The effects of input power and ambient temperature on the thermal performance of conical pin fin heat sink in natural convection

In the present study, thermal performance tests of horizontally oriented HSconical, HScross-cut, and HSflat with a base plate dimensions of 80*80*5 mm3 were performed in natural convection. The effects of ambient temperature (30 and 40 °C), input power (16.5 and 33 W), and conical pin fin geometry on the thermal performance of the HSs were investigated. The thermal resistance of the heat sinks decreases while the convective heat transfer coefficient, average surface temperature, and average junction temperature increase with increasing ambient temperature and input power. However, the Nusselt number increases with increasing ambient temperature for all HSs at 16.5 W, while the Nusselt number decreases with increasing ambient temperature at 33 W. The highest convective heat transfer coefficients are 32.17, 30.68, and 19.61 W/m2K for HSconical, HSflat, and HScross-cut at 33 W and 40 °C, respectively. The lowest thermal resistances are 2.75, 2.80, and 3.81 K/W for HSconical, HScross-cut, and HSflat at 33 W and 40 °C, respectively. Thermal resistances of HSconical and HScross-cut decreased by 27.78 % and 26.44 % at maximum and 27.06 % and 24.58 at minimum, respectively, compared to HSflat. The results show that the conical fins have better thermal performance in natural convection.