Verification of Thermal Models in the Design of Personal Protective Equipment Against Cold

IOP Conference Series: Materials Science and Engineering

PAPER • OPEN ACCESS Verification of thermal models in the design of personal protective equipment against cold

To cite this article: I V Cherunova et al 2021 IOP Conf. Ser.: Mater. Sci. Eng. 1029 012035

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Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

Verification of thermal models in the design of personal protective equipment against cold

I V Cherunova1,2*, M P Stenkina1, N V Kornev2 1Department of Design and technology, Don State Technical University, Shakhty, Russia 2 Chair of Modeling and Simulation, University of Rostock, Rostock, Germany

*Corresponding author: [email protected]

Abstract. In the article research results are presented, which aim to verification of thermal models in the design of personal protective equipment against cold. Under the effect of wind, movement, and pressure of the human being himself on the clothing, the design thermal resistance of the clothing decreases and does not provide the stable human comfort. To eliminate such risks, special heated garments are being developed, which are fitted with electric batteries.The basis for such a development is the mathematical model of the system "Human- Clothes-Environment", which allows to establish the main parameters of the heating intensity of each individual section of the clothing, taking into account the overall functioning of the system. Such a model has been developed. The problems of verification of thermal models for designing if the clothing are associated with the assessment of experimental data on the parameters of the system under study. A structure for the formation of a method for experimental verification of the models of thermal protective clothing has been developed. Design of experimental protective clothing against cold with heating based on a mathematical model has been developed.The ratio of feelings of thermal comfort and temperature under heated clothing of small thickness under wind load, cold and lack of physical activity has been installed.

1. Introduction The prospects for the development of the northern regions, offshore, and maritime territories require great attention to the safety and comfort of human labor in the regions with the severe cold climate. There are scientific and technical designs of passive protective clothing, which is intended for the specified cold conditions [1]. All of them are based on the design parameters of the thickness of clothing made from a set of textile materials with certain characteristics of thermal conductivity [2,3]. Under the effect of wind, movement, and pressure of the human being himself on the clothing and under the changes in the humidity of the environment, the design thermal resistance of the clothing decreases and does not provide the stable human comfort [4]. To eliminate such risks, special heated garments are being developed, which are fitted with electric batteries [5]. As a rule, in case of lack or excess of heat under the clothes, the vest heating control is performed directly by a human, which reduces the convenience of the clothes use. An alternative solution is the active control of the thermal balance of the under-clothing space based on the information about the temperature distribution over the surface of the human body [6,7]. Wherein, the clothes heating control system is to be based on the knowledge about the aerodynamic and thermodynamic interactions between the human body, protective clothing, and the environment [8]. The basis for such a development is the mathematical model of the system "Human-

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Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

Clothes-Environment", which allows to establish the main parameters of the heating intensity of each individual section of the clothing, taking into account the overall functioning of the system [9]. Such a model has been developed [10]. It is characterized by a large number of factors, variable conditions, and the complexity of the mathematical apparatus, and therefore it requires special attention to the processes of verification of the model and its results [11]. The problems of verification of thermal models for designing if the clothing are associated with the assessment of experimental data on the parameters of the system under study. Experimental studies of the system, with taking into account the technical and biological components, require special complex conditions and techniques [13], which is subject to new R & D studies.

2. Theoretical part There are a number of up-to-date ways to ensure and verify that the thermal protection of the clothing is sufficient for expected cold conditions. They are used to verify the models in the designing of protective clothing. The traditional criterion for ensuring the thermal protection of clothing is based on the formation of thermal insulation of a package of clothing materials, in which no additional heating is provided [14]. This method applies to special clothing for protection from the cold for employees of various professions who work in open areas and in unheated premises. The special clothing is designed, fabricated, and tested taking into account the operation in various climatic regions. Using the example of Russia, special climatic regions are distinguished, for which characteristic average climate parameters are established (temperature of the cold period / wind speed, respectively) [14]:  Zone 1 (-1.0 ℃ / 2.7 m/s);  Zone 2 (-9.7 ℃ / 5.6 m/s);  Zone 3 (-18.0 ℃ / 3.6 m/s);  Zone 4 (-41.0 ℃ / 1.3 m/s). For experimental tests of thermal protective clothing, the standard rules established by the standard method for testing of general thermal insulation without additional heat sources are used [13]. The standard value of the thermal insulation parameter of such clothes is set taking into account the stay in the cold no more than 3 hours. The main criterion for evaluating the results of designing of the clothes is the level of "permissible thermal state" at which the working capacity and health of the employee are preserved, taking into account the requirements of continuous stay in the cold environment. Normalized thermal insulation values for this technique are given in Table 1. In order to verify the models that allow to obtain the design parameters for packages of materials and from thermal insulation in clothes, the methods for determining the thermal insulation of a set of ready- made clothes are used [13]. This method has two versions of implementation: A – with the participation of a human, and B – with a thermal dummy. In the first case (version A), the method consists of determining the thermal insulation of the clothing based on the results of measurement of the temperature of the human skin and the density of the dry thermal flow from the surface of the human body in the required test conditions [13].

