回热式布雷顿热泵的生态学性能优化研究

Due to the destruction of the ozone sphere by chlorofluorocarbon (CFC) and the pressure of environment protection, the traditional vapor-compression heat pump using CFC as working fluid is increasingly restricted. Brayton heat pump, of which working fluid is environmental-safe air has been paid more attention. The Brayton heat pump cycle is one of the most important air heat pump cycles. In this paper, a performance analysis and optimization of a regenerated Brayton heat pump cycle has been carried out by taking the ecological coefficient of performance (ECOP), i.e., the ratio of heat load to the loss rate of availability (or entropy generation rate), as the optimization objective. The irreversibilities considered in the analysis include the finite heat transfer rate in the hot- and cold-side heat exchangers and the regenerator, the non-isentropic compression and expansion losses in the compressor and expander, and the heat leakage. The maximum of the ecological performance criterion and the corresponding optimal conditions have been derived analytically. The effects of the temperature of the working fluid on the performance of this cycle have been investigated. The influences of the effectiveness of the regenerator as well as the hot- and cold-side heat exchangers, the isentropic efficiencies of the compressor and expander on the ECOP are examined and shown by numerical examples.