A Passive, Vapor Compression Refrigerator for Solar Cooling

Abstract

A new, completely passive, vapor compression refrigerator is described in this paper. This refrigerator combines elements of the heat pipe and the vapor jet refrigerator and is referred to here as a heat pipe refrigerator. It may be driven with heat from low temperature solar collectors or with industrial waste heat and used to provide cooling. Compression work is provided by gas dynamic processes and liquid pumping may be obtained using gravitational or capillary forces. No power is required for operation. The device has no moving parts and may be externally similar to a heat pipe with three heat transfer zones. The working fluid is chosen to match the desired operating temperature range. Water, at subatmospheric pressure, is an appropriate fluid for operation around room temperature. Theoretical considerations indicate that the thermal coefficient of performance of the heat pipe refrigerator will depend strongly on the magnitude of the temperature differences over which it is designed to operate. Results from a laboratory test confirm the concept and demonstrate cooling down to the freezing point using water vapor at 51°C to drive the device and with heat rejection at 18°C.