Cooling systems

Some days in Iraq the temperature soars to well over 100 degrees Fahrenheit. But even on relatively cooler days, U.S. military personnel wearing heavy protective clothing and performing labor-intensive tasks not only are uncomfortable, but may be vulnerable to heat stress.

Current cooling systems can be integrated with protective suits to provide some degree of relief. Unfortunately, these systems are heavy--weighing 25 pounds or more.

Researchers at Pacific Northwest National Laboratory are working on some cool solutions for hot situations. Supported by funding from the U.S. Army's Natick Laboratory, the researchers are developing a self-contained personal unit that would provide approximately 150 watts of cooling and weigh about six pounds. Additionally, funding from Ft. Belvoir, Va., is providing opportunities to explore development of other lightweight, portable cooling devices.

Chief Engineer Bob Wegeng said PNNL's efforts are centered on the creation of a miniature version of a heat-actuated heat pump, including microchannel heat exchangers and other microchannel components. "This approach is substantially more process intensive than if the same unit operations were performed using conventional technologies," he explained, "resulting in a system that is much smaller and lighter."

The key to the device is the development of an extremely compact "thermochemical compressor," which would replace the bulky, mechanical compressor that is present in conventional cooling systems and which requires an electrical supply in order to operate.

PNNL staff members are joined in the project by Oregon State University researchers via the Microproducts Breakthrough Institute, a PNNL-OSU collaborative research effort focused on developing advanced microproducts.

In addition to cooling for soldiers, Wegeng said other military-related applications that may emanate from the research activities include thermal control for electronics equipment as well as air conditioning for military vehicles and cooling systems for transportable containers.