Clothing Microclimate Research Articles

Investigating the short-term effects of using full-body hospital personal protective equipment and changes in physical workload intensity on human physiological and cognitive performance

The present study investigated the short-term effects of using Personal Protective Equipment (PPE) and physical workload intensity on human physiological and cognitive performance among 21 males and 19 females. PPE1 consisted of a medical coverall and surgical mask, while PPE2 consisted of impermeable full-body coverall, shoe covers, latex gloves, N95 mask, and face shield. Objective assessments were heart rate, energy expenditure, core body temperature, clothing microclimate temperature and humidity, and cognitive performance were the continuous performance test and N-Back test. Subjective assessments included thermal sensation, perceived fatigue/skin wetness/clothing moisture. Using PPE2 and increased workload intensity significantly increased the values of all physiological parameters and the subjective ratings of fatigue, thermal sensation, skin wetness, and clothing moisture. Moreover, the participants’ cognitive performance was not affected by the type of PPE. Practitioner summary: Healthcare workers are at the highest risk in the fight against pandemics. Therefore, these people are required to use personal protective equipment. Using this equipment may have difficulties. The results show physiological strain and higher subjective ratings associated with using full-body hospital PPE and increased physical workload.

Analysis of clothing microclimate conditions for lower body part workwear dedicated for motor impaired employees

Workwear dedicated for motor impaired employees was designed. The woven fabrics used meet the requirements for light to moderate effort according to PN-P-08525:1998, reaching suitable level of water vapor resistance meanwhile. The workwear’s design was carefully chosen to meet the requirements of motor impaired employees during their work activities. The analysis of microclimate was carried out to investigate the garment’s ability to transport water vapor outside from gaps between body part and item of clothing. Two sets of workwear were tested, showing that both garments’ construction and woven fabrics properties influence thereon.

A Trimode Thermoregulatory Flexible Fibrous Membrane Designed with Hierarchical Core-Sheath Fiber Structure for Wearable Personal Thermal Management.

Advanced textiles designed for personal thermal management contribute to thermoregulation in an individual and energy-saving manner. Textiles incorporated with phase changing materials (PCMs) are capable of bridging the supply and demand for energy by absorbing and releasing latent heat. The integration of solar heating and the Joule heating function supplies multidriving resources, facilitates energy charging and storage, and expands the service time and application scenarios. Herein, we report a fibrous membrane-based textile that was developed by designing the hierarchical core-sheath fiber structure for trimode thermal management. Especially, coaxial electrospinning allows an effective encapsulation of PCMs, with high heat enthalpy density (106.9 J/g), enabling the membrane to buffer drastic temperature changes in the clothing microclimate. The favorable photothermal conversion performance renders the membrane with the high saturated temperature of 70.5 °C (1 sun), benefiting from the synergistic effect of multiple light harvesters. Moreover, a conductive coating endows the composite membrane with an admirable electrothermal conversion performance, reaching a saturated temperature of 73.8 °C (4.2 V). The flexible fibrous membranes with the integrated performance of reversible phase change, multi-source-driven heating, and energy storage present great advantages for all-day, energy-saving, and wearable individual thermal management applications.

Heat release and wear comfort characteristics of the ceramic imbedded fabrics for cold weather protective clothing

This paper examined the heat release and wear comfort characteristics of clothing made of aluminium oxide (Al2O3)/graphite imbedded yarn fabrics for cold weather protective clothing. The wear comfort of the clothing was compared and discussed in terms of the moisture vapor resistance of the fabric, which was verified by far-infrared and light heat emission experiments. The maximum surface temperature of the Al2O3/graphite-imbedded sheath/core yarn fabric was 3.4°C higher than that of the regular one, which was attributed to heat release by the far-infrared radiation emitted from the Al2O3/graphite imbedded in the yarns. The moisture vapor resistance of the Al2O3/graphite-imbedded sheath/core yarn clothing, as measured by a sweating thermal manikin test, was 3.6% lower than that of the regular PET one. In addition, the clothing microclimate temperature of the Al2O3/graphite sheath/core yarn fabric measured by wearer trials was approximately 1°C higher than that of the regular PET fabric, which revealed the superior thermal insulation of the Al2O3/graphite sheath/core yarn clothing compared to the regular PET one. Finally, the superior breathability with thermal insulation of the Al2O3/graphite-imbedded sheath/core yarn fabric were revealed due to its good heat release and storage properties, which support the possible applications for cold weather protective clothing.

