Solar Chimney Turbine: Part 1 of 2 — Design

The solar chimney is a simple renewable energy source consisting of three main components, a solar collector, chimney and turbine. Air under the collector is heated by the greenhouse effect. This less dense air rises up a chimney at the collector centre and drives an electricity-generating turbine. The operation of a solar chimney power plant is simple but high component efficiencies are needed for successful operation. A turbine design based on the design requirements for a full-scale solar chimney power plant is presented. The design integrates the turbine with the chimney. It is proposed that the chimney base legs be offset radially to act as inlet guide vanes and introduce pre-whirl before the rotor to reduce the exit kinetic energy. A three-step turbine design method is presented. A free vortex analysis method is used to determine the major turbine dimensions. A matrix throughflow method predicts the flow path through the inlet guide vanes and rotor. Finally the blade profiles are design using an optimization scheme coupled to a surface vortex method to achieve blades of minimum chord and low drag. The proposed turbine design can extract over 80% of the power available in the flow.