A numerical study on the performance of a solar chimney with expanded inlet

With passive designs, such as solar chimney, solar radiation absorbed on building envelopes can help to reduce the energy consumption of the building. Solar chimneys can be employed for natural ventilation and/or heating. The performance of a solar chimney has been reported in the literature to depend mainly on the dimensions and designs of the air channel where the air flow is induced. Particularly, the design of the inlet area plays an important role. In this study, effects of the expansion of the inlet area of a vertical solar chimney were investigated numerically with a Computational Fluid Dynamics (CFD) model. The induced flow rate and temperature rise through the chimney were assessed when the inlet area was expanded in both horizontal toward the right side of the air channel and vertical directions and at different heat fluxes. With the expansion, the induced flow rate is always enhanced as the expanded height is equal to and more than the gap of the air channel due to the reduction of the area of the recirculation zone in the air channel. However, no significant enhancement of the temperature rise or the thermal efficiency is seen as the thermal boundary layer along the heated (left) wall changes insignificantly. Similar trends are seen for both values of the heat fluxes. The findings in this study can serve as a reference for different design options for the inlet of solar chimneys. Keywords: Solar chimney, CFD, flow rate, temperature rise, expanded inlet.