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Physiologically derived critical evaporative coefficients for protective clothing ensembles
W L Kenney1, D A Lewis, D E Hyde
1Laboratory for Human Performance Research, Pennsylvania State University, University Park 16802.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 1, 1987
Summary
Heavy clothing impairs evaporative cooling by limiting sweat evaporation. This study developed a method to quantify clothing
Area of Science:
- Environmental Physiology
- Human Thermal Comfort
- Clothing Science
Background:
- Evaporative cooling is crucial for thermoregulation.
- Heavy clothing can impede sweat evaporation, reducing cooling efficiency.
- Understanding clothing's role in heat exchange is vital for performance and safety.
Purpose of the Study:
- To refine the measurement of effective evaporative coefficients (he) for clothing.
- To account for sweating efficiency (Ke,eta") in heat balance calculations.
- To quantify the impact of different clothing ensembles on evaporative heat loss.
Main Methods:
- Physiological approach using a general heat balance equation.
- Systematic increase of ambient water vapor pressure to determine critical pressure (Pw).
- Testing various clothing ensembles from cotton to impermeable suits.
Main Results:
- Derived effective evaporative coefficients (he) for different clothing types.
- Quantified the decrement in evaporative cooling due to clothing resistance.
- Identified critical water vapor pressure thresholds for thermal balance.
Conclusions:
- The refined method provides accurate measures of clothing evaporative resistance.
- Effective evaporative coefficients are essential for predicting thermal strain in various clothing conditions.
- This research aids in designing protective clothing for diverse environments.