Think about this. If you have a desktop or laptop computer, the machine is most likely equipped with a fan that keeps the electronics inside from overheating.
Now, multiply your PC by millions in the U.S. That's a lot of fans, many running 24-7, keeping those computers cool. Scientists at the University of Alabama in Huntsville (UAH) estimate the electricity cost of running all those computer fans at more than $6.3 billion a year.
The scientists say they have tested a completely different kind of computer cooling system that could eliminate all those fans and that $6.3 billion in electricity costs.
The system uses convection to circulate 3M’s Fluorinert FC-72 liquid through channels in a computer’s processor and then into a heat sink that serves as an external radiator.
There are other fanless machines just starting to make their way into the consumer marketplace. Intel's latest mobile chip, the Core M, is fanless and is available in some of the latest laptop models from Acer, Asus, HP, Lenovo and other major manufacturers.
An Israeli company called CompuLab, has been making small, air-cooled computers for 15 years. They use a ribbed metal case that acts as a heat sink. A CompuLab model called the mintBox has been running continuously in our none-too-cool office for several years with no problems.
Some component manufacturers, including Corsair, combine traditional fans with liquid cooling.
Computers might cost less
In addition to saving more than $6 billion in energy costs, the Alabama scientists say their system could save computer makers $540 million a year because they wouldn't need to install fans or the wiring they require. They base that projection on a future in which there are 300 million computers with their system in use.
It would be a revolutionary development in the U.S. – but that could be just the tip of the iceberg.
“If you can do this for the world, we can save a whole lot of pollution globally,” said Dr. James Smith, a UAH chemical engineering professor emeritus who is working with graduate students to optimize the system. “Think of what could be done in China alone.”
The heat removal system is based on Fluorinert FC-72, the 3M brand name for an electronic cooling liquid and electrical insulator. It is colorless, odorless, biologically inert and chemically stable. It's also nonflammable, with a boiling point at 56 degree Celsius, or 133 degrees Fahrenheit.
Here's how it works; heat generated by the computer processor vaporizes liquid FC-72. That vapor then moves to a heat exchanger, where it releases its heat into the environment and condenses into a heavier liquid.
The heavier liquid then moves to a holding tank, where it travels to the processor again to start the cycle all over.
Cuong Nguyen, an engineering graduate student, wrote his master's thesis comparing the passive cooling system with traditional solid-state passive cooling and traditional fan cooling in computers.
For the comparison, the computers were run for up to 12 hours under no load and heavy load conditions. The system was tested using modified Intel Pentium 4 and Core i3 processors.
12 hours in stable condition
“Our system can absolutely work, and it can work for 12 hours in a stable condition,” Nguyen said.
The series of experiments found the passive FC-72 cooling system could maintain a near steady 56-degree Celsius processor operating temperature. Nguyen said an acceptable temperature range is 50-90 degrees Celsius.
The bottom line? Replacing a computer's fan with a passive heat removal system could be a plus all the way around.
“When we remove the cooling fan, it saves material costs, but it also eliminates the noise, vibration and dust contamination of fan cooling,” Nguyen said. “When you remove the dust, you remove the chance that it can build up. Build up of dust can destroy the electronic components.”
Smith says the system could have applications beyond computers. He says it could help stabilize temperatures in electronic guidance and propulsion controls in outer space while making things operate more smoothly here on earth.
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