The Short-circuit Flow Analysis And Structure Optimization Of The Oil-gas Separator Of The Electric Scroll Compressor

In recent years,the electric vehicle industry has ushered in rapid development,and as an electric vehicle-related industry chain,electric air-conditioning scroll compressors have also been greatly developed.The built-in oil and gas separator of the electric scroll compressor is extremely important for the smooth operation of the compressor.The main function is to separate the lubricating oil carried in the refrigerant cycle,and prevent excessive lubricating oil from entering the condenser and evaporation of the refrigeration system.The heat exchange efficiency is affected by the air-conditioning system and the performance of the air-conditioning system is reduced.The lubricating oil separated and recovered by the oil-air separator enters the back pressure cavity,the second oil storage cavity and each compression cavity of the compressor in order to play the role of lubricating and cooling compressor components and sealing.If a large amount of lubricating oil is lost,it will cause poor lubrication of the compressor and abnormal wear,and even a dry burning accident of the compressor scroll,resulting in the paralysis of the air-conditioning system.In this paper,the oil-gas separator in the front shell of a company’s electric scroll compressor is used as a reference model.Aiming at its internal flow field,the swirling flow of high-pressure gas-liquid two-phase flow is simulated and analyzed.Taking separation efficiency and pressure drop as evaluation indicators,using range analysis method,the influence of the changes of the four structural parameters of the exhaust pipe on the performance of the oil and gas separator is studied,and the order of influence of the structural parameters of the exhaust pipe is determined.Transient simulation of the whole process of the airflow entering the cyclone of the separator,the flow characteristics of the short-circuit flow were obtained,the position and morphology of the short-circuit flow area in the oil-gas separator were analyzed and characterized,the proportion of the short-circuit flow was calculated,and the formation mechanism of the short-circuit flow was determined.Finally,the separator was optimized from the two structural optimization directions of the volute inlet and the cone-shaped riser.The study shows that in the study of the four structural parameters of the exhaust pipe,the diameter of the exhaust pipe has the greatest influence on the pressure drop,the offset distance of the exhaust pipe has the greatest influence on the separation efficiency,and the weakest influence on the pressure drop and separation efficiency is the insertion depth of the exhaust pipe.It is found that part of the airflow does not enter the separation space downwards after entering the oil and gas separator,but escapes directly from the exhaust port in a short circuit.That is to say,a steady short-circuit flow field has been formed in this process.Exploring and determining the radial velocity can well characterize the short-circuit flow area,using the three-dimensional iso-surface of the radial velocity can determine the morphology and flow field size of the short-circuit flow,and intercepting and calculating the proportion of the shortcircuit flow.The inlet structure and riser structure of the oil and gas separator were optimized,and it was found that the swirling flow in the volute inlet oil and gas separator was more stable than that of the traditional direct cut inlet oil and gas separator.The larger the inlet volute wrap angle,the higher the separation efficiency.For small particles below 2 ?m,the separation efficiency increases by more than 20%.Through the simulation study of the conical,straight and conical riser oil and gas separators,it is found that under the same boundary conditions,the flow field parameters of the conical riser are better than other riser structure oil and gas separators.The static pressure distribution of the flow field is symmetrical,the tangential velocity distribution is larger than that of other types of oil and gas separators,and the separation performance is better.