Evaporative cooling air conditioners are commonly used to cool the internal spaces of homes, factories and other buildings, especially in dry climates. Hydrophilic membranes, or laminates of hydrophilic and hydrophobic membranes, are used to transport and distribute water over a sufficiently large surface area. Warm dry air is blown or otherwise directed across the surface area to cause evaporation of the water, resulting in humidification and cooling of the air and cooling of the hydrophilic membrane or laminate. The cooled humidified air can then be used to cool the internal space. Alternatively, a separate stream of warm dry air can be passed along the hydrophobic side of the evaporatively cooled laminate. The separate air stream can be cooled by the laminate without humidification, and the cooled dry air can be used to cool the internal space.
In each case, the cooling capacity is dependent upon the evaporation rate of water from the hydrophilic membrane or laminate. The evaporation rate in turn depends upon the wet surface area of the hydrophilic membrane or laminate, the rate of water transport across the membrane or laminate, and the temperature, humidity and flow rate of the warm dry air. The rate of water transport depends upon the wicking rate and capacity of the hydrophilic membrane or laminate, which in turn depends upon the specific material(s) used to form the hydrophilic membrane.