MIT scientists are developing a new type of chemical composite that can absorb heat from the sun or other sources, store it for a period of time, and then release it in a controlled manner when exposed to light. The phase change material, made from a mixture of fatty acids and organic compounds, is expected to be stored and delivered to people in developing countries someday in the future, a device that can be used on a solar-powered cooktop that absorbs solar energy during the day and Free at night.
GraceHan, a MIT postdoc, holds a new compound that can be used as a thermal battery.
Scientists and engineers are interested in the potential applications of phase change materials that can absorb or release large amounts of heat (or vice versa) as they change from solid to liquid, a technology that can be used to regulate building heat and create 'Hot batteries' and keep coffee hot even while driving to work.
The principle of using phase change materials as a source of heat is simple: for example, when ice cubes change from solid to liquid water, they need to absorb a certain amount of heat, which is why snow does not melt abruptly on an unusually warm day; and why One of the reasons ice cubes in the refrigerator cool the beverage more than stainless steel cubes.
Like waxes, fatty acids, and molten salts, the difficulty of phase change materials lies in how they change their phase at a reasonable temperature, remain liquid for long periods of time, and release heat as needed. The second material requires thick insulation and the third There is a need for phase change materials that can release energy with slight heating, or contact with the catalyst.
The study, led by MIT postdocs Grace Han and Huashan Li, and Jeffrey Grossman, essentially introduces small molecules that act as photo-triggers for phase transition transitions (here using tris fatty acids, azobenzene dopants And tridecyl ester).
This form of chemical energy can be maintained for a long time until it is activated by light.
This hybrid material liquefies when heated, but when exposed to ultraviolet light, it can remain liquid even when cooled down, which means most of the heat is locked in this compound 200 joules), which is already quite good for organic phase change materials.
With another light, it triggers the curing of fatty acids and phase-change materials and releases energy, a feature the researchers say makes it well suited as a 'chemical heat cell' that releases heat on demand, Storage for more than 10 hours, but there is room for improvement.
Currently, MIT's Phase Change Materials are in proof-of-concept phase, but it has been able to handle temperature changes of 10 ° C (18 ° F) not only for use in solar cookers but also for drying cereals or Recycle plant or vehicle waste heat for later use.
Details of the study have been published in a recent issue of Nature Communications.
