Efficiency improvement of the solar chimneys by insertion of hanging metallic tubes in the collector: Experiment and computational fluid dynamics simulation

Abstract

The solar chimney power plant (SCPP) is a straightforward and clean technique to generate electricity from solar radiation. However, this technology still faces major challenges, such as low efficiency, which has hindered its industrialization. This study experimentally develops a novel collector design to improve the solar chimney collector's efficiency. The new design includes metallic tubes as solar radiation absorbers hung from the canopy of the collector. The metallic tubes are open at the top and sealed with transparent sheets at the bottom to decrease the solar radiation reflected into the ambient air. Experimental and 3-D computational fluid dynamics (CFD) analyses are performed to validate the new design. The effects of hanging metallic tubes on temperature and velocity distribution are explored. The temperature increased by about 5 K at the chimney inlet, causing a roughly 8% rise in collector efficiency due to the fact that metallic tubes operate as an extended surface. The impact of various tube geometries on solar chimneys' efficiency is examined. The CFD findings reveal that the metallic tube geometry variation has considerably impacted the collector's efficiency. Thus, the collector efficiency is increased by changing tube diameter by around 33.7%, similar to changing tube length by 30%.