Scientists from the USA and China come up with how to quickly cool a smartphone and convert its heat into electricity
Almost all electronic gadgets significantly heat up during intensive use. If heat is not removed in a timely manner, this can slow down the speed of the device, damage its components, or even cause the battery to explode or catch fire . To solve this problem, a group of scientists from the University of Wuhan and the University of California at Los Angeles have developed a universal, efficient and inexpensive technology for heat recovery through a hydrogel film, which can not only quickly reduce the temperature of the device, but also convert its heat into electricity. The research results were published in the journal Nano Express.
The conflict between heat dissipation and its conversion to electricity
Many components of electronic equipment, including batteries, LEDs and microprocessors, generate heat during their normal operation. If it does not dissipate over time, overheating can occur, leading to a decrease in the efficiency, accuracy, sensitivity and life of the electronics.
Ancillary equipment, such as fans or cooling liquid pumps, are typically added at present to achieve effective heat dissipation, which also leads to additional energy costs.
Traditional methods of heat recovery, for example, thermoelectric modules , usually increase the thermal resistance of the system, which, in turn, complicates the task of heat removal and leads to an even higher temperature increase of the main components.
Until now, scientists have sought effective heat dissipation and the conversion of waste heat into electricity separately, but could not simultaneously implement these two conflicting processes in the same system.
Smart hydrogel
In the course of their work, the researchers created a new type of hydrogel based on specially ionized water and polyacrylamide. A film of such a material has received two important thermal properties. Firstly, it can maintain its own moisture level, which solves the problem of drying in open environmental conditions. Secondly, with increasing temperature, the hydrogel film evaporates and loses part of the water, but when the temperature drops, it absorbs moisture from the air in order to restore its original state.
Of course, these thermal properties meet only the functional requirements for rapid heat dissipation. But in fact, when the hydrogel is exposed to heat, the ions in it are used as charge carriers between the electrodes and thereby generate an electric current.
Thus, water and ions in the new “intelligent hydrogel” go through two independent thermodynamic cycles. This carefully thought-out reversibility scheme not only solves the problem of rapid cooling of electronic devices, but also maximally recovers excess heat.
To test the viability of the idea, scientists put a 2 mm thick hydrogel film on their mobile phone. During the fast discharge of the battery, it was noticed that its temperature dropped by 20 ° C, while 5 μW of electricity was generated, which is enough, for example, to power the cooling system. It was also found that the level of ionization and the thickness of the hydrogel provide accurate control of the time of evaporation and regeneration of water.
Researchers are sure that their work proves the huge potential of the technology in the implementation of the simultaneous cooling of electronic devices and the conversion of waste heat into electrical energy, which will lead to the creation of new energy-efficient and cheap equipment.
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