HEAT-TRANSFER ENHANCEMENT FROM A VERTICAL, ISOTHERMAL CHANNEL GENERATED BY THE CHIMNEY EFFECT

A numerical and experimental investigation of free convection from ver tical, isothermal, parallel-walled channels has been undertaken to exp lore the heat transfer enhancement obtained by adding adiabatic extens ions of various sizes and shapes. Investigations were carried out for air (Pr = 0.7) over a wide range of wall heating conditions. In all ca ses, the adiabatic extensions were able to increase heat transfer. The increase varied from 2.5 at low Ra to 1.5 at high Ra*. The experimen tal and numerical results are in excellent agreement. A single correla tion accounting for the channel aspect ratio L(h)/b, expansion ratio, B/b, modified Rayleigh number, Ra and heated length ratio, L(h)/L is presented.