Numerical evaluation of a solar chimney geometry for different ground temperatures by means of constructal design

Abstract

The present work aims to numerically study the influence of geometric parameters over the available power of solar chimney power plant (SCPP) by means of Constructal Design. The influence of different imposed ground temperatures (mimicking the effect of different solar incidence on collector device) over the optimal shapes is also evaluated. The geometry is submitted to three constraints: collector, turbine and chimney areas. Moreover, three degrees of freedom are taken into account: R/H (ratio between collector radius and its inlet height), R1/H2 (ratio between the radius and height of chimney) and H1/H (ratio between the height of collector base and collector inlet height) which is constant (H1/H = 10.0). The mixed convective flow is incompressible, turbulent, steady, in two-dimensional axisymmetric domain. Time-averaged conservation equations of mass, momentum and energy (RANS) are numerically solved using the finite volume method (FVM). For closure modeling of turbulence it is employed the standard k – ε model. Results showed a strong influence of the chimney and collector geometry over the available power. Moreover, geometric parameters of collector and chimney must be evaluated in a combined way. It was also noticed a large sensibility of the ground temperature over the available power and geometric effects.