Determination of Clothing Evaporative Resistance for - Thermo-Physiology Modelling using a Thermal Mannequin
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Vysoké učení technické v Brně. Fakulta strojního inženýrství
Abstract
Globálne otepľovanie a klimatické zmeny sú aktuálne jednou z najdiskutovanejších tém na svete. Keďže začíname vidieť jasné známky klimatických zmien, je nutné sa čoraz viac zaoberať ochranou ľudského zdravia pred tepelnou záťažou aj na miestach sveta, kde táto téma nebola v minulosti aktuálna. Pracovníci vo viacerých profesiách, hlavne v tých ktoré využívajú špeciálne ochranné odevy, môžu byť potencionálne ohrozený vplyvom tepla. Je známe že vyparovanie potu z tela je hlavným termoregulačným prvkom ľudského tela a práve použitie takýchto ochranných odevov, obmedzujúcich toto vyparovanie, v kombinácií s vysokou aktivitou môže byť zdraviu nebezpečné. Z týchto dôvodov sa do popredia dostávajú termofyziologické modeli alebo predikčné modeli tepelnej záťaže, ktoré sú neustále vylepšované a aplikované v rôznych situáciách. Jednými z najproblematickejších vstupných dát takýchto modelov patria vlastnosti odevu – tepelná izolácia, faktor oblasti prekrytia oblečením a odpor odevu proti vyparovaniu, ktorých nepresné hodnoty môžu spôsobiť veľké nepresnosti vo finálny predikciách týchto modelov. Napriek tomu že meranie tepelnej izolácie odevu pomocou tepelných manekýnov je už zavedené, spoľahlivé a presné, to isté nie je možné povedať o meraní odporu odevu proti vyparovaniu, ktoré je stále vo svojich začiatkoch. Cieľom tejto práce bolo vyvinúť a implementovať experimentálne zariadenie, procedúru merania a spôsob kalkulácie pre získanie odporu odevu proti vyparovaniu pomocou manekýna NEWTON-a na VUT v Brne. Výsledky merania boli validované na základe dát nameraných pomocou manekýna TORE na Univerzite v Lunde. Reprodukovateľnosť merania bola na úrovni do 4 % rozdielu od strednej hodnoty takmer vo všetkých prípadoch. Výsledky ukazujú že je možné dosiahnuť dobrej reprodukovateľnosti merania pri striktnom dodržaní metodológie merania. Výsledky taktiež ukázali dobru opakovateľnosť merania, kedy bol dosiahnutý výsledok opäť na úrovni 4 % na oboch manekýnoch, čo je zároveň aj požadovaná hranica určená v normách pre meranie tepelnej izolácie odevu. Ďalším bodom práce bola verifikácia samotnej kalkulácie výparného odporu. Aj keď mass loss metóda určuje priamo intenzitu prenosu hmoty vyparovaním a najbližšie opisuje samotný jav vyparovania potu z ľudského tela, nie je vhodná pre určenie lokálnych hodnôt odporu proti vyparovaniu odevov z dôvodu technických limitácií senzorov a tepelných manekýnov. Z tohto dôvodu je použitá heat loss metóda, ktorej výpočet však musí byť korigovaný. Súčasťou práce bolo testovanie a verifikácia viacerých korekcií tejto metódy, čo môže byť prínosom výskumných pracovníkov z oblasti termofyziológie, keďže tieto lokálne hodnoty vlastností odevov sú pre dosiahnutie presných predikcii priam nevyhnutné. Úspešná implementácia a validácia možnosti merania odporu odevu proti vyparovaniu na VUT v Brne pomocou tepelného manekýna prináša taktiež nové možnosti pre ďalšie projekty a kooperácie v rámci výskumnej ci komerčnej činnosti Univerzity.
