Keep It Cool

By Treva Lind

Mechanical engineer Don Tilton has made a pioneering field of maintaining a stable temperature for advanced electronics, especially in rugged military or space conditions. He first pondered the idea of spray-cooling technology for electronics while working with the 1980s Star Wars space-based defense program. Tilton went on to launch his own company and invent a self-enclosed spray-cooling chassis currently being tested inside military vehicles and aircraft.

Tilton founded the Washington state-based Isothermal Systems Research (ISR) in 1988 while completing his doctorate at the University of Kentucky and his graduate fellowship work under a team of scientists developing the Star Wars technology at Wright-Patterson Air Force Base in Dayton, Ohio. “The space-based defense systems and electronics were really challenging,” Tilton recalls about the program. “How do you cool these multi-megawatt weapons and all the computers and communication equipment? And all this had to be cooled in a spacecraft small and light enough they can actually launch it? It was all incredibly technically challenging.”

Inspired by that challenge, Tilton selected spray-cooling as the topic for his doctoral dissertation. At the time, little was known about the topic and the fundamental physics of how it would work. “I felt I could do some pioneering research,” he reveals.

Although the Star Wars program got canceled around 1992, Tilton continued developing his ideas. He eventually created a design for a spray-cooling chassis built into a cabinet about the size of a small microwave oven. A chemical liquid inside the chassis is sprayed onto electronics, dissipating heat on circuit boards and processors through evaporation, keeping the electronics at a stable, uniform temperature.

“From 1988 to 1992, we focused on understanding how spray cooling works,” Tilton says in explaining ISR’s evolution. “We had to develop our own components such as spray nozzles to make it work. All the components then available weren’t adaptable to our use. Then from 1992 to 1996, we knew how spray cooling worked, and we focused on making viable systems and having all the components to build a functioning and reliable system.” By the late 1990s, Tilton and his company had secured contracts for testing the ISR technology, first in the U.S. intelligence field and then with the military.

Today, the ISR systems are being tested in the U.S. Marine Corps Expeditionary Fighting Vehicle (EFV) that works as a tank on land and a jet ski in the water, in the Navy's tactical jamming aircraft called the EA6B Prowler, and in the Air Force's Global Hawk, an unmanned aerial vehicle that flies at 70,000 feet. The ISR system also plays a part in new equipment being tested to detect sniper gunfire. A weapons surveillance counter sniper device based on an infrared camera that classifies the type of weapon fired would have the company's product inside.

As ISR’s vice chairman,Tilton has responsibility for strategic planning and technology direction. Although the military wants the latest and best, any new technology has to withstand extreme conditions, he explains. "We need to take the latest commercial electronics, package it in a cooling system that will survive conditions the military would put it through, and have them be self-contained so they're not affected by dust."

Recently, ISR announced it has received a $3 million federal appropriation to help develop cooling solutions for advanced supercomputers. "Major semiconductor companies are now in the development process for the next-generation chips for servers or desktops," says Tilton. "We're developing cooling systems for diagnostic testers for these next generation chips."

Another ISR project involves doing demonstrations for a military command center, to deal with such problems as a 72-hour dust storm in the Iraq war. "Before, they'd shut off all the electronics," Tilton says. "There's a lot of motivation to develop our technology that would prevent them from having to do that."

Tilton received a B.S. in mechanical engineering in 1985 from Washington State University. He completed his master’s in mechanical engineering at the University of Kentucky in 1987, focusing on transient response of liquid metal heat pipes. And in 1989, he completed his Ph.D. dissertation in mechanical engineering, also at the University of Kentucky, with a focus on spray cooling. His decision to enter the mechanical engineering field was inspired by his brother Chuck, who also got his BSME from Washington State. Chuck also works at ISR as vice president and chief technology officer.

Today, with ISR’s horizons expanding, Don Tilton looks forward to tests of the ISR system in the Air Force's high-altitude Global Hawk, a scenario reminiscent of his early Star Wars focus. "It's a major milestone for us getting our technology in a flying aircraft. I think we will eventually get into space, but not until we get about 10 years of reliability on the ground and in the air."

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For more information on Isothermal Systems Research and their spray-cooling systems for electronics, visit www.spraycool.com

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Treva Lind is a freelance writer in Newman Lake, Washington