World’s First Refrigerator Run By Flexing Artificial Muscles Revealed

Saarland University and ZeMa built a small, compact refrigerator prototype to demonstrate the novel cooling technique.

The technology uses elastocaloric heat transfer by stretching and releasing wires. Shape-memory wires made of super-elastic nitinol, nicknamed "artificial muscles," absorb heat in the cooling chamber and release it into the air.

ZeMa research professor Stefan Seelecke said, “Our elastocaloric process enables us to achieve temperature differences of around 20 degrees Celsius without using climate-damaging refrigerants in a far more energy-efficient manner than today's conventional technologies.”

Elastocaloric materials are a viable future solution for climate change, energy scarcity, and rising cooling and heating needs. Over times more efficient than existing air conditioning and freezers.

Engineers demonstrate elastocalorics in small cooling chambers, but they can remove and provide heat to bigger environments.

Superelastic wires can also transfer heat for heating, according to experts. For environmental and energy issues, elastocaloric technology is revolutionary.

The researchers use shape memory to transmit heat with nitinol-based artificial muscles. Wires made of this alloy may remember their original shape after being stretched or deformed.

They contract and relax like muscles. They can also lengthen and shorten. Due to its two crystal lattices, or phases, nitinol can alter internally. The wires absorb and release heat at crystalline structure phase transitions.

The concept may sound simple, but researchers say building a cooling circuit raises difficult challenges. A research team will display a mini-fridge with a patented cam drive that rotates 200 micron-thin nitinol wires around a cooling chamber at Hanover.

The wires collect heat from the chamber's flowing air when they are mechanically loaded and unloaded. After cooling, air circulates around unloaded wires. Stretched revolving wires emit heat outside the chamber.

Saarbrücken engineers study the drive's continuous motion, ideal airflows, efficiency, wire bundling, and stretching for cooling aims. The complete cycle—material production and recycling—is studied and customized heating and cooling software is developed.

The crew is just beginning its refrigerator trip. Motzki stated, “We want to leverage the innovative potential of elastocalorics in a wide range of applications, such as industrial cooling of electric vehicles to advance e-mobility and household appliances.