Investigators at Triangle Research and Development Corporation (TRDC) have developed materials and applications for enhanced thermal management using both micro-and macro-encapsulated phase change materials (PCMs) since 1983; including: microPCM coolants, coatings, composites, fibers and PCM apparel. The PECS™ (Personal Environmental Control System) was developed for microclimate body cooling beneath NBC (Nuclear-Biological-Chemical) protective clothing for the US NAVY and USMC (Colvin, 1997 and 2000). Similar cooling apparel using 3–4mm macroPCM COOLBEADS™ were developed for costumed characters at two theme parks as well as potential use by firemen (Colvin, 1998). The results for these programs were reported at the 2000 and 2002 ASME ICEME (Colvin, 2000 and 2002). Civilian apparel has included 3.5 lb and 5 lb vests, a 1.5 lb cowl as well as a 1-lb collar, which suggested the potential for the microclimate cooling of athletes. Extreme heat during outdoor sporting events can be a major problem for athletes. Competitive runners, who often generate 700–900 W/m2, commonly deal with temperatures above 32.2°C (90°F) and a relative humidity greater than 80%. Natural cooling by evaporation and convection are often inadequate for a vigorously exercising athlete. Many athletes fatigue, drop out or have to wrap their chest and shoulders with ices and towels in order to finish the races. Ice and frozen gels, however, are uncomfortable, heavy, and can cause the blood vessels to constrict, thus restricting good blood circulation. Encapsulated PCMs can store 60 J/kg and the air spaces between the particles permit evaporation and convection as well as rapid thermal recharging. Development of an effective cooling collar could potentially permit competitive athletes to combat heat exhaustion and increase the body’s ability to dissipate heat.

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