On the coupled system performance of transcritical CO_2 heat pump and rankine cycle

摘要

As one of the natural refrigerants, CO_2 is a potential substitute for synthesized refrigerants with favorable environmental properties. In order to improve the performance of rankine cycle(RankC), the coupled system cycle(CSC)was designed and the performance was analyzed in this paper, which the CSC is combined by the RankC and the transcritical CO_2 heat pump cycle with an expander. Based on thermodynamic principles, the performance analysis platform was designed and the performance analysis was employed. The results show that the average efficiency of the RankC is about 30 %, and the extraction cycle is about 32 %, while the CSC is about 39 %, and the last one is better than the others at the same parameters. With increasing of the boiler feed water temperature, the efficiencies of the three kinds of cycles show increasing trend. With increasing of pressure in conderser-evaporator or outlet temperature of gas cooler, the efficiency of the CSC shows a downward trend. Some fundamental data were obtained for increasing the RankC efficiency by waste heat recovery, and play an active role in improvement the efficiency of power plants.