Experimental investigation of natural convective heat transfer from a round plate of complex configuration

Experimental results of free convective heat transfer on a round plate with additional elements on the surface at ambient air temperatures are present ed. The tests were performed at horizontal and vertical positions of the pl ate. The influence of an annular non-heated barrier and partial upper insul ation was studied. Experimental data were obtained at steady-state and tran sient modes over the Rayleigh number range from 1 x 10(7) to 2 x 10(8). Val idity of the quasi-steady-state postulation for transient heat transfer was evaluated. Results were reduced to power-type relations Nu = f(Ra) and com pared with tile known steady-state data for free convection over smooth sur faces. (C) 2001 Elsevier Science Ltd. All rights reserved.