameters: Different methods to control the capacity with of a compressor system. The quality of • The ability to adapt the capacity to the cooling demand accurately, i.e., how well • The ability to adapt the capacity tocapacity the cooling wellof Different methods exist to control the of a demand compressor system.i.e., Thehow quality the capacity control systems can be measured with differentaccurately, parameters: a certain suction pressure set point can be followed; Different methods exist to control the capacity of a compressor system. The quality of acapacity certain suction pressure set be point can cooling be followed; control systems can measured withdemand differentaccurately, parameters: •the The ability to adapt the capacity to the i.e., how well • The influence onsystems the efficiency the compressor and theparameters: drive line, i.e., how the capacity control can beofmeasured with different influence on pressure thethe efficiency oftothe and the drive line,i.e., i.e.,how howwell • aThe ability to adapt capacity the cooling demand accurately, certain suction set point cancompressor be followed; much the coefficient of performance (COP) of the systemaccurately, is affected; • The ability to adapt the capacity to the cooling demand i.e., how well thesuction coefficient performance (COP) of the and system affected; amuch certain set point can be followed; • The influence on pressure the of efficiency of the compressor the isdrive line, i.e., how • aThe requirements of and load on thecan power supply; certain suction pressure set point be followed; requirements of and load on power supply; • much The influence on the efficiency ofthe the(COP) compressor the isdrive line, i.e., how the coefficient of performance of the and system affected; • The influence possibilityon to the cover a large capacity range between minimum andi.e., maximum efficiency of the compressor and the drive line, how possibility to cover a load largeon capacity range between minimum and maximum muchrequirements the coefficient of performance of the system is affected; • The of and the (COP) power supply; load; the coefficient of performance (COP) of the system is affected; much load;possibility requirements of anda load the power supply; • The to cover largeon capacity range between minimum and maximum • The requirements cost of the capacity of andcontrol load onsystem; the power supply; cost of the to capacity system; range between minimum and maximum • load; The possibility cover acontrol large capacity Operational reliability; • The possibility to coverand a large capacity range between minimum and maximum Operational reliability; load; • The cost of the capacityand control system; • load; Noise and vibration levels. Noisecost andofvibration levels. The the capacity control system; • Operational reliability; and • The cost of the capacity control system; Operational reliability; and • Noise and vibration levels. • Operational reliability; and • Noise and vibration levels. • Noise and vibration levels. 4 4 38

| CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration

Technical Paper #3 Technical Paper #3 Technical Paper #3

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Parallel Operation of Screw Compressor Packs Parallel Operation of Screw Compressor Packs Parallel Operation of Screw Compressor Packs Parallel Operation Screw Compressor Packsdescription BITZER (2014)ofprovides a thorough

