Development of a Heat Collection System Using a Two-phase Natural Circulation Loop and/or a Direct Expansion Heat Pump

Abstract

Performance characteristics tests have been carried out on a new heat collection system which has been developed for the purpose of utilizations in thermal treatments or unit operations of foods and agricultural products. The system can be operated as a solar radiation heat collector with two-phase natural circulation of working fluid and/or a direct expansion heat pump, depending on the conditions of insolation, ambient air temperatre and heat demand. In natural circulation mode, the collector efficiency was assessed to be more than 50%, and the COP was found to vary in the range of 2.5-5 when the system was operated as a heat pump.