The PMC and CVC is used for capacity regulation in refrigeration, freezing and air conditioning plants for ammonia and fluorinated refrigerants.
The PMC is a servo-operated regulator with screwed-on pilot valves.
PMC and CVC can be used in all types of refrigeration plants:
-with direct expansion
-with pump recirculation
-with natural circulation
The function of the capacity regulator is to match the fixed output of the compressor and the varying load on the system. This function is obtained when the PMC and CVC is installed in a bypass line between the discharge and suction sides of the compressor.
If the load on the evaporator, and with it the load on the compressor, falls, an "artificial" load in the form of hot gas from the high pressure side of the compressor is applied to the evaporator or compressor.