Hygro-thermo-chemical transfer analysis of clothing microclimate using three-dimensional digital clothing model and computer-simulated person

Several studies regarding indoor environmental quality assessments based on computational human models have been reported. Recently, various computer-simulated persons for computational fluid dynamics (CFD) simulations that reproduce a detailed human body geometry has been developed. However, clothing is usually treated with simplification as a resistance to heat/contaminant transfer, and detailed hygro-thermo-chemical transfer phenomena in clothing-centred area with complex geometry have not been fully discussed. It is also important to investigate the ventilation characteristics inside the air gap between the clothing and the human body. Thus, this study aimed to develop an analytical method of three-dimensional clothing model that can be applied to a computer-simulated person (CSP) for indoor computational fluid dynamics analysis. To identify the impact of the clothing model on the human and the microclimate around the body, hygro-thermo-chemical transfer analyses were conducted in a virtual simplified model room. By reproducing the detailed clothing geometry, ventilation inside the air gap and clothing-centred hygro-thermo-chemical transfer characteristics were quantitatively investigated. The data analysis technique established in this study could contribute to preparing foundational data for simplification of numerical modelling of clothing.

Airflow and Heat Transfer Characteristics in Clothing Microclimate around Simulated Clothing Human Body

Airflow and Heat Transfer Characteristics in Clothing Microclimate around Simulated Clothing Human Body

Investigation on Air Flow Inside Clothing Microclimate and Clothed Human Thermal Environment Through PIV Measurement and CFD Analysis

Investigation on Air Flow Inside Clothing Microclimate and Clothed Human Thermal Environment Through PIV Measurement and CFD Analysis

Effects of body positions and garment design on the performance of a personal air cooling/heating system.

Heating and cooling efficiencies of a personal air thermoregulatory system are not only determined by the physics of energy conversion efficiency but also influenced by the interactions between human body and clothing microenvironment. It was found that for a wearable air ventilating system, sedentary position can lead to higher heating and cooling power than standing position. Also, leaning on the chair backrest during sitting can further improve the air cooling performance in hot condition compared with a non-leaning position. These improvements are mainly attributed to the change of clothing microclimate at chest and back areas, where cooling/heating air is directed. It was also found locations of air outlets in a wearable air ventilating system can affect the cooling/heating performance. With the improved understanding of the influence of human and design factors, the study provides a guideline for the design of personal air thermoregulatory systems used for different body positions.

Thermal and Wet Comfort of Modified Linen Clothing in Humid Environment

Kuang, C., 2020. Thermal and wet comfort of modified linen clothing in humid environment. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 1144–1148. Coconut Creek (Florida), ISSN 0749-0208.It is important that the moisture permeability of clothing maintain the thermal balance of the human body in humid environment or at the stage of motion. In this paper, the dressing comfort difference between the long sleeve shirt made of modified treatment linen fabric and that made of unmodified linen fabric was analyzed. Air permeability, wicking ability and moisture permeability was tested to explore the water absorption property and moisture permeation property of the linen fabrics. The wear trials of the long sleeve shirt made of modified or unmodified linen fabrics were carried out in constant temperature and humidity chamber. The results show that modified linen fabric enhances the water absorption and moisture penetrability, and weakens the air permeability. Comparing with the long sleeve shirt made of unmodified linen fabric, it was clear that the thermal transfer performance of that made of modified fabric after sweating was improved. And the wet transfer property of the shirt made of modified fabric was better than that of the unmodified fabric, as well as the shirt made of refined fabric was better than that of the preliminary modified fabric. So the modified linen fabrics maintain a comfortable clothing microclimate.

Development and experimental validation of a 3D numerical model based on CFD of the human torso wearing air ventilation clothing

Building energy demands can be reduced significantly with the use of personal cooling clothing where only the microclimate around body is cooled instead of cooling the entire building or rooms using HVAC systems. In the present study, a three-dimensional numerical model of a virtual thermal manikin wearing an air ventilation cooling clothing with actual dimensions and shape was developed to determine heat transfer between the human body and the environment. The actual geometric model was developed based on data obtained from 3D body scanning experiments. Governing fluid flow and energy equations were solved along with the standard k-ε turbulence model. Experiments were carried out to determine accuracy of the developed numerical model. Validation studies were performed by comparing numerical results with experimental results obtained by conducting both thermal manikin experiments and human trials. Good agreement between the two was found. Fluid flow and temperature distribution in the clothing microclimate, local heat flux and convective heat transfer coefficients at various locations in the human body, the sensible heat transfer between the human body and environment and the effect of fan air flow rate on body cooling performance were also analyzed. Maximum heat transfer or cooling was observed in the lower back segment of the body with convective heat transfer coefficient 38.62 W/m2K. Overall, torso heat transfer was found to be 273.44 W/m2 which corresponds to 154.73 W cooling power and 0.24 cooling efficiency of the air ventilation clothing at 20.0 ± 0.5 °C, 65 ± 5% and 0.4 ± 0.1 m/s. It was noted that the area-weighted average torso heat flux increased as the fan air flow rate increased.