Table 1. Normalized thermal insulation Protection class Temp- Speed* Standard value of clothing insulation, °C * m / W Wind / Climate air in zone (region) temperature winter For air permeability of the upper material, dm /(m ·s) * in winter months, months, °C m / s 10 20 30 40 4 / " Special " (IA) - 25 6,8 0,669 0,714 0,764 0,823 3 / IV (1Б) - 41 1,3 0,744 0,752 0,759 0,767 2 / III (II) - 18 3,6 0,518 0,534 0,551 0,569 1 / II-I (III-IV) - 9,7 5,6 0,451 0,474 0,500 0,528 *Probable air temperature and wind speed

Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

Version A2 implies a method for determining the thermal insulation of the clothing based on the measurement of the power of the energy consumed by the dummy to maintain the temperature of its surface in the desired test conditions [15]. The shape and size of the dummy conforms to an adult and must have a constant average surface temperature. The temperature distribution over the surface of the dummy's body should be the same as that of a human [14, 16]. A particularly difficult requirement is that the dummy must walk with a frequency of (45 ± 2) steps per minute, have a head, chest, back, abdomen, buttocks, arms with shoulders, forearms and hands with fingers, legs with thighs and lower legs and feet. Wherein, the total surface area of this thermal dummy is (1.8 ± 0.3) m, the height is (1,75 ± 0,1) m, anthropometric parameters of all parts of the body in accordance with the standard sizes of a human clothing. In addition to the enormous difficulties in ensuring the functioning of the listed requirements for the thermal dummies, it should be noted that such tests of experimental clothing depend on the respective special laboratory [16]. Such laboratories provide energy supply and an automated control system for the thermal dummies and the conditions for the formation of external climatic factors in the laboratory space, close to natural and industrial ones [17, 18, 19]. With all the technical difficulties in providing such a method, which includes a thermal dummy, the established problem should be highlighted that limits its use for heated clothing. This method allows to verify the models for a passive system with thermal protection of clothing based on thermal insulation of the shell thickness. In the presence of local areas with active heating, a complex of neural reactions arises, that differ from the perception of the general temperature of the skin and allow a human to feel the warmth due to targeted heating [20,21]. Therefore, such clothes require either a higher level of compliance of the thermal dummies with thermal reactions to neural stimuli that are identical to human (this is an extremely difficult task), or to be used in human tests [22]. Such methods involve the experiments to be conducted in laboratory and field conditions [22-24].

3. Experimental part As a result of the conducted studies and systematization of existing methods of assessment and testing, a structure for the formation of a method for experimental verification of the models of thermal protective clothing has been developed (Figure 1). In the case of using the embedded heating in clothes, the primary criterion for verification of mathematical models is formed: the temperature of the under-clothing space, human sensations, reference parameters of the human body temperature. To provide such verification criteria, the method of a full-scale experiment is the most informative as a reference test. For this method, the basic requirements for the experiment are developed as follows: 1. Requirements for the physical condition of a human in accordance with GOST [14]; 2. The duration of the full-scale experiment is subject to the conditions of the expected operation (maximum – the period of time of continuous wearing of clothes); 3. A preliminary assessment can be carried out taking into account the time constraints in accordance with; 4. A full assessment should be carried out with the involvement of the number of testers, taking into account the requirements of the accuracy of the results obtained for small samplings. 5. The mode of human activity should be as close as possible to real; 6. The place of performing full-scale tests is localized in the area of real types of work and, if possible, is equipped with additional access to a remote electric power source in accordance with the requirements of instrumentation (if available).

Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

Figure 1. Structure for the formation of a method for experimental verification of the models of thermal protective clothing

To test the presented test method, an experimental sample of special heat-protective clothing has been used, which has been developed and manufactured on the basis of the results of simulation and distribution of a local heating system with a reduced level of passive thermal insulation of the package of materials (Figure 2) shows the design solution of the product under study.

Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

Figure 2. Design of experimental protective clothing against cold with heating based on a mathematical model

Table 2 shows the technical characteristics of the studied material object of simulation and designing of human thermal protection.

Table 2. Technical characteristics of clothing materials Fiber Density, g / m2. Thickness, Fabric finishing composition, % mm Prem'er – Cotton 80, komfort PE 20 255,0 0,28 PU Taffeta PE 100 145,0 0,10 - Hollofiber PE 100 300,0 28,8 -

Table 3 presents the characteristics of the conditions for natural experimental verification of the simulation results and the design on its basis.

Table 3. Characteristics of the conditions for natural experimental verification Parameters Value Air temperature -40,0 ℃ Wind speed 12,0 m/s Wind direction for a person From the back Active job Motionless Gender of the person Man Age of the person 176.0 sm The height of a man 75 kg A person's size (circumference of trunk, chest) 100,0 sm

Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

4. Results The results of the field study are shown in Figure 3.

Figure 3. The ratio of feelings of thermal comfort and temperature under heated clothing of small thickness under wind load, cold and lack of physical activity

5. Conclusion The analysis of the experimental results has shown that the developed heating system in heat-protective clothing allows to provide thermal criteria under the clothing for the operating conditions under consideration. Despite the reduced thickness and weight of the heat-insulating shell, not the lowest possible value of thermal conductivity of heat insulating materials, complete absense of physical activity and the output of own human biological heat in conditions of critical cold -40 °C and the wind of 12 m/s, the standard indicator of the comfortable temperature under clothes persisted for 23 minutes. The main area of clothing, which was the first to form the accumulation of excess cold, was the area of the back of the jacket, turned to the windward side. This area, under the action of strong winds, lost the original thickness of the thermal insulation shell, which led to an accumulation of cool sensations. Such conclusions have allowed to verify the model under the most critical real cold conditions and establish the minimum time interval at which, with all the most critical climate loads and the exclusion of reserves of active thermal self-regulation of a human, the designed thermal protection with a heating system ensures the thermal balance. When included in the system for assessing the physical activity and materials with increased thermal resistance, the clothing acquires and provides additional reserves of time for thermal safety and comfort of a human in the cold conditions.

Dynamics of Technical Systems (DTS 2020) IOP Publishing

IOP Conf. Series: Materials Science and Engineering 1029 (2021) 012035 doi:10.1088/1757-899X/1029/1/012035

