Experimental natural convection heat transfer from isothermal spherical zones

Results of an experimental investigation of laminar convective heat transfer from segments or zones (other than a hemisphere) of a sphere placed on a horizontal surface are discussed. The zones tested were 60, 90, and 120-deg parts of a sphere. All zones exhibited a variation in the dependence of the Nusselt number on the Rayleigh number from a slope of 0.25, which is associated with experimental error. Overall, a good agreement is noted to exist between the results of the experiment and previous data for a hemisphere on an insulated base in water, an isolated isothermal sphere, and a flat horizontal plate heated on the upper surface.