A conceptual wearable monitoring system for physiological indices and clothing microclimate measurement

Purpose The purpose of this paper is to investigate physiological indices related to comfort and health condition, based on which corresponding electronic equipment are selected and applied. A wearable monitoring system using sensor and liquid crystal display (LCD) techniques are then designed. Sensors are used to collect and transmit recording required signals from the wearer. A microcomputer with the type of AT89C52 is used to record and analyze the collected data. LCD is applied to display the health and comfort condition of the wearer. Design/methodology/approach A novel wearable monitoring system for the measurement of physiological indices and clothing microclimate is proposed in this study in order to monitoring both health and comfort condition of the wearer. Findings The proposed system provides reference for the application of sensor and display technologies in the field of smart clothing, which can be further applied to infant and child care, health care, home entertainment, military and industry. Originality/value This paper, first, investigated a framework of a wearable monitoring system considering both comfort and health condition and summarized the related physiological indices. The requirements of both comfort and health condition monitoring are analyzed to select appropriate electronic elements.

고혈압 고령자 대상 웨어러블 혈압계의 측정 타당성 및 의복기후의 영향

고혈압 고령자 대상 웨어러블 혈압계의 측정 타당성 및 의복기후의 영향

소방복 내 노멕스 냉각복 착용이 모의 소방동작 동안 소방관의 작업 효율에 미치는 영향

The purpose of the present study was to investigate the efficiency of mobility of newly-developed Nomex cooling pack shirt inside firefighting personal protective equipment (FPPE) during simulated firefighting tasks. Sixteen firefighters participated in the following four experimental conditions: FPPE (Control), cooling vest A + FPPE (Vest A), cooling vest B + FPPE (Vest B), and Nomex cooling shirt + FPPE (Nomex cooling shirt). As a result, there were no significant differences in completion time, heart rate, total sweat rate, and blood lactate acid among the four conditions. Clothing microclimate temperature on the chest was lower for Nomex cooling shirt (31.2 ± 1.1℃) than Control (33.6 ± 0.8oC) or Vest A (33.5 ± 0.9℃) (P0.001). Clothing microclimate humidity and sweat sensation showed no differences among the 4 conditions. Firefighters expressed less hot and less uncomfortable for Nomex cooling shirt and Vest B compared to Vest A and Control (all P0.05). There were no significant differences in mass perception among Vest A, B and Nomex cooling shirt, while Nomex cooling shirt was perceived as less stiffness than Vest A and B. In conclusion, wearing Nomex cooling shirt inside FPPE did not interrupt firefighters’ mobility and improved thermal sensation and comfort.

Influence of Clothing Opening Shape on Air Flow and Heat Transfer Characteristics in Clothing Microclimate

Influence of Clothing Opening Shape on Air Flow and Heat Transfer Characteristics in Clothing Microclimate

PREDICTION OF AIR PERMEABILITY OF KNITTED FABRIC BY USING COMPUTATIONAL METHOD

Air permeability is one of the very important factors which need to be considered at the development stage of textile fabrics because it affects the comfort of the clothing. During normal and extreme environmental conditions human body releases heat and the heat can be controlled by the air exchange between the body and clothing microclimate and the external environment; the exchange phenomena depends on the air permeability of the fabric. The air permeability of fabric can be evaluated by both the experimental and computational methods. In this work, a computational method is used for the prediction of air permeability of fabrics. The geometrical model of weft knitted structures was generated by using the actual dimensional parameters of the fabric and was further analysed by applying appropriate boundary conditions. The simulated results obtained from computational analysis were compared to the experimental results. Furthermore, the validated models were further used to predict and analyse the effect of stitch length, stitch density and fibre volume fraction on the air permeability of the fabric.

Research trends on prevention of heat stroke using clothing: Focusing on practical research in Japan

This study identifies Japanese study content on heat stroke prevention measures using clothes, provides basic data for quantitative wearing assessment studies, presents a developmental direction for those, and helps invigorate further research. Studies were collected concerning clothing-based heat stroke measures in order to analyze the following factors: current status of heat stroke by industry and working environment, heat stroke and body cooling method, clothing microclimate and air circulation in a hot environment, hot environments and wearable sensors, and heat stress reduction and skin exposure. The current WBGT standard does not consider the diversity of wearing clothes according to the working environment. Therefore, it is preferable to add a correction value in consideration of design, materials, and ventilation to prevent heat strokes. For the heat stroke and body cooling method, wearing water-perfused clothing is effective to reduce heat stress and maintain exercise ability. Changing the material and design of clothing or wearing air-conditioned clothing can improve ventilation and the clothing microclimate. However, further evaluation is needed on the effectiveness of air-conditioned clothing as a heat stroke prevention product. The measurement method using a wearable sensor can provide real-time data on the body response due to working in a hot environment. Therefore, it is an effective alarm for heat stroke. Skin exposure area and heat dissipation efficiency should be considered to prevent heat stroke. Reducing the covering area by exposing the head, neck, and limbs, and wearing breathable material can prevent heat stroke from increased body temperature.

