Twenty-four hour simulation of solar chimneys

Abstract

A model for time dependent analysis of solar chimneys is presented. The energy balance equations for three components of solar chimneys, absorbing plate, cover glass and air-gap are discretized with respect to time using an implicit finite difference model. The discretized nonlinear energy balance equations are solved for numerous time steps over a 24-h period using the Newton–Raphson method. The time dependent solar irradiation is determined using the clear sky model. The model's performances for various parameters of solar chimney that affect the thermal mass of the absorbing plate are tested. It was determined that a solar chimney with a relatively large thermal-mass produces airflow well into night and early morning when no solar irradiance is present. Also, a high thermal mass of the absorbing plate results in smaller variations in the airflow rate. The results of the present model for a solar chimney with no thermal storage compare well with the previously published data.