Numerical study on laminar flow forced‐convection heat transfer for air in a channel with offset plates heated by radiation heat flux

Abstract

A two‐dimensional numerical study was carried out to investigate laminar forced‐convection heat transfer characteristics of air flow in a two parallel plate channel with offset plates and heated by a radiation heat flux. The SIMPLE method was used for the numerical prediction of the flow and thermal fields. The flow field temperature boundary conditions were obtained by applying the energy balance equation to boundary elements. The ray tracing technique was used to obtain the net absorbed radiation fractions in the boundary elements. The numerical results were validated with measured temperature values and experimentally calculated values of local Nusselt number (Nu_x), and a reasonable agreement was shown. Then the numerical simulation was used to study effects of design parameters on the convective heat transfer coefficient. It was found that in Re numbers from 650 to 2,550, the optimum spacing of offset plates relative to the nearest channel wall was around one third of the channel height. Also, the optimum offset plates’ numbers can be calculated based on one offset plate length being equal to one and a half times the channel hydraulic diameter. A correlation of average Nusselt number between the flowing air and the offset plates was obtained as follows; —Nu = 1.81 Re ^0.352Pr^1/3(D_h/l)^1/2.

Citation

Hamza H. Ali, A., Kishinami, K., Hanaoka, Y. and Suzuki, J. (1998), "Numerical study on laminar flow forced‐convection heat transfer for air in a channel with offset plates heated by radiation heat flux", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 8 No. 5, pp. 539-558. https://doi.org/10.1108/09615539810220289