Mixed Convection Heat Transfer With Longitudinal Fins in a Horizontal Parallel Plate Channel: Part I—Numerical Results

Abstract

Numerical calculations for laminar, fully developed mixed convection in a longitudinally finned horizontal channel have been performed for two sets of boundary conditions: (i) an isothermal, heated bottom plate with an isothermal, cooled top plate, and (ii) a uniform heat flux at the bottom surface with an adiabatic upper surface. Heat transfer and the strength of the buoyancy-driven secondary flow increase with increasing Rayleigh number and fin height. Fin spacing affects heat transfer through changes in the axial velocity distribution, the strength of the secondary flow, and the heated surface area, with decreased spacing acting to inhibit secondary flow. For the uniform heat flux condition and a small available pressure drop, close fin spacing can significantly reduce the channel flow rate and increase maximum plate temperatures.