Effect of wind speed over the chimney on the updraft velocity of a solar chimney power plant: An experimental study

The effect of wind speed on the updraft velocity and the overall performance of solar chimney power plants (SCPP) is still unclear, either positive or negative. This study is partially to investigate the effect of wind speed over the chimney on the updraft velocity. Therefore, an experimental SCPP porotype (installed in Aswan, Egypt) was used. The measured parameters were the wind speed over the chimney, ambient temperature, solar radiation intensity, and the updraft velocity at the exit of the chimney tower. The measurements were accomplished on several clear sunny days under different climatic conditions and wind speed levels. The results showed that increasing wind speed at the top of the chimney increases the updraft velocity, thereby increasing the plant performance. Wind speed values higher than 2.1 m/s generate a considerable updraft velocity inside the chimney despite the absence of the buoyancy effect. During the night times (in the absence of solar energy and heat storage effect in the collector elements), high wind speed (>6 m/s) over the chimney tower can generate updraft velocity equal to that generated under high solar insolation based on the ejector concept. However, a wind speed >6 m/s significantly increases the heat losses from collector surfaces and reduces the buoyancy effect; consequently, the generated updraft velocity in the chimney tower is attributed mainly to the ejection effect of the crosswind over the chimney.