When choosing refrigeration equipment for a new installation, the equipment is selected to provide the required refrigeration effect to either reduce and/or maintain a product’s temperature. This capacity is normally stated in Btuh. The unit cooler (evaporator), compressor, and metering device are all selected based on this Btuh requirement for the selected refrigerant. The only major component not selected based on this Btuh requirement is the condenser.
A condenser must be selected for the system’s total of heat rejection (THR), which is the sum of the heat energy absorbed by the evaporator and the additional heat energy added to the refrigerant by the compressor. This additional heat energy is referred to as the heat of compression. The heat of compression varies with the compressor design, so the compressor manufacturer’s information should be used whenever possible. If this information is not available, many condenser manufacturers will provide a reference table to determine that value.