Thermodynamic analysis and parametric optimization of ejector heat pump integrated with organic Rankine cycle combined cooling, heating and power system using zeotropic mixtures

To improve the coefficient of performance (COP) of ejector refrigeration cycle (ERC), a novel ejector heat pump integrated with organic Rankine cycle combined cooling, heating and power system (ORC-CCHP) using zeotropic mixtures is established in this study. The comprehensive thermal efficiency is proposed considering exergy efficiency and heat recovery efficiency simultaneously. Results show that the entrainment ratio can be determined with the objective of exergy efficiency, while generator temperature and mass fraction of zeotropic mixture are optimized with the comprehensive thermal efficiency. With the optimized entrainment ratio of 0.2 and generator temperature of 351.15 K, R141b/R134a (55%/45%) achieves the power efficiency of 4.21%, refrigeration efficiency of 14.6% and COP of 1.12, which are considerably higher than those of pure R141b or R134a. Meanwhile, R141b/R134a with optimum mass fractions in ORC and heat pump loop can generate plentiful refrigeration capacity, great temperature glides in the high-temperature evaporator and high-temperature condenser. The comparative analysis of basic ORCs, ORC with post ejector, ORC with ejector heat pump, ORC combined with ejector (EORC) is carried out. The ejector heat pump integrated with ORC-CCHP system is thermodynamically feasible and economically attractive, thanks to optimized system parameters and optimum compositions of zeotropic mixture, giving support of new applications of ERC coupled with positive and reverse Carnot cycles.