Analysis of enhancement and impairment mechanisms of natural convection heat transfer on a vertical finned plate

We investigated the heat transfer enhancement and impairment mechanisms of the laminar natural convection on a vertical finned plate. Numerical analyses were performed for wide ranges of Prandtl numbers 0.7-2014, Rayleigh numbers 3.69x10(5)-8.49x10(10) and fin heights 0.0025-0.5 m. Experiments were performed for a few cases for verification. Four different heat transfer mechanisms were identified: corner, core acceleration, chimney and in-flow effects. The competitions of these mechanisms depending on the fin geometries and the Prandtl number resulted in complex variations of the heat transfer. The results showed the heat transfer enhancement of maximum 6.9 % for Pr = 2014, L = 0.1 m and H = 0.015 m and impairment up to 47 % for Pr = 0.7, L = 0.1 m and H = 0.015 m compared with that of a flat plate with the same heat transfer area and baseplate length.