Combined Convective-Radiative Thermal Analysis of Inclined Roof Top Solar Chimney

A model for the combined spectral radiative and convective heat transfer analysis of solar chimneys is developed. The radiation part of this model is based on the spectral distribution of the solar heat flux and spectral radiative properties solar chimney components. Two methods are used for the convective part of this model, empirical correlations and a CFD analysis. The empirical correlations consist of stack effect correlation for air flow motion and convective heat transfer correlation for heat transfer coefficient calculations. The empirical correlations were used to obtain an initial estimation of surface temperatures which were then used in a CFD model to determine an improved estimation of the heat transfer coefficients and flow rates. By iterating between the spectral radiative and CFD models a converged value for the solar chimney flow rate and its thermal characteristics is obtained. The model is used to predict the volume flow rate of air moved for various configurations of solar chimneys (slopes and air gap distance).