Dew yield from passive Condensers in a coastal arid Area - Kutch

Dewfall occurs over a season of nine months in coastal arid district of Kutch. Quantity too is appreciable. A research program has been started to develop efficient passive condensers to harvest dew and use it as a supplementary source of drinking water which is scarce in the area. A passive condenser is a device that cools itself at night by radiative exchange with clear sky. Under favorable conditions condenser may become colder than the dew point of surrounding humid air and attract condensation. Condensers need to be inexpensive, compact and high yielding. We report in this paper, comparative dew yield of condensers made from six different materials including, aluminum sheet, galvanized iron sheet and polyethylene mixed with titanium oxide and barium sulfate, polyethylene, fiber reinforced plastic plain and corrugated. A test condenser is a panel 1 X 1 m in size and 25 mm thick. Top surface is made of the material being tested for condensation. Its underside is insulated by 25 mm thick styrene foam sheet. Panel is mounted on a metal frame at an angle of 30° from horizontal. Higher end of the panel is 2 m above the ground. Condensate flows down the sloping surface into a collection bottle via a channel and tube. Yield is measured daily in the morning. Ambient conditions are continuously recorded by a ten channel data logger. In this paper results of the first three months are presented. Dew yields are correlated with ambient conditions and material properties.