Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects

Research output: Contribution to journalArticle

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Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects. / Havenith, George; Richards, Mark; Wang, Xiaoxin; Bröde, Peter; Candas, Victor; den Hartog, Emiel; Holmér, Ingvar; Kuklane, Kalev; Meinander, Harriet; Nocker, Wolfgang.

In: Journal of Applied Physiology, Vol. 104, No. 1, 2008, p. 142-149.

Research output: Contribution to journalArticle

Harvard

Havenith, G, Richards, M, Wang, X, Bröde, P, Candas, V, den Hartog, E, Holmér, I, Kuklane, K, Meinander, H & Nocker, W 2008, 'Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects', Journal of Applied Physiology, vol. 104, no. 1, pp. 142-149. https://doi.org/10.1152/japplphysiol.00612.2007

APA

Havenith, G., Richards, M., Wang, X., Bröde, P., Candas, V., den Hartog, E., ... Nocker, W. (2008). Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects. Journal of Applied Physiology, 104(1), 142-149. https://doi.org/10.1152/japplphysiol.00612.2007

CBE

Havenith G, Richards M, Wang X, Bröde P, Candas V, den Hartog E, Holmér I, Kuklane K, Meinander H, Nocker W. 2008. Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects. Journal of Applied Physiology. 104(1):142-149. https://doi.org/10.1152/japplphysiol.00612.2007

MLA

Vancouver

Author

Havenith, George ; Richards, Mark ; Wang, Xiaoxin ; Bröde, Peter ; Candas, Victor ; den Hartog, Emiel ; Holmér, Ingvar ; Kuklane, Kalev ; Meinander, Harriet ; Nocker, Wolfgang. / Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects. In: Journal of Applied Physiology. 2008 ; Vol. 104, No. 1. pp. 142-149.

RIS

TY - JOUR

T1 - Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects

AU - Havenith, George

AU - Richards, Mark

AU - Wang, Xiaoxin

AU - Bröde, Peter

AU - Candas, Victor

AU - den Hartog, Emiel

AU - Holmér, Ingvar

AU - Kuklane, Kalev

AU - Meinander, Harriet

AU - Nocker, Wolfgang

PY - 2008

Y1 - 2008

N2 - Investigating claims that a clothed person’s mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34°C in ambient temperatures of 10, 20, and 34°C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (Emass) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (Eapp) were compared. A clear discrepancy was observed. Emass overestimated Eapp in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34°C, apparent latent heat ((lambda)app) of pure evaporative cooling was lower than the physical value ((lambda); 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, (lambda)app increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, (lambda)app even exceeds (lambda) by four times that value at 10°C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

AB - Investigating claims that a clothed person’s mass loss does not always represent their evaporative heat loss (EVAP), a thermal manikin study was performed measuring heat balance components in more detail than human studies would permit. Using clothing with different levels of vapor permeability and measuring heat losses from skin controlled at 34°C in ambient temperatures of 10, 20, and 34°C with constant vapor pressure (1 kPa), additional heat losses from wet skin compared with dry skin were analyzed. EVAP based on mass loss (Emass) measurement and direct measurement of the extra heat loss by the manikin due to wet skin (Eapp) were compared. A clear discrepancy was observed. Emass overestimated Eapp in warm environments, and both under and overestimations were observed in cool environments, depending on the clothing vapor permeability. At 34°C, apparent latent heat ((lambda)app) of pure evaporative cooling was lower than the physical value ((lambda); 2,430 J/g) and reduced with increasing vapor resistance up to 45%. At lower temperatures, (lambda)app increases due to additional skin heat loss via evaporation of moisture that condenses inside the clothing, analogous to a heat pipe. For impermeable clothing, (lambda)app even exceeds (lambda) by four times that value at 10°C. These findings demonstrate that the traditional way of calculating evaporative heat loss of a clothed person can lead to substantial errors, especially for clothing with low permeability, which can be positive or negative, depending on the climate and clothing type. The model presented explains human subject data on EVAP that previously seemed contradictive.

KW - heat balance

KW - evaporative cooling efficiency

KW - condensation

KW - sweat evaporation

KW - protective clothing

U2 - 10.1152/japplphysiol.00612.2007

DO - 10.1152/japplphysiol.00612.2007

M3 - Article

VL - 104

SP - 142

EP - 149

JO - Journal of Applied Physiology

T2 - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 1522-1601

IS - 1

ER -