Performance of a Solar Chimney for Cooling Building Façades under Different Heat Source Distributions in the Air Channel

Abstract

Solar chimneys can be employed in buildings for natural ventilation, cooling, or heating of the building envelope, hence saving energy. In open double-skin facades, the air channel's thermal effects between the two layers of a façade are similar to those in a solar chimney. Most studies about solar chimney in the literature have been focusing on heating one air channel wall. In this study, the performance of a solar chimney under different distributions of the heat source on both walls of the air channel was studied numerically by the Computational Fluid Dynamics method. Induced flow rate, temperature rise, and thermal efficiency of the chimney were investigated. Chimneys with practical dimensions with the height ranging from 0.5 m to 1.5 m and the gap-to-height ratio ranging from 0.025 to 0.15 were examined. The results showed that together with the chimney's dimensions, location, and distribution of the heat source on the channel's walls strongly affect the performance of the chimney. While heating the whole left wall induced more flowrate than heating the whole right wall, heating part of the left and the right walls resulted in peak performance at specific portions of the right wall heated from the bottom or the top of the channel. The peak values of the investigated parameters and the specific portions of the heated wall to achieve those peaks also changed with the channel's gap–to–height ratio.