Laptops cool off with 'smart' heat pipes

A researcher at Sandia National Laboratories says he has created technology to disperse the heat generated within laptop computers more efficiently than today's cooling systems.

Sandia's Mike Rightley said he has developed tiny liquid-filled pipes that shift heat to the edge of the computer where air fins or a tiny fan can disperse it into the air.

Although chipmakers like Intel and several other computer and component makers have been using pipes to dispel heat for several years now, experts say the technology developed at Sandia is a refinement of existing systems. Current heat pipes are relatively bulky, analysts say, but this one is extremely fine-grained, allowing the tube to be a self-powered mechanism.

This development could lead to smaller and more efficient notebook computers as engineers and designers eliminate the space needed to house bulky and noisy fan cooling systems.

The technology may have an even greater impact on the growing trend of using desktop processors in notebook systems. Mobile chips have become more power-efficient, generating less heat, but are markedly more expensive than desktop processors. In recent years, the consumer notebook market has been driven by laptop systems configured with desktop processors to deliver desktop-level power at a lower cost.

"The trade-off of course is battery life and the amount of heat these processors create in such a small chassis," said Alan Promisel, a portable computer analyst at research firm IDC. The excess heat "often affects the processor's potential clock speed or shuts down the laptop. Being able to remove the heat from the package is critical for delivering that advertised performance."

Computer engineers are also close to bumping up against a thermal barrier as they try to design faster, smaller and lighter laptops. As they try to cram more powerful chips around smaller circuit sizes in a smaller area, dispersing the heat from the confined space is increasingly difficult using fans.

"It's clear now that the smaller we go, the more that cooling engineers need to be involved early in product design," Rightley said in a statement.

How it works
In the heat pipe method, heat from the chip converts a liquid--methanol--to vapor. The vapor releases the heat it is carrying in a chosen area, turns back to liquid, and returns to collect more heat.

The "wick" used for the heat pipe is made of finely etched lines that are about as deep as fingerprints. The liquid is able to defy gravity--much like a kerosene lamp wick--as it flows between several locations and an arbitrary end point.

"That is the uniqueness--the ultra-fine etching," said Kevin Krewell, a senior editor at the Microprocessor Report. "Most of the heat pipes are tubes about the width of a piece of spaghetti or thicker."

Typical laptops contain a heat sink--a plate of metal across the bottom of the system--that absorbs the heat from the circuits and yields it up to air blown through the space by a cooling fan.

Rightley's method could also be used in desktop computers, which face similar cooling obstacles, according to the researcher and analysts. Designers could create more powerful systems in smaller packages by allowing them to stack chips one atop the next for greater computational capacity.

Rightley said that people living in colder climates could buy systems designed to dump heat into well-placed vents that would act as hand warmers.

The new technology is being licensed to a start-up. A Sandia representative declined to provide the name or any further information about the start-up.

Analysts noted that it remains to be seen if these new heat pipes can be manufactured in high volume and low costs.

The research, which will be published in an upcoming issue of Microelectronics Journal, is part of the Defense Advanced Research Projects Agency's Heat Removal by Thermal Integrated Circuits project--a joint effort between Sandia and the Georgia Institute of Technology.