Research On The Flow Distribution And Heat Transfer Enhancement Of Micro-Channel Condenser

The improvement of energy-saving emission reduction requirements for car,leads to the heat exchanger also put forward higher requirements.Therefore,with a heat exchanger enterprises in Chongqing developed a 1mm high efficiency microchannel condenser together.Microchannel parallel flow condenser has the advantages of high heat transfer efficiency,light weight,small installation space,small amount of refrigerant required and so on.One-dimensional modeling of the condenser and its flow heat transfer are carried out using the structural parameters of a 1mm microchannel condenser.The change of temperature,pressure and heat transfer coefficient along the length of the length of the flat tube is studied.And compared with the experimental results,the outlet temperature error is 3.34%,the total pressure drop error on the refrigerant side is 7.43%,the total pressure drop of the air side is 3.58%,the total heat exchange error on the refrigerant side is 2.52%,and the air side heat exchange error is 5.09%.The accuracy of the numerical calculation model is verified,can be used for engineering analysis.One-dimensional numerical calculation is based on the average distribution of flow,while in the actual process,the flow of the flat tube is uneven distribution.The more average the flow allocates,the better heat transfer performance of the condenser has.Therefore,three-dimensional CFD simulation is carried out for the flow of the microchannel condenser inlet section.First of all,the influence of the geometry of the inlet pipe on the uniformity of the flow distribution is studied.The simulation results show that the flow distribution uniformity of the refrigerant inlet is basically same while the refrigerant inlet moves between 1/3 and 1/2 of the first flow of the manifold.Then,the influence of the relative position of the inlet pipe and the manifold on the uniformity of the flow distribution is studied.The simulation results show that the flow variance reaches the minimum and the flow distribution uniformity is improved when the refrigerant inlet pipe is perpendicular to the length of the flat tube;Then,a splitter is added at the entrance and the simulation results show that the flow of the variance drops from the original 2.227 × 10-9 to 4.376 × 10-10 when the entrance plus sub-film,It’s close to an order of magnitude.The flow distribution uniformity has great improve.Finally,this paper analyzes and improves the heat transfer of 1mm microchannel condenser flat tube.Five columns(interval 2.56mm)and 68 rows(interval 8mm)of bumps are added to the inner surface of the flat tube,and the CFD simulation of the phase change process of the refrigerant in the flat tube is carried out.The results show that the rate of temperature drop increases,and the liquid volume fraction of the flat tube outlet improves about 7%,which provides the basis and direction for enhancing heat transfer of the flat tube.