摘要
歧管式微通道(manifold microchannel, MMC)热沉散热技术是新兴的微尺度电子冷却技术,具有较高的散热潜力和应用前景.本文使用基于开源软件OpenFOAM编写的自编程求解器,对MMC热沉内过冷流动沸腾的过程进行数值模拟研究.与实验数据进行比对验证之后,对微通道热沉的通道宽度和翅片宽度变化带来的影响进行了初步探讨.结果表明,当通道和翅片的宽度相同时,尺寸越小,热沉加热面的平均温度越低,换热性能越好;但是当宽度过小时(小于15μm),热沉进出口总压降将随着宽度变小而大幅增加.当MMC热沉的通道总数保持不变时,增大微通道宽度,翅片宽度减小,加热面平均温度逐渐上升,进出口压降减小.与经过实验测试的热沉样品A相比,热沉C在牺牲少量换热性能的前提下,可以大幅度降低热沉进出口的压力损失.
Recently, various miniaturized electronic systems and the rapid increase in power density of microelectronic devices have created additional requirements for micro-scale heat dissipation technology. To dissipate heat in a micro-scale region efficiently, several creative cooling methods for high heat flux dissipation have been designed on the order of 1000 W/cm^2.Due to its high surface-to-volume ratio, the microchannel heat sink has become the most popular one among emerging technologies and an effective tool for high heat flux thermal management. Nevertheless, in common electronic microchannel cooling systems, the traditional parallel microchannel causes a dramatic pressure loss along channel length.In this regard, the manifold microchannel heat sink cooling technology becomes promising with its high heat dissipation potential and moderate pressure drop penalty. The shortened effective flow length compared with the traditional microchannel provides a smaller pressure drop and delays the onset of the critical-heat-flux point. However, while a number of numerical and experimental studies have been conducted for the single-phase flow in the manifold microchannel, two-phase flow boiling in this kind of channel is not widely employed because of its issues with flow pattern prediction.This work develops a new solver based on open source software Open FOAM to perform the transient process of subcooled flow boiling in the manifold microchannel heat sink. Additionally, heat transfer in the silicon substrate is considered to improve the accuracy of simulation. Similar to single-phase flow simulation for the manifold microchannel, a unit cell model extracted from the whole cooling plate is employed for the two-phase boiling flow to avoid huge computational costs. Through several reasonable assumptions, the symmetry boundary condition is applied on four lateral surfaces in the unit cell, while uniform heat flux is adopted on the bottom wall. A uniform inlet velocity boundary estimated from the total volume flow rate condition is coupled with a fixed temperature value of 7°C lower than saturation temperature. After the mesh independence test, the self-programming solver and numerical methods are validated by comparing numerical results with experimental data. It is determined that the boiling curve obtained by the empirical rate phase-change model with parameters rl=rv=100 agrees well with experimental results.Furthermore, heat transfer and pressure drop performance differences are caused by microchannel width wcand fin width wf. In comparison to sample A(wc=wf=15 μm), decreasing wcand wfsimultaneously leads to lower average wall temperature of the heated surface;the channel pressure drop between inlet and outlet surfaces rises dramatically when the widths decrease. When the total number of microchannels in the manifold microchannel cooling plate remains unchanged,increasing wcresults in a decreased wf. Based on experimental results, heat sink sample C shows that the pressure loss can be considerably reduced under the premise of sacrificing a small degree of heat transfer performance, which can be attributed to the increased microchannel hydraulic diameter. The manifold microchannel heat sink with wc>wfis recommended for practical application due to lower pressure loss and average temperature variation.
作者
李蔚
骆洋
张井志
Wei Li;Yang Luo;Jingzhi Zhang(Department of Energy Engineering,Zhejiang University,Hangzhou 310027,China;School of Energy and Power Engineering,Shandong University,Ji’nan 250061,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2020年第17期1752-1759,共8页
Chinese Science Bulletin
基金
浙江省自然科学基金(LY19E060004)资助。
关键词
歧管式微通道热沉
过冷流动沸腾
数值模拟
OPENFOAM
强化换热
manifold microchannel heat sink
subcooled flow boiling
numerical simulation
Open FOAM
heat transfer enhancement
