Análise da transferência de calor por convecção natural em dissipadores de calor usando planejamento de experimentos

Abstract

Heat sinks are devices capable of improving the operating temperature of a wide range of equipment. Design of Experiments (DOE) was used for experiments and subsequent statistical data analysis. Experiments were carried out to obtain the distribution of temperatures in the heatsinks. The calculation of heat loss by radiation was performed considering the view factor of the heat sink fins. Tests were made with heatsinks of different geometries, which in this case were considered as factors, such as height (7 mm and 20 mm), spacing (5.55 mm and 14.35 mm) and base length (50 mm and 100 mm) in addition to a heatsink with a 75 mm x 75 mm base. The tests were performed in horizontal and vertical positions, with variations in the calorie flow at the base. Heat flux variations were applied to the heat sink bases of 800 W/m2, 1600 W/m2 and 1200 W/m2. Analyzes were accomplished with experimental data involving the coefficient ℎ̅ , the convection thermal resistance, the geometric parameters (height, spacing and base dimensions) in addition to the heat flux applied to the base and the positioning of the heat sinks. Comparisons of heat lost by radiation were made by taking into account the view factor of the fins. Finally, statistical analyses were conducted, seeking to know the behavior of the convective thermal resistance and its variation according to the geometries of the heat sinks and applied heat flux. With the results obtained it was concluded that the heat sinks tested on the vertical position have better performance when compared to those on the horizontal position. The inclusion of the view factor is of paramount importance in the study of heat exchange by radiation between the fins. Rt may be influenced by the area under convection and the coefficient ℎ̅ and Rt behaves in different ways depending on the geometry and position of the heat sinks. It was possible to observe a great contribution from DOE for the statistical analysis of convective thermal resistance.