U of M Develops Metal Alloyto be Used as Refrigerant

July 20, 2010
The approach is expected to increase cooling efficiency 175%

Researchers at the University of Maryland are developing a new "thermally elastic" metal alloy for use in advanced refrigeration and air conditioning systems. University sources say the technology promises far greater efficiency and reductions in greenhouse gas emissions. The Maryland team will soon begin testing of a prototype system, with economic stimulus funding from the U.S. Department of Energy.

The new grant is part of a program designed to bring "game-changing" technologies to market.

"Air conditioning represents the largest share of home electric bills in the summer, so this new technology could have significant consumer impact, as well as an important environmental benefit," says Eric Wachsman, director of the University of Maryland Energy Research Center (UMERC). "The approach is expected to increase cooling efficiency 175%, reduce U.S. carbon dioxide emissions by 250 million metric tons per year, and replace liquid refrigerants that can cause environmental degradation in their own right," Wachsman adds.

The lead researchers on the project, Ichiro Takeuchi, Manfred Wuttig and Jun Cui, materials science engineers in Maryland's A. James Clark School of Engineering, have developed a solid coolant to take the place of fluids used in conventional refrigeration and air conditioning compressors. They claim their system represents a fundamental technological advance. In the next phase of research, the team will test the commercial viability of their smart metal for space cooling applications.

This two-state alloy alternately absorbs or creates heat in much the same way as a compressor-based system, but uses far less energy.

The 0.01-ton prototype is intended to replace conventional vapor compression cooling technology. Instead of fluids, it uses a solid-state material — the thermoelastic shape memory alloy. This two-state alloy alternately absorbs or creates heat in much the same way as a compressor-based system, but uses far less energy, the Maryland team explains. Also, it has a smaller operational footprint than conventional technology, and avoids the use of fluids with high global warming potential.

General Electric Global Research and the Pacific Northwest National Laboratory are partnering with the University of Maryland on the project. The Department of Energy has given the team $500,000 — one of only 43 grants nationwide — as part of its Advanced Research Projects Agency-Energy (ARPA-E) program, designed to advance out-of-the-box, transformational research from the laboratory to marketplace. The grants are funded with money from the federal American Recovery and Reinvestment Act.

"These grants are highly competitive and require a demonstration that the technology has genuine commercial potential," Wachsman explains. "This represents a significant investment in the state of Maryland and the development of its 'green' economy." Wachsman — who began at Maryland eight months ago, is working to make UMERC the campus focal point of interdisciplinary energy research. He's also submitted a proposal to the Department of Energy to locate a $130 million multi-institutional research hub in the Washington, D.C. region, focusing on a broad array of green building research (including including technology such as this). The agency is expected to make a decision next month on the highly competitive grant. The grant to develop Maryland's solid-state coolant is part of a $92 million package of ARPA-E awards distributed to 18 states.