Combined natural convection and non-gray radiation heat transfer in a horizontal annulus. (February 2018) - Sun, Yujia
Highlights: Non-gray radiation is considered in annulus natural convection. Gas radiation reduce the temperautre stratification. Nusselt number is larger when considering gas radiation. Gas radiation become more important with larger annulus size. Abstract: Natural convection and non-gray radiation in an annulus containing a radiative participating gas is investigated. To determine the effect of non-gray radiation, the spectral line based weighted sum of gray gas is adopted to model the gas radiative properties. Case with only surface radiation (transparent medium) is also considered to see the relative contributions of surface radiation and gas radiation. The finite volume method is used to solve the mass, momentum, energy and radiative transfer equations. Comparisons between pure convection, case considering only surface radiation and case considering both gas radiation and surface radiation are made and the results show that radiation is not negligible and gas radiation becomes more important with increasing Rayleigh number (and the annulus size).