Thermal studies on heat sinks exposed to solar irradiation

The effect of solar irradiation on the temperature of an electronic device attached to a heat sink is studied. Heat sinks with different surface treatments are considered for this study. The contribution of absorbed solar heat by the Alumina coated fin surface varies from 2.1 % to 12.4 % of the heat generated by the electronic devices and it reveals that the amount of solar heat absorbed by the black painted heat sink is almost equal to the heat generated by the electronics system. It is also found that the percentage of heat transfer by radiation varies from 6.2 % to 11.0 % for commercial finish heat sinks and is as high as 58.7% for a black painted heat sink. The combined effect of emissivity and solar absorptivity is studied to optimize the heat sink. For 10 mm fin height, the black painted heat sink illustrates better performance and for 20 mm and 30 mm fin height, the Alumina coated heat sink exhibits better performance. The temperature of the electronic device increases when the base area of the heat sink is increased beyond 700 cm2, which is the optimum base area. When the fin height is increased to 20 mm, the optimum base area for the black painted and Alumina coated heat sink is also increased to 780 cm2 and 850 cm2 respectively, thus reducing the device temperature further. The CFD results are validated with the temperature measurement conducted on the heat sink exposed to solar irradiation.