A small bracelet will cool a person more efficiently than an air conditioner

San Diego is getting hotter every year, and the University of California is keen to develop new, mobile and economical climate systems. One of the new products is intended to be worn directly on the human body and cools or heats it directly. Because of this, energy consumption in comparison with traditional air conditioners is reduced by tens, or even hundreds of times.

The prototype looks like a bandage on a hand, between two layers of which there is a heat transfer system made of a thermoelectric alloy of bismuth telluride. One of the variants of a heat pump is implemented here, which, when an electric current is applied, begins to transfer heat between the plates of the elastomers making up the dressing. When the skin is hotter than the surrounding air, the heat is removed to the outside - and vice versa.

The temperature difference is small, only 5-10 degrees, however, the energy losses are symbolic. In addition, all the heat or cold is received directly by the part of the body with which the dressing is in contact. If we increase it to the scale of a vest, we get a personal air conditioner. On a normal warm day, it will consume 26 W of energy, in extreme heat - up to 80 W, and a noticeable effect will appear in a few minutes. These figures cannot be compared with wall-mounted air conditioners, the energy consumption of which is measured in kilowatts, and it takes much more time to cool the room.

If we imagine that all office workers in a skyscraper in a sunny region will wear a cooling vest along with their corporate uniforms, then the cost of air conditioning the premises will drop tenfold. However, the design of such vests is still in development, the release of a commercial version in the near future should not be expected.