| 摘要 |
A single lightweight thermoelectric module (TEM) is mounted in a housing in turn mounted centrally atop a helmet to be worn by a worker in a hot atmosphere. The heat abstraction side of the TEM is disposed within the housing, the heat dissipation side dissipates heat to the ambient atmosphere. It has been found that the personal comfort of the worker is surprisingly improved by flowing a very small stream, 3-15 SCFM, of cooled air across only his face if the temperature of the air stream is in the range from about 1 DEG F. to 7 DEG F. cooler than the ambient air. This discovery allowed the air duct carrying cooled air from downstream the heat abstraction side of the TEM to be less than about 1 ft long, presenting substantially insignificant pressure drop of air flowing through the duct. This allows the use of a miniature fan means to blow the air through the housing. Two thermistors sense the temperature of air upstream and downstream, respectively, of the heat abstraction side of the TEM. A manual selection means allows the worker to set the temperature difference of air he wishes to be delivered to his face. Surprisingly, the hotter the ambient, the closer to the maximum temperature difference (set by the worker) is the air delivered to him.
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