of different methods of controlling the BITZER (2014) provides a thorough description of methods different used methods of analysis controlling the capacity of a compressor system. Here only those in the later BITZER (2014) provides asystem. thorough description of methods different used methods of analysis controlling the capacity of a compressor Here only those in the later in this article are briefly adescribed: BITZER (2014) provides thorough description of different methods of controlling the capacity of a compressor system. Here only those methods used in the analysis later in this article are briefly adescribed: (2014) provides thorough description of different methods of controlling the •BITZER On/off cycling, capacity of a compressor system. Here only those in the later BITZER (2014) provides thorough description of methods different used methods of analysis controlling the this article are briefly adescribed: •in On/off cycling, of a compressor system. Here only those methods used in the analysis later •capacity Speed variation (variable speed drive), and in article are briefly described: capacity ofcycling, a compressor system. Here only those methods used in the analysis later •• this On/off Speed variation (variable speed drive), and this article are briefly described: •in Slide valve regulation. •in On/off cycling, this article are briefly described: Speedvalve variation (variable speed drive), and ••• Slide regulation. cycling, •• On/off Speed variation (variable speed drive), and On/off cycling, Slide valve regulation. •• Speed variation (variable drive), and The first two methods are notspeed incorporated in the compressor itself, but concern how Slide regulation. Speedvalve variation (variable speed drive), and The first two methods are not incorporated in theconstruction compressor inside itself, but how • operate Slide valve regulation. to it. The last method requires a specific the concern compressor. •TheSlide valve regulation. first two methods are not requires incorporated in theconstruction compressor inside itself, but how to operate it. The last method a specific the concern compressor. The first method offers stepwise control, whereas the other two methods enable The first two methods are not requires incorporated in theconstruction compressor inside itself, but how to operate it. The last method a specific the concern compressor. The first method offers stepwise control, whereas the other briefly two methods enable how The first two methods are not incorporated in the compressor itself, but concern continuous variation of capacity. Each method is described in the following to operate it. The last method a specific inside the concern compressor. The first methods are not requires incorporated in theconstruction compressor itself, but The first two method offers stepwise control, whereas the other briefly two methods enable how continuous variation of capacity. Each method is construction described inthe the following to operate it. The last method requires specific inside compressor. sections, but Blumhardt (2006) details a comparative study on speed and capacity The first method stepwise control, whereas the other briefly two methods enable to operate it.variation The offers lastof method requires a specific inside compressor. continuous capacity. Each method is construction described inthe the following sections, but Blumhardt (2006) details a comparative study on speed and capacity The first method offers stepwise control, whereas the other briefly two methods enable slide control for screw compressors continuous variation of capacity. Each method is described in the following The first method offers stepwise control, whereas the other two methods enable sections, but for Blumhardt (2006) details a comparative study on speed and capacity slide control screwofcompressors continuous variation capacity. Each method is described in the sections, butvariation Blumhardt (2006) details a comparative study briefly on speed andfollowing capacity continuous capacity. Each method is described briefly in the following slide control for screwofcompressors sections, but Blumhardt (2006) details a comparative study on speed and capacity slide control screw compressors sections, but for Blumhardt (2006) details a comparative study on speed and capacity On/off cycling slide control screw compressors On/off cyclingfor slide control for screw compressors On/off cycling On/off cycling is the simplest way to vary capacity. In simple systems, it can lead On/off cycling On/off cycling is the simplest way to vary capacity. In simple systems, it cansense lead On/off to largecycling variation in operating condition and high cycling rates. It can make On/off cycling On/off cycling is the simplest way to vary capacity. In simple systems, it cansense lead to large variation in operating condition and high cycling rates. It canThe make on systems with small load variation or large system buffer capacity. ability On/off cycling is the simplest way to vary capacity. In simple systems, it can leadto to large variation in operating condition and high cycling rates. It canThe make sense on systems with small load variation or large system buffer capacity. ability On/off cycling is the simplest way vary capacity. In simple itofcan leadto regulate capacity precisely with thisto method improves with thesystems, amount parallel to large variation in operating condition and high cycling rates. It can make sense On/off cycling is the simplest way to vary capacity. In simple systems, it can leadto on systems with small loadwith variation or largeimproves system buffer capacity. Theofability regulate capacity precisely this method with the amount parallel to large variation in operating condition and high cycling rates. It can make sense mounted compressors. on systems with small loadwith variation or large system buffer capacity. to large variation in operating condition and improves high cycling rates. It canThe make senseto regulate capacity precisely this method with the amount ofability parallel mounted compressors. on systems with small loadwith variation or largeimproves system buffer capacity. Theofability to regulate capacity precisely this method with the amount parallel on systems with small load variation or large system buffer capacity. The ability to mounted compressors. regulate capacity precisely with this method improves with the amount of parallel mounted compressors. regulate capacity precisely with this method improves with the amount of parallel Speed regulation mounted compressors. Speed regulation mounted compressors. Speed regulation The flow through the compressor varies with the rotational speed of the rotors. The Speed regulation The flow throughscrew the compressor varies with the rotational speed of Expo, rotors. TheTX 2017 IIAR Natural Refrigeration Conference &drive Heavy line Equipment San In Antonio, Speed regulation speed-regulated compressor requires a specific with athe VSD. most 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, Speed regulation The flow throughscrew the compressor varies with the rotational speed of athe rotors. TheTX speed-regulated compressor requires achanges specific drive line with VSD. Inbut most cases the speed regulation does not require to the compressor itself, it The flow throughscrew the compressor varies with the rotational speed of athe rotors. The speed-regulated compressor requires achanges specific drive line with VSD. Inbut most cases the speed regulation does not require to the compressor itself, it The flow the compressor varies with the rotational speed of athe rotors. The affects thethrough way the compressor operates. speed-regulated screw compressor requires a specific drive line with VSD. In most The flow through the compressor varies with the rotational speed of the rotors. The cases the regulation does operates. not require changes to the compressor itself, but it affects thespeed way the compressor speed-regulated screw compressor specifictodrive line with a VSD. most Slide valve regulation cases the speed regulation does operates. notrequires require aachanges the compressor itself,In it speed-regulated screw compressor requires specific drive line with a VSD. Inbut most affects the way the compressor Slide valve regulation cases the speed regulation does not require changes to the compressor itself, but it affectsthe thespeed way the compressor cases regulation does operates. not require changes to the compressor itself, but it affects way the compressor A slide the valve parallel to the rotoroperates. shaft can be moved to create an internal bypass. affects the way the compressor operates. A slide valve parallel to the rotor shaft can be moved to create an internal bypass. Just before the gas is compressed in the rotor cavities, it can bypass internally to Just before the gas is compressed in the rotor cavities, it can bypass internally to the suction side. The slide valve system makes a fairly simple and robust system for the suction side. The slide valve system makes fairly simple and robust system for Technical Paper #3 © IIARa2017 both stepwise and step-less variation of capacity. The slide valve regulation will also Technical Paper #3 © IIAR 2017 both stepwise and step-less variation of capacity. The slide valve regulation will also affect thePaper volume Technical #3 ratio (VI) of the compressor. © IIARThe 2017influence on VI depends on the affect the volume ratio (VI) of the compressor. The influence on VI depends on the TechnicalofPaper © conditions. IIAR 2017 design the #3 compressor and the operating Some compressor designs are design the #3 compressor and the operating Some compressor designs are TechnicalofPaper © conditions. IIAR 2017 capable independent regulation of capacity and VI. Technical of Paper #3 © IIAR 2017 capable of independent regulation of capacity and VI.

