MIT News November 11, 2020
A camel’s coat, or a person’s clothing, can help to reduce loss of moisture while at the same time allowing enough sweat evaporation to provide a cooling effect. Tests have showed that a shaved camel loses 50 percent more moisture than an unshaved one, under identical conditions. Researchers at MIT have developed a system with a two-layer material with the bottom layer, substituting for sweat glands. It consists of hydrogel, a gelatin-like substance that consists mostly of water, contained in a sponge-like matrix from which the water can easily evaporate. This is covered with an upper layer of aerogel, playing the part of fur by keeping out the external heat while allowing the vapor to pass through. In the experimental setup, it took 200 hours for a 5-millimeter layer of hydrogel, covered with 5 millimeters of aerogel, to lose all its moisture, compared to 40 hours for the bare hydrogel. The two-layered material’s cooling level was slightly less but the effect was much longer-lasting. Once the moisture is gone from the hydrogel, the material can then be recharged with water so the cycle can begin again. The passive cooling system can keep foods and pharmaceuticals cool for days without the need for electricity…read more.