Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin

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Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin. / Havenith, George; Bröde, Peter; Emiel, den Hartog; Kuklane, Kalev; Holmér, Ingvar; Rossi, Rene M; Richards, Mark; Farnworth, Brian; Wang, Xiaoxin.

I: Journal of Applied Physiology, Vol. 114, Nr. 6, 2013, s. 778-785.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

Harvard

Havenith, G, Bröde, P, Emiel, DH, Kuklane, K, Holmér, I, Rossi, RM, Richards, M, Farnworth, B & Wang, X 2013, 'Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin', Journal of Applied Physiology, vol. 114, nr. 6, s. 778-785. https://doi.org/10.1152/japplphysiol.01271.2012.

APA

CBE

Havenith G, Bröde P, Emiel DH, Kuklane K, Holmér I, Rossi RM, Richards M, Farnworth B, Wang X. 2013. Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin. Journal of Applied Physiology. 114(6):778-785. https://doi.org/10.1152/japplphysiol.01271.2012.

MLA

Vancouver

Author

Havenith, George ; Bröde, Peter ; Emiel, den Hartog ; Kuklane, Kalev ; Holmér, Ingvar ; Rossi, Rene M ; Richards, Mark ; Farnworth, Brian ; Wang, Xiaoxin. / Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin. I: Journal of Applied Physiology. 2013 ; Vol. 114, Nr. 6. s. 778-785.

RIS

TY - JOUR

T1 - Evaporative Cooling: effective latent heat of evaporation in relation to evaporation distance from the skin

AU - Havenith, George

AU - Bröde, Peter

AU - Emiel, den Hartog

AU - Kuklane, Kalev

AU - Holmér, Ingvar

AU - Rossi, Rene M

AU - Richards, Mark

AU - Farnworth, Brian

AU - Wang, Xiaoxin

PY - 2013

Y1 - 2013

N2 - Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available which has found little use in recent literature. In this experiment a thermal manikin (MTNW, Seattle) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used and different numbers of layers were used. Tests took place in 20ºC, 0.5 m.s-1 at different humidities and were performed both dry and with a wet layer allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin λeff is close to the theoretical value (2430J.g-1), but starts to drop when more clothing is worn, e.g. by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base-layer) increasing towards 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed.

AB - Calculation of evaporative heat loss is essential to heat balance calculations. Despite recognition that the value for latent heat of evaporation, used in these calculations, may not always reflect the real cooling benefit to the body, only limited quantitative data on this is available which has found little use in recent literature. In this experiment a thermal manikin (MTNW, Seattle) was used to determine the effective cooling power of moisture evaporation. The manikin measures both heat loss and mass loss independently allowing a direct calculation of an effective latent heat of evaporation (λeff). The location of the evaporation was varied: from the skin or from the underwear or from the outerwear. Outerwear of different permeabilities was used and different numbers of layers were used. Tests took place in 20ºC, 0.5 m.s-1 at different humidities and were performed both dry and with a wet layer allowing the breakdown of heat loss in dry and evaporative components. For evaporation from the skin λeff is close to the theoretical value (2430J.g-1), but starts to drop when more clothing is worn, e.g. by 11% for underwear and permeable coverall. When evaporation is from the underwear, λeff reduction is 28% wearing a permeable outer. When evaporation is from the outermost layer only, the reduction exceeds 62% (no base-layer) increasing towards 80% with more layers between skin and wet outerwear. In semi- and impermeable outerwear the added effect of condensation in the clothing opposes this effect. A general formula for the calculation of λeff was developed.

KW - sweat Latent heat of evaporation evaporative cooling efficiency protective clothing wicking indirect calorimetry

U2 - 10.1152/japplphysiol.01271.2012.

DO - 10.1152/japplphysiol.01271.2012.

M3 - Article

VL - 114

SP - 778

EP - 785

JO - Journal of Applied Physiology

T2 - Journal of Applied Physiology

JF - Journal of Applied Physiology

SN - 1522-1601

IS - 6

ER -