Experimental Study on Performance of a Solar Thermal-Driven Vapor Absorption System Integrated With Hot Thermal Energy Storage for Milk Chilling

Abstract

Solar thermal-driven vapor absorption system has proven to be a feasible and viable cooling source. However, most reported installations for milk chilling applications are equipped with an auxiliary heater that consumes significant electricity/gas, making it economically unviable. In this study, the experimental investigation of the performance of a solar-powered vapor absorption chiller has been reported for milk chilling applications as per standard ISO 5708–2 II. It has been identified that the performance of the vapor absorption chiller is quite uncertain and underperforming while operated with the heat directly fed through the evacuated tube compound parabolic concentrator solar field due to diurnal and seasonal variations of solar radiation intensity. Therefore, hot thermal energy storage integration has been studied and analyzed in this study. The performance of the vapor absorption chiller has improved significantly with the use of hot thermal energy storage in the solar circuit as the coefficient of performance (COP) of the vapor absorption chiller improved up to 0.4, which was earlier around 0.25. Further, hot thermal energy storage provides better thermal management to increase the productivity and performance of the vapor absorption chiller, and the cooling time for the first milking is 2 h and 45 min. The performance of the vapor absorption chiller enhanced further up to 0.52 when supplied heat entirely with thermal energy storage. The energy efficiency ratio has a maximum value of 6.1, with an average of 4.3, whereas the thermal COP has an average of 0.35 and a maximum value of 0.52 when run with thermal energy storage alone.