Underground condensation of humid air: a solar driven system for irrigation and drinking-water production

University essay from Luleå tekniska universitet/Samhällsbyggnadsteknik/Vattenteknik

Abstract: The objective was to investigate the feasibility of using warm, humid air for subsurface irrigation and drinking water production. By letting air flow over the water surface in a solar still with saline or polluted water, vapour mixed with the air and saturated it. The vapour-saturated airflow was conducted down into buried pipes, where the air gradually cooled and the water precipitated along the pipe surface. For the irrigation system, drainage pipes were used, in which the condensed water penetrated the slits out to the soil. Replacing the drainage pipes with common PVC-pipes resulted in a system for drinking-water production, where the condensed water could be collected at the end of the pipes. In order to drive the air through the pipes, a fan was used in the irrigation system and a solar chimney in the drinking-water system. To visualise the cooling process in a buried pipe and the temperature distribution in the soil, a small-scale field test was conducted at the Çukurova University in Adana, Turkey. A secondary purpose was to get a feeling for the planning and execution process of a field experiment. The designed irrigation system was found to be more water-efficient, involve less transportation and be a sustainable solution. In addition, the economic estimations showed that condensation irrigation system has the potential of being competitive with traditional irrigation methods.

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