Thermal Properties Of Clothing Research Articles

Heat strain in chemical protective clothing in hot-humid environment: Effects of clothing thermal properties.

Heat strain experienced by individuals wearing chemical protective clothing (CPC) is severe and dangerous especially in hot-humid environment. The development of material science and interdisciplinary studies including ergonomics, physiology and heat transfer is urgently required for the reduction of heat strain. The aim of this paper was to study the relationship among clothing thermal properties, physiological responses and environmental conditions. Three kinds of CPC were selected. Eight participants wore CPC and walked (4 km/h, two slopes with 5% and 10%) on a treadmill in an environment with (35±0.5) °C and RH of (60±5)%. Core temperature, mean skin temperature, heart rate, heat storage and tolerance time were recorded and analyzed. Physiological responses were significantly affected by the clothing thermal properties and activity intensity in hot-humid environment. The obtained results can help further development of heat strain model. New materials with lower evaporative resistance and less weight are necessary to release the heat strain in hot-humid environments.

The Study on Effects of Walking on the Thermal Properties of Clothing and Subjective Comfort

Abstract Former studies done by other authors investigated the first- and second-layered air gaps beneath the clothing garments. None of the previous studies reported multidisciplinary clothing design testing approach linking both the objective measuring methods and subjective responses, while testing the thermal properties linked to a microclimatic volume formed between the layers of garments forming the ensemble. Neither was determined the limiting value of the microclimatic volume for outerwear garments, after which the thermal insulation will start to decrease due to convection. By taking the advantage of the precise three-dimensional (3D) body scanning technology and reverse engineering 3D CAD tool, the volume of the microclimatic air layers formed under outerwear garments was determined to study the impact of the ensemble’s microclimatic volume on the overall insulation value, measured by means of the thermal manikin. The jacket with the smaller microclimatic volume provided 5.2–13.5% less insulation than wider jackets, while the ensembles with tighter jackets showed 0.74–1.9% less insulation in static and 0.9–2.7% more insulation in dynamic conditions, thus proving that the limiting value of the microclimatic volume is greater than previously reported for three-layered ensembles. The effective thermal insulation value was reduced in average by 20.98–25.34% between standing and moving manikins. The thermal manikins are designed for steady-state measurements and do not work well under transient conditions, so three human subjects were employed as evaluators of the clothing thermal quality. In cooler climatic conditions, the measured physiological parameters and subjects’ grades pointed to discomfort while wearing ensembles with tighter jackets.

The impact of structural solutions used in clothing protecting against cold on its thermal insulation

Purpose The purpose of this paper is to analyze the impact of design solutions used in clothing on the thermal resistance of the material systems from which the clothing is made, design solutions used in clothing on its thermal insulation and clothing size on its thermal insulation properties. Design/methodology/approach This study involved laboratory tests of clothing protecting against cold and textile systems used in this type of garment using a “skin model” test stand and a thermal manikin. Findings Analysis of the results obtained from tests carried out showed that the design solutions used in a garment can model its local and overall insulation. It was found that using a bib in trousers has a dominant influence on the thermal properties of clothing. An important parameter is also the use of a hood, as well as the length of the jacket. No significant effect of other structural solutions, such as jacket fastening, pockets and reflective tapes, on the thermal performance of the clothing set was noted. Originality/value Although the reports available in the literature pay a lot of attention to the impact of the design of clothing protecting against cold on its thermal performance, most of the presented research results relate to the aspects of fit, whereas the analyses of the effects of other aspects of garment construction on thermal properties are lacking. Therefore, the analysis of the impact of design solutions used in clothing on its thermal insulation properties is a key original factor of this paper.

기차 승객의 온열 쾌적성에 관한 수치해석

This paper presents computational fluid dynamics (CFD) analysis on passenger thermal comfort in a train. Human thermal comfort in vehicles depends mainly on air temperature, mean radiant temperature, air velocity, humidity, and direct solar flux, as well as the level of activity and thermal properties of clothing and seat. The velocity and temperature distribution in a train with and without passengers are reported. The thermal comfort in a passenger train are also presented based on PMV and PPD indices with 16 segments of the human body.

