Performance Assessment of Solar Chimneys: Part 2 – Impacts of Slenderness Value and Collector Slope on Power Output

Abstract

In the previous part, impacts of chimney height thus pressure difference on the power output of solar chimneys have been numerically evaluated. Within the scope of this research, slenderness and slope of collector are analysed in terms of their potential influence on average velocity of air at the chimney inlet. The analyses are based on a commercial and reliable CFD software ANSYS FLUENT. Chimney height is considered to be 100 m in the research and the chimney diameter is varied through a dimensionless parameter (β). Basically, β is defined as inverse slenderness and its value of 0.1 corresponds to a chimney diameter of 10 m as expected. Average velocity of air at the chimney inlet is numerically assessed for the β values in the range of 0.1-0.5. Collector slope is also investigated in the analyses through a dimensionless parameter (δ). The term δ is defined as the ratio of inlet height of collector to the collector height at the centre. Similarly, average velocity of air at the chimney inlet is determined for the δ values in the range of 0.2-1.0. The analyses are conducted for a constant solar intensity of 200 W/m2. The chimney height at the centre is taken to be 4 m in the slenderness analyses and 10 m in the collector slope assessments. The height of collector inlet is constant and 1 m in the slenderness research. On the other hand, it is varied from 2 to 10 m in the collector slope analyses. The results reveal that the velocity figures exponentially decrease from 15.93 to 11.85 m/s when the β value rises from 0.1 to 0.5. On the contrary, velocity figures increase with increasing δ value, the enhancement is determined to be about 23%.