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An innovation in thermoregulating clothing

Thermoregulating garments powered by solar energy and bidirectional electrocaloric devices are under development. They are said to be effective for outdoor temperatures of 12.5 to 37.6°C.  

Researchers at Nankai University in China have developed a new type of temperature-regulating garments that could be useful in extreme conditions. 

  

Garments of this type already exists in aerospace industry, for instance. But these systems have various limitations:

  • When a refrigerant is used, a mechanical compressor is required and the garment must be connected to a cooling circuit. 
  • Systems equipped with a battery do not have sufficient autonomy. 
  • Thermoelectric devices based on the Peltier effect require a lot of energy. 
  • Passive cooling systems can only heat or cool the user: they do not adapt to the outside temperature as needed. 

 

The system developed by Z. Wang and his team (1) could avoid these pitfalls: it is powered by solar energy, which avoids the need to connect to a compressor and allows access to a source of energy throughout of the day. The garment has a 24-hour battery life, which allows it to work at night. 

Thanks to an electrocaloric system, this garment can both warm or cool its user: according to tests carried out, it would be effective in external temperature ranging from 12.5 to 37.6°C. It would maintain skin temperature at between 32 and 36°C. In 1936, William Bierman wrote that normal skin temperature usually ranges between 33.5 and 36.9°C. (1) 

The garment developed in China would keep its user in relatively good comfort conditions, particularly at high external temperatures. 

 

The photovoltaic panels it is equipped with are flexible and have an effective surface area of ​​25.2 cm². They are very thin (180 μm). They are placed on the outside of the garment. 

Electrocaloric panels are made of a flexible polymer that allows significant adiabatic temperature change close to ambient temperature. An energy storage system allows the garment to function at night. In order to diffuse heat or cool the user, these electrocaloric panels are located inside the garment, close to the skin. 

A voltage control system allows the user to switch between heating and cooling depending on their environment and comfort needs. 

 

This type of garment could facilitate human activity in hostile environments (desert, space, etc.). 

 

In a related article (3), two Chinese scientists write: "It is possible to imagine a future of all-weather thermal management that is not limited by an energy supply and where extra collected energy might even power electronic devices under special conditions.” 

 

Sources:

(1) https://www.science.org/doi/10.1126/science.adj3654

(2)  https://jamanetwork.com/journals/jama/article-abstract/1155856

(3) https://www.science.org/doi/10.1126/science.adl5650

https://www.optica-opn.org/home/newsroom/2023/december/solar-powered_clothing_for_thermoregulation/