Flow Field Analysis And Structure Optimization Of Oil-Gas Separator For Electric Scroll Compressor

In recent years,the booming development of the electric vehicle industry has brought unprecedented opportunities for the development of scroll compressor.The built-in oil separators play a vital role in the stable operation of the compressor.The function of the oil separator is to separate the lubricating oil mixed in the refrigerant gas in the exhaust chamber,to avoid excessive lubricating oil entering the refrigeration system and affecting the heat exchange efficiency;the separated and recovered lubricating oil not only lubricates and seals the compressor,but also insufficient recovery of lubricating oil will lead to a reduction in back pressure,which ultimately affects the balance of the orbiting scroll.In this paper,the oil-gas separator of electric scroll compressor was taken as the research object.The numerical simulation method was used to simulate the flow condition of gas-liquid two-phase flow.The important performance indexes of separation efficiency and pressure drop were studied,and the response surface method was used to analyze the structure parameters.The influence of parameters on the performance of the oil-gas separator was studied to design a set of separators with the best performance.Firstly,the ICEM CFD was used to classify the computational domain of the scroll compressor oil-gas separator.The Reynolds Stress Model(RSM)suitable for strong swirl flow in Fluent was used to simulate the pressure and 3D velocity distribution of the gas phase.The local secondary flow existing in the flow field was analyzed,and the pressure loss of the oil separator was studied.The influence of the exhaust pipe on the pressure loss was also explored.Then,based on the gas phase flow,the Discrete Phase Model(DPM)was used to simulate the tracking of the oil droplets.The classification efficiency of oil-gas separation was obtained by the movement of oil droplets with different particle sizes,and the separation efficiency and pressure drop in oil-gas separation at different speeds was studied.The results show that the separation efficiency increases with the increase of particle size,but it has nothing to do with the initial inlet position of oil droplets;the movement of oil droplets has nothing to do with the initial position of the inlet,but has a great correlation with the particle size of oil droplets;Both separation efficiency and the pressure drop increases with the increase of the compressor speed,and the pressure drop increases in proportion to the square of the rotational speed.Finally,the response surface method was used to analyze the significance and interaction effects of the main factors affecting separation efficiency and pressure drop.It was concluded that the inner diameter of the intake pipe and the inner diameter of the exhaust pipe are the main factors affecting the pressure drop.The pressure drop decreases with the increase of the inner diameter of the intake and exhaust pipes.The inner diameter of the intake pipe is the main factor affecting the separation efficiency.Separation efficiency is increased with the inner diameter of the intake pipe decreases.The regression equations of pressure drop and separation efficiency were obtained by analysis of variance.Considering the pressure drop and separation efficiency,the optimal oil-gas separation was obtained.Comparing and analyzing simulated values of CFD and the predicted values of regression equations,the results were in good agreement,indicating that the response surface method can accurately predict the separation efficiency and pressure drop of the oil separator,which can be used as a new method for optimal design of oil-gas separators.The research results in this paper can provide reference for the optimization design and in-depth study of oil-gas separators.