Energy, exergy, and economic (3E) analyses and multi-objective optimization of a cascade absorption refrigeration system for low-grade waste heat recovery

In the present study, an innovative cascade absorption refrigeration (CAR) system for recovering low-grade waste heat is proposed. Based on the simulation results, the energy, exergy and economic (3E) analyses of the cascade refrigeration system have been conducted. The analysis results show that there is a contradiction between economic performance and thermodynamic performance. Then, the optimization scheme aiming at total exergy destruction (EDt), the optimization scheme aiming at total annual cost (C-t) and multi-objective optimization scheme (C-t and E-Dt) are optimized by non-dominated sort genetic algorithm-II (NSGA-II) technology. EDt is 11% more than its minimum result in the optimization scheme aiming at total annual cost, which shows that the thermal performance of the scheme is poor. C-t is 14.8% more than its minimum result in the optimization scheme aiming at total exergy destruction, which shows that the scheme is not economical. C-t and EDt are only 5.9% and 4.5% respectively higher than their minimum results in the multi-objective optimization scheme. Therefore, multi-objective optimization scheme is the most comprehensive and optimal scheme of the CAR system.