Performance analysis of a new mechanical superheat coupled-orc refrigeration system with thermoelectric conversion

Abstract

This paper proposes a new refrigeration and energy conversion system, namely Expander Mechanical Overheating-Organic Rankine Cycle (EMO-ORC) system. Compared with the existing carbon dioxide (R744) refrigeration system, the new system can not only improve the coefficient of performance (COP) of the system and reduce the discharge pressure, but also effectively recover the waste heat of the system, and convert it into electrical energy. Simulation were conducted to compare its system performance with R744 refrigeration system (with heat exchanger), at the same time, the effect of different factors on the performance of new system is analyzed. The results demonstrate that, at the same evaporation temperature and gas cooler outlet temperature, compared with the system (with heat exchanger), the COP of the new system increased by 8.2% and 8.9% on average, respectively. And the discharge pressure decreased by 0.88% and 0.79%, respectively. In the given superheat degree range, compared with the system(with heat exchanger), the COP of the new system is increased by 4.5% on average, and increased by 10.2% at the highest level. Under the most given working conditions, the cooling capacity of new system is higher than that of the system (with heat exchanger), and the power consumption is lower than that of the system (with heat exchanger). In the new system, the narrow point temperature difference and the outlet temperature of the first stage gas cooler have a greater impact on the COP, with the increase of both, the COP of the new system increases by 5.6% and decreases by13.7%, respectively.