Theoretical modeling of combined solar chimney and water wall for buildings

Abstract

In this paper, a combined solar chimney and water wall is proposed to provide ventilation as well as moderate heating to an attached room. A transient heat balance model (THBM) is established to predict the thermal performance of the combined system under mild winter conditions in Sydney, Australia. The effects of the glass panel thickness, air gap width, water column thickness, surface tinting and the relative position of solar chimney and water wall are studied respectively. The results show that the combined solar chimney and water wall is capable of providing ventilation throughout the day and night while maintaining the warmth level of the room even though it continuously draws fresh air from the ambient into the room. It is found that increasing the glass panel thickness or reducing the water column thickness enhances the thermal performance of the combined system by increasing both the room temperature and the ventilation rate. On the other hand, increasing the air gap width helps to increase the ventilation rate, but will cause the room temperature to decrease. In addition, between the two configurations, one with the water wall in front of the solar chimney (referred to as the WW-SC configuration) and the other with the solar chimney in front of the water wall (referred to as the SC-WW configuration), the ventilation rate and room temperature obtained with the SC-WW configuration are higher, and thus the latter configuration is more favorable. Furthermore, it is found that surface tinting generally degrades the thermal performance of the proposed system.