Exergoeconomic Performance Comparison and Optimization of Single-Stage Absorption Heat Transformers

Three single-stage absorption heat transformer (SSHT) configurations are modeled, analyzed and compared from the viewpoints of thermodynamics and economics, using the Engineering Equation Solver (EES) software. In addition, a multi-objective optimization is carried out for the three configurations to specify the optimal design point considering the second law efficiency and the product unit cost as two objective functions. The configurations differ from one another considering the number of heat exchangers used in them. The results show that the coefficient of performance (COP) and exergy coefficient of performance (ECOP) for configuration 3 are around 35% and 30% higher than the corresponding values for configuration 1, respectively. Also, configuration 2 is found to be more economic with a product unit cost of about 21% and 5% lower than those for configurations 1 and 3, respectively. Furthermore, it is observed that relatively higher absorber temperatures can be achieved by configurations 2 and 3 compared to configuration 1. It is concluded from the multi-objective optimization that the conditions at which the evaporator, condenser and absorber temperatures are 86.51 degrees C, 39.03 degrees C and 123.1 degrees C, respectively, represents an optimal solution.