5 5 5 5 5 5

The variation of capacity can influence both the volumetric and isentropic efficiency The variation of capacity can influence both the volumetric and isentropic efficiency of the compressor. How much efficiencies are affected differs for each method and www.iiar.org A Publication of the International Institute of Ammonia of the compressor. How much efficiencies are affected differs for each Refrigeration method| June and2017 | CONDENSER also depends on the operating conditions and the construction of the compressor. also depends on the operating conditions and the construction of the compressor.

design of the compressor and the operating conditions. Some compressor designs are capable independent regulation of capacity and affect theofvolume ratio (VI) of the compressor. TheVI. influence on VI depends on the capable of independent regulation of capacity and VI. design of the compressor and the operating conditions. Some compressor designs are PARALLEL OPERATION OF SCREW COMPRESSOR PACKS The variation of capacityregulation can influence both the volumetric and isentropic efficiency capable of independent of capacity and VI. The variation of capacity can influence both the volumetric and isentropic efficiency of the compressor. How much efficiencies are affected differs for each method and of the compressor. How much efficiencies are affected differs for each method and also variation depends on the operating conditions andthe thevolumetric construction the compressor. The of capacity can influence both andofisentropic efficiency also depends on the operating conditions and the construction of the compressor. Volumetric efficiency relates toefficiencies actual swept this article themethod term part load of the compressor. How much arevolume. affectedIndiffers for each and Volumetric efficiency relates to actual swept volume. In this article the term part load indexdepends (λ) is used to indicate theconditions ratio between actual volume flow (at compressor. a certain load) also on the operating and the construction of the index (λ) is used to indicate the ratio between actual volume flow (at a certain load) and the nominal swept volume at maximum capacityIn (full capacity Volumetric efficiency relates to actual swept volume. thisload). articleVariation the termofpart load and the nominal swept volume at maximum capacity (full load). Variation of capacity will also efficiency of thebetween drive line (motor and or VSD). index (λ)influence is used tothe indicate the ratio actual volume flow (at a certain load) will also influence the efficiency of the drive line (motor and or VSD). and the nominal swept volume at maximum capacity (full load). Variation of capacity will also influence the efficiency of the drive line (motor and or VSD).

Description of Efficiency of Capacity Control Methods Description of Efficiency of Capacity Control Methods

6 6 6

The efficiency of compressor, motor, and the VSD can each be expressed as Description ofthe Efficiency of the Capacity Control Methods The efficiency of the compressor, the motor, and the VSD can each be expressed as a function of some form of capacity (not necessarily the system cooling capacity). a function of some form of capacity (not necessarily the system cooling capacity). These efficiency also called performance data, expressed in theas The efficiency of data, the compressor, the motor, and the are VSDtypically can each be expressed These efficiency data, also called performance data, are typically expressed in the of graphs, tables, functions. The the totalsystem efficiency of the system can aform function of some formorofpolynomial capacity (not necessarily cooling capacity). form of graphs, tables, or polynomial functions. The total efficiency of the system can be obtained by coupling thecalled performance data data, of different components in series and/ These efficiency data, also performance are typically expressed in the be obtained by coupling the performance data of different components in series and/ or in parallel. The relation between cooling capacity efficiency cannot can be form of graphs, tables, or polynomial functions. The and totalsystem efficiency of the system or in parallel. The relation between cooling capacity and system efficiency cannot be obtained directly fromCompressor the supplied but components requires some be obtained byofcoupling the performance data of data, different incalculation. series and/ Parallel Operation Screw Packsperformance obtained directly from the supplied performance data, but requires some calculation. Theinrelation depend on thecooling operation condition the system (evaporating or parallel.will Thealso relation between capacity and of system efficiency cannot be The relation will also depend on the operation condition of the system (evaporating and condensing obtained directlytemperatures). from the supplied performance data, but requires some calculation. and condensing temperatures). The relation will also depend on the operation condition of the system (evaporating Figure 2 shows typical dependencies of the compressor part load index (λ) and and condensing temperatures). isentropic efficiency (ηc) for a typical chiller condition (T0/Tc = +5/+35 °C / +41/95 °F). The left figure shows the efficiencies as a function of capacity slide valve position (CR), and the right figure shows them depending on compressor shaft © IIAR 2017 Technical Paper #3 speed. The software to calculate compressor contains © IIAR 2017 performance (BITZER 2016) Technical Paper #3 data based on extensive measurements with different compressor models over the © IIAR 2017 Technical Paper #3 whole range of operating conditions, shaft speeds, and capacity slide positions.

