Effectiveness of an Air Cooled Vest Using Selected Air Temperature, Humidity and Air Flow Rate, Combinations

摘要

This study evaluated the effectiveness of reducing thermal strain in soldiers by supplying an air-cooled vest with each of four different dry bulb (db) and dew point (dp) temperatures and air combinations. The four combinations were selected to determine minimal air conditioning requirements for several military vehicles. Six male soldiers attempted four, 300-min heat exposures (49 C db, 20 C dp) at metabolic rates of either 175 and 315 W. The soldiers wore chemical protective clothing over the combat vehicle crewman uniform and the air-cooled vest. Air supplied to the vest ranged from 22.5-27.5 C db, 15.5-21.1 dp at flow rates of either 10 or 14.5 cfm. Endurance times with the vest were 272-300 min (175 W) and 159-220 min (315 W). In summary, at the 175 W metabolic rate the vest condition which provided the 10 cfm air flow was effective in reducing thermal strain and extending endurance time. At the 315 W metabolic rate, typical of a tank commander or loader, either vest condition would extend endurance time, but would not be as effective in reducing thermal strain as the vest combinations tested in an earlier study. Keywords: Thermoregulation; Exercise; Heat stress; Microclimate cooling; Body temperature.