A single basin-type solar still with an area of 0.65 m2 is
constructed in Menoufiya University and tested under the transient
operation conditions. The hourly variation of basin water, glass cover
and ambient temperatures, as well as the evaporative mass transfer rate
are measured during the operation. A thermal model has been developed
for predicting the performance of the unit. The model is based on the
outdoor measurements of distillate water collected from the still and the
heat balance equations. Experimental data for evaporative mass transfer
rate, basin-water temperatures, glass cover temperatures and heat
transfer coefficients have been compared with the predictions data
obtained from the model. The comparisons are also made with the
experimental data using three mathematical models: Turbulence,
McAdams, and Adhikari models. The Grashof number was ranged from
5.13~10 to 2.10~10 * .
It is found that the general trends of the model predictions are in
a reasonable agreement with the experimental data. However, the
predictions for the solar distillation are found to be sensitive to the
empirical correlation employed to describe the unit performance. For the
three models tested, the turbulence model overpredicted the evaporative
mass transfer rates and heat transfer coefficients. The other two models,
McAdams and Adhikari, underpredicted these rates and coefficients.
The basin water and glass cover temperatures have the predictions
inverted. It is concluded that the present model has the better
predictions of the still performance compared with other models.
Particular care, however, must be taken in4he choice of the heat transfer
correlation necessary for calculations.