EVAPORATOR INLET WATER TEMPERATURE CONTROL SYSTEM

摘要

078254-Y EVAPORATOR INLET WATER TEMPERATURE CONTROL SYSTEM : An evaporator inlet water temperature control system (80) for controlling the inlet water temperature of an evaporator utilized in an inverter driven centrifugal chiller. The system creates the proper chilled water set point at the evaporator outlet needed to maintain the inlet water at its set point for greater efficiency of operation. Control is accomplished by generating an electrical error signal (85) which is a function of an inlet water set point voltage and the actual inlet water temperature. A logic signal (93) is produced as a function of the error signal detected by the circuit and establishes a dead zone band representing a range in which the error signal is acceptable. Output of the control system is passed to the capacity control circuit (50) of an inverter driven centrifugal compressor chiller. When the inlet water temperature reaches its set point during pull-down, the logic output of the circuit (90) sets a flip-flop (92) which enables transmission gates (106,108,109) to control changes in the outlet water set point as needed to balance the load of the cooling system.