Coupled radiation‐convection heat transfer of high‐temperature participating medium in heated/cooled tubes

Abstract

The coupled radiation-convection heat transfer of high-temperature participating medium in heated/cooled tubes is investigated numerically. The medium flows in a laminar and fully developed state with a Poiseuille velocity distribution, but the thermal status is developing. By the discrete ordinate method, the nonlinear integrodifferential radiative transfer equation in a cylindrical coordinate form is solved to give the radiative source term in the energy equation of coupled heat transfer. The energy equation is solved by the control volume method. The local Nusselt number and wall heat flux of convection as well as the total wall heat flux are employed to evaluate the influence of radiation heat transfer on convection. The analysis shows that the radiation heat transfer weakens the convection effect, promotes the temperature development, and significantly shortens the tube length with obvious heated/cooled effect. There is an obvious difference between the coupled heat transfer in a heated tube and that in a cooled tube, even though the medium properties are kept constant. The wall emissivity, the medium thermal conductivity and scattering albedo have significant influences on the coupled heat transfer, but the effect of medium scattering phase function is small. Nu: N u sselt number

Thermal radiation effects of a high‐temperature developing laminar flow in a tube

“…By integrating over the control volume and using an interpolation formula to eliminate the radiative intensity of the downstream interface, the radiative intensity field can be solved iteratively [9].…”

“…The thermal radiation effects on the laminar mixed convection in an inclined square duct were analyzed by Yan and his fellows [8]. The coupled heat transfer of fully developed laminar flows in heated/cooled tubes were compared and discussed by Xia and his group [9].…”

Numerical study of the radiation effect on the flowing of mixed convection along a vertical channel

“…The coupled radiation-convection heat transfer of hightemperature participating medium in heated/cooled tubes was investigated numerically by Xin-Lin Xia et al [5]. They show that there is an obvious difference between the coupled heat transfer in a heated tube and that in a cooled tube, even though the medium properties are kept constant.…”