Effects of vertical fins on local heat transfer performance in a horizontal fluid layer

Enhancement of natural convection heat transfer in a horizontal fluid layer is an important problem pertinent to suppression of thermal stratification inside low-temperature liquid storage tanks. The experiments are carried o ut with an air layer between horizontal plates of aspect ratio 8.4, of whic h the bottom surface is isothermally heated, the upper surface is cooled at a constant room temperature and the vertical side wall are adiabatic. Some visualized results are reported of flow and temperature fields induced by natural convection in a horizontal fluid layer of finite extent; the former is measured with the laser light sheet methods and the latter with the hol ographic interferometry. The effects of partition intervals attached to the bottom surface and the Rayleigh number on local Nusselt numbers are discus sed. It is disclosed that (1) increases in the Rayleigh number result in en hancement of the vortex convection and the heat transfer performance improv es, (2) upward flows are created at the fin positions, and the heat transfe r is enhanced to the greatest extent when downward flows occur between the fins, and (3) there is the optimum pitch of the partitions to enhance the h eat transfer effects. (C) 1999 Elsevier Science Ltd. All rights reserved.