Impact of non-uniform heat flux on ventilation performance of solar chimney

Abstract

Solar chimney (SC) is an effectively practical way to enhance building natural ventilation through thermal buoyancy force, which is induced due to the temperature difference between indoor and outdoor air temperatures. The ventilation performance of solar chimney directly depends on the heat flux distributions and values in the absorbed plate. Recently, many researches have been done on the thermal performance of solar chimneys under uniform heat flux. However, the uniform heat flow distribution cannot reflect the uneven characteristics of the solar radiation. There are few studies focused on the flow characteristic and thermal performance of solar chimneys under non-uniform heat flux distributions. In this paper, a two-dimensional numerical model of solar chimney integrated building is firstly established to explore the natural ventilation performance under non-uniform heat flux distributions. The numerical simulation is conducted to predict the flow and heat transfer characteristics in the room as well as in solar chimney. Subsequently, the effects of the location of the vent are analyzed to evaluate the performance of the solar chimney system. Finally, a comparison between the ventilation performance of solar chimney under the uniform heat flux and the non-uniform heat flux distributions is presented, and the thermal and flow structures of the solar chimney integrated building are further illustrated simultaneously. Research results show that the ventilation performance of solar chimney is closely related to its heat flux distribution, and the inhomogeneity of the heat flux of solar chimney will decrease the ventilation performance of the building. In addition, the position of the vent have highly influence on the flow structure and thermal performance for the solar chimney as well as the building. This paper will provide theoretical basis and technical approach for the improvement of the performance of the solar chimney, especially for the nonuniform heat flux distribution.