An experimental study of flow and heat transfer characteristics of natural convection heat transfer from a horizontal heated surface with a heated cylinder

Natural convection heat transfer from an upwards-facing horizontal heated surface above which a heated cylindrical pipe was placed was estimated experimentally. The purpose of this study was to clarify the effects of the basic parameters on the flow characteristics with a cylindrical heater, and to determine available factors to enhance the heat transfer from the horizontal heater. The parameters estimated were the distance between the horizontal heater and the cylindrical heater, and the size and heat flux of each heater. Flow characteristics have three distinct patterns: no reversed flow, reversed flow that reaches the horizontal heater, and reversed flow that does not reach the heater. Heat transfer was enhanced using the cylindrical heater. In the cases of no reversed flow and reversed flow not reaching the horizontal heater, the heat transfer enhancement increased with the modified Rayleigh number of the cylindrical heater. In the range of low numbers, the reversed flow reaching the heater provided heat transfer enhancement.