Heat Transfer Performance Of Wavy MicroChannel Heat Sinks

Microchannel heat sinks(MCHS)become one of the most promising cooling devices for electronic chip due to its outstanding advantages such as small size,light weight,high surface area-to-volume.Wavy MCHS can decrease thermal resistance by generating Dean vortices and recirculation zones,which appeals to many attentions of the academic field.There are so many researches of wavy MCHS heat transfer performance,but the difference between bottom and side rib is undefined.Thus,a three-dimensional solid-fluid conjugate heat transfer model is established to evaluating the heat transfer performance of bottom rib and side rib.The simulation analyze the influence of amplitude,wavelength,aspect ratio and width ratio,under the same cross-sectional area and pump power.Dean vortices has been verified is the main mechanism to enhance the heat transfer performance of wavy MCHS,the more violent of Dean vortices,the better heat transfer performance.It is found Dean vortices become drastic with high amplitude,short wavelength,high aspect ratio and width ratio,which lead to wavy MCHS has smaller thermal resistance.With high aspect ratio or high width ratio,bottom rib has better heat transfer performance than side rib because it has more drastic and longer distance of Dean vortices under short wavelength,while side rib perform better in long wavelength.With low aspect ratio or low width ratio,bottom rib is better under the same amplitude or small wavelength,while there has no obvious difference between bottom rib and side rib in long wavelength.In addition,as for all the condition in simulation,side rib has the lowest thermal resistance with different wavelength when amplitude remains unchanged.Wavy MCHS with side rib designs can be divided into symmetry and asymmetry based on the pattern of wavy rib.With the same cross-sectional area,the Nusselt number of symmetry and asymmetry pattern has insignificant difference in Reynolds number 50?700,but symmetry wave has high pressure drop.According to Venturi based secondary flow,this paper proposed perforated structure in crest or trough of symmetry wavy MCHS to reducing the pressure drop penalty,and heat transfer performance can be improved to the maximum 27.85%above traditional wavy MCHS.The advantage of secondary flow become unnoticeable when relative amplitude increasing.When asymmetry wavy MCHS has the same perforated structure in the same location as symmetry wavy MCHS,its thermal performance is worse than symmetry wavy MCHS.Change the perforated structure from crest to saddle,both symmetry and asymmetry has better heat transfer performance than before.And symmetry also performs better than asymmetry.What's more,compared with perforated structure in crest or trough,perforated structure in saddle has higher heat transfer coefficient,and its superiority become more evident with the increase of relative amplitude.