Comprehensive Parametric Study of a Solar Absorption Refrigeration System to Lower Its Cut In/Off Temperature

Solar-driven ammonia-water absorption refrigeration system (AARS) has been considered as an alternative for the conventional refrigeration and air-conditioning systems. However, its high initial cost seems to be the main problem that postpones its wide spread use. In the present study, a single-stage NH3/H2O ARS is analyzed in depth on the basis of energetic and exergetic coefficients of performance (COP and ECOP, respectively) to decrease its cut in/off temperature. This study was carried out to lower the required heat source temperature, so that a less-expensive solar collector could be used. Effects of all parameters that could influence the system’s performance and cut in/off temperature were investigated in detail. Presence of water in the refrigerant and evaporator temperature glide was considered. Results revealed that appropriate selection of system’s working condition can effectively reduce the driving temperature. Besides, the cut in/off temperature can be significantly decreased by inserting an effective solution heat exchanger (SHX). Required driving temperature can be lowered by up to 10 °C using SHX with 0.80 effectiveness. The results also showed that effects of water content in the refrigerant could not be neglected in studying NH3/H2O ARS because it affects both COP and ECOP. Additionally, a large temperature glide in the evaporator can substantially decrease the ECOP.