Energy Performance Evaluation of an Ammonia–Water Absorption Chiller for Varying Operating Conditions

A thermodynamic model of an ammonia–water absorption refrigeration cycle with heat integration was developed using Aspen Plus to investigate the impact of selected process variables on the energy efficiency and operational feasibility of the system. The coefficient of performance (COP), evaporator temperature, and refrigeration cycle heat flows were analyzed as a function of the high and low pressures of the system, as well as ammonia concentration in the generator feed, and UA, which is the product of the overall heat transfer coefficient (U) and the heat transfer area (A) of the solution heat exchanger. This article presents parametric studies that reveal the interdependence of these factors and quantifies their effects on system performance. The results indicate the feasibility of driving the cycle using low-temperature heat sources (e.g., solar thermal energy) for a range of cooling temperatures.