A cascade lithium bromide absorption refrigeration/dehumidification system for efficient energy recovery: Development, 3E optimization and life cycle assessment

Abstract

In recent years, the problems of energy shortage and environmental pollution are becoming increasingly prominent, research on the optimization of energy systems and environmental pollution is imperative. Exergy, economic, and environmental (3E) analysis of a cascade LiBr-H2O absorption refrigeration/dehumidification system driven by low-grade waste heat is developed in this paper. Ecological Indicator 16 (EI16), total exergy destruction (EDtotal), and total annual cost (TAC) are considered as the objective functions of the 3E optimization model, and then, the optimal solution is obtained by TOPSIS and Shannon entropy method. Finally, life cycle assessment (LCA) of the cascade system is performed using EI16 and the environmental benefits of the cascade system are assessed in four stages, further enriching the evaluation criteria of this coupled system. The results shows that with the refrigeration temperature elevated from 2 °C to 10 °C, the EDtotal of cascade system increases from 336.90 kW to 339.14 kW, an increase of 0.66%, and the exergy efficiency decreased from 10.34% to 10.06%. At the same time, the cascade system TAC was reduced from 5.97 × 105$ to 5.77 × 105$, a 3.35% reduction. Economic analysis indicates that the investment cost increases with the increase of the refrigeration temperature, and the operating cost decreases with the increase of the refrigeration temperature. The optimal solution of the cascade system is obtained, and the EI16, EDtotal, TAC, and exergy efficiency are 2.6, 336.90 kW, 112.32 × 104 $ and 10.34%, respectively. The LCA illustrates that the construction process has serious impact on the environment, accounting for 95%, followed by the recovery phase. And improvements during the use phase determine the environmental benefits of the cascade system. In this work, multi-objective optimization and LCA are combined to provide a viable solution for the multi-angle analysis and evaluation of the cascade energy systems, and further refines the evaluation criteria for the cascade energy systems.