Studies of a Sky Radiative Thermosyphon Cooling System for Storing Thermal Energy

Abstract

The performance of a sky radiative thermosyphon cooling system for storing thermal energy in a tank was studied experimentally and analytically. The system consisted of a storage tank of 66.7 litters and one or two black-painted plates (1.8 or 3.6m²) facing the sky. They were connected by insulated tubes of 16 mm in inner diameter. The terperature at the outlet of the palte was 2∼6°C below ambient temperature during clear nights. The water in the storage tank was cooled down to about ambient temperature. In the analysis, the temperature distributions in the storage tank were calculated numerically by considering the thermosyphon flow rate and the temperature changes of the fluid along the radiator and the connecting tubes. The analytical results were found to agree well with the experimental results.