Figure 2. Example of compressor performance data curves.

Figure 3 shows a typical dependency of motor (ηm) and drive efficiency (ηd), depending on the ratio of shaft torque to nominal motor torque (T/Tn), for three different shaft speeds (1,200; 2,400; and 3,600 rpm). Motor and drive data are 40 | CONDENSER | June 2017 | A Publication of the International Institute of Ammonia Refrigeration calculated with software from a major global supplier of motors and variable

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Figure 2. Example of compressor performance data curves. Figure 2. Example of compressor performance data curves.

Figure 3 shows a typical dependency of motor (ηm) and drive efficiency (ηd), Figure 3 shows a typical (ηm)motor and drive efficiency (ηd), depending on the ratio ofdependency shaft torqueoftomotor nominal torque (T/Tn), for three depending on the ratio of shaft torque to nominal motor torque (T/T ), for three different shaft speeds (1,200; 2,400; and 3,600 rpm). Motor and driven data are different (1,200; and 3,600supplier rpm). Motor and drive data are calculatedshaft withspeeds software from2,400; a major global of motors and variable calculated with software from a major global supplier of motors and variable speed drives. speed drives.

2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX Figure 3. Example of motor and drive performance data curves. Figure 3. Example of motor and drive performance data curves.

The graphs show that cooling capacity is not mentioned directly. It must be derived The graphs show that cooling capacity is not mentioned directly. It must be derived from the performance data and the actual operating conditions of the system. from the performance data and the actual operating conditions of the system. The capacity regulation systems can have©other positive or negative effects on system Technical Paper #3 IIAR 2017 The capacity regulation systems can have other positive or negative effects on system Technical Paper #3 © IIAR 2017 performance, other than on energetic efficiency. Some of these effects include performance, other than on energetic efficiency. Some of these effects include • Potential for increased capacity with operation at speeds above synchronous with • Potential for increased capacity with operation at speeds above synchronous with VSD. VSD. • Built-in soft-start function in the VSD resulting in low motor and power supply • Built-in soft-start function in the VSD resulting in low motor and power supply load at start-up. load at start-up. • Positive displacement compressors that require practically constant torque over • Positive displacement compressors that require practically constant torque over the complete speed range. Therefore voltage vs. frequency ratio of the VSD must the complete speed range. Therefore voltage vs. frequency ratio of the VSD must be constant. A VSD can normally not supply voltages above the supply voltage, be constant. A VSD can normally not supply voltages above the supply voltage, which means that the motor will be supplied with “under-voltage” during which means that the motor will be supplied with “under-voltage” during operation above synchronous speed. This means it cannot supply the full torque, operation above synchronous speed. This means it cannot supply the full torque, limiting the possible operating conditions of the compressor in this speed range. limiting the possible operating conditions of the compressor in this speed range. • Operation with economizer that can be utilized for a large capacity range with • Operation with economizer that can be utilized for a large capacity range with speed regulation for most compressor designs. The economizer port is normally speed regulation for most compressor designs. The economizer port is normally closed very early in the unloading process on compressors with slide valve closed very early in the unloading process on compressors with slide valve regulation in combination with a fixed economizer port. regulation in combination with a fixed economizer port. • Parallel compounding, which will require smaller compressors to deliver the same • Parallel compounding, which will require smaller compressors to deliver the same maximum capacity. maximum capacity. • Compressor, motor, and drive efficiency that will increase to some degree with • Compressor, motor, and drive efficiency that will increase to some degree with size. size. • Parallel compounding that automatically gives redundancy. • Parallel compounding that automatically gives redundancy. • Complexity of systems that increases with the number of compressors and • Complexity of systems that increases with the number of compressors and combination of different regulation systems. combination of different regulation systems. www.iiar.org

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Parallel Operation of Screw Compressor Packs

PARALLEL OPERATION OF SCREW COMPRESSOR PACKS

Method of Part Load Efficiency Evaluation The part load efficiency of a compressor system can be evaluated based on the performance data of the components and the equations described in this section. The definitions and units for each symbol used in this section are listed in the nomenclature at the end of this paper. Equation (1) defines the cooling capacity that a screw compressor can deliver: (1) Equation (2) defines the shaft power of a screw compressor: (2) Equation (3) defines the electrical power consumption of the screw compressor package: (3) Equation (4) defines the COP of the screw compressor package: (4) Plotting the COP as a function of the cooling capacity ( ) is the traditional way to evaluate the part load performance. The previous equations show that for a certain operating condition and for a certain size of compressor system, a linear relation exists between the cooling capacity and the part load index (λ) and between the COP and the energetic efficiency (η). By showing the energetic efficiency as a function of the part load index we have a way to show the part load performance 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX on a dimensionless scale from 0 to 1, which makes it easy to compare for different operating conditions and different sizes of systems. The total part load index and energetic efficiency for a compressor package with multiple compressors can be found from the weighted sum of the individual efficiencies according to Equation (5) and©Equation Technical Paper #3 IIAR 2017 (6).

