Experimental study on a heat driven refrigeration system based on combined organic Rankine and vapour compression cycles

Abstract

Waste heat recovery has been considered as an attractive technique to improve the overall energy utilization efficiency of internal combustion (IC) engines. In this paper, as distinct from most past research work, a thermally driven refrigeration system based on combined organic Rankine and vapour compression cycles is proposed to recover the IC engines’ waste heat contained in the cooling water. Based on the proposed concept, a lab-scale prototype has been designed and constructed using off-the-shelf components to prove the feasibility of producing refrigeration for ships and refrigerated lorries. In this prototype, the power generated by the Organic Rankine cycle (ORC) is used to drive the compressor of a Vapour Compression Cycle (VCC) through a belt transmission mechanism. Pentafluoropropane (R245fa) and Tetrafluoroethane (R134a) are used as the working fluids for ORC and VCC systems, respectively. An electrical water heater is used to simulate the cooling jacket, while a cooling enclosure is used to simulate the cooling load. With the hot water at a temperature around 95 °C, the system produces around 1.8 kW refrigeration effect at −4 °C, leading to an overall heat-to-cooling efficiency of 0.18, which is defined as the ratio of the cooling capacity of the refrigerator to the heat input to the ORC power plant. The system performance could be significantly improved if optimal components could be utilized.