Influence of the operational conditions on the performance of a chemisorption chiller driven by hot water between 65 °C and 80 °C

Abstract

We designed, built and experimentally assessed the cooling power and the coefficient of performance (COP) of a chemisorption chiller that used a consolidated composite made of NaBr impregnated in expanded graphite as sorbent and ammonia as refrigerant. The influence of the operation conditions on the COP and the cooling power was calculated through the values of inlet and outlet water temperature and water mass flow across the chiller’s heat exchangers. From the experimental results, we concluded that the utilization of mass recovery simultaneously to heat recovery improved the COP and cooling power up to 11.7% and 15.4%, respectively, when compared to the values obtained when only heat recovery was employed. Regarding the influence of the heat source temperature, maximum cooling power and COP were obtained when that temperature was, respectively, 75°C and 65°C. As for the influence of the cycle time, the highest values of COP were obtained with an 88min cycle, whereas the highest values of cooling power were obtained at different cycle time, depending on the value of other operation conditions. When the chiller was driven by hot water at 70°C, and the inlet water temperature in the evaporator was not kept constant, it cooled water from 23°C to 10°C in 90min with mean cooling power of 1400W and COP 0.33.