(5) 42

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(6)

The total part load index and energetic efficiency for a compressor package with multiple compressors can be found from the weighted sum of the individual efficiencies according to Equation (5) and Equation (6). (5) 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX

(6) The total part load index and energetic efficiency for a compressor package with multiple compressors can be found from the weighted sum of the individual The performance datatocurves (Figure 2) show that part efficiencies according Equation (5) and Equation (6). load index (λ) and energetic efficiency (ηc) for a compressor can be controlled by two parameters: speed and capacity slide position. Operating conditions are assumed to be constant in (5) this paper, but they can also depend on capacity, i.e., evaporating temperature will rise as evaporator load decreases. (6) The energetic efficiency of the motor (ηm) and the VSD (ηd) depend on speed and torque (as seen in Figure 3). The torque and, in case of VSD, the speed will vary with capacity. The compressor shaft power2)relates thepart torque speed to The performance data curves (Figure show to that loadand index (λ) according and energetic Equation (7). efficiency (η ) for a compressor can be controlled by two parameters: speed and c

capacity slide position. Operating conditions are assumed to be constant in this (7) rise as paper, but they can also depend on capacity, i.e., evaporating temperature will evaporator load decreases. The shaft speed is either constant or controlled actively, thus the shaft torque depends only efficiency on compressor load energetic efficiency, and speed. A The energetic of thepart motor (ηindex, m) and the VSD (ηd) depend on speed and motor is with reserve at maximum torque (astypically seen in selected Figure 3). Theapproximately torque and, in10% casetorque of VSD, the speed will vary(or with nominal)The load, giving the shaft torque at maximum load and as 90% of according the nominal capacity. compressor power relates tosystem the torque speed to motor torque (T/T = 0.9). The factor 0.9 is not constant and differs based on the n Equation (7). available motor sizes and application type. Equation (8) defines the part load torque of the motor relative to its nominal torque: (7) The shaft speed is either constant or controlled actively, thus the shaft torque depends only on compressor part load index, energetic efficiency, and speed. A motor is typically selected with approximately 10% torque reserve at maximum (or 10 © IIAR 2017 Technical Paper #3 nominal) load, giving the torque at maximum system load as 90% of the nominal motor torque (T/Tn = 0.9). The factor 0.9 is not constant and differs based on the available motor sizes and application type. Equation (8) defines the part load torque of the motor relative to its nominal torque:

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Parallel Operation of Screw Compressor Packs Parallel Operation of Screw Compressor Packs PARALLEL OPERATION OF SCREW COMPRESSOR PACKS

(8) (8) (8)

(8) The part load performance, described by the dependency between part load(8) The part load performance, described by the dependency between part load indexpart andload energetic efficiency, can be derived quite easily between from thepart compressor The performance, described by the dependency load index and energetic efficiency, can be derived quite easily from the compressor performance data. By combining (8)dependency with interpolation ofpart motor indexpart andload energetic efficiency, canEquation be derived quite easily between from the compressor The performance, described by the loadand performance data. By combining Equation (8) with interpolation of motor and The part loaddata. performance, described by the between load drive data, deriving the load efficiency the motor and drive performance combining (8)dependency with interpolation ofpart motor and as index performance and energeticBy efficiency, canEquation bepart derived quite easilyoffrom the compressor drive performance data, deriving the part loadquite efficiency offrom the motor and drive as index and energetic efficiency, can be derived easily the compressor aperformance function of data. the part load index is also possible. Figure 4ofshows an example of the drive performance data, deriving the part load efficiency the motor and drive as By combining Equation (8) with interpolation of motor and aperformance function of data. the part load index is also possible. Figure 4 shows an example of the By combining Equation (8) with interpolation of motor and between the part load index (λ) and the energetic efficiency (η). arelation function of the part load index isthe also possible. Figure 4ofshows an example of the drive performance data, deriving part load efficiency the motor and drive as relation between the partderiving load index (λ) and the energeticofefficiency (η). drive performance data, the part load efficiency the motor and drive as between the part index (λ)possible. and the energetic efficiency (η). arelation function of the part loadload index is also Figure 4 shows an example of the a function of the part load index is also possible. Figure 4 shows an example of the relation between the part load index (λ) and the energetic efficiency (η). relation between the part load index (λ) and the energetic efficiency (η).

