A new type of solar tower was developed through laboratory experiments and numerical\nanalyses. The solar tower mainly consists of three components. The transparent collector area is an\naboveground glass roof, with increasing height toward the center. Attached to the center of the inside\nof the collector is a vertical tower within which a wind turbine is mounted at the lower entry to the\ntower. When solar radiation heats the ground through the glass roof, ascending warm air is guided\nto the center and into the tower. A solar tower that can generate electricity using a simple structure\nthat enables easy and less costly maintenance has considerable advantages. However, conversion\nefficiency from sunshine energy to mechanical turbine energy is very low. Aiming to improve this\nefficiency, the research project developed a diffuser-type tower instead of a cylindrical tower, and\ninvestigated a suitable diffuser shape for practical use. After changing the tower height and diffuser\nopen angle, with a temperature difference between the ambient air aloft and within the collector,\nvarious diffuser tower shapes were tested by laboratory experiments and numerical analyses. As a\nresult, it was found that a diffuser tower with a semi-open angle of 4ââ??¦ is an optimal shape, producing\nthe fastest updraft at each temperature difference in both the laboratory experiments and numerical\nanalyses. The relationships between thermal updraft speed and temperature difference and/or tower\nheight were confirmed. It was found that the thermal updraft velocity is proportional to the square\nroot of the tower height and/or temperature difference.
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