Thermal modeling and analysis of single and double effect solar stills: An experimental validation

Highlights: • Formulating a mathematical model to predict performance of single and double effect solar still. • Designing two similar experimental desalination units to validate the mathematical model. • Separating condensing surface from solar energy receiving surface increased daily production. • By reusing latent heat, total yield of double effect became more than that of a single effect. • Raising water depth from 1 to 3 cm resulted in 14% and 26% decrease in the daily production. - Abstract: In this paper, a mathematical model has been formulated to predict the performance of single and double effect solar still by using modified heat and mass transfer correlations. Two similar experimental desalination units (single and double effect) were designed to validate the mathematical model. The production of a solar still is strongly influenced by latent heat reuse and increase the temperature difference between the water and condensing surface. The results showed that the separation of condensing surface and solar energy receiving surface would result in enhancement of 94% for daily production compared to conventional one. Moreover, by reusing the latent heat the total yield of double effect showed a 70% increase with respect to a single effect. Increasing the power input from 200 to 500 $\frac{\text{W}}{{\text{m}}^2}$ led to 236% and 240% production increase for single and double effect, respectively. Furthermore, raising the water depth from 1 to 3 cm resulted in 14% and 26% decrease in the daily production rate of single and double effect respectively.