Air cooled water chillers
Air cooled water chillers are vapour compression refrigeration systems. The main components of a vapour compression refrigeration system are the compressor, condenser, expansion valve & evaporator.
Vapour compression refrigeration systems have a refrigeration cycle. The cycle starts with a cool low pressure mixture of liquid & vapour refrigerant entering the chiller evaporator. Once inside the chiller evaporator it absorbs the heat from the relatively warm water or fluid that the fluid chiller is cooling. This transfer of heat boils the liquid refrigerant in the chillers evaporator and the super-heated vapour is pulled into the chillers compressor.
The chillers compressor compresses the refrigerant to a high temperature & pressure, high enough to allow the chillers condenser to give up its heat to the cooler ambient air. Within the chillers condenser, heat is transferred from the hot refrigerant to the relatively cool ambient air this reduction in the chillers refrigerant causes it to de-superheat and condense into a liquid, then further sub-cool before leaving the chiller condenser.
The high pressure liquid refrigerant then enters the chiller expansion valve causing a large pressure drop across the chillers refrigerant circuit. The pressure reduction causes a small portion of the refrigerant to boil off, or flash, this would be seen in the chillers site glass. The site glass indicates if the chiller is short of gas, if the chiller is short of refrigerant gas the flashing inside the chillers site glass will increase. The boiled off refrigerant helps cool the remaining refrigerant to the desired temperature before the mixture enters the chiller evaporator to start the cycle again.