Giant barocaloric cooling effect offers a new route to refrigeration

A groundbreaking cooling technique based on the principles of dissolution barocaloric cooling has the potential to revolutionize refrigeration, offering a more environmentally friendly alternative to traditional methods. Developed by researchers from the Institute of Metal Research of the Chinese Academy of Sciences, this innovative approach can reduce the temperature of water by nearly 27 K in just 20 seconds, achieving a cooling capacity of 67 J/g and an efficiency of nearly 77%. This remarkable performance far surpasses what is possible with standard barocaloric materials.

Traditional refrigeration systems, which have been in use since the 19th century, rely on the vapour-compression cycle. In this process, a refrigerant fluid changes phase, absorbing heat from its surroundings as it evaporates. A compressor then forces the refrigerant back into its liquid state, releasing the heat. While effective, this method consumes a significant amount of electricity, and its efficiency is limited by the Carnot cycle. Additionally, many refrigerants are toxic, contributing to environmental harm.

In recent years, researchers have explored caloric cooling as a potential alternative to traditional refrigeration. Caloric cooling works by controlling the entropy, or disorder, within a material using magnetic or electric fields, mechanical forces, or applied pressure. Among these methods, barocaloric cooling, which uses pressure, has shown the most promise. However, most known barocaloric materials are solids, which suffer from poor heat transfer efficiency and limited cooling capacity. Transferring heat in and out of such materials is therefore slow and inefficient.

The new dissolution barocaloric cooling technique overcomes these limitations by leveraging a fundamental thermodynamic process called endothermic dissolution. When a salt dissolves in a solvent, some of the bonds in the solvent break. This process absorbs heat, causing the temperature of the solvent to drop. By carefully controlling the pressure and the concentration of the dissolved salt, researchers can manipulate the entropy of the system, leading to significant temperature reductions.

This liquid-based system allows for much faster heat transfer compared to solid barocaloric materials, enabling the new method to achieve its impressive cooling performance in just 20 seconds. The researchers achieved this by using a mixture of water and a salt, specifically sodium tungstate, under high pressure. As the salt dissolves in the water, the system absorbs heat, causing the temperature to drop. When the pressure is released, the salt precipitates out of the solution, releasing the absorbed heat and allowing the system to return to its original state.

The potential applications for this new cooling technique are vast. It could be used in refrigeration systems, air conditioning, and even in energy storage devices. By offering a more efficient and environmentally friendly alternative to traditional refrigeration methods, dissolution barocaloric cooling has the potential to significantly reduce energy consumption and minimize the environmental impact of cooling technologies.

Further research will be needed to optimize the performance of this new method and to explore its scalability for various applications. However, the groundbreaking work by the Chinese researchers marks a significant step forward in the development of sustainable cooling technologies. As the world continues to grapple with the need to reduce energy consumption and minimize environmental damage, innovative solutions like dissolution barocaloric cooling offer hope for a more sustainable future.