Tiny refrigerator taking shape to cool future...( WEST LAFAYETTE Ind. - Researchers a...)

WEST LAFAYETTE, Ind. - Researchers at Purdue University are developing a miniature refrigeration system small enough to fit inside laptops and personal computers, a cooling technology that would boost performance while shrinking the size of computers.

Unlike conventional cooling systems, which use a fan to circulate air through finned devices called heat sinks attached to computer chips, miniature refrigeration would dramatically increase how much heat could be removed, said Suresh Garimella, the R. Eugene and Susie E. Goodson Professor of Mechanical Engineering.

The Purdue research focuses on learning how to design miniature components called compressors and evaporators, which are critical for refrigeration systems. The researchers developed an analytical model for designing tiny compressors that pump refrigerants using penny-size diaphragms and validated the model with experimental data. The elastic membranes are made of ultra-thin sheets of a plastic called polyimide and coated with an electrically conducting metallic layer. The metal layer allows the diaphragm to be moved back and forth to produce a pumping action using electrical charges, or "electrostatic diaphragm compression."

In related research, the engineers are among the first to precisely measure how a refrigerant boils and vaporizes inside tiny "microchannels" in an evaporator and determine how to vary this boiling rate for maximum chip cooling.

The research is led by Garimella and Eckhard Groll, a professor of mechanical engineering.

"We feel we have a very good handle on this technology now, but there still are difficulties in implementing it in practical applications," said Garimella, director of the Cooling Technologies Research Center based at Purdue. "One challenge is that it's difficult to make a compressor really small that runs efficiently and reliably."

Findings will be detailed in two papers being presented during the 12th Internati
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