Technical
tube surface area absorbs heat energy discharging it back into the ambient surroundings . Similar to an air-cooled condenser , a lower ambient air temperature offers a greater ΔT between the ambient and the system set point aimed for during operation . The operating temperatures can be relatively high in most cases but comparable to some HFC applications . Most commonly a GC is manufactured using thin-walled Grade 304SS to withstand the required safe operating pressures , but suitable copper tubing is also used in some cases . Processing the 304SS tubing requiring specific skills and it is also more time consuming , but it is more popular with manufactures .
Thermocoil
Figure 2 - 304SS return bends welded into tubes .
One of the main limiting factors being the operating pressures of trans-critical system components , like compressors for example , as the safe operating pressures for compressors increase the required GC operating pressures also increase .
Adiabatic pre-cooling walls installed in the airstream prior to the gas cooler face area can reduce the ambient temperature airflow the gas cooler receives . This is primarily an option in areas with extremely high ambient conditions making a transcritical system viable where it would otherwise not be suitable . In other cases , adiabatic pre-cooling walls are used to reduce the ambient air onto the gas cooler face area to mainly reduce operational energy consumed .
When making a gas cooler selection the following information is crucial towards making the calculations accurately . The more accurate the input parameters you can provide the more likely the selected design will serve the system needs during very warm ambient conditions .
Site Installation The GC is installed outside within the ambient air , similar to traditional condensers and some literature refers to GC as a condenser . This is not technically incorrect since the GC will condense the R774 discharge gas during cooler ambient conditions .
RACA Journal I April 2023 49