Effects of the forced air temperature on the induced flow rate through a combined natural–forced flow in a solar chimney

With a good design, solar chimney is able to provide sufficient natural ventilation for buildings. In practice, natural ventilation performance depends on many factors, such as solar radiation, which is intermittent. Therefore, in this study, a proposed combined natural–forced flow solar chimney is investigated. Induced ventilation rate is estimated under the effects of the temperature of the forced flow and compared to that of the base case which has no forced flow. The results show that, with a forced flow velocity of 1.0 m/s and a heat flux of 500 W/m, the induced mass flow rate increases when the forced flow temperature increases from 20 to 352oC. Compared with the base case, the combined natural–forced flow offers more flow rate as the gap G is above 0.05 m at the height, H, of solar chimney H of 0.45 m; 0.1 m at H=0.95 m; 0.15m at H=1.45 m, and 0.2 m at H=2.0 m. It is expected that with a proper design, improvement of ventilation performance of a solar chimney can be achieved by this combined natural–forced flow. Keywords: Solar chimney, natural ventilation, forced flow, CFD, flow rate.