Analysis of Force Pulsating Convection from Two Heat Sources Mounted with Porous Blocks

• Main Authors: Chao-Fu Yang, 楊朝富
• Other Authors: Po-Chuan Huang
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/8xa5ax

碩士 === 國立臺北科技大學 === 冷凍空調工程系所 === 93 === Recently, the rapid development in the design of electronic packages for modern high-speed computers has led to the demand for new and reliable methods of chip cooling. The purpose of this study is to explore the cooling enhancement from heat sources by using fiber-porous heat sink and flow pulsation. In this work, a numerical study has been carried out for forced pulsating flow in a parallel-plate channel with two porous-block-attached strip heat sources at the bottom wall. The flow over the fluid region is governed by the Navier-Stokes equation, and the flow through the porous medium is governed by the Darcy-Brinkman-Forchheimer equation that account for the effects of the impermeable boundary and inertia. Through the use of a stream function-vorticity transformation, solution of the coupled governing equations for the porous/fluid composite system is obtained using the control-volume method and hybrid scheme. The harmonic mean formulation was used to handle the discontinuous thermophysical properties across the interface. Comprehensive time-dependent flow and temperature data are calculated and averaged over a pulsation cycle in a periodic steady state. The dependence of streamline, isotherm, and enhanced heat transfer rate on the governing parameters defining the problem, such as Reynolds number, Darcy number, pulsation frequency and amplitude, geometric parameters and is documented in detail. The numerical results show the periodic change of shape of recirculation flows caused by porous blocks, which will push the core flow approach to the trailing edge of heat sources, has significant enhanced effect on the cooling of heat sources. This enhanced effect is found to increase with the increase of Reynolds number Re, pulsation amplitude A and frequent St, geometric parameters and , and conductivity ratio , but decrease with the increase of Darcy number. In addition, the oscillation amplitude of pressure drop factor caused by these two methods is increases with Re, A, and , but slightly increases with Da, St, and . In summary, the method combining the pulsating flow with the porous heat sink can be used as an augment heat transfer tool cooling high-speed electronic devices. However, it should be noted that the high heat transfer rate with low pressure lose will be an efficient thermal device in employing the present proposed enhanced method.