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posted by Fnord666 on Wednesday November 22 2017, @01:27PM   Printer-friendly
from the getting-warmer dept.

Heat all day, cool all night:

a new chemical composite developed by researchers at MIT could provide an alternative. It could be used to store heat from the sun or any other source during the day in a kind of thermal battery, and it could release the heat when needed, for example for cooking or heating after dark.

A common approach to thermal storage is to use what is known as a phase change material (PCM), where input heat melts the material and its phase change -- from solid to liquid -- stores energy. When the PCM is cooled back down below its melting point, it turns back into a solid, at which point the stored energy is released as heat. There are many examples of these materials, including waxes or fatty acids used for low-temperature applications, and molten salts used at high temperatures. But all current PCMs require a great deal of insulation, and they pass through that phase change temperature uncontrollably, losing their stored heat relatively rapidly.

Instead, the new system uses molecular switches that change shape in response to light; when integrated into the PCM, the phase-change temperature of the hybrid material can be adjusted with light, allowing the thermal energy of the phase change to be maintained even well below the melting point of the original material.

The rate of cooling can be controlled.

Grace G. D. Han, Huashan Li, Jeffrey C. Grossman. Optically-controlled long-term storage and release of thermal energy in phase-change materials. Nature Communications, 2017; 8 (1) DOI: 10.1038/s41467-017-01608-y


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  • (Score: 2) by JoeMerchant on Thursday November 23 2017, @01:45PM

    by JoeMerchant (3937) on Thursday November 23 2017, @01:45PM (#600650)

    I wonder if a flexible pipe heat exchanger might be longer lasting - not as efficient, sure, but if it's efficient enough to get the ice bank frozen using whatever process (solar is common) - I'd rather have a 30% bigger collector on a device that runs 20 years maintenance free, instead of a smaller unit that needs its coils replaced every 2-3 years.

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