Experimental investigation on heat transfer and pressure drop of a novel cylindrical oblique fin heat sink

A novel cylindrical oblique fin minichannel heat sink, in the form of an enveloping jacket, was proposed to be fitted over cylindrical heat sources. The presence of the oblique fins disrupts and reinitializes the boundary layer development at the leading edge of each fin. This results in a significant reduction of the boundary layer thickness and causes the flow to remain in the developing state. Experimental investigations were conducted to compare its heat transfer performance with conventional straight fin minichannel heat sink. The test pieces were fabricated from copper and measurements on the heat transfer characteristics were performed for Reynolds number ranging from 50 to 500. In addition, the effects of flow distribution were examined and it was found that cylindrical oblique fin structure eliminates the edge effect which is present in the planar oblique fin configuration. The uniform secondary flow generated by the cylindrical oblique fin structure improves fluid mixing and enhances heat transfer significantly. The experimental results showed that the average Nusselt number for the cylindrical oblique fin minichannel heat sink increases up to 75.6% and the total thermal resistance decreases up to 59.1% compared to the conventional straight fin heat sink. For a heat flux of 6.1 W/cm2 and Reynolds number of 300, the average surface temperature of cylindrical heat sink is reduced by 4.3 °C compared to conventional straight fin heat sink while the required pumping power remains comparable.