Refrigerant temp control - for wide demand fluctuations in circuit

摘要

A method for maintaining constant temperature in a refrigerating circuit comprising rotary compressors uses a motor-actuated guide vane adjuster for the coolant suction intake; below its control range, a valve in a line leading from the h.p. side to the evaporator is opened to admit gaseous coolant into the evaporator. The control parameter used is the refrigerant temp. fed into a regulator operating both the guide plate adjuster and the valve. Temp. deviations from the predetermined value cause the regulator to emit at intervals a pulse which passes to the guide blade adjusting motor; in the closure position, this motor actuates a switch which changes the control over to a motor valve in the gaseous coolant line. The pulses then open/close the motor valve; as the coolant demand increases, the motor valve, when in the closed position actuates a further switch, which resets the regulator into position for controlling the guide blade motor.