Hydrothermal performance in the Hydrodynamic Entrance Region of Rectangular Microchannel Heat Sink

Abstract

Microchannel heat sink is an advanced cooling technique that can fulfil cooling demand for the compact electronic devices which have high power density in its microchip. However, fast development in electronic industry increases the power density rapidly. As consequence, innovation of microchannel heat sink design is required in order to remove the high heat flux generated by the electronic device. In the microchannel innovation, basic problem that has been experienced by the conventional microchannel heat sink (rectangular microchannel heat sink, CR MCHS) need to be identified first before the new microchannel design is proposed. The hydrodynamic entrance region is one of the issues in a microchannel heat sink because it will affect hydrothermal performance in the conventional microchannel heat sink. Thus, in this paper, the effect of hydrodynamic entrance region on fluid flow and heat transfer characteristic had been investigated numerically for the Reynold number of 100 – 800 at the constant wall heat flux of 100 W/cm2. The result showed that the thermal resistance in the hydrodynamic entrance region of CR MCHS is lower than in the developed region. However, pressure drop in the developing region is higher that developed region due to the highest wall shear stress in the entrance region. For hydrodynamic diameter, Dh = 133 μm, the hydrodynamic entrance length of Re = 100 is 4 mm from channel inlet, while Re = 800 is 9 mm from the channel inlet.