THE UK CAN LEARN FROM DENMARK’S HEAT PUMPS

carbon footprint reduction strategies. Transcritical CO2 HPU technology is considered well-suited for significant heat sink temperature differential (between inlet and outlet temperature) above 40K. Heat pumps require electricity to work but can produce around three or four kilowatts of heat for every kilowatt of power they consume, making them highly efficient. Plus, some designs can provide cooling as well.

The emission-free MAN Heat Pump solution HPU makes efficient use of the special properties that CO2, as a working fluid, has to offer. Operating with an optimised transcritical heat pump cycle, this high temperature industrial heat pump system is able to generate temperatures from 0°C (32°F) up to 150°C (302°F) and up to 60 MW (204.72 MMBtu/h) of thermal heat and 30 MW (8530 tons of refrigeration) of thermal cold with using just one single heat pump unit.

Imagine 2.5 million litres of water in an Olympic-sized swimming pool. If for some reason you wanted to bring it from a pleasant 20C to boiling point, MAN Energy Solutions (MAN ES) has a heat pump which could do it.

“We can do this in less than four hours,” reports Raymond Decorvet of MAN ES. “Or we could freeze the whole thing in about 11 hours.”

The HPU from MAN ES offers the following benefits to heat pump users:

- Large scale supply of heating or cooling

- High supply temperatures

- Environmentally friendly refrigerant

- High power density

- Adaptable to project or site specific requirements

– An all inclusive electric solution for low maintenance and remote operations

– Participation in secondary control power market

– Quick start-up, shut down and load change reaction time.

Using CO2 as a refrigerant offers a number of advantages: Carbon-dioxide is a naturally occurring component which is available in large quantities and is inexpensive compared to synthetic refrigerants.

CO2 also ticks all the boxes of an environmentally- friendly, low GWP, non-toxic and non-explosive medium. It is a very dense refrigerant with a high volumetric heating capacity; this allows the piping sizes and equipment volume to be much smaller than an equivalent HFC system

Transcritical CO2 HP systems like these provide users with a a high discharge temperature, therefore removing the need for cascade heat pump systems or additional heating devices. There is no impending legislation phasing out carbon-dioxide; hence it can be considered as a safe refrigerant, says MAN ES, matching the average clients’ long- to 150°C (302°F) and up to 60 MW (204.72 MMBtu/h) of thermal heat.”

Heat pumps are increasingly popular with some home owners but domestic devices are relatively small and tend to have outputs of several kilowatts or so.

MAN ES’s biggest commercial heat pump is thousands of times more powerful - with a total heating capacity of 48 megawatts (MW).

It can produce temperatures of up to 150C and could heat thousands of homes in the UK, not just one.

The company has two ETES-based heat pumps in the port city of Esbjerg, in Denmark. In this installation example, the heat pumps’ CO2 refrigerant will absorb a small amount of heat from seawater. Compressors boost the temperature of the CO2 and the system can then transfer this heat, providing water of up to 90C to heat, providing water of up to 90°C to a district heating system serving 27,000 households.

Industrial-sized heat pumps are a thousand times more powerful than domestic versions

“The demand for district heating is exploding,” comments Raymond Decorvet.

The district heating system in Stockholm, Sweden is often referred to as the largest heat pump set-up in the world. This has a maximum capacity of 215MW - but that total is the sum of seven heat pumps, two 40MW and five 27MW devices, reports a spokesman for energy provider Stockholm Exergi explains.

Gothenburg also has a 160MW heat pump system which consists of four units. Two of them are actually bigger than those in Stockholm, with capacities of 50MW each.

A company spokesman commented: “With the MAN HPU, you can decarbonise the complete energy supply for district heating networks, urban quarters, small towns and large facilities like airports, universities or shopping malls.”

According to the manufacturer, the MAN HPU provides cost-efficient carbon-neutral heating or cooling for all kinds of industrial processes with intensive heating or cooling demands, especially in the food, beverage and pharmaceutical industries.

Selected applications

Scalable and modular, the MAN Heat Pump HPU is said to be suitable for mid- to large-scale thermal consumers. Data centre operators can reduce their CO2 emissions and electricity costs with a direct supply of cooling energy. An additional revenue stream can be created by participating in the power markets and exporting