| Because of its environmental performance and thermal physical properties, CO2, a natural working fluid, has great advantages when being compared with other alternative refrigerants. Transcritical CO2heat pump system is a typical application of CO2. Studies have shown that the throttling loss of transcritical CO2cycle can be reduced by adding an ejector to the system. Ejectors are simple and easy to manufacture. However, the internal flow process of the ejector is very complex. Ejector’s geometry design is critical to the transcritical CO2ejection system’s stability and efficiency. Therefore, to design ejectors matched with the certain transcritical CO2heat pump system, and study it’s performance under a large range of working conditions, is of significant importance to improve the system performance. In this research, method on ejector design was studied. A fixed type ejector was designed, as well as a transcritical CO2heat pump system with ejector. Experimental investigation on CO2ejection system was also carried out. The main contents of the research are as follows.1) Experimental investigation on a transcritical CO2system was carried out. The relationship between working parameters and performance of the ejector was studied. A performance comparison of ejection system and conventional system was also studied.2) By using the method of air dynamics, the geometries of a fixed type ejector were calculated. An ejector for the transcritical CO2ejection heat pump system was designed and manufactured. 3) A transcritical CO2ejection heat pump system was designed. The system can be switched between conventional transcritical CO2system, transcritical CO2system with ejector, transcritical CO2system with ejector and internal heat exchange. The main components of the system such as the calorimeter, gas-liquid separator, and internal heat exchanger were designed and selected. |
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