For many years, liquid refrigerants that damage the ozone layer, such as CFCs and HCFCs, were heavily utilized in air conditioning systems and refrigerators. They were eventually replaced with HFCs, which do not damage the ozone layer, but they are a powerful greenhouse gas that have a warming effect several orders of magnitude greater than CO2. This dilemma brought Dr. Takeuchi and his research team at the University of Maryland to develop a novel elastocaloric cooling device, which changes temperature when exerted upon by mechanical pressures such as pulling or pressing. This device is made of nitinol, an alloy of nickel and titanium, and when experiencing mechanical stress, the nitinol releases heat, but when the pressure is removed, it absorbs heat, which cools the area around it. 

Elastocaloric materials are cheaper to employ than similar alternatives such as electrocaloric or magnetocaloric materials, all of which can be used to relocate heat. However, magnetocaloric devices have received the most attention and funding, and can exceed the temperature change of 22.5 ℃ reached by the elastocaloric device developed by Dr. Takeuchi’s team. That being said, they typically function at very low temperatures, making them less applicable at room temperature and encouraging the study of elastocaloric devices. 

In the case of elastocaloric materials, this can be achieved by running heat exchange fluid around the nitinol device as it releases heat to a new location. The heated fluid will release its energy into this new location and then be cycled through to come back into contact with the nitinol, at which point will have been relieved of mechanical strain and can absorb the heat of the fluid. This cold fluid can be sent to a desired place, such as a refrigerator, cooling the surrounding area. 

Nitinol is a shape-memory alloy, which means it returns to a previous shape when applied pressure is relieved. The device designed by Dr. Takeuchi’s team consists of two nitinol tubes inside a stainless steel tube, which are used in tandem to reduce electricity expenditure. While one nitinol tube is allowed to reform to its full length, the energy released compresses another set of nitinol tubes.

Elastocaloric devices and similar technology have the potential to revolutionize cooling systems to make them much better for the environment, and hopefully reduce costs as well. These resources could benefit every human, and depending on when they’re commercially introduced, possibly be integrated into developing nations as they industrialize, allowing them to skip investing in less advanced technology that has been used for decades. Replacing existing appliances and systems is costly and has a significant environmental impact, but if caloric devices are introduced to the market at a reasonable cost soon, regions might be able to “leapfrog” less efficient refrigerator and air conditioning systems. This phenomenon has been observed with landlines, which were barely ever employed in Ghana, India, and Nigeria, as the countries were able to cut out the outdated technology and move straight onto mobile phones (Landline Internet subscriptions per 100 people, 1998 to 2022).

As always, the brunt of the information presented came from the first source linked below, with some supporting information from the subsequent sources, which are cited in text. I don’t know if I ever clearly established that notation, so if you’re ever wondering where certain information originated from, that’s how you can find it.

To really understand the mechanism in which elastocaloric devices function, I did some research on similar technology like magnetocaloric devices, which seem to have a lot of potential for appliances such as fridges and freezers. It has been receiving funding for many years, and is expected to use “20%–30% [less energy than] conventional vapor compression systems,” which would be really great. Hopefully we will see these alternatives on the market soon (Office of Energy Efficiency & Renewable Energy).

The concept of leapfrogging wasn’t especially relevant to this topic, but I’ve been thinking about it a lot as I’ve been researching advancing technologies. Cutting out the middleman gives developing nations an advantage that can hopefully foster further progress. A prime example of leapfrogging is seen in the energy sector, and we’ll talk about that next week! Stay tuned to learn with me!

A New Way to Beat the Heat: Scientists Develop an ‘Elastocaloric’ Cooling Device 

A New Way to Beat the Heat: Scientists Develop an ‘Elastocaloric’ Cooling Device 

“Data Page: Landline Internet subscriptions per 100 people”. Our World in Data (2024). Data adapted from International Telecommunication Union (via World Bank). Retrieved from https://ourworldindata.org/grapher/broadband-penetration-by-country [online resource]

https://www.energy.gov/eere/buildings/articles/magnetocaloric-refrigeratorfreezer