Mathematical modeling of solar chimney power plants

The solar chimney power plant is a system with promise to generate electrical power from free solar energy. In this study, a solar collector, chimney and turbine are modeled together theoretically, and the iteration techniques are carried out to solve the resulting mathematical model. Results are validated by measurements from an actual physical plant. Moreover, the model is employed to predict the performance characteristics of large-scale commercial solar chimneys, indicating that the plant size, the factor of pressure drop at the turbine, and solar heat flux are important parameters for performance enhancement. In addition, the study proposes that the most suitable plant, affordable by local government standards to respond to the electricity demand of a typical village in Thailand, is the one with a collector radius and chimney height of 200 m and 400 m, respectively. Furthermore, it is shown that the optimum ratio between the turbine extraction pressure and the available driving pressure for the proposed plant is approximately 0.84. A simple method to evaluate the turbine power output for solar chimney systems is also proposed in the study using dimensional analysis.

► The solar collector, chimney and turbine are modeled together theoretically.
► The factor of pressure drop at the turbine is not essentially 2/3 as used in the literature.
► The appropriate plant size for the villages in Thailand is proposed.
► The simple method to primarily evaluate the turbine power output for solar chimney systems is proposed.
► The mathematical model presented here is relatively simple while it provides a very accurate result.