Performance of a heat pipe assisted night sky radiative cooler

A passive radiative cooling system was designed, constructed and tested under clear skies. This refrigerator operates by losing heat to the night sky through infrared (i.r.) radiation emission. It consists of a radiator, an array of heat pipe elements and a cold chamber. The heat pipe elements are so arranged that they act as thermal diodes, transferring heat from the cold chamber to the radiator. Performance tests show that the system has a cooling capacity of 628 kJ/m² per night with a sky coefficient of performance of 0.26. The lowest temperature attained in the cold chamber was 12.8°C for an ambient temperature of 20°C. The overall results indicate that the system has a great potential for providing a cold storage facility in developing countries and in remote areas.