Physiological Tolerance Times while Wearing Explosive Ordnance Disposal Protective Clothing in Simulated Environmental Extremes

Explosive ordnance disposal (EOD) technicians are required to wear protective clothing to protect themselves from the threat of overpressure, fragmentation, impact and heat. The engineering requirements to minimise these threats results in an extremely heavy and cumbersome clothing ensemble that increases the internal heat generation of the wearer, while the clothing’s thermal properties reduce heat dissipation. This study aimed to evaluate the heat strain encountered wearing EOD protective clothing in simulated environmental extremes across a range of differing work intensities. Eight healthy males [age 25±6 years (mean ± sd), height 180±7 cm, body mass 79±9 kg, V˙O2max 57±6 ml.kg−1.min−1] undertook nine trials while wearing an EOD9 suit (weighing 33.4 kg). The trials involved walking on a treadmill at 2.5, 4 and 5.5 km⋅h−1 at each of the following environmental conditions, 21, 30 and 37°C wet bulb globe temperature (WBGT) in a randomised controlled crossover design. The trials were ceased if the participants’ core temperature reached 39°C, if heart rate exceeded 90% of maximum, if walking time reached 60 minutes or due to fatigue/nausea. Tolerance times ranged from 10–60 minutes and were significantly reduced in the higher walking speeds and environmental conditions. In a total of 15 trials (21%) participants completed 60 minutes of walking; however, this was predominantly at the slower walking speeds in the 21°C WBGT environment. Of the remaining 57 trials, 50 were ceased, due to attainment of 90% maximal heart rate. These near maximal heart rates resulted in moderate-high levels of physiological strain in all trials, despite core temperature only reaching 39°C in one of the 72 trials.

Occupational Health Impacts of Climate Change: Current and Future ISO Standards for the Assessment of Heat Stress

The current system of International Standards (ISO) is assessed to consider whether standards are fit for purpose for the future in the context of climate change. ISO 7243, ISO 7933 and ISO 9886 provide the current ISO system for the assessment of heat stress. These involve a simple monitoring index, an analytical approach and physiological monitoring, respectively. The system relies on accurate measurement of the thermal conditions experienced by the worker (ISO 7726); and estimations of metabolic heat production due to work (ISO 8996) and the thermal properties of clothing (ISO 9920). As well as standards for heat stress assessment, the full range of ISO standards and the physical environment is listed as well as current work and proposed standards. A particular 'gap' in anticipating requirements for ISO standards in the future is the link between meteorological data and ISO standards. This is important for predicting the global consequences of a changing climate and anticipating potential impacts on occupational health across countries and cultures.

F135 人体熱収支モデル化にむけた衣服物性の計測(OS-1: 広がる熱物性)

F135 人体熱収支モデル化にむけた衣服物性の計測(OS-1: 広がる熱物性)

Assessment of Clothing Effects in Thermal Comfort Standards: A Review

AbstractThere are four international standards covering the measurement of thermal resistance of clothing, i.e., ISO 15831, ASTM F 1291, ASTM F 1720, and EN 342. They employ the same measurement technique, but they differ in manikin size, test conditions, formula for calculating the insulation, and the parameters for reporting the test results. ASTM F 2370 is the only standard that addresses the measurement of evaporative resistance of clothing. It specifies the configuration of sweating thermal manikin, test protocol and test conditions, and does not call for a specific technique to simulate body sweating. ISO 9920 provides formulas for estimating thermal insulation and evaporative resistance of clothing. The international standards for the assessment of thermal comfort or thermal strain of a clothed body include ISO 7730, ISO/TR 11079 and ISO 7933, for evaluating moderate thermal, cold and hot environments, respectively. Their applications of thermal properties of clothing, principles, and limitations vary. Several suggestions are finally projected with regard to the future revision of these standards.

The effects of wind and human movement on the heat and vapour transfer properties of clothing

This paper integrates the research presented in the papers in this special issue of Holmér et al. and Havenith et al. [Holmér, I., Nilsson, H., Havenith, G., Parsons, K. C. (1999) Clothing convective heat exchange: proposal for improved prediction in standards and models. Annals of Occupational Hygiene, in press; Havenith, G., Holmér, I., den Hartog, E. and Parsons, K. C. (1999) Clothing evaporative heat resistance: proposal for improved representation in standards and models. Annals of Occupational Hygiene, in press] to provide a practical suggestion for improving existing clothing models so that they can account for the effects of wind and human movement. The proposed method is presented and described in the form of a BASIC computer program. Analytical methods (for example ISO 7933) for the assessment of the thermal strain caused by human exposure to hot environments require a mathematical quantification of the thermal properties of clothing. These effects are usually considered in terms of 'dry' thermal insulation and vapour resistance. This simple 'model' of clothing can account for the insulation properties of clothing which reduce heat loss (or gain) between the body and the environment and, for example, the resistance to the transfer of evaporated sweat from the skin, which is important for cooling the body in a hot environment. When a clothed person is exposed to wind, however, and when the person is active, there is a potentially significant limitation in the simple model of clothing presented above. Heat and mass transfer can take place between the microclimate (within clothing and next to the skin surface) and the external environment. The method described in this paper 'corrects' static values of clothing properties to provide dynamic values that take account of wind and human movement. It therefore allows a more complete representation of the effects of clothing on the heat strain of workers.