Performance Evaluation of a Small Scale Ammonia-Water Absorption Cooling System for Off-Grid Rural Homes: A Numerical and Experimental Study

Abstract

In areas with unreliable electricity, the absorption system serves as a crucial, eco-friendly refrigeration technology. This study addresses the system's performance gaps, evaluating the 100 W NH3-H2O absorption cooling system under various conditions. The focus is on its suitability for electricity-challenged areas, employing theoretical and experimental methods. Two configurations are tested based on input heat sources, using bifacial Photovoltaic (PV) or solar parabolic troughs integrated with the absorption chiller. The Engineering Equation Solver (EES) program determines thermodynamic properties, with the model split into sections-one with the solution heat exchanger (SHX) excluding the liquid-vapor heat exchanger (LVHX) and the other incorporating both. The findings indicate a direct correlation between higher evaporator and generator temperatures and an increase in the Coefficient of Performance (COP). The theoretical and experimental cooling COP values reach 0.62 and 0.63, respectively, at 7℃ evaporator temperature and 85℃ generator temperature. Similarly, at 95℃ generator temperature, the COP values are 0.629 and 0.637 for the same evaporator temperature. The theoretical maximum COP at 3℃ evaporator temperature is 0.512 at 90°C generator temperature, with experimental COP approaching 0.52 at generator temperatures of 96℃, 98℃, and 100℃. The integration of an LVHX into the chiller module demonstrates a notable improvement in cycle performance, enhancing efficiency by approximately 7-7.5%. In conclusion, this study offers crucial insights into optimizing the NH3-H2O absorption cooling system for off-grid scenarios, contributing to a broader understanding of absorption refrigeration technology in diverse environmental conditions.