Combined Cenvection and Non-Gray Radiation in Simultaneously Developing Turbulent Flow and Heat Transfer

초록

Combined convection and non-gray radiation in simultaneously developing turbulent flow and heat transfer in smooth tubes is numerically investigated. The working fluid is combustion products consisting of carbon dioxide, water vapor, and nitrogen. The fundamental conservation equations are solved by a finite difference technique, with the P-1 approximation used to transform the radiative transfer equation into a second-order partial differential equation. The exponential wide band model is adopted to obtain the mixture absorption coefficient which is strong function of temperature and wave number. The bulk mean temperature and Nusselt number variation along the tube axis are shown for several inlet and wall temperature pairs to show the effect of temperature on the heat transfer characteristics. In addition, the effect of the mole fraction of the non-gray gases on convective and radiative Nusselt numbers is explored. Based on the results from the numerical model, a simple correlation for predicting the radiative heat flux of non-gray turbulent flow a smooth tube is suggested.