Abstract
The potential of coupled solar stills as a mean for improving solar distillation yield is investigated. A model for a simple solar still assisted by an external solar collector is presented. The governing coupled heat and momentum balance equations are solved for a quasi-steady-state condition with temperature dependent physical properties. The results show that for coupled stills the fresh water productivity increases as the solar collector area of the assisting device increases. For an ideal system, neglecting the thermal inertia, the yield is linearly dependent upon the solar insolation. The thermal inertia causes a significant drop in the system yield and deviation from linearity. The net efficiency of the coupled system is higher than that of a similar simple still by a value that depends mainly upon the system configuration and independent of the meteorological conditions. Comparison of the analysis with experimental data is satisfactory.