Paramertric thermal analysis of plate-fin heat sink using embossed impressions

Abstract

Thermal management for heat generation in the power electronics, concentrated solar panels and fuel cells requires a special and effective cooling system. A series of numerical runs for parametric study, such as the effect of fins space, heights of fins, effect of embossed impressions, the shape of embossed impressions and the angle of attack of the embossed impressions have been carried out. Firstly, six geometries, have 0.2 mm, 0.5mm 1mm fins space and with 3 and 5 mm heights compared to smooth heat sink were studied. Secondly three different geometries heat sinks with fin spacing's of 0.2 mm, 1.0 mm and Embossed fins along were studied numerically to investigate the effect of embossed impressions. Thirdly three different geometries heat sink with triangular, rectangular and semicircle embossed impressions attached to the fins were studied numerically to investigate the effect of embossed shape. Finally, the embossed impressions angles 30, 45, 60 and 90 degree were investigated. Source load 325 W at the bottom of heat sink and different volumetric flow rate 0.5, 0.75 and 1 liter per minute were used. The results have shown that, the fined heat sink has more heat transfer rate, 194.3 watts at 1liter per minute. Moreover, thermal resistance and base temperature reduced 58 % and 30.7 % compared to flat plate respectively. Also, the height of fins reduced the base temperature 2.84?. Likewise, the embossed impressions heat sink reduced the base temperature about 5.8% lower than the best reported base temperature using a water compared with commercial heat sink in the open literature. In addition to, for spacing 0.2 mm heat sink, the highest thermal resistance was 0.0578 K/W that was decreased to as little as 0.0292 K/W by using an embossed heat sink. The triangular embossed impression has attained the lowest heat sink base about 6.45% lower than the best reported base temperature in the open literature. The thermal resistance was 0.028, 0.030 K/W and 0.025 of rectangular, semicircle and triangular embossed shapes respectively at mass flow rate 1LPM. Angle of attack 45 degree was the best compared as, the lowest heat sink base temperature of 37.2 C was achieved by using a triangular embossed heat sink at angle 45 which was about 3.5 C lower than the best reported base temperature of 40.7 C. The average heat transfer coefficient was attained to be 3239 W/m2 K, 2828 and 3474 W/m2 K for the case of rectangular, semicircle and triangular embossed shapes, respectively. Finally, two embossed and smooth heat sinks were fabricated at IIUM laboratory, then tested experimentally under forced convection using water, Reynolds 800-2800.This work suggests that one can adapt larger number of embossed channel and smaller fins space to have less thermal resistance rather than only increasing the pumping power.