Global warming and environmental changes are currently one of the main topics discussed around the world. As we could start to see the signs of climate changes, more attention needs to be placed on the protection of humans health, as the changing climate could have impact also in places, were it was not the case in the past. Many professions, especially the ones using some kind of protective clothing, could be in danger from heat stress. It is known that sweat evaporation is the main thermoregulatory feature for a heat dissipation from the human body to the environment and these protective clothing, with combination with higher metabolic rates during the work, could be potentially dangerous. These are the reason why heat stress prediction models and thermo physiological models are being enhanced and used widely. One of the most problematic input data for these models are clothing properties - thermal insulation, clothing area factor and evaporative resistance, whose inaccuracy could have huge impact on the resultant physiological prediction. Although thermal insulation measurements on thermal manikins are well tested, precise and reliable, this cannot be said about measurement of evaporative resistance using manikins, including manikin NEWTON at Brno University of Technology. Thus, the aim of this study was the development of the measurement procedure and calculation methods to determine clothing evaporative resistance using thermal manikin NEWTON at BUT. Measurement setup and methodology was successfully validated using dataset measured on manikin TORE at Lund University, with the results laying within 4 % of the mean values in all but two cases. The results shows that with strict measurement methodology, it is possible to achieve good reproducibility of the measurement, which was not the case in previous studies. Furthermore, the results shows that repeatability of the measurement is also within 4 % on both manikins, as same repeatability precision is set in the standards for thermal insulation measurements. Lastly, the mass loss method is essentially correct and closer to the physical nature of heat transfer by sweating, but with the current technical limitations, it is very challenging to obtain local evaporative resistance values from this method. Thus, heat loss method must be used to obtain these local values. Multiple corrections for the calculation of evaporative resistance values from the heat loss method were tested and verified. This could be of interest to engineers and researchers in the field of thermo physiological modeling, as local values of clothing properties are essential to obtain precise physiological predictions. Finally, the possibility to obtain evaporative resistance values at BUT could potentially bring new opportunities for projects and cooperations.
Global warming and environmental changes are currently one of the main topics discussed around the world. As we could start to see the signs of climate changes, more attention needs to be placed on the protection of humans health, as the changing climate could have impact also in places, were it was not the case in the past. Many professions, especially the ones using some kind of protective clothing, could be in danger from heat stress. It is known that sweat evaporation is the main thermoregulatory feature for a heat dissipation from the human body to the environment and these protective clothing, with combination with higher metabolic rates during the work, could be potentially dangerous. These are the reason why heat stress prediction models and thermo physiological models are being enhanced and used widely. One of the most problematic input data for these models are clothing properties - thermal insulation, clothing area factor and evaporative resistance, whose inaccuracy could have huge impact on the resultant physiological prediction. Although thermal insulation measurements on thermal manikins are well tested, precise and reliable, this cannot be said about measurement of evaporative resistance using manikins, including manikin NEWTON at Brno University of Technology. Thus, the aim of this study was the development of the measurement procedure and calculation methods to determine clothing evaporative resistance using thermal manikin NEWTON at BUT. Measurement setup and methodology was successfully validated using dataset measured on manikin TORE at Lund University, with the results laying within 4 % of the mean values in all but two cases. The results shows that with strict measurement methodology, it is possible to achieve good reproducibility of the measurement, which was not the case in previous studies. Furthermore, the results shows that repeatability of the measurement is also within 4 % on both manikins, as same repeatability precision is set in the standards for thermal insulation measurements. Lastly, the mass loss method is essentially correct and closer to the physical nature of heat transfer by sweating, but with the current technical limitations, it is very challenging to obtain local evaporative resistance values from this method. Thus, heat loss method must be used to obtain these local values. Multiple corrections for the calculation of evaporative resistance values from the heat loss method were tested and verified. This could be of interest to engineers and researchers in the field of thermo physiological modeling, as local values of clothing properties are essential to obtain precise physiological predictions. Finally, the possibility to obtain evaporative resistance values at BUT could potentially bring new opportunities for projects and cooperations.
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Citation
TOMA, R. Determination of Clothing Evaporative Resistance for - Thermo-Physiology Modelling using a Thermal Mannequin [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. .
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en
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Konstrukční a procesní inženýrství
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doc. Ing. Jiří Pospíšil, Ph.D. (předseda)
prof. Ing. Luboš Hes, DrSc. (člen)
Ing. Kamila Lunerová, Ph.D. (člen)
doc. Ing. František Lízal, Ph.D. (člen)
Ing. Pavel Častulík, CSc. (člen)
Ing. Petr Nasadil (člen)
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Defence
Student přehledně komentoval zjištění a závěry disertační práce. Zodpověděl všechny vznesené dotazy. Diskutována byla dosažená zjištění a použité metody.
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práce byla úspěšně obhájena
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Standardní licenční smlouva - přístup k plnému textu bez omezení