Effect of forced convection inside the solar still on heat and mass transfer coefficients

In this study, the effect of forced convection inside the solar still on the coefficients of heat and mass transfer is studied using a mathematical model through a computer programme. It is found from previous experimental study [1] that the forced air (air and vapour mixture) motion inside the solar still enhances the product of the still on the heat and mass transfer coefficients. Different parameters are studied, such as flutting of the water surface due to the air motion, air turbulent eddies, vapour velocity inside the still and accumulation of noncondensable gas. The experimental results are obtained from an experimental 3 m² solar still, and good agreement is obtained between the two results. The results show that the productivity of the solar still increases with Reynolds number but then falls after a maximum value. The reason of enhancement in solar still productivity with forced convection is found mainly to be due to the considerable increase in heat and mass transfer coefficients due to the turbulent air-vapour mixture motion.