References [1] Wölfling B-M, Classen E, Gerhardts A 2020 Comfort and Personal Protective Clothing Proc. of the 2nd International Comfort Congress Delft https://www.researchgate.net/publication/342040617_Comfort_and_Personal_Protective_Cl othing [2] Kyosov M, Angelova R A, Stankov P 2016 Numerical modeling of the air permeability of two- layer woven structure ensembles Textile Research Journal vol. 86 (19) pp.2067–2079 doi:10.1177/0040517515619358 [3] Rui Qiong Shao 2019 Optimal Thickness Design of Thermal Protective Clothing. Applied Physics 09 (11):462-476 DOI: 10.12677/APP.2019.911057. [4] Cherunov P, Cherunova I, Knyazeva S, Stenkina M, Stefanova E, Kornev N 2015 The Development of the Research Techniques of Structure and Properties of Composite Textile Materials when Interacting with Viscous Fractions of Hydrocarbon Compounds. Proc. of the int. conf.on “Textile Composites and Inflatable Structures” (Structural Membranes 2015) pp.555-564. [5] Cherunova I V, Stenkina M P , Cherunov P V 2017 Investigation of the structure and properties of flexible polymeric materials for integration with thin heat conductors structural membranes Proc. of the VIII Int. Conf. on Textile Composites and Inflatable Structures (STRUCTURAL MEMBRANES 2017) pp. 210-216. [6] Wang F, Gao C, Kuklane K, Holmér I 2010 A Review of Technology of Personal Heating Garments International journal of occupational safety and ergonomics JOSE vol.16(3) pp.387-404. [7] Cherunova I, Kornev N Brink I 2012 Mathematical model of the ice protection of a human body at high temperatures of surrounding medium Forschung im Ingenieurwesen vol.76 (3-4) pp.97-103. [8] Cherunova I , Samarbakhsh S, Kornev N 2016 CFD Simulation of thermo-aerodynamic interaction in a system human-cloth-environment under very low temperature and wind conditions Proc.of the ECCOMAS Congress vol.4 pp.7703-7710. [9] Cherunova I, Kornev N, Jacobi G, Treshchun I, Groß A, Turnow J, Schreier S, Paschen M 2014 Application of calculations of heat transfer and computational fluid mechanics to the design of protection clothes Journal of Engineering Physics and Thermophysics vol. 87(4) pp.855-863 [10] Cherunova I, Dhone M, Kornev N 2015 Coupled thermo-aerodynamical Problems in design of protection Cloth Proc. VI Int. Conf. COUPLED PROBLEMS-2015 pp.1303-1311. [11] Sabirova Z A, Tashpulatov S S, Parpiev A P 2018 Mathematical substantiation of the rational package (BAG) of fully-formed FUR articles with content of polymer composition Journal of Engineering and Applied Sciences Vol.13(23) pp.10145-10147. [12] Gupta D 2011 Design and engineering of functional clothing Indian Journal of Fibre and Textile Research vol.36. pp.327-335. [13] GOST 12.4.303-2016 2019 System of labor safety standards (SSBT). Special clothing for protection from low temperatures. Moscow : STANDARTINFORM 32p. [14] GOST R 12.4.185-99 2000 System of labor safety standards (SSBT). Personal protective equipment against low temperatures. Methods for determining the thermal insulation of a set Moscow: IPK Publishing House of standards 24p. [15] Xu X, Gonzalez J A, Karis A J, Rioux T P, Potter A W 2016 Use of Thermal Mannequins for Evaluation of Heat Stress Imposed by Personal Protective Equipment In book: Performance of Protective Clothing and Equipment Vol.10 pp.285-295. [16] Angelova R A 2016 Infrarnfrared thermography for assessment of human thermophysiological reactions: hands and feet temperature responses to fast cooling Journal of Research in Mechanical Engineering vol.2(9) pp. 1-7. [17] Angelova R A, Georgieva E, Markov D, Bozhkov T, Simova I, Kehaiova N, Stankov P. 2019 Estimating the Effect of Torso Clothing Insulation on Body Skin and Clothing Temperatures

Dynamics of Technical Systems (DTS 2020) IOP Publishing

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in a Cold Environment Using Infrared Thermography FIBRES & TEXTILES in Eastern Europe vol.26 4(130) pp.122-129. DOI: 10.5604/01.3001.0012.1323 [18] Ke Y, Raj U, Li Z, Wang F 2018 Hot Plates and Thermal Manikins for Evaluating Clothing Thermal Comfort: Performance, Protection, and Comfort. In book: Firefighters’ Clothing and Equipment. Taylorfrancis. Ch.7 34 p. DOI: 10.1201/9780429444876-7 [19] Spelic I, Rogale D, Mihelić – Bogdanić A 2018 The laboratory investigation of the clothing microclimatic layers in accordance with the volume quantification and qualification Journal of the Textile Institute vol.110(1) pp.1-11 DOI:10.1080/00405000.2018.1462087 [20] [20] Maeda-Minamia A, Yoshinob T, Katayamac K, Horibab Y, Hikiamid H, Shimadae Y, Namikif T, Taharag E, Minamizawah K, Muramatsui Sh, Yamaguchij R, Imotok S, Miyanoc S, Mimal H, Mimurab M, Nakamuraa T, Watanabeb K 2020 Discrimination of prediction models between cold-heat and deficiency-excess patterns Complementary Therapies in Medicine Vol.49: 102353 [21] Li M-J, Zhu M, Han J-X, Zhang Yu-B 2019 Heat Transfer Model of Multilayer Thermal Protective Clothing for High-Temperature Operation. Modern Applied Science 13(11):21 DOI: 10.5539/mas.v13n11p21. [22] Amin R, Teli D, James P 2018 Exploring the Link between Thermal Experience and Adaptation to a New Climate. March Future Cities and Environment. vol. 4(1) DOI: 10.5334/fce.5 [23] Taieb A H, Baklouti A, Maroini D, Msahli S 2016 Modeling thermal clothing comfort index International Journal of Engineering Sciences & Research Technology vol.5(1) p.217-222 [24] Færevik H 2014 CLOTHING AND PROTECTION IN ARCTIC ENVIRONMENTS. Proc. of the Int. Conf. Ambience 14 & 10i3m Invited speak Tampere, Finland Vol.http://www.ambience14.fi/10i3m/ DOI: 10.13140/RG.2.1.1931.1444.