Numerical study on the mixed convection around inclined-pin fins on a heated plate in vertical channels with various bypass ratios

Abstract

Natural and mixed convections around heat sinks with inclined-pin fins had been studied for various design parameters, showing that careful trade-off studies were necessary depending on operating conditions. Previous studies, however, assumed heat sinks in an open space or limited channel heights. In this study, the mixed convection around inclined-pin fins on a heated plate in a vertical channel were investigated for various bypass ratios. Solutions of three-dimensional governing equations were calculated with the Boussinesq approximation. A representative computational domain was constructed assuming the periodic condition in the spanwise direction. While varying the bypass ratio from 2 to 10 based on the fin height, we compared the thermal and flow characteristics for the range of Richardson number Ri = 0.3–10. The fin-inclination angle was also varied from −45° to +45°. We summarized the flow pattern, temperature distribution, local and average Nusselt numbers for various parameters variation. The negatively inclined fins have shown better thermal performance when the bypass ratio was high, but the positively inclined fins have a larger average Nusselt number for Hb/Hf = 4. The presented results will contribute to heat sink design by offering new information on practical installation conditions with limited space envelop.

Keywords

• Heat sink
• Inclined-pin fins
• Mixed convection
• Bypass effect
• CFD