Maximum Water Harvest from Soil by Means of Solar Radiation: A Theoretical and Parametric Study

Abstract

The need for potable water is becoming growing drastically and different methods of freshwater production are explored theoretically and experimentally. Meanwhile, water harvesting from soil is a method through which soil water is attempted to be extracted as much as possible in form of vapor and condensed on the inner surface of a plastic cover and collected in a container. In the present study, the maximum amount of harvested water from soil is theoretically calculated and a parametric study is conducted to find the effects of contributing parameters on the highest level of harvested water from soil. Soil of interest is located under a plastic cover which absorbs solar rays and get heated. Therefore, its water turns into vapor and the condensate is collected afterwards. In fact, such a small harvesting water structure resembles a solar greenhouse. So, the governing equations seem roughly the same. Based on the results of the theoretical and parametric study, increases in difference between temperatures of trapped air under the plastic cover and soil surface brought about lower levels of harvested water as a 10 ℃ increase led to a 13% decrease in harvested water. In contrast, solar radiation intensity, area of soil under the plastic cover and soil absorptivity were all directly proportional to the quantity of harvested water. Moreover, it was concluded that solar radiation intensity acts as a marginally (around 5%) more significant parameter in comparison to area of soil in the amount of harvested water.