The process of magnetic refrigeration has been employed for more than a decade, but recent developments have decreased the weight and cost of earlier models.

The Ames Lab has been researching methods to make the process more commercially viable.

Prototypes for magnetic refrigeration units work by placing pockets of a metal called gadolinium alloy in a donut-shaped ring. A team of ISU scientists led by Karl Gschneidner, distinguished professor of materials science and engineering, developed a new process for creating gadolinium alloy in greater amounts with better purity.

There has been a great deal of interest from major companies around the world, Gschneidner said.

“We put out a news release in February 1997, and we’ve had probably over 600 inquiries since,” he said.

The ring is mounted on a motor, and the gadolinium spins through a hole in a magnet. Originally, super-cooled electromagnets were used in this process, making the unit bulky and expensive, but Gschneidner’s team developed a strong permanent magnet that is cheaper and smaller.

When the gadolinium goes through the magnet, the atoms in the metal are aligned and the metal heats up. This process is called the magnetocaloric effect.

Liquid is passed by the gadolinium to draw off the heat and cool the metal, and the gadolinium then contacts another closed liquid system, cooling the liquid. The cooled liquid functions as the refrigerant, much like conventional refrigerators use freon or other gases.

In five years or less, companies will start to produce refrigerators or air conditioners with this technology, Gschneidner said.

“Whoever is adventurous enough with a good vision of the future will produce them,” he said.

Carl Zimm, senior engineer at Astronautics Corporation of America, the company that designed the rotary system for magnetic refrigeration, said researchers wanted to get more power out of the same size machine. Another primary aim was to make the entire process cheaper, he said.

The new cooling system also has a host of commercial applications.

“It can be used for refrigerators, portable coolers,” Zimm said. “It’s very efficient at cooling water and so could be used for cooling industrial military and laboratory equipment.”