HEAT TRANSFER AUGMENTATION OF HEAT SINKS THROUGH INCREASING EFFECTIVE TEMPERATURE DIFFERENCE

The present study proposes the step and trapezoid fin patterns applicable to the air-cooled plate fin heat sinks and plate-pin fin heat sinks. A total of four fin structures are designed and studied, including 1/2 step cut, 1/3 step cut, 1/2 trapezoid cut, and 1/3 trapezoid cut. The test results indicated that for the plate fin heat sinks, the heat transfer coefficient of the 1/2 step cut, 1/3 step cut, 1/2 trapezoid cut, and 1/3 trapezoid cut fin patterned heat sinks can be increased by up to 11%-16% with a 24%, 32%, 18%, and 23% reduction of surface area, respectively. Moreover, for the plate fin heat sinks with cut designs, the proposed designs can offer a maximum of 45% pressure drop reduction over the conventional design. The heat transfer augmentation is mainly attributed to the fresh air entrainment and the formation of multiple developing flow regions at the back end of the heat sink. As far as the plate-pin fin heat sink is concerned, the proposed fin patterns offer only a minor improvement (< 2%-3%) in the heat transfer coefficient, whereas it can reduce the pressure drop penalty up to 45% by suppressing the wake formation.