Experimental and numerical study on heat transfer enhancement using a microchannel heat sink subject to an impinging jet

Abstract

This thesis is to introduce a microchannel heat sink subject to an impinging jet, which has characteristics of the high heat transfer coefficient and the small pressure drop. For the purpose, the thesis first investigates the fluid flow and heat transfer phenomena of the microchannel heat sink subject to an impinging jet experimentally. In order to investigate the thermal characteristics of the heat sink experimentally, a micro-thermal sensor array is developed to measure temperature distributions at the surface of microstructures. Microfabrication processes for the micro-thermal sensor array and their advantages are described. The main objective of the thesis is to present correlations for the pressure drop and the thermal resistance in terms of geometric variables and the Reynolds number. In order to present a correlation for the pressure drop a similarity solution of velocity profiles for a microchannel heat sink subject to an impinging jet is obtained by using a porous medium approach. The pressure drop obtained by a similarity solution is compared with that of experimental results. Based on the similarity solution and experimental results, a correlation of the pressure drop is proposed. In order to present a correlation of the thermal resistance, the thermal characteristics of the microchannel heat sink subject to an impinging jet are experimentally investigated with a micro-thermal sensor array. Based on the experimental results a correlation of the thermal resistance is presented. Effects of the channel height and the width on the pressure drop and the thermal resistance are experimentally explained. The microchannel heat sink subject to an impinging jet is shown to be capable of minimizing the two inherent disadvantages of the microchannel heat sink with a parallel flow, which are the high pressure drop and the large temperature difference between the inlet and the outlet within the heat source. In addition, it is shown that the microchannel heat sink ...