We have reported at several occasions about how phase change cooling could be used to cool laptops, and by that we don’t mean to sub-zero degrees, but just to keep them at a safe temperature. The technology has been used in refrigerators for many years, but so far we haven’t seen a commercial cooler for laptops. There have been promising products shown like the cooperation between Embraco and Intel, but technically it did not cool the processor but only the ambient air.
The cooling solution presented by Intel and Embraco did have one key component though, a micro-compressor, that was a big step forward toward actually integrating refrigerator cooling inside our laptops. The research team at Purdue University, USA, have been focusing on the same thing, minimizing the size of the components, both the compressor and the evaporator.
They have developed an analytical model for designing a small compressor that can move the refrigerant through membranes the size of a penny. These ultra-thin membranes are made from polyimide, a plastic, and covered with electrically conducting metal. The metal makes it possible for the compressor to move the membranes back and forth through electrical charges. The researchers call it “electrostatic diaphragm compression.”
“We feel we have a very good handle on this technology now, but there are still difficulties in the implementation in practical applications; one challenge is that it’s difficult to make a compressor really small that runs efficiently and reliably.” – Garimella Groll, Professor of Mechanical Engineering in Purdue University
The technology is still in development and not quite ready to go commercial. To pump enough volume they need to put several membranes in parallel, 50-100, and depending on the direction they stack the membranes they can adjust the pressure. The design has been optimized to fit inside a laptop, but can also be individually adapted depending on the cooling performance needed. The computer designer can tailor the compressor depending on the need of the specific laptop model.
“This overall project represents the first comprehensive research to carefully obtain data showing what happens to heat transfer in arrays of micro channels for miniature refrigeration systems and how to design miniature compressors,” Garimella added. “Eventually, we will be able to design both the miniature compressors and evaporators.”
As with most research projects the biggest problem is finding out how to make everything in a cheap, or cheap enough, manner.
