Conjugate Mixed Convection with Surface Radiation From a Horizontal Channel with Heat Generating Component

• Main Authors: Chih-Hung Wang, 王智弘
• Other Authors: 黃博全
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/tk79h6

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 101 === In recent years, due to the rapid development of electronic products, the relative electronic components heat is getting higher and higher, how to effectively remove the heat of electronic components to ensure the efficiency and life of the electronic equipment has become an important issue. However, the general studies in the electronic cooling almost ignored the effect of radiation and only took conduction, and convection into consideration. The obtained results can not accurately reflect the actual situation. The purpose of this study is to investigate the cooling of the electronic components under the consideration of surface radiation and the conduction in the wall. In this work, a numerical study was carried out for the thermal and flow field distributions and heat transfer characteristics from a steady-state flow, horizontal channel with the rectangle electronic package heat source blocks. The thermal-flow field is governed by energy and Navier-Stokes equations in the fluid region. Through the use of a stream function-vorticity transformation, solution of the coupled governing equations for the fluid/solid system is obtained using the control-volume method. Then importing the solid/fluid interface energy conservation conditions with the radiant heat transfer to obtain the total heat transfer. The radiation heat transfer is based on the radiosity / irradiation method. This study details the effects of variations in the Reynolds number, surface emissivity of packaging materials and the channel walls, thermal conductivity ratio of the packaging materials and the channel walls, and the modified Grashof number, to illustrate the important fundamental relations between the thermal-fluid field and the heat-source cooling. Selected basic operating parametersRe=500、Gr=2.89x105、qv=3x106、kp/kf=100、ks/kf=50、εp=0.55、εs=0.55. The numerical results obtained the following conclusions: (1) While carrying out a thermal analysis of circuit boards with electronic chips, the consideration of radiation heat transfer is absolutely essential to accurately predict the non-dimensional maximum temperature, in this study the maximum temperature drops from 355K in the pure convection case to 343K in same case with radiation, (2) The cooling effect of rectangle electronic package devices increases with the Reynolds number, and the maximum temperature drop is about 16 degrees, (3) compared to the surface emissivity of packaging material, increasing the surface emissivity of channel walls can be more effectively reduce the system temperature, (4) Increasing the thermal conductivity ratio leads to strong the heat transfer phenomena in rectangle electronic package blocks and the channel walls. Overall, in the low Reynolds number condition or the system under the conditions of high temperature, the cooling effect of the radiation heat transfer is more significant resulting in further improvements to achieve the desired working environment.