Air flow optimization for drinking water production through air dehumidification

Drinking water availability is one of the emerging challenges of the 21 st century. Different approaches have been investigated as possible sources of water for arid regions. Atmospheric water vapor processing is a developing approach whose aim is to cool air to condensate the water available in the atmospheric moisture. Air dehumidification allows obtaining pure drinking water for geographical regions far from sea, rivers or lakes. This paper presents the optimization of a refrigeration system for drinking water production through air dehumidification. The system uses a fan to force the atmospheric air through an heat exchanger, in which it is cooled. The water vapor condensates on the cooled heat exchanger surfaces and it is collected by gravity in a tank. The system aim is to condensate the maximum water quantity achievable for every atmospheric air condition, represented by temperature and humidity. Thus, a mathematical model is proposed to determine the optimal atmospheric air flow that maximizes the condensed water production for every atmospheric air condition. An experimental campaign is set up to validate the proposed model. Experimental test results show that the mathematical model accurately predicts the drinking water production (error between +4.1% and -5.6%). Thus, for every atmospheric air condition, the optimal air flow value and the related condensed water production are determined. Relative humidity greater than 70% and temperature higher than 35°C guarantee more than 1.0 liter of drinking water produced per hour and kW of refrigeration power installed.