Numerical investigation and optimization of fluid flow and heat transfer performances of cross-cut heat sinks

Minichannel heat sinks are used extensively since their ability to transfer large amount of heat load from small space. In this study thermal and flow performance of cross-cut heat sinks are investigated numerically. The flow characteristics in the heat sinks are investigated such that Reynolds number of the flow is found to be greater than that of critical Reynolds number in the internal flows which is specified as 2300. Consequently the flow is turbulent and the turbulence effects are taken into account in the analyses. Then the results of numerical analyses are compared to the experimental results in the literature. Parameters that affect the flow and thermal performance of the heat sinks are analyzed individually. The geometric parameters that affect performance of cross-cut heat sinks are determined to be channel width and cross-cut length. The values fall into interval 1mm and 3mm are investigated as channel width. Increase in channel width results in increase in flow and thermal performance. However for a fixed value of total heat sink width increase in channel width will lower the number of channels in the heat sink which will decrease the thermal performance. The values fall into interval 3mm and 10mm are investigated as cross-cut length. As the cross cut length increases the flow performance of the heat sink is also increased. Thermal performance is decreased up to the value of 6mm for values greater than 6mm thermal performance began to increase. After the numerical investigations, an optimization code in written in C programming language. Then the code is used to find optimized values of channel width, cross-cut length and inlet velocity of the fluid for 0,01W, 0,05W and 0,1W values of pumping power. The results obtained from numerical analyses are compared to the thermal resistance values in the literature. For pumping power of 0,01W obtained thermal resistance value is %14,8 smaller, for pumping power of 0,05W obtained thermal resistance value is %9,7 smaller and for pumping power of 0,1W obtained result is %3,12 greater than the result in the literature.