Combined Convective Radiative Thermal Analysis of an Inclined Rooftop Solar Chimney

Abstract

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 of solar chimney components. Two approaches are used for the convective part of this model, empirical correlations and a CFD analysis. The empirical correlations are based on the stack effect correlation for airflow motion and a convective heat transfer correlation for the heat transfer coefficient. The empirical correlations are used to obtain an initial estimation of surface temperatures, which are then used in the CFD model to determine an improved estimation of the heat transfer coefficients and airflow rate. Iterating between the spectral radiative and the CFD models resulted in a converged set of values for the solar chimney airflow rate and its thermal characteristics. The model is used to predict the airflow rate for various configurations and solar irradiances of solar chimneys.