Wetenschap

Magnetic cooling also fit for heating

The champagne for celebrating Professor Ekkes Brück’s Valorisation Grant was served from a magnetic refrigerator. Brück expects magnetic cooling to hit the market in five years.

Magnetic cooling is a promising technique. Its main advantage is the absence of chemical coolant gasses, many of which are toxic or ozone depleting. A magnetic fridge works with (salt) water for heat transport and is simpler in construction. On top of that, Brück estimates that magnetic fridges can be 30% more energy-efficient than conventional freezers. But the biggest surprise may be its potential as a domestic heat pump.

FOM Valorisation Prize

FOM awarded the 2016 Valorisation Prize to Ekkes Brück, professor in fundamental aspects of materials and energy at the Faculty of Applied Sciences. FOM stated: ‘The selection committee recognises that besides the high scientific quality of his work, he also has a clear vision regarding the applicability of that work and manages to convey this vision to the industry.’

Brück has been working on the application for magnetic cooling since before 2010, when a PhD candidate of his graduated on the giant magnetocaloric effect. This effect can be used for cooling by applying an intermittent magnetic field. Switch the field on, and the magnetocaloric material will heat up. Switch the magnets off, and the temperature will drop so that the material can absorb heat from its surroundings.

Funding from BASF

At the Gustav Lorentzen conference, two years later, Brück announced his five-year research plan with funding from BASF on magnetocaloric materials.

Another three years later, in November 2015, a prototype magnetic refrigerator was announced and discussed –but not shown- during the Delft Days on Magnetocalorics.

This year, finally, a functional prototype was put to work for Dr. Brück’s reception in the RID building on Thursday, January 19, 2017.

FOM jury report

The FOM jury report had praised Brück’s persistence in realising applications for energy materials, including revolutionary cooling technologies, efficient heat pumps, and the generation of electricity from low caloric heat. Brück reacted: “The entire industrial chain is important if you want to use new materials in a better final product. I found that really interesting.”

When asked for the interest from Dutch manufacturers, Brück said that they were not interested in the technology. “The industry reacted restrained, conservative,” he found. Thus, the Chinese appliances manufacturer Haier produced the demo.

Melting a mixture

The heat engine in the demo consists of packed magnetocaloric material, made by BASF in De Meern. BASF’s senior scientist Bennie Reesink explained that he had melted the mixture of manganese, iron, phosphor and silicon in an induction oven. The material was then packed into a porous structure through which salt water flows as a heat transport medium. “The material is available,” Reesink observed. “Now it’s a matter of engineering it into energy efficient applications.”

The demo fridge has an electric power of 50 Watt and a heat transport of 150 Watt (coefficient of performance or COP = 3). Heat pumps in the order of 1.5 kiloWatt are within reach, Brück and Reesink estimated. Magnetic heat pumps of that size may heat Dutch homes in the post-gas era ahead.

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