Simulation of an absorption refrigeration system with solar thermal energy for use in remote locations

Ronaldo Bueno de Souza¹; Jacqueline BianconCopetti¹; Mario Henrique Macagnan¹

¹ Unisinos

doi:10.20906/CPS/COB-2015-1789

Resumo

This paper presents the results of a study of refrigeration absorption system assisted by solar thermal energy applied to the cooling of an ecotourism lodge located in a remote location, not connected to the conventional electricity grid.The proposed system consists of a water-lithium bromide absorption chiller with a cooling tower, solar thermal collectors, hot and cold water tanks, circulating pumps for hot and cold water, heat exchangers and other control systems. The system is designed to meet the thermal cooling loads of six rooms and a dining room.A computational model using TRNSYS was developed to simulate three system configurations. For each configuration it was analyzed the influence of the following parameters on the system performance: area, slope, and mass flow rates of two types of collectors (flat with selective surface and evacuated tubes), volumes of thermal reservoirs of high and low temperature, the chiller temperature activation, and the temperature of cooling water. In the first configuration, the water, heated by the solar thermal collector, is stored in a thermal reservoir and used directly by the absorption chiller when its temperature is equal or higher than the chiller activation temperature, without auxiliary heating. The chilled water is stored in another thermal reservoir, where it is available to meet the thermal loads. With this model it was observed that for 120 m² of evacuated tube collectors is possible to reach an index solar fraction higher than 0.87. The second configuration is similar to the first, with the inclusion of an auxiliary heater to supply chillerwater. In this one, it was observed that the auxiliary power consumption, for 120 m² of flat plate collectors, is less than 195 GJ and for the same area of evacuated tube collectors is less than 150 GJ, achieving in this case a unitary solar fraction. In the third configuration is implemented a reusing system of chiller cooling water, for use in the consumption of hot water for bath. In this configuration it was noted th

Palavras-chave: absorption refrigeration ; solar thermal ; remote locations