Optimization of exergetic performance and payback period of organic rankine cycle integrated vapor compression refrigeration system based on exergy, economic, and environmental criteria

Abstract

In this paper, a multi-objective optimization study is carried out to determine the optimal exergetic performance (𝜂𝑒𝑥) and the payback period (PB) of the organic Rankine cycle (ORC) integrated vapor compression refrigeration (VCR) system based on exergy, economic, and environmental criteria using non-dominated sort genetic algorithm-II (NSGA-II). Moreover, a sensitivity analysis is carried out to improve the exergetic performance of the system. The working fluid, the pinch-point temperature difference of the ORC evaporator (ΔToep ), con-denser (ΔTpcond), and the VCR evaporator (ΔTpve), cooling water inlet temperature (Tcw1), chilled fluid temperature (Tcf2), and heat-source inlet temperature (Th1) are taken as the decision vari-ables. The results of this study indicate that butane is the most suitable working fluid for op-timal exergetic efficiency, 𝜂𝑒𝑥 (33.7%) and payback period, PB (4.9 years) of the system. The optimal values of other decision variables such as Th1, Tcw1, Tcf2, ΔToep , ΔTpve , and ΔTpcondare 378 K, 313 K, 276 K, 10 K, 5 K, and 5 K respectively.