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- Bröde, Peter, et al.
(författare)
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Einfluss der unteren Schichten von Schutzbekleidung auf die Erwärmung durch Infrarotstrahlung
- 2008
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Ingår i: Produkt- und Produktions-Ergonomie : Aufgaben für Entwickler und Planer : Bericht zum 54. Kongress der Gesellschaft für Arbeitswissenschaft vom 9. - 11. April 2008 - Aufgaben für Entwickler und Planer : Bericht zum 54. Kongress der Gesellschaft für Arbeitswissenschaft vom 9. - 11. April 2008. - 9783936804065 ; , s. 239-242
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Konferensbidrag (refereegranskat)abstract
- Mit einer Thermopuppe wurde die Erwärmung durch langwellige Wärmestrahlung beim Tragen von Schutzkleidung erfasst, wobei Material und Anzahl der Schichten der Unterbekleidung variiert wurden. Die Unterbekleidung minderte die durch Strahlungs-Absorption hervorgerufene Erwärmung. Die dabei beobachtete hohe negative Korrelation mit der thermischen Isolation zeigt Möglichkeiten zur Berücksichtigung von Effekt modifizierenden Eigenschaften wie Materialdichte oder -dicke bei der Modellierung auf.
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- Bröde, Peter, et al.
(författare)
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Heat transfer through protective clothing under symmetric and asymmetric long wave thermal radiation
- 2008
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Ingår i: Zeitschrift für Arbeitswissenschaft. - 0340-2444. ; 62:4, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- This report considers results of an ED funded research on thermal properties ofprotective clothing and their use in the assessment of the thermal strain at work. In order to study the effects of the asymmetry oflong wave thermal radiation on the heat transfer through protective clothing, the heat loss under all-side and unilaterally applied radiation with the same incident radiant power of 279 W/m2 was measured with a thermal manikin and compared to a reference condition where mean radiant temperature was equal to air temperature. With exposure to radiation a lowered heat loss, i.e. heat gain for the whole covered body area was observed, which did not depend on radiant asymmetry for the dry as well as for the combined dry and evaporative heat loss, and which was attenuated when wearing a more insulating underwear. However, under one-sided radiation a more inhomogeneous spatial distribution occurred with higher heat gains and higher surface temperatures at the irradiated body parts. Practical Relevance The direction ofthermal radiation in the horizontal plane may be neglected when assessing the physiological heat strain in protective clothing by heat budget models. In contrast to this, it may be advisable to consider radiant asymmetries with respect to thermal comfort with low intensity radiation, and the most intense radiant source when assessing the risk of skin burns.
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| 6. |
- Bröde, Peter, et al.
(författare)
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Infrared radiation effects on heat loss measured by a thermal manikin wearing protective clothing
- 2005
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Ingår i: Environmental ergonomics XI : proceedings of the 11th International Conference, 22-26 May, 2005, Ystad, Sweden - proceedings of the 11th International Conference, 22-26 May, 2005, Ystad, Sweden. - 1650-9773. - 9163170620 ; , s. 74-77
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Konferensbidrag (refereegranskat)
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- Bröde, Peter, et al.
(författare)
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Non-evaporative effects of a wet mid layer on heat transfer through protective clothing
- 2008
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 104:2, s. 341-349
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Tidskriftsartikel (refereegranskat)abstract
- In order to assess the non-evaporative components of the reduced thermal insulation of wet clothing, experiments were performed with a manikin and with human subjects in which two layers of underwear separated by an impermeable barrier were worn under an impermeable overgarment at 20 °C, 80% RH and 0.5 ms-1 air velocity. By comparing manikin measurements with dry and wetted mid underwear layer, the increase in heat loss caused by a wet layer kept away from the skin was determined, which turned out to be small (5-6 Wm-2), irrespective of the inner underwear layer being dry or wetted, and was only one third of the evaporative heat loss calculated from weight change, i.e. evaporative cooling efficiency was far below unity. In the experiments with 8 males, each subject participated in two sessions with the mid underwear layer either dry or wetted, where they stood still for the first 30 minutes and then performed treadmill work for 60 minutes. Reduced heat strain due to lower insulation with the wetted mid layer was observed with decreased microclimate and skin temperatures, lowered sweat loss and cardiac strain. Accordingly, total clothing insulation calculated over the walking period from heat balance equations was reduced by 0.02 m2 °C W-1 (16%), while for the standing period the same decrease in insulation, representing 9% reduction only showed up after allowing for the lower evaporative cooling efficiency in the calculations. As evaporation to the environment and inside the clothing was restricted, the observed small alterations may be attributed to the wet mid layer’s increased conductivity, which, however, appears to be of minor importance compared to the evaporative effects in the assessment of the thermal properties of wet clothing.
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- Gao, Chuansi, et al.
(författare)
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The comparison of thermal properties of protective clothing using dry and sweating manikins
- 2006
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Ingår i: [Host publication title missing].
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Konferensbidrag (refereegranskat)abstract
- The thermal insulation of clothing is commonly determined by dry thermal manikins either made of plastic or metal. For the determination of evaporative resistance of clothing ensemble, there exist three types of manikin methods: pre-wetted underwear or “skin” covered on dry manikins, the manikin with regulated constant water supply to the “skin” surface and the sweating fabric manikin based on a water filled body covered with waterproof but vapour permeable fabrics. The purpose of this study was to compare thermal insulation and moisture evaporative resistance of a set of protective clothing measured using different type of manikins. The total thermal insulation of seven EU project ensembles (Subzero A and B, Permeable (PERM), Impermeable (IMP), Nomex coverall (with two types of underwear) and Cotton coverall) were measured using the manikin Tore in Sweden, the sweating fabric manikin Walter in Hong Kong, and the manikin Newton in the UK. The results showed that total thermal insulation is reproducible for the seven clothing ensembles measured on the manikins Walter and Tore. The coefficient of variance is less than 8%. Nomex coverall with cotton underwear has 8-16% higher total insulation than that with polypropylene underwear. The apparent evaporative resistance of the impermeable coverall with cotton underwear measured on Newton was 44.5% lower than the evaporative resistance measured on Walter. The effect of condensation and conduction at room temperature environment and measuring time allowing full accumulation of moisture in clothing ensembles might be two important factors affecting the evaporative resistance.
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| 10. |
- Havenith, George, et al.
(författare)
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Apparent latent heat of evaporation from clothing: attenuation and “heat pipe” effects
- 2008
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Ingår i: Journal of Applied Physiology. - : American Physiological Society. - 1522-1601 .- 8750-7587. ; 104:1, s. 142-149
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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