View Factor of Solar Chimneys by Monte Carlo Method

Abstract

A typical solar chimney power plant (SCPP) system mainly contains three components, namely, solar collector, tower and turbine. The collector heats up ambient air entering to the system by buoyancy force. Updraft airflow is then generated in the chimney and drives the pressure-staged turbine in the chimney base to generate electricity or ventilation of buildings. A part of the solar radiation is absorbed by solar collector directly, which is greater than which reflected by collector to the tower. But this amount of reflection can enhance the efficiency of the system. Determining more precise view factor between collector and the tower is essential for solving heat transfer equation. In this study, results obtained by Monte Carlo method are compared with analytical method which is available in literature for calculating the view factor. With increasing the ratio of the length to the radius of the tower, configuration factor increases slightly. Also, at higher radius of the collector, supposing length and outer radius of the chimney are unchanged, the view factor decreases. This behaviour can also be seen by analytical solution, but the result of analytical solution is much lower than that one obtained by Monte Carlo solution. It is suggested to designers and researchers to use the results obtained by Monte Carlo method, which seems to be more accurate.