Keeping cool without warming the planet
Assistant Professor of Chemistry Jarad Mason and co-author Jinyoung Seo
Assistant Professor of Chemistry Jarad Mason (left) and co-author Jinyoung Seo have developed a new solid-state refrigerant that enables energy-efficient and zero-emission cooling.
A revolutionary new mechanism could turn on eco-friendly air conditioning Summer’s conundrum is like King Solomon: How to stay cool on hot and humid days without using traditional air conditioners, which consume huge amounts of electricity, side by side Emit strong greenhouse gases that cause climate change.
The answer may involve a new solid-state refrigerant that enables energy-efficient and zero-emission cooling. Now, researchers from the Department of Chemistry and Chemical Biology have developed an environmentally friendly mechanism to achieve solid-state cooling with two-dimensional perovskites. Their findings are published in a new study in Nature Communications.
"Moving away from vapor compression systems has been in use for a long time and is part of the overall effort to drive a more sustainable future," said Jarad Mason, first author of the paper and assistant professor of chemistry and chemical biology. "Our focus is to delve deeper into the intrinsic properties of these materials and see what possibilities solid-state cooling has as a sustainable alternative."
This 2D perovskite is also known as a heavy thermal material. , as they expand and contract, they release and absorb heat as the pressure changes. This effect is based on a phenomenon you're probably familiar with, if you've ever stretched a balloon and felt it heat up on your lips. Likewise, these materials also release heat when pressed. This mechanism removes heat in the solid state using low actuation pressures without releasing any harmful emissions.
This work was led by members of the Mason Lab, including Jinyoung Seo, Ryan D. McGillicuddy, Adam H. Slavney, Selena Zhang ’22, Rahil Ukani, and X-ray Laboratory Director Shao-Liang Zheng. The company also conducted advanced testing in collaboration with scientists at Argonne National Laboratory in Lemont, Illinois.
This new mechanism of solid-state cooling has the potential to overcome the limitations of traditional vapor compression cooling technology, which has remained largely unchanged since the early 20th century.
Any kind of refrigeration system operates in a cycle, from a low-entropy state (the material can absorb heat, thereby cooling the space) to a high-entropy state (energy can be released in the radiator, where it is dissipated). Vapor compression air conditioners circulate volatile liquid refrigerant that evaporates and condenses at varying pressures through metal coils, cooling the enclosed space and injecting heat outdoors. Operating the vapor compression cycle is energy intensive and currently accounts for nearly 20% of the electricity used in buildings around the world. In addition, the leaking refrigerant is a greenhouse gas more than 1,000 times more powerful than carbon dioxide .
This new mechanism (pictured) could replace traditional vapor compression cooling technology, which has remained largely unchanged since the early 20th century.
The team identified 2D perovskites as an ideal alternative because they can undergo reversible phase changes with minimal pressure while remaining solid; the more a material's entropy changes, the more efficient its cooling cycle will be. . When the hydrocarbon chains of organic double-layer structures switch between ordered and disordered states, they are able to experience huge entropy changes. The research team predicts that 2D perovskite can serve as a highly tunable solid-state cooling material. Can work under less pressure than imagined. The
research team synthesized these materials in their laboratory and tested them in a high-pressure calorimeter to measure changes in the material's heat flow at different pressures and temperatures. These experiments reveal how much heat can be removed in a potential refrigeration cycle and how much pressure is needed to drive the cycle. "Once we started testing this material, we realized we could remove very large amounts of heat with very small changes in pressure," said
Mason. "That's when we knew there was something interesting here. .The
researchers also conducted high-pressure powder X-ray diffraction experiments at Argonne to understand phase changes at the molecular level. With the x-ray synchrotron, the team was able to characterize the structural changes in each material at different temperatures and pressures.
Seo said: “In addition to their promising properties, these materials are worthy of investigation. They can also help chemists understand fundamental properties that are critical to realizing this technology on a large scale.
The next step for the Mason lab is to prototype the thermal cooling device while continuing to explore the potential uses of different materials.
Professor Xu said: "It is very possible to use a new generation of materials on the prototype device." “We are working hard to develop new technologies to address cooling challenges. ”
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