INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2004; 28:495–510 (DOI: 10.1002/er.978) Numerical and analytical calculations of the temperature and flow field in the upwind power plant Henry Pastohr 1, * ,y , Oliver Kornadt 1 and Klaus G . urlebeck 2 1 Bauhaus-Universit . at Weimar, Lehrstuhl Bauphysik, Germany 2 Bauhaus-Universit . at Weimar, Lehrstuhl Angewandte Mathematik, Germany SUMMARY The upwind power plant is an interesting system to generate electrical power from free solar energy. The authors have carried out an analysis to improve the description of the operation mode and efficiency. The pressure drop at the turbine and the mass flow rate have a decisive influence on the efficiency. This can be determined only by coupling of all parts of an upwind power plant. In this study the parts ground, collector, chimney and turbine are modelled together numerically. The basis for all sections is the numerical CFD programme FLUENT. This programme solves the basic equations of the thermal fluid dynamics. Model development and parameter studies particularly arise with this tool. Additional to the calculations using FLUENT a simple model is developed for comparison purposes and parameter studies. The numerical results with FLUENT compare well with the results given by the simple model, therefore, we can use the simple model for parameter studies. The basis for the geometry is the prototype Manzanares. Copyright # 2004 John Wiley & Sons, Ltd. KEY WORDS: computational fluid dynamics; free and forced convection; analytical and numerical modelling; solar chimney; solar collector; upwind power plant 1. INTRODUCTION The energy supply on our earth will become a problem in future. This is conditional by a shortage of the natural resources, like coal, gas and oil, as well as an increase in the concentration of gaseous CO 2 in the atmosphere. Regenerative energy sources must be used more increasingly to safeguard the increasing energy consumption. Upwind power plants (Schlaich, 1995) represent an interesting possibility for the use of solar energy. There are practical experiences with a prototype built in Manzanares (Spain). It delivered electrical power from 1986 to 1989 (Schlaich, 1986; Becker, 2002). It consists of a collector, ground, a chimney and one or several turbines (see Figure 1). Received 21 May 2003 Accepted 4 September 2003 Copyright # 2004 John Wiley & Sons, Ltd. *Correspondence to: Henry Pastohr, Bauhaus-Universit . at Weimar, Lehrstuhl Bauphysik, Coudraystrasse 13 C Raum 106, 99423 Weimar, Germany. y E-mail: henry.pastohr@bauing.uni-weimar.de Contract/grant sponsor: Ministry of Education and Research in Thuringia (Germany)