The effect of rectangular ribs dimension in solar chimney

In the recent years, the solar energy has beenwidely considered due to availability, no pollution and reducing the consumptionof fossil energy. Solarair heaters with natural convection such as solar chimney are used for heating and cooling spaces.The rate of heat transfer is improved using theribs on absorber surface. Many studies in forced convection focused on this method.Howeverin natural convection effect of ribs rarely has been studied.In this paper, solar chimney is simulated by a CFD code. Finite volume methodis used to decompose the equations and study heat transfer and turbulent flow in a three dimensional domain under steady state condition. Numerical results are validated by comparing with existing experimental results in the literature and were in a good agreementand maximum difference between the results wasless than 12%. In this paper,the solar chimney with a flat absorber surface is compared with a non-flat (with rectangular ribs) one. Effects of rectangular ribs on air temperature and mass flow is discussed and the results are compared with flat absorber. Furthermore geometry parameters of the channel and rectangular ribs such as depth of the channel, depth and width of ribs are investigated.As it is expected, the results showed that ribs on absorber surface will cause improvement in solar chimney performance due to extending heat transfer area.Increasing the channel depth cause an inclination in mass flow and decrease the air temperature.