Optimization and exergoeconomic analysis of a solar-powered ORC-VCR-CCHP system based on a ternary refrigerant selection model

Ternary refrigerants surpass traditional single-component and binary refrigerants in performance, efficiency, and environmental impact in refrigeration systems, but the abundance of combination possibilities makes it challenging to experimentally determine the optimal mixture for a specific system. This research proposes a mechanism model for screening ternary refrigerants, which selects the composition of mixed refrigerants from 24 types of refrigerants and realizes simultaneous optimization of the composition and process parameters of mixed refrigerants. The model is applied to a new ORC-VCR-CCHP (Organic Rankine Cycle- Vapor Compression Refrigeration- Combined cooling, heating and power) system. This system can effectively recover solar energy and convert it into cooling, heat and electricity to meet the energy demand of the university campus to a great extent. Taking the highest exergoeconomic efficiency as the objective function and satisfying excellent economy, environmental protection, thermodynamic stability, and low toxicity at the same time, a mixed integer nonlinear programming (MINLP) model was established. The optimization results show that the optimal exergoeconomic efficiency can reach 42.49 %. The optimal composition with safety and environmental protection in the ORC system and VCR system are R245fa/R41/R1336mzz (z) and R1234ze/R1234yf/R32, with mass fractions of 0.5339/0.4310/0.0351 and 0.2202/0.2073/0.5725 respectively. The article concludes with an Exergoeconomic analysis.