Graphite keeps pilots cool

Engineers at Oak Ridge National Laboratory are designing a personal cooling system for the Navy that circulates chilled air through the flight suits and helmets of fighter pilots. Unlike other approaches that circulate chilled water, the new system augments the body's natural cooling system. "Instead of simply cooling the skin through a fabric, our approach removes heat from the body surface and provides cool air to breathe," says James Klett. He points out that the lungs have large surface areas for dissipating heat and blood serves as an effective heat transfer medium. The enabling technology for the cooling system uses the high thermal conductivity of a new graphite foam developed by Klett and his team. "Thermal conductivity is basically how fast heat is transferred through a material," says Klett. The foam is as thermally conductive as aluminum. However, the thermal conductivity-to-weight ratio is five times better than aluminum. "So if you put an ice cube on a block of graphite foam and another on a block of aluminum, you would feel the ice 5 times faster," says Klett. The foam reduces heat losses and improves efficiencies. Potential applications include suits worn by firefighters, racecar drivers, hazardous materials workers, and ground troops. For more information contact, contact Bill Corwin at (865) 574-1000 or visit www.ornl.gov.