Experimental and economic analysis with a novel ejector-based detection system for thermodynamic measurement of compressors

The research of the high-temperature heat pump compressors above 100 degrees C has brought great challenges by its detection system, and in this study, a novel ejector-based detection system has been proposed to measure the thermodynamic performance of the heat pump compressors. The paper began with a numerical method to design the nozzle and diffuser of the ejector. Compared with the results of gas dynamics calculation, the deviations of nozzle and the diffuser were lower than 10.38% and 3.38%, respectively. Furthermore, the compressor performance was analyzed at the suction temperature in the range of 90-110 degrees C while the speed in the range of 2820-3060 r/min. The results showed that the compression ratio varied from 2.3 to 2.7, and the volumetric efficiency as well as isentropic efficiency was 90% and 70%, respectively. Assuming that the compressor was used in a heat pump system at the same operating condition, it was noteworthy that the highest discharge temperature was 184.8 degrees C and the coefficient of performance was more than 3.9. In an actual case, the initial investment cost of the ejector-based detection system is 3311 $, while that of the heat pump detection system is 59,795 $, the economical saving can reach to 94.5%. This is due to the exchanger has been omitted in ejector-based detection system compared with the traditional heat pump detection system. All in all, the novel system was reliable and economical.