Browsing by Author "Hana Gebremariam"

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    Experimental Investigation on Cylindrical and Divergent Solar Chimney Power Plants
    (Addis Ababa University, 2024-01) Hana Gebremariam; Solomon Tesfamariam (PhD)
    The solar updraft tower (SUT) is an innovative renewable energy power plant that converts low-temperature solar heat into electricity. This system operates by heating air beneath a large, greenhouse-style roof, which surrounds the base of a tall chimney. The heated air rises through the chimney, creating an updraft that drives wind turbines to generate electricity. This research evaluates the performance of a small-scale solar chimney power plant (SCPP) by developing two prototypes: one with a cylindrical chimney and another with a divergent chimney. The study focuses on analyzing the impact of chimney design on power output and efficiency using local solar radiation data. Experimental results reveal that the average power outputs for the cylindrical and divergent chimneys were 5.29 W and 23.6 W, respectively. The divergent chimney with a 2° angle achieved an efficiency of 1.9%, which is significantly higher than the 0.44% efficiency of the cylindrical chimney. These findings indicate that the area ratio and air velocity substantially influence the power plant's performance. Furthermore, theoretical calculations showed that increasing the chimney height from 1.5 meters to 2.5 meters led to a 66.6% increase in power output for both chimney types, while increasing the height from 2.5 meters to 3.5 meters resulted in a 40% increase. A 2.5-meter-high divergent chimney produced 3.1 times the power output compared to a 3.5-meter cylindrical chimney, and a 1.5-meter divergent chimney exhibited an 86.46% increase in power output compared to a 3.5-meter cylindrical chimney. Overall, the divergent chimneys enhanced power output by 335.4% at the same height, demonstrating the significant impact of chimney configuration.