CAPACITY CONTROL FOR COMPRESSION EXPANSION REFRIGERATION SYSTEMS

摘要

A compression expansion refrigeration system is provided with a hot gas line to connect hot gas from the compressor directly to the expansion coil for reducing its capacity and a servo operated suction pressure modulation valve is provided in the intake line to the compressor to vary the capacity of the system to obtain a controlled load temperature. Thermostatic control means disables the servo operated modulation valve in the open position and maintains closed a valve in the hot gas line to provide maximum capacity so long as the controlled temperature is above a predetermined amount above the desired controlled temperature and when the controlled temperature falls below the predetermined amount the valve in the hot gas line is opened to provide a direct step reduction in capacity and the suction modulation valve is activated to vary the lowered capacity to obtain the desired controlled load temperature.