Study On The Modulation Characteristic Of Scroll Compressor With Refrigerant Release

The heat pump air conditioner and the air source heat pump water heater have beenwidely used in residential buildings and light commercial buildings. Decreasing thepower consumption of these equipments is an important way-out for energy-saving ofthose buildings. Compared to the design condition, the real air conditioner works inmuch moderate environments at most of the time and can’t provide outstanding seasonalenergy efficiency performance. This paper focuses on both the capacity and innercompression ratio regulation of the compressor when the air conditioners and heatpumps work in mild environments and part load situations. It has a great meaning forthe heat pump research.Firstly, this paper has discussed the requirements to regulating method ofcompressors according to buildings’ actual demand. The annual hourly load distributionof office buildings and residential buildings in Beijing, Shanghai and Guangzhou arecalculated using building energy-consumption simulating software DeST. The heatpumps with suitable capacity are selected based on indoor load and simulations arecarried on to study the system compression ratio at different hour. It shows thatair-sourced air conditioner used in residential buildings and light commercial buildingsdo usually need to work in a part capacity condition and the needed cooling capacitydecreases with the decrease of the outdoor temperature. The compressors in the systemsalso need to work in low compression ratio conditions most of time and the requiredcompression ratio in cooling decreases with the decrease of the outdoor temperature.Therefore, the compressor used in high seasonal efficient air conditioners should havethe ability of capacity reduction as well as compression ratio reduction.Secondly, a test plant is built and some experiments are conducted for research theinfluence of scroll compressor with refrigerant release. The result shows that therefrigerant release can reduce the inner compression loss of the scroll compressor underover compression conditions, decrease the heating/cooling capacity of therefrigeration/heat pump system and enhance the system COP.Thirdly, the scroll compressor model is modified by experimental data. Thesimulation results are compared with experimental results and it shows good agreement. The effects of the release parameters to the performance of the scroll compressor andthe heat pump system are simulated and analyzed based on the model of the scrollcompressor. Then, theoretical optimal control strategies for refrigerant release systemare put forward and the optimal design method to the release port is also advanced.Finally, based on previous research of effects of refrigerant release on the scrollcompressor and its air conditioner, the annual performance of the heat pump airconditioner and heat pump water heater using scroll compressor with refrigerant releaseare simulated in different climates. The energy-saving potential of refrigerant release isverified under different climates and the result shows that the refrigerant release is apromising technique for both heat pump air conditioner and split heat pump waterheater.