2008 Volume 64 Issue 4 Pages 205-213
“Solar Pump” is a new concept of solar still where water is distilled as well as transported by solar energy. In the water reservoir, a column of porous material is immersed, which absorbs and transmits water. Water thus transported along the water potential gradient evaporates at the end of the column where the solar radiation is absorbed. It is then recovered with a condensing cover. To examine the feasibility of this concept, simultaneous transportation of heat and moisture through the sand column from varying depths of water table under constant irradiance was examined. A mathematical model, based on Philip and de Vries (1957), predicted that the rate of evaporation from a uniform sand column is maximum when the water table is 0.1 m deep. This is because the water potential decreases with height from the water table, whereas the temperature increases with height. Experimental results partially supported such a prediction. The results also suggested that the evaporation rates from the surface of the sand column were slightly higher than that from the water table. Thus, the proposed method could be useful if a proper porous material is selected.
