Carry-on Cooler
Soldiers, firefighters and others who risk exposure to hazardous materials
must wear hot, heavy protective clothing for prolonged periods. Research at
the Department of Energy's Pacific Northwest National Laboratory (PNL) in
Richland, Wash., is leading to a small, lightweight heat pump that could be
worn inside such garments to provide hours of cooling relief.
Heat pumps use the condensation-evaporation cycle of a working fluid to
move heat from one place to another. The PNL device mechanically constrains
the fluid to microchannels in a film only about 100 micrometers thick-10
times thinner than in conventional heat pumps. The thin film maximizes the
surface-to-volume ratio and hence the efficiency of heat transfer between
the fluid and the environment, says PNL researcher Michele Friedrich. Based
on tests of the individual components, Friedrich believes it will be
possible to build a prototype of a portable heat pump weighing only about 5
kilograms.
