Anand Gondchawar, Bhavesh Kanabar, Ramesh Bhoraniya
A solar chimney power generation plant is a green energy option suitable for use in both rural and urban areas, especially where solar energy is available in abundant quantity. The solar thermal storage is one of the important types of thermal storage systems used in conjunction with solar chimney power plants. This numerical investigation mainly focuses on the use of different solar absorber materials to optimize the performance of a solar chimney plant. Rajkot city, which is part of the Saurashtra region in India, has semi-tropical climatic conditions and is therefore considered for the numerical study. Primarily, two different kinds of solar chimney power plants are considered, namely those with and without the use of a solar nozzle. Seven different absorber materials, namely gravel, ceramics, pebbles, sand, sawdust, stone, and wood, are numerically evaluated using the finite volume method. Among these materials, the maximum air release velocity is obtained when ‘sawdust’ is used as the solar absorbing material. The air exit velocity for sawdust as an absorption material is found to be 1.48 m/s for a convergent solar chimney power plant with overall height of 5.6 m, as analyzed using numerical methods. The percentage increase in air exit velocity achieved with sawdust compared to stone is 4.96%. However, in tropical countries like India, sand is generally better choice for absorber bed material, as it is easily available and possesses good mechanical strength.