CFD ANALYSIS OF MICROCHANNEL HEAT SINK WITH PILLARS

Abstract

In the present study fluid flow, heat transfer characteristics and pressure drop channel heat sinks have been analyzed using computational fluid dynamics. One of them is a single phase straight rectangular micro-channel heat sink on which validation is done. Water is taken as the working fluid for the simulation. The material for heat sink is copper. The micro-channels have a width of 0.226mm and height of 0.71mm. The validation for the straight rectangular microchannel heat sink will be done for five values of Reynolds number 390, 590, 790, 990, and 1190. The input flux to the sink will be taken as 100 W/cm2 and 200 W/cm2 during the simulation .The simulations is done on CFX after modelling in the SOLID WORKS. The work will be extended to include the heat augmented surfaces pillar like structures of cylindrical cross section of length 0.60mm and diameter 0.02602 mm along the flow direction to enhance the thermal performance of heat sink for a given length. Five values of Reynolds number will be used i.e.390, 590, 790, 990, 1190.Four heat flux values are used i.e.100 W/cm2, 125 W/cm2, 200 W/cm2 and 225 W/cm2. The modelling will be done in solid works and its analysis will be done using ANSYS CFX using the same set of five Reynolds number. It was found after the analysis that for constant properties of fluid, there was a linear relationship between Reynolds number and pressure drop. For constant heat flux to the base of the heat sink and inlet temperature of water, the outlet temperature is decreasing with increase in Reynolds number which in turn increases the water viscosity and hence the pressure losses along the flow. Hence pressure losses were more pronounced at higher Reynolds number. The outlet temperature at the channel with pillars was found to be more than that of channel without pillars for same inlet temperature of water and power input. The pressure losses were on a higher side due to the presence of the obstruction in the form of pillars.