Patent ID: 9605885
Date: 2017-03-28
CPC Classifications: F25B

Claim:
1. An air conditioning system, comprising: first and second utilization side heat exchangers and a heat source side heat exchanger respectively connected in series; a compressor connected between the first utilization side heat exchanger and the heat source side heat exchanger; an expansion valve connected between the first utilization side heat exchanger and the second utilization side heat exchanger, the expansion valve comprising first and second expansion valves connected in series; a bypass valve connecting piping at an outlet of the heat source side heat exchanger with piping between the first expansion valve and the second expansion valve during a defrost system operation; and a pressure control device connected between the second utilization side heat exchanger and the heat source side heat exchanger; and, wherein the pressure control device is configured to maintain refrigerant that flows from the second utilization side heat exchanger to the heat source side heat exchanger at a predefined pressure, the bypass valve is configured to make refrigerant from the expansion valve bypass the second utilization side heat exchanger and the pressure control device, and the pressure control device and the bypass valve are configured in cooperation with each other to keep a temperature of the compressor below a maximum allowable temperature predetermined for the compressor.