Thermodynamic and economic analysis of refrigerant mixture R290/ R1234ze used in an ORC-EERC system for low temperature heat sources

In the process of promoting carbon neutrality, heat driven refrigeration technology has been widely concerned due to its ability to make use of low-grade thermal energy and improve energy utilization. A novel combined organic Rankine cycle and ejector expansion refrigeration cycle (ORC-EERC) system is proposed in this study. To lower global warming potential and flammability, refrigerant mixture R290/R1234ze is chosen as the working fluid. The proposed ORC-EERC system with ejector and vapor-liquid separator are compared with those of the traditional organic Rankine cycle and vapor compression refrigeration cycle (ORC-VCC) by thermodynamic and economic analysis. The simulation results show that the ORC-EERC can achieve higher exergy efficiency and produce lower cooling temperature. Under typical conditions, the total coefficient of performance of ORC-EERC increased by 17.32% and its levelized cost of cooling decreased by 10.45% compared with the ORC-VCC. Furthermore, the ORC-EERC can remarkably improve performance at a lower freezing temperature or a higher condensing temperature. The results of the proposed cycle show that the ORC-EERC system has great application potential in freezers.