Scientists from the University of Tokyo have developed a technology to multiply the thermoelectric effect in electricity generation, even with small temperature differences. This waste heat can be taken from anywhere. For example, when air is cooled by an air conditioner, when a little energy is released in the process of moisture condensation. And such phenomena occur everywhere from the manufacture of ice cream to the smelting of glass, which can be used.
The proposal of Japanese scientists is based on the fact that even the slightest difference in temperature can be used to significantly enhance the thermoelectric effect. The very difference in the temperature of a substance (liquid or gas) arises in the process of the transition of a substance from one state of aggregation to another – this is the condensation or crystallization of water and similar processes.
During a phase transition, energy is released (or absorbed under other conditions). In a limited volume, it is not enough, for example, inside the same air conditioner. But the Japanese have come up with a way to increase the return on this energy. They assembled a polymer that, when cooled, straightens into a spiral, and when heated, folds into a ball (globule). In fact, the polymer either dissolves in water when it is cooled below a certain value, or “condenses” when heated above the limit for dissolution. From the point of view of chemistry, redox reactions occur, as scientists described in the Advanced Materials article.
The coil-globule transition sharply releases water molecules from polymer chains – the polymer completes its phase transition. It’s like launching an avalanche from a mountain. A small fraction of the energy of the “primary” phase transition, for example, in the process of water condensation in an air conditioner, starts an avalanche-like process of polymer condensation, which multiplies the heat release and enhances the operation of the thermoelement.
In fact, the process increases the so-called Seebeck coefficient, a measure of the efficiency of a thermoelectric converter, to +2.1 mV/K. This is more than twice as high as for the already studied organic solutions. The discovery is so successful, scientists say, that it’s time to look for a manufacturer for such systems. And then “it will be possible to generate electricity by cooling a server room or a car engine,” the participants in the study say.
“We have confirmed for the first time that latent heat can be used for thermoelectric conversion,” said Professor Teppei Yamada from the Department of Chemistry at the University of Tokyo’s Graduate School of Science. — We believe that various types of materials can be used for thermocouples. Every substance can undergo a phase transition under the right conditions: for example, cream into ice cream, sand into glass, water into steam, and so on. In principle, with this method it is possible to extract electrical energy from even the slightest temperature difference, which greatly increases the number of situations in which thermoelectric conversion can be used.”
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