rexresearch
Xavier MOYA, et al.
Neopentylglycol Refrigeration
https://www.cam.ac.uk/research/news/green-material-for-refrigeration-identified
Green material for refrigeration identified
Researchers from the UK and Spain have identified an eco-friendly solid that could replace the inefficient and polluting gases used in most refrigerators and air conditioners...
When put under pressure, plastic crystals of neopentylglycol yield huge cooling effects – enough that they are competitive with conventional coolants. In addition, the material is inexpensive, widely available and functions at close to room temperature. Details are published in the journal Nature Communications.
The gases currently used in the vast majority of refrigerators and air conditioners —hydrofluorocarbons and hydrocarbons (HFCs and HCs) — are toxic and flammable. When they leak into the air, they also contribute to global warming.
“Refrigerators and air conditioners based on HFCs and HCs are also relatively inefficient,” said Dr Xavier Moya, from the University of Cambridge, who led the research with Professor Josep Lluís Tamarit, from the Universitat Politècnica de Catalunya. “That’s important because refrigeration and air conditioning currently devour a fifth of the energy produced worldwide, and demand for cooling is only going up.”
To solve these problems, materials scientists around the world have sought alternative solid refrigerants. Moya, a Royal Society Research Fellow in Cambridge’s Department of Materials Science and Metallurgy, is one of the leaders in this field.
In their newly-published research, Moya and collaborators from the Universitat Politècnica de Catalunya and the Universitat de Barcelona describe the enormous thermal changes under pressure achieved with plastic crystals.
Conventional cooling technologies rely on the thermal changes that occur when a compressed fluid expands. Most cooling devices work by compressing and expanding fluids such as HFCs and HCs. As the fluid expands, it decreases in temperature, cooling its surroundings.
With solids, cooling is achieved by changing the material’s microscopic structure. This change can be achieved by applying a magnetic field, an electric field or through mechanic force. For decades, these caloric effects have fallen behind the thermal changes available in fluids, but the discovery of colossal barocaloric effects in a plastic crystal of neopentylglycol (NPG) and other related organic compounds has levelled the playfield.
Due to the nature of their chemical bonds, organic materials are easier to compress, and NPG is widely used in the synthesis of paints, polyesters, plasticisers and lubricants. It’s not only widely available, but also is inexpensive.
NPG’s molecules, composed of carbon, hydrogen and oxygen, are nearly spherical and interact with each other only weakly. These loose bonds in its microscopic structure permit the molecules to rotate relatively freely.
The word “plastic” in “plastic crystals” refers not to its chemical composition but rather to its malleability. Plastic crystals lie at the boundary between solids and liquids.
Compressing NPG yields unprecedentedly large thermal changes due to molecular reconfiguration. The temperature change achieved is comparable with those exploited commercially in HFCs and HCs.
The discovery of colossal barocaloric effects in a plastic crystal should bring barocaloric materials to the forefront of research and development to achieve safe environmentally friendly cooling without compromising performance.
Moya is now working with Cambridge Enterprise, the commercialisation arm of the University of Cambridge, to bring this technology to market.
https://www.nature.com/articles/s41467-019-09730-9
Colossal barocaloric effects near room temperature in plastic crystals of neopentylglycol
P. Lloveras, et al.
[ PDF ]
Abstract -- There is currently great interest in replacing the harmful volatile hydrofluorocarbon fluids used in refrigeration and air-conditioning with solid materials that display magnetocaloric, electrocaloric or mechanocaloric effects. However, the field-driven thermal changes in all of these caloric materials fall short with respect to their fluid counterparts. Here we show that plastic crystals of neopentylglycol (CH3)2C(CH2OH)2 display extremely large pressure-driven thermal changes near room temperature due to molecular reconfiguration, that these changes outperform those observed in any type of caloric material, and that these changes are comparable with those exploited commercially in hydrofluorocarbons. Our discovery of colossal barocaloric effects in a plastic crystal should bring barocaloric materials to the forefront of research and development in order to achieve safe environmentally friendly cooling without compromising performance.
WO2018069506 -- USE OF BAROCALORIC MATERIALS AND BAROCALORIC DEVICES
Abstract -- Described herein is the use of organic materials in methods of barocaloric cooling. The barocaloric effects may be exhibited where the organic material is near a non-isochoric phase transition, such as a non-isochoric first-order phase transition. The organic material has one or more carbon atoms and may be an organic compound or a salt thereof. In some cases that organic material is a soft matter material, such as a plastic crystal or a liquid crystal. The methods may be adapted for use of the organic material as a heating agent.