Thermodynamic Analysis of a Combined Vapor Compression Refrigeration Cycle and Organic Rankine Cycle via a Sharing Heat Exchanger

Abstract

AbstractIn this paper, an attempt has been made to carry out thermodynamic investigation of an integrated organic Rankine cycle for waste heat recovery from a vapor compression refrigeration cycle (VCRC). The heat rejected by the vapor compression cycle is utilized and converted into electrical energy by running an organic Rankine cycle (ORC). A sharing heat exchanger (SHX) is used to transfer the heat from VCRC to the ORC. It works as the condenser in VCRC as well as the evaporator in ORC. Six refrigerants are selected as the working fluids for the refrigeration subsystem, which are R134a, R407C, R404A, R407C, R600a, and R410A. Four different working fluids (R123, R227ea, R600, and R245fa) are chosen as the candidates for the ORC subsystem. Coefficient of performance (COP), the energy output, and the thermal efficiency of the combined arrangement consisting of ORC and VCRC are considered as main performance parameters for this numerical work. For the present investigation, total of 24 working fluid combinations are considered, and the system performances with these combinations are analyzed and compared. Results show that the maximum COP of about nearly 3.5 is obtained when R134a is taken as the working fluid in the VCR cycle, and R600 is taken as the working fluid in the ORC. The maximum thermal efficiency and the maximum energy output are obtained when R123 and R245fa are used as working fluid in the ORC, respectively. The corresponding values are 3.1% and 3.5 kW for a 10-ton capacity refrigeration plant.KeywordsOrganic Rankine cycleVCR cycleSHXCOPCombined thermal efficiency