Thermoeconomic performance analysis of different configurations of a combined ORC-VCR system using zeotropic mixtures

Abstract

From the perspective of environmental protection, the application of new environment-friendly working fluids provides more feasibility for sustainable development. In addition, the improvement of system configuration increases the possibility of improving system performance. In this paper, the thermodynamic and economic performance model of the organic Rankine cycle (ORC)-vapor compression refrigeration (VCR) combined system is established. Four system configurations and 12 zeotropic mixtures on the system performance are researched and compared. The effect of operating parameters on system performance is studied. The results show that the recuperative-regenerative ORC-VCR (RR-ORC-VCR) system is confirmed as the optimal system configuration. Compared with the basic ORC-VCR (B-ORC-VCR) system, the coefficient of performance (COP) and exergy efficiency are improved by 14.65 % and 10.03 %, respectively. While the total cost increases by 6.85 %. The most suitable working fluid is R245fa/R1234yf (0.55/0.45). Higher glide temperature can be an important criterion in the selection of zeotropic mixtures. When the suction pressure ratio is 0.6, exergy efficiency and total cost are optimal, which are 11.95 % and 1.34 × 105$, respectively. While the highest COP with 0.73 is achieved when the suction pressure ratio is 0.65. With the increase of boiler temperature, the thermodynamic performance of the system increases obviously, but the economic performance decreases. The increase in condenser temperature has a negative impact on the system thermodynamic and economic performance. The growth of evaporator temperature is positively correlated with COP and negatively correlated with exergy efficiency and total cost.