Figure 4. Energetic efficiency as a function of compressor part load index for compressor only (left) Figure 4. Energetic efficiency and complete system (right). as a function of compressor part load index for compressor only (left) Figure 4. Energetic efficiency and complete system (right). as a function of compressor part load index for compressor only (left) and complete system (right). Figure 4. Energetic efficiency as a function of compressor part load index for compressor only (left) Figure 4. Energetic efficiency and complete system (right). as a function of compressor part load index for compressor only (left) and complete system Comparison of (right). Different Solutions

Comparison of Different Solutions Comparison of Different Solutions This section compares the partSolutions load performance of different compressor package Comparison of Different This section compares the partSolutions load performance of different compressor package Comparison of Different solutions. The most basic regulates solely with a compressor slide valve. The next This section compares the compressor part load performance of different package

solutions. The most basic compressor regulates solely with a slide valve. The next step to add amost VSD basic and to use multiple compressors. Simulations of many solutions. The compressor regulates solely with a compressor slide valve. The next This is section compares thefinally part load performance of different package step is to addcompares a VSD and finally to use multiple compressors. Simulations package of many This section the part load performance of different compressor different were to to map different combinations. step is to solutions add VSD anddone finally usethe multiple compressors. Simulations of many solutions. Theamost basic compressor regulates solely with a slide valve. The next different solutions were done to map the different combinations. solutions. The most basic compressor regulates solely with a slide valve. The next 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX different were done to to map different combinations. step is to solutions add a VSD and finally usethe multiple compressors. Simulations of many step is to add a VSD and finally tosame use multiple compressors. Simulations of many All comparisons arewere done for the total maximum capacity. For easy comparison, different solutions done to map the different combinations. All comparisons arewere done for the samethe total maximum capacity. For easy comparison, different done to map different combinations. the valuessolutions for part index were scaled (indicated bycapacity. λs) to beFor exactly at All comparisons areload done for the same total maximum easy one comparison, the values for part load index were scaled (indicated by λs) to be exactly one at the comparisons values for part index were scaled (indicated bycapacity. λs) to beFor exactly one at All areload done for the total maximum easy maximum capacity. of same size, where larger machines tend havecomparison, better All comparisons are The doneeffect for the same total maximum capacity. Fortoeasy comparison, the values for part load index were scaled (indicated by λs) to be exactly one at efficiency, by were usingscaled actual(indicated performance datatofrom appropriate the values is foraccounted part load for index by λs) be exactly one at sizes of compressors, motors, and drives. The effect of size and the effect of using Technical Paper #3 © IIAR 2017 a VSD become nominal Technical Paper #3evident when looking at the © IIAR 2017 maximum load efficiency. Technical #3 compressors will have a © IIAR 2017 MultiplePaper smaller slightly lower maximum load efficiency Technical Paper #3 with fewer larger compressors. © IIAR 2017 when compared Solutions with VSD will have a Technical Paper #3 © IIAR 2017 slightly lower maximum load efficiency than comparable size compressors without. The losses in a VSD on multiple compressor systems naturally only affect the one compressor with VSD. 44

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Figure 5 compares the total efficiency over the capacity range for a solution with one

Parallel Operation of Screw Compressor Packs

Figure 5. Comparison of part load efficiency for package with one or two compressors.

Figure 6. Comparison of part load efficiency for package with two or three compressors.

Figure 6 compares a solution with either two or three compressors. Again, solutions 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX with VSD evidently have a constant high efficiency. The solution with three compressors (one VSD) can even keep very high efficiency down to approximately 17% capacity. Furthermore, a three-compressor solution with only slide regulation (CR) has a high efficiency down to approximately 23% capacity, except from a minor load area around 37– 43%. Technical Paper #3

The analysis of the different scenarios was done for operation at a fixed operating condition (T0/Tc = +5/+35 °C / +41/95 °F). The results will change depending on the operating conditions, which should be considered when searching for the optimum solution. The results for low-temperature operation are not elaborated www.iiar.org A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER here, but will have a tendency to show lower maximum efficiency and larger drop in

load area around 37– 43%. PARALLEL OPERATION OF SCREW COMPRESSOR PACKS

The analysis different scenarios Parallel Operationof of the Screw Compressor Packs was Parallel Operation of Screw Compressor condition (T /T = +5/+35 °CPacks / +41/95

done for operation at a fixed operating °F). The results will change depending 0 c on the operating conditions, which should be considered when searching for the Parallel Operation of Screw Compressor Packs optimum solution. The results for low-temperature operation are not elaborated here, but will have a tendency to show lower maximum efficiency and larger drop in efficiency at part load. This is basically due to the relatively larger increase in losses in the screw compressor when unloading at higher pressure ratios. The results show that the flexibility to vary capacity increases with the number of compressors and the addition of a VSD. Multiple compressors, combined with variable speed, increase the capacity range significantly allowing the efficiency to stay very close to the full load efficiency. This will be appreciated in such cases where actual operating conditions and loads are difficult to predict or vary much more than originally foreseen. Figure 7. Comparison of typical starting current for three-compressor package Beside7. thesingle previously mentioned load efficiency, the parallel operation Figure of typical startinghigher current part for three-compressor package versus oneComparison compressor. versus one single compressor. of smaller compressors also considerably reduces the load on the power supply Figure 7. Comparison of typical starting current for three-compressor package during startup of the compressors. The use of multiple smaller compressors leads versus one single compressor.

