CPU Cooling: Microchannels and Microjets
Will we all carry air-conditioned laptops around with us in the near future? It's highly unlikely; not only would it make computers several times more expensive, but it would be an entirely unnecessary addition. Microprocessors in our personal computers generate a good amount of heat -- if you've ever worked with a laptop poised on your thighs for a long period of time, chances are after a while you noticed the bottom of the machine is warm to the touch.
Personal computers never generate more than 100 watts of heat for every half-inch square of microprocessor [source: Callahan]. That's why internal fans (the whirring sound you hear while your computer's on) and clever uses of space and materials are sufficient enough to keep a desktop or a laptop from suffering a meltdown.
The devices the team at Purdue University hopes to cool down aren't our measly personal computers. Instead, the air-conditioning research is directed at high-flux thermal management, the heating problems associated with more complex computing systems used for weapons systems and defense devices such as radar, directed-energy laser and microwave weapons and aviation electronics.
As the microprocessors for these systems become significantly smaller and more powerful, the heat generated also increases dramatically -- experts expect heat fluxes from future defense systems to reach more than 1,000 watts per half inch, or 10 times the amount of heat produced from a powerful home computer [source: Callahan]. Not only is this a big waste of electricity, but a meltdown from such a system could damage expensive equipment and potentially cause a great deal of harm to the people operating it.
The new air-conditioned chip cooling system would attempt to reduce temperatures to no greater than 257 degrees Fahrenheit by combining two prominent cooling technologies: Microchannels and microjets (or jet impingement). The surfaces of computer chips would be cut with microchannels, which are simply very small grooves about three millimeters deep, and covered with metal plates punched with microjets, or tiny holes. The system would pump hydrofluorocarbons (HFCs), the same liquid used in conventional air conditioners, through the microjets and into the microchannels. The HFCs would vaporize inside the grooves, cooling the chips, and cycle around via a small loop.
The school has received $500,000 from the Office of Naval Research, and although the concept is still in the experimental stages, the Purdue scientists hope to team up with defense contractors in the near future to further develop the technology.
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- Callahan, Rick. "Cool tech: Air-conditioned computer chips." MSNBC.com. July 16, 2008. (Aug. 29, 2008) http://www.msnbc.msn.com/id/25702898/
- Mudawar, Issam and Myung Ki Sung. "Single-phase and two-phase hybrid cooling schemes for high-heat-flux thermal management of defense electronics." Boiling and Two-Phase Flow Laboratory (BTPFL) and Purdue University International Electronic Cooling Alliance (PUIECA). May 2008. http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel5/4538254/4544243/04544262.pdf