Kakitsuba N, Bondi K R
Aviat Space Environ Med. 1987 Mar;58(3):227-36.
We studied the physics of heat transfer from the human body under conditions of low air velocity (LAV) (less than 0.1 m.s-1). For 1 ATA, we calculated values of the evaporative heat transfer coefficient (he, kcal.m-2.h-1.mm Hg-1) of 5.24 and 5.37 where ambient temperature/relative humidities were 38 degrees C/70% and 35 degrees C/80%, respectively, and ambient velocities of 0.06 m.s-1 in both cases. This is near our newly conceived "minimum he value" of 4.94, significantly greater than the 2.8 and 3.4 values that are calculated using the Lewis relation. We further described an "iso-vapor pressure temperature difference," delta Tp, which transcribes a water vapor pressure difference into a temperature difference, thus allowing use of classical nondimensional analysis to account for the increasing importance of heat loss through evaporation in LAV. Water vapor pressure differences in LAV hypobaric environments will account for increased heat losses since, for example, the minimum value of he doubles from 4.94 to 9.88 at 0.5 ATA.
我们研究了低风速（LAV，小于0.1米·秒⁻¹）条件下人体的热传递物理过程。对于1个标准大气压，当环境温度/相对湿度分别为38℃/70%和35℃/80%，且两种情况下环境风速均为0.06米·秒⁻¹时，我们计算出蒸发传热系数（he，千卡·米⁻²·小时⁻¹·毫米汞柱⁻¹）的值分别为5.24和5.37。这接近我们新设想的“he最小值”4.94，显著大于使用刘易斯关系式计算出的2.8和3.4的值。我们进一步描述了一个“等蒸气压温差”ΔTp，它将水蒸气压力差转化为温度差，从而允许使用经典的无量纲分析来解释在低风速条件下通过蒸发散热的重要性不断增加的情况。在低风速低压环境中的水蒸气压力差将导致热损失增加，例如，在0.5个标准大气压下，he的最小值从4.94翻倍至9.88。
