NATURAL CONVECTIVE HEAT TRANSFER FROM A THIN TWO-SIDED HORIZONTAL ISOTHERMAL CIRCULAR PLATE WITH A CIRCULAR HOLE IN THE CENTER

Abstract

The natural convective heat transfer rate from a thin, horizontal, two-sided circular plate might be increased by having a small hole in the center of the plate and this has been investigated in the present numerical study. It has been assumed that the upper and lower plate surfaces are isothermal and at the same temperature, and that the flow is axisymmetric about the vertical center-line through the plate. The Boussinesq approach has been adopted. The solution has been obtained using ANSYS FLUENT © . The mean heat transfer rates from the top and bottom plate surfaces and the total heat transfer rate from the entire heated surface have been expressed in terms of Nusselt numbers based on the effective plate diameter. These Nusselt numbers are dependent on the Rayleigh number based on the effective diameter of the plate, the ratio of the diameter of the hole in the center of the plate to the outer diameter of the plate, and on the Prandtl number, results being obtained for a Prandtl number of 0.74. Heat transfer rate for a plate having a hole in its center has been compared with the heat transfer rate existing under the same conditions for a plate without a hole. The results show that there is some increase in the heat transfer rate in certain situations resulting from the presence of the center hole. This increase is generally relatively small. The results also show that in other situations the heat transfer rate decreases due to the center hole.