Numerical Analysis And Structural Optimization Of Flow And Heat Transfer Characteristics In Rectangular Microchannels

With the rapid development of science and technology,the size of the micro equipment is gradually reduced and the degree of integration is increasing,which leads to the rapid increase of the heat flow density per unit size,so the heat dissipation problem in the microelectronic system is becoming more and more prominent.At present,it is of great significance to design and develop a micro-channel heat exchanger with higher heat transfer efficiency and more reasonable structure to improve the heat transfer performance at micro scale.This article selects the smallest flow units of microchannel heat sink,with a single microchannel as the research object,based on the continuum assumption,the variable physical parameters settings.Numerical simulation is used to study the flow and heat transfer problem of rectangular microchannel with different section shapes and rectangular groove structures,which can put forward some suggestions on the structural design of microchannel heat exchanger.In order to solve the problem of flow and heat transfer of deionized water in rectangular microchannel with different sectional shapes,a 3D model was established and the corresponding numerical simulation was carried out.The results of numerical analysis show that,with the increase of inlet velocity,the flow resistance of microchannel increases,the heat transfer performance and comprehensive performance are improved,and the heat transfer surface temperature is significantly reduced.In the case of the same aspect ratio,with the increase of the hydraulic diameter,the flow resistance decreases,the heat transfer performance decreases,and the comprehensive performance of the microchannel improves.Under different restriction conditions,increasing the aspect ratio of the channel section and changing trend of the flow and heat transfer characteristics of the microchannel are different,but all of them can improve the uniformity of the temperature distribution of the channel,effectively improve the cooling effect of the heat transfer surface and enhance the comprehensive performance of the microchannel.In the case that the section width remains unchanged,when the aspect ratio is higher than 2 and continues to increase,the improvement range of temperature uniformity and cooling effect is significantly reduced,while the comprehensive performance is slightly reduced.Considering the available space around the micro-equipment,the section aspect ratio should be designed between 2 and 4 in the design of microchannel structure.In order to strengthen the heat transfer in the micro channel,the numerical simulation method is used to study the flow and heat transfer characteristics inside grooved rectangular microchannel,analyze the comprehensive performance of microchannel and discuss the influence of slot depth,slot width,slot spacing,slot number and groove arrangement.The results of numerical analysis show that,adding grooves to the side wall of the micro-channel will lead to increase flow resistance and reduced comprehensive performance of the micro-channel.In the case of low inlet flow rate,that is,when the inlet flow rate is less than 2m/s,its heat transfer performance will be inferior to that of flat and straight microchannel.At this time,the flat and straight microchannel radiator with better performance should be selected.At high inlet flow rate,when the inlet velocity is greater than 4m/s,the design of groove structure with shallow groove depth,moderate groove width and small groove spacing is helpful to improve the heat transfer performance of the microchannel and enhance cooling effect on heat transfer surface.In this paper,the grooved rectangular micro channel with a depth of 0.02mm,a width of 0.3mm and a spacing of 0.3mm has the best heat transfer effect compared with the flat microchannel,the heat transfer factor j is increased by 12.2%,and the heat transfer surface temperature is reduced by 4.8k.The increase in the number of grooves will lead to the increase of the flow resistance,the improvement of the heat transfer performance,and a small reduction in the comprehensive performance.However,when the number of grooves reaches a certain level,the heat transfer performance and comprehensive performance of the micro channel will decrease significantly.Therefore,a large number of rectangular grooves should be avoided in the design.The dislocation arrangement of the groove can significantly reduce the flow resistance in the channel,reduce the heat transfer performance,and improve the comprehensive performance.The heat transfer performance is better than the dislocation arrangement when the groove is symmetrically arranged.Although the comprehensive performance decreases slightly,it can effectively improve the cooling effect of electronic components.The research results above play a certain guiding role for the structural design of micro-channel heat exchanger.