Performance indicators investigation of two configurations of combined power-cooling system activated by low-grade thermal energy: Improved design and comparative analysis

Abstract

This article presents a novel design for a power-cooling system consisting of a combined organic Rankine cycle and an ejector-expansion refrigeration cycle (ORC–EERC) activated by low-grade thermal energy. The hydrocarbon R600 (butane) is used as the working fluid for both cycles. A thermodynamic analysis has been performed to investigate the performance, in particular the performance indicators (overall coefficient of performance (COP_oval) and working fluid mass flow rate per kW of cooling capacity (MkW)) of the proposed system by comparing it with the conventional (ORC–VCR) system widely used in the literature, which combines the ORC with the vapor compression refrigeration (VCR) cycle under various operating conditions (boiler exit temperatures (T_boil= 60 to 90 °C), condenser temperatures (T_cond= 30 to 55 °C) and evaporator temperatures (T_evap= −15 to 15 °C)). It was found that the ORC–EERC exhibited a higher COP_oval and a lower MkW than the ORC–VCR. When the T_boil reaches 90 °C and the other input parameters are at typical values, the COP_oval of both systems (ORC–EERC and ORC–VCR) reaches 0.4984 and 0.4704, respectively, which represents an increase of 5.95%. On the other hand, the MkW of both systems reaches 0.0074 and 0.0084, respectively, which represents a decrease of 11.90%. Overall, the study shows that the ORC–EERC driven by low-grade thermal energy can be considered a promising system to replace the ORC–VCR.