Thermodynamic analysis and optimization of variable effect absorption refrigeration system using multi-island genetic algorithm

Low efficiency is one of the major concerns associated with absorption refrigeration cycle (ARC). The performance of ARC is affected by internal parameters such as the solution distribution ratio and the generator outlet solution concentration, especially to the absorption-generation heat exchange (AGX) LiBr–water variable-effect ARC. Therefore, the performance of the AGX variable-effect ARC was optimized and analyzed. AGX variable-effect ARC thermodynamic model has been implemented in Engineering Equation Solver (EES). Operation parameters including temperatures of all the units of ARC, solution distribution ratio, and generator outlet solution concentration had been optimized. The effects of the solution distribution ratio and generator outlet solution concentration on constraint conditions, coefficient of performance (COP), exergy efficiency (ηex), and operating range had also been analyzed. Multi-island genetic algorithm (MIGA) was used to optimize the solution distribution ratio and generator outlet solution concentration. The results showed that the optimal COP for the AGX cycle was from 0.885 to 1.249 for THGfrom 95 °C to 140 °C. The optimized COP was increased by 10.65% on average and 45.49% on maximum, compared with the COP obtained at the same temperature. The MIGA optimization method had proven to be an effective and robust tool that could be utilized to the optimization of AGX variable-effect ARC.