| The heat pump air conditioning system is energy-saving and high efficiency.So this air-conditioning system has a good development prospect and value in new energy vehicles.The scroll compressor has many advantages of small and lightweight,simple structure,high efficiency,and low noise.So the scroll compressor is widely used in the heat pump air-conditioning system of new energy vehicles.There are two main problems in the operation of the scroll compressor,one is the traditional circular involute scroll profile is limited in space utilization and efficiency,the other is the discharge temperature of the scroll compressor is too high caused by the heat pump system of energy loss in winter.To solve the above two problems,the scroll compressor in the heat pump air-conditioning system of new energy vehicles was taken as the research object in this paper.Based on the CFD method and dynamic grid technology,the transient internal flow simulation was investigated.The internal flow field distribution of different types of scroll compressors was compared to obtain the optimal internal structure direction of scroll compressors.The main research contents and conclusions of this paper are as follows:(1)The three-dimensional working chamber models of single circular involute line and combination line(circular involute-circular arc-circular involute)of scroll compressor were established by the calculation of scroll profile equations,and the law and distribution of internal flow with crankshaft working were explored.The results showed that the temperature in the compression chamber increased as the pressure increased.The average pressure and average temperature of the central compression chamber of the combined profile compressor were 30.33 kPa and 2.35 K higher than those of the circular involute compressor,respectively.Both of the two profile compressors had high velocity near the meshing site,and there were tangential leakages.However,the meshing point of the combined profile scroll compressor was less than that of the circular involute compressor.And the combined profile compressor’s volumetric efficiency was 18.9% higher than that of the circular involute.At the same size,the combined profile could effectively improve the pressure ratio and compressor efficiency.(2)On account of compressor working performance with vapor injection,a computational model was established and transient numerical simulation was carried out.Compared with the no-injection scroll compressor,the differences in unsteady flow and performance of these two working forms of the scroll compressor were analyzed.The results showed that the imbalance of pressure distribution affected the fluctuation of pressure in the central compression chamber.Compared with a noinjection compressor,the vapor injection could reduce this imbalance distribution in the central compression chamber.What’s more,the average discharge temperature of the central compression chamber was reduced by 6 K,and the isentropic efficiency was increased by 8.51%.The vapor injection technology for improving compressor efficiency and reducing discharge temperature was proved.(3)The compressor models with two connected circular injection holes with the center distance of 1.2mm,2.2mm and 2.4mm were established.The effect of the connection center distance on compressor performance was analyzed and the connected hole shape was optimized.The results showed that the center distance of connected circular holes increased,the isentropic efficiency rose,while the discharge temperature decreased accordingly.The average discharge temperature of the connected hole with a center distance of 2.4 mm was 3.08 K lower than that of the single circular hole model,and the isentropic efficiency of the model was 0.78% higher than that of the single circular hole model.Moreover,compared with the arc structure,the vector direction near the linear structure was relatively consistent,which was more likely to produce a vortex trend,which affected the refrigerant injection effect. |
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