Artificial Roughness-Aided Performance Improvement of a Solar Chimney Power Plant: A Numerical Investigation of Conjugate Heat Transfer

Abstract

A solar chimney power plant (SCPP), consisting of four essential components: a chimney, a collector, a turbine and an energy storage layer, is a typical kind of thermal power plant that converts solar radiation into electricity using natural convection. The collector is the most important part of an SCPP, where the air is heated up due to solar radiation. The heated air finds its path through the chimney, resting vertically at the central portion of the collector. Thus, a better collector design always ensures greater effective buoyancy, considered as the driving mechanism of the turbine. Here, we utilize artificial roughness elements either at the roof or at the ground of the collector to enhance the effective heat transfer and, thereby, the net buoyancy. We consider rectangular roughness elements, the height varying from 4 to 25 mm. The parametric study is performed by computational fluid dynamic (CFD) simulations incorporating conjugate heat transfer effects. The fluid and solid domains of the SCPP are resolved separately in the simulations by solving the Navier–Stokes equations and the Laplace equation, respectively. The standard k–Ɛ model resolves the turbulence within the fluid domain. Finally, we obtain that the ground roughness yields better performance than the roof roughness. The maximum overall performance is achieved at a ground roughness height of 11 mm.