Comparative performance analysis of ORC-VCRC combined systems based on refrigerant selection

Abstract

In this study, the combined power and refrigeration cycles driven by low-grade thermal energy are evaluated. An organic Rankine cycle (ORC) and a vapor compression refrigeration cycle (VCRC) are linked for both power generation and cooling. Three different combined cycle configurations are considered in the analyses. These are a basic ORC-VCRC, a dual-fluid basic ORC-VCRC, and a dual-fluid ORC-VCRC with an internal heat exchanger (IHE) and liquid-vapor heat exchanger (LVHE). The effects of the combined cycle configuration design on overall coefficients of performance (COPs) and the exergy efficiency of the system are examined. The highest overall COPs and exergy efficiency values at the operating conditions are obtained for the dual-fluid ORC-VCRC with IHE-LVHE as 0.72 and 19.5%, respectively. A comprehensive energy and exergy analysis is also performed for the dual-fluid ORC-VCRC with IHE-LVHE. The selection of the optimum fluid pair for ORC-VCRC is also investigated in the study. Thirty different fluid pair combinations are evaluated and compared using R123, R245fa, R600, R114, R141b, R290, R134a, and R143a refrigerants. The parametric analysis of the integrated system is performed depending on various operating conditions. Results show that the best performance among the cases considered is observed when the refrigerant R123 is used in the ORC-VCRC combined system.