A New Aspect in Analysis and Improvement of Standalone Solar-Driven Absorption Refrigeration Systems

Solar-driven absorption refrigeration systems (ARSs) are subjected to work under off-design conditions due to the driving temperature variation. In this study, a model of NH3/H2O ARS with 100-kW cooling capacity has been developed. Energetic and exergetic coefficients of performance (COP, ECOP), besides cooling production (Qeva), have been investigated at off-design conditions. The analysis indicates a reduction in the effectiveness of the generator and solution heat exchanger (SHX) under such conditions. A new method to improve the off-design system’s performance by modifying the generator and SHX heat capacities is suggested. Results revealed that an increase in heat capacities of the generator and SHX (UAgen, UASHX) effectively improves the system’s performance. Raising the values of UAgen and UASHX by 20% maintains the system’s COP, ECOP, and Qeva near their designed values under a wider range of driving temperatures (100 oC to 92 oC). Moreover, this adjustment helps decrease the system’s cut-in/off temperature.