Comparing plastic foils for dew collection: Preparatory laboratory-scale method and field experiment in Kenya

Passive dew collection could be a viable option as a source of irrigation water in arid areas. The plastic foil acting as a condensing surface plays a key role in the passive dew collection regime. A laboratory method for comparing various plastic foils for dew collection was prepared and tested. The focus was on creating a method for measuring the attributes affecting dew condensation and the flow of dew droplets on the measured surface. A low-density polyethylene foil designed for dew collection, white polyethylene plastic, black polyethylene plastic, and white polyvinyl chloride plastic were used as the test plastics. The laboratory dew yields were compared with model calculations. In addition, field trials were conducted in arid conditions in Maktau, Kenya, to compare with the laboratory measurement. Results from the hardware model tests were not reflected in the results obtained from the field conditions. The laboratory tests showed that the dew-harvesting quality of plastic foils is difficult to evaluate using the laboratory test rig. A more comprehensive evaluation regime requires tests performed in field conditions or further development of the test rig used here.