to strongly reduced starting current. Figure 7 shows a principle comparison of the Reliability through Redundancy Reliability through Redundancy starting current between a three-compressor unit with VSD on first compressor and

star/delta on configuration the other two of (continuous and onepack, larger single unit The simplest a multiple line) compressor with twocompressor parallel Reliability through Redundancy The configuration ofalready a multiple compressor pack, with two parallel withsimplest star/delta startingVSD), (dashed line).offers The two solutions have same total cooling compressors (without full redundancy on the the complete compressors VSD), already full to redundancy onthe thestarting complete capacity. VSD(without on all compressors canoffers be used ensure that compressor-motor unit. Both operate independently and provide the current ability towill The simplest configuration of can a multiple compressor pack, with two parallel compressor-motor can operate independently and provide thegive ability to not exceed full unit. load Both current (no peaks). However, this solution will penalty service one the compressor-motor unit, while continues and deliver compressors (without VSD), already offersthe fullother redundancy on to theoperate complete service one compressor-motor unit, while thethree-compressor other continues to operate and deliver with of regard to energy efficiency in the whole capacity range, due to the losses in each 50% the maximum capacity. The variant naturally compressor-motor unit.cooling Both can operate independently and provide the ability offers to 50% of the maximum cooling capacity. The three-compressor variant naturally offers VSD. an evenone higher level of redundancy. The redundancy offered bytomultiple service compressor-motor unit, while the other continues operate compressorand deliver an even higher level of redundancy. The redundancy offered by multiple compressormotorofunits is expressed in terms of 50% the maximum cooling capacity. The three-compressor variant naturally offers motor units is expressed in terms of •an even Pack higher design level that enables the exchange of a complete compressor-motor unit, of redundancy. The redundancy offered by multiple compressor• Pack design that enables the exchange of a complete compressor-motor unit, without the other(s). motor units stopping is expressed in terms of stopping the other(s). •• without Multiple usethat of2017 smaller compressors and motors. These compressors, Pack design enables the exchange ofConference a complete compressor-motor unit, IIAR Natural Refrigeration & Heavy Equipment Expo,motors, San Antonio, TX • Multiple use of smaller compressors and motors. These compressors, motors, 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San starter equipment, etc.other(s). are typically more feasible in terms of cost and areAntonio, more TX without stopping the © IIAR 2017 Technical Paper #3 starter equipment, etc.the arecomparable typically more feasible in terms of cost andcost areinmore than larger ones.These This means lower case • readily Multipleavailable use of smaller compressors and motors. compressors, motors, readily available than the comparable larger ones. This means lower cost in case of stocking spare parts cases or typical shorter delivery starter equipment, etc. for are unforeseen typically more feasible in terms of cost and times. are more • of Redundant sensors on critical positions. Each can delivery come with its stocking spare parts for unforeseen cases orcompressor typical shorter times. available than the comparable larger ones. This means lower with cost in • readily Redundant sensors on critical positions. Each compressor can come its case individual set of pressure and temperature sensors. The oil management system of stocking spare parts forand unforeseen casessensors. or typical shorter delivery times. individual of pressure temperature The oil management system can also beset equipped with redundant oil pressure and temperature sensors. can also be equipped with redundant oil pressure and temperature sensors. For even higher reliability the redundancy can be increased by adding more

Technical #3 reliability the redundancy©can IIARbe 2017 For evenPaper higher increased adding compressor-motor units, or by using two © parallel units (eachbywith two more compressors) Technical Paper #3 IIAR 2017

compressor-motor units,one or by using two parallel units (each twounits compressors) instead of, for example, pack with four compressors. Thewith parallel will give instead of, for example, one pack with four compressors. The parallel units Technical Paper #3 on all components, like oil © IIAR 2017 switchboard, controller, will full redundancy system, etc. give | June 2017 | A Publication of the International Institute of Ammonia Refrigeration 46 | CONDENSER full redundancy on all components, like oil system, switchboard, controller, etc.

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Parallel Operation of Screw Compressor Packs

internal volume ratio; the oil return system; and other related functions. The separate internal volume ratio; the oil return system; and for other related Thein separate distributed module philosophy can also be used other mainfunctions. components the distributed module philosophy can also be used for other main components in the internal like volume ratio; the oil system return system; and board. other related functions. The separate system, oil management and switch system, likemodule oil management system andbe switch distributed philosophy can also used board. for other main components in the system, like oil management The distributed modules mustsystem all be and ableswitch to workboard. independently to ensure maximum The distributed modules able to work independently to ensuremodules maximum redundancy. At the same must time, all thebe communication among the individual redundancy. the same time, thebe communication among thecomponent individual The distributed modules all able to ensuremodules maximum increases theAt potential to must optimize the usetoofwork eachindependently individual and to increases theAt potential to time, optimize the use of each individual and to redundancy. theefficiency same the entire communication among thecomponent individual modules ensure maximum of the system. ensure maximum efficiency of the entire system. increases the potential to optimize the use of each individual component and to ensure maximum efficiency of the entire system.

