Thermal analysis on Natural convection heat transfer from inclined plate-fin heat sinks

Abstract

Natural convection is a mechanism, or type of heat transport, in which the fluid motion is not generated by any external source (like a pump, fan, suction device, etc.) but only by density differences in the fluid occurring due to temperature gradients .Natural convection has attracted a great deal of attention from researchers because of its presence both in nature and engineering applications.

In this project natural convection from heat sinks with parallel arrangement of rectangular cross section vertical plate fins on a vertical base are numerically investigated in order to obtain a validated model that is used for investigating inclined orientations of a heat sink. Taking a previous experimental study as a basis, aluminum heat sinks with two different practical lengths are modeled, Natural convection and radiation heat transfer rates from the fronts of the heat sinks heated from the back with a heater are obtained from the inverse method and three-dimensional CFD commercial software. The sensitivities of the heat transfer rates to the geometric parameters are determined. The validated model is used for several upward and downward inclination angles by varying the direction of gravitational acceleration. At small inclinations, it is observed that convection heat transfer rate stays almost the same, even increases slightly for the downward inclinations. At larger angles, the phenomenon is investigated for the purpose of determining the flow structures forming around the heat sink. For the inclination angles of ±9°, ±24°, ±32°, ±45°, ±60°, ±90° from the vertical modifying of the inclination angle. It is also observed that the flow separation inside the fin channels of the heat sink is an important phenomenon and determines the validity range of the modified correlation.