MODULE
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PROUDLY SPONSORED BY
AIRAH
WATER-COOLED CONTROLS CONDENSERS AND FUNDAMENTALS COOLING TOWERS
■ What?
Controls are an increasingly important consideration in new building design and existing building renovation. They are directly system, linked to The condenser is a most important unit in a refrigeration building performance and energy management, commissioning and as it is into this that all of the heat-laden vapour pumped by the retro-commissioning, operation and maintenance and broader links compressor is forced under high pressure. It must be of greater to building sustainability, building health and safety, and ultimately capacity than the evaporator because the condenser must dissipate building satisfaction and productivity. the mechanical energy from the compressor as well as the heat absorbed in theand evaporator. The operation control of environmental systems in buildings is a
■ Who?
critical activity in terms of operating costs, environmental footprint, Condensers are classified according to the type of cooling medium occupant comfort, and indoor environment quality. The operation of used – and are of three general types: air-cooled, water-cooled and many building systems is sub-optimal and the performance of these evaporative. This skillswith workshop looks at evaporative condensers. systems can improve better control strategies. Efficient buildings
Skills summary A description An overview of ofbuilding the different controls types and the terms commonly of water-cooled condensers used and when discussing them. cooling towers.
need efficient controls. This Skills Workshop also looks at cooling towers. All water‑cooled refrigeration and air‑conditioning systems must the water This Skills Workshop provides a broad overview ofrecirculate control system fundamentals and explains of theby common terms used when using cooling towers to coolsome the water evaporation. discussing control systems.
Relevant for mechanical Maintenance service providers, contractors, controls vendors consultants, OEMsand andintegrators, installers designers and operating within contractors, refrigeration, air construction and project conditioning processmanagers, cooling facility managers, and heating applications. building owners and developers, tenants and occupants.
Evaporative (Type 3) condensers Evaporative condensers utilise both air and water to achieve heat rejection. The refrigerant flows into a condenser located in an enclosure; water is sprayed over the condenser to promote cooling of the refrigerant and air flows over the condenser to promote evaporation of the water and removal of heat energy. The water cycle is all in the condenser cabinet in this system. Longer refrigerant runs are usually needed to carry refrigerant to the evaporative condensers.
solenoid stop valve sight glass
At distances greater than these, problems of liquid condensing in the discharge line and flowing back to the compressor and of liquid refrigerant in the heads dictate the choice of separate water-cooled condenser and cooling water. The cooling capacity is affected by the relative humidity of the air (water will not evaporate readily at high humidity) and by high water and condensing temperatures.
Usually the evaporative condenser is mounted out of doors; however, it is possible to locate an evaporative condenser indoors by providing air ducts linking the condenser to the outside.
strainer
Evaporative coolers are often used in preference to cooling towers where the distance from the compressor to the preferred location of the condenser does not exceed 10–30 metres in a horizontal direction, or six metres vertically from the compressor.
evaporator capillary tube equaliser tube
liquid shut-off valve thermostatic expansion valve
evaporative condenser
remote bulb blower section suction line
liquid line hot gas line suction valve discharge valve
purge valve
sprays
condenser shut-off valve liquid valve
Fig 2 Typical custom-built evaporative condenser
emergency shut-off valve
Some systems pump the water to a tray located above the condenser and the water drips over the coils as air is forced through the coils. A fan operates to blow air over the condenser at all times when the condensing unit is operating. The water normally circulates continually, although, as with cooling towers, the fan may be slowed or turned off if water temperature falls too low.
condensing coil
rubber hose
compressor unit
vibration insulators
pump liquid receiver
pressure relief valve
fusible plug liquid sight glass
This type is most economical with the water – and makes a most effective condenser. As the condenser heat evaporates the water, the water absorbs heat at the rate of the
Fig 1 Evaporative condenser installation (Reproduced from Trane Reciprocating Refrigeration Manual. Courtesy of Trane, Ingersoll Rand.)
February 2020
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www.airah.org.au/nation
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HVAC&R Nation
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