Performance analysis of a hybrid compression-assisted absorption system using heat recovery ammonia generator

Abstract

A hybrid compression-assisted absorption refrigeration system using condensation in a heat recovery ammonia generator was proposed for the slaughtering industry considering the importance of reducing the high demand for energy in the industrial refrigeration systems. The proposed system operates with double evaporators and generators at different pressures and temperatures that use the available condensation heat from the ammonia generator of the subsystem operating at high pressure and temperatures to the subsystem under low pressure and temperatures. In addition, compressors are included in the system to increase the pressure of the saturated vapor generated from the ammonia generator to enable condensation heat to have a sufficient minimum temperature difference for heat rejection to surroundings. The investigation was carried out using energy and exergy analyses, and the results show that the proposed system is promising compared with a simple compression cycle or conventional absorption system. Among several advantages, this system demands less power compared with the simple compression system and less heat compared with the conventional absorption refrigeration system owing to the possibility to promote a better thermal integration between the subsystems, adjusting the operation pressures in accordance with the availabilities and demands of heat and power. The external demand of the heat source can be decreased by 57.4% compared with the conventional absorption system and by 34.2% compared with the power demand of a simple compression cycle. The coefficient of performance of conventional absorption ranged from 0.453 to 0.6145, while the exergy efficiency ranged from 0.2786 to 0.3223, indicating that a hybrid compression-assisted absorption system can be a good option where there is a residual heat source to the absorption cycle, but this availability is not sufficient to satisfy the complete demand.