Figure 8. Control system with distributed module layout. Figure 8. Control system with distributed module layout. Figure 8. Control system with distributed module layout.

Conclusion Conclusion Conclusion Parallel compressors, where one is optionally fitted with VSD, provide high

Parallel compressors, oneover is optionally fitted with VSD, provide high redundancy and high where efficiency a wide capacity range. The three-compressor redundancy and high efficiency over a wide capacity range. The three-compressor Parallel where oneof is redundancy optionally fitted with VSD, provide high over packagecompressors, offers the highest level and high part load efficiency package offers the highest level redundancy and high part loadthree-compressor efficiency over redundancy and high efficiency over athree widecompressors, capacity range. The the widest capacity range. More of than however, do not add much the widest capacity range. level More than three compressors, however, do and not add much package offers the highest of redundancy and will highdrop part load efficiency over regarding part load efficiency. Maximum efficiency slightly, a wider regarding part load efficiency. Maximum efficiency will drop slightly, a wider the widest capacity range.needed. More than three compressors, however, do and notbasic add much capacity range is seldom A pack with two compressors provides capacity range is seldom needed. A pack with twocompressors. compressors provides regarding partwhich load efficiency. Maximum efficiency will drop slightly, andbasic a widerwith redundancy, naturally increases with more A control system redundancy, which naturally increases with more A control system with capacity range is seldom needed. A pack with twocompressors. compressors provides distributed modules fits the potential parallel operating compressors offer.basic The control 2017 Natural Refrigeration Conference & Heavy Equipment offer. Expo, San Antonio, TX distributed fitsIIAR the operating compressors The control redundancy, which increasesparallel with more compressors. A control system system mustmodules ensurenaturally that thepotential compressors and related components are operated inwith an system must ensure thepotential compressors and related areoffer. operated in an distributed modules fits the parallel operating compressors The control optimum way under that all circumstances with respect tocomponents efficiency and reliability. optimum wayensure under that all circumstances with respect tocomponents efficiency and system must the compressors and related arereliability. operated in an optimum way under all circumstances with respect to efficiency and reliability. Nomenclature COP

Coefficient of performance

Technical Paper #3 Technical Paper #3 CR Capacity Technical Paper #3

slide regulation position

[-] [%]

Total energetic efficiency of the compressor package

[-]

ηc

Isentropic efficiency of the compressor

[-]

ηd

Energetic efficiency of the variable speed drive

[-]

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ηm

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A Publication of the International Institute of Ammonia Refrigeration | June 2017 | CONDENSER |

Energetic efficiency of the electrical motor

[-]

2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo, San Antonio, TX PARALLEL OPERATION OF SCREW COMPRESSOR PACKS

Nomenclature COP

Coefficient of performance

[-]

Capacity slide regulation position

[%]

Total energetic efficiency of the compressor package

[-]

ηc

Isentropic efficiency of the compressor

[-]

ηd ω ηm n λ

Energetic efficiency of the variable speed drive Shaft rotational speed Energetic efficiency of the electrical motor Subscript to indicate nominal values at maximum load Part load index, related to compressor nominal swept volume

[-] [rad/s] [-] [-] [-]

λs

Scaled part load index, related to compressor nominal capacity

[-]

Mass flow of refrigerant through compressor

[kg/s]

Parallel Operation of Screw Compressor Packs

References

BITZER. (2016). “Performance data for compressors.” BITZER Software v. Electrical power consumption of screw the compressor package [kW] Pel 6.4.2, Sindelfingen, Germany, 2016. Pis Isentropic power consumption of the compressor [kW] BITZER. (2014).isentropic “Competence in capacity control.” BITZER publication A-600-5, pis Specific compression work [kJ/kg] Sindelfingen, Germany. Cooling capacity of the compressor [kW] Blumhardt, R. (2006). q0 Specific cooling “Capacity capacity control of screw compressors: Speed or slide [kJ/kg] control—A comparitive study.” BITZER publication SV-0402-GB, Sindelfingen, ρ Density of refrigerant at compressor inlet [kg/m3] Germany. T Shaft torque [Nm] EN12900:2013 Refrigerant compressors – Rating conditions, tolerances, and T0 Evaporating temperature [°C] presentation of manufacturer’s performance data, European Committee for Standardization, Brussels, 2013. Tc Condensing temperature [°C] Nominal swept volume of the compressor at maximum load [m3/s] Vs Pijnenburg, B.,and J. Ritmann. (2015). “Parallel operation of NH3 screw compressors—The optimum VSD Variable speed drive way.” Presented by BITZER at IIR Ohrid Macedonia, [-] 2015.

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Technical Paper #3

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