Numerical analysis of the flow and heat transfer in cylindrical clothing microclimates – Influence of the microclimate thickness ratio

Clothing microclimates, i.e. the space between the skin and the clothing, can play a central role in the heat and mass exchanges from or to the body. This is especially true for protective clothing, where microclimates are generally thicker and natural convection is more likely to occur. We used a computational fluid dynamics approach to perform numerical studies of fluid flow and heat transfer across cylindrical clothing microclimates for Reynolds number of 3900. Transient simulations were performed for three different values of microclimate thickness to diameter ratio (0.05, 0.10 and 0.25), considering a two-dimensional cross-section of a human limb surrounded by a porous fabric and exposed to cool external air (10°C). The obtained local heat transfer along the skin shows that increasing the microclimate thickness ratio from 0.05 to 0.25 decreases the convective heat fluxes by up to 100% in the upstream regions of the microclimate, and increases them up to 190% in the downstream regions. This asymmetry, which indicates an increasingly important role of natural convection as the microclimate thickness ratio is increased, is often overlooked in space-averaged approaches due to the opposite changes in the different regions of the microclimate. Local variations in temperature along the outer fabric and in convective fluxes along the skin were significant, reaching up to 14K and 90%, respectively. The critical thickness ratio above which natural convection should not be ignored was found to be 0.1 (e.g. corresponding to a microclimate thicknesses of 11 mm or 8 mm, around an upper arm or forearm, respectively).

Thermal properties of combat uniforms treated with microencapsulated octadecane and change in clothing microclimate via thermal manikin

This study examined how the heat storage property and the heat release property of three different PCM (Phase Change Material) treatment concentrations of combat uniform fabrics affected microclimate inside clothing after the octadecane-treated fabrics were made into garments. Three combat uniforms were constructed with fabrics treated by three different octadecane concentrations (0, 8, and 16%) at the same curing temperature of 113.6 °C. The thermal properties of the octadecane-treated fabrics were acquired by using DSC (Differential Scanning Calorimeter) analysis. Also, water vapor and air permeability were measured before the thermal comfort of the octadecane-treated combat uniforms was evaluated. And then, a thermal manikin was used to measure skin temperature, skin humidity, and microclimate temperature, while the chamber was set at various environmental temperatures (0, 0–35, 35, and 35–0 °C). And, to analyze the differences among skin temperature, skin humidity, and microclimate temperature of the garments according to the three different octadecane concentrations, ANOVA and a post hoc test were conducted. As a result, heat of fusion and heat of crystallization (ΔHf and ΔHc) were observed to increase as the octadecane concentration increased. The 8% octadecane-treated fabrics had 3.56 J/g of ΔHf, 3.80 J/g of ΔHc, and the 16% octadecane-treated fabrics had 7.46 J/g of ΔHf, 7.44 J/g of ΔHc. Also, the more octadecane was added, the less water vapor and air permeability had the fabrics because many open spaces were covered due to the microcapsules after octadecane treatment. It might influence on clothing microclimate. However, the 8% octadecane-treated garment (G1) exhibited less differential skin temperature and humidity and clothing microclimate temperature than the 16% octadecane-treated garment (G2) even though the octadecane concentration was lower. It means that the 8% octadecane-treated garment exhibited better thermal performance than the 16% octadecane-treated garment. This is because the higher octadecane concentration caused the fabric to become stiffer, thereby causing the still air layer to decrease the thermal insulation efficiency and the octadecane treatment was not affected. It differed from the result of the thermal properties (ΔHf and ΔHc) of the octadecane-treated fabrics. The reason for this result is that when the thermal manikin wore the octadecane-treated garments, various factors had effects on thermal properties such as environmental aspects, physiological aspects, and clothing aspects.

Investigation of heat transfer and temperature distribution in outdoor human–clothing–environment systems with double-layered ensemble

The thermal behavior in a clothing microclimate is an important aspect related to thermal comfort. Situation-dependent analyses are required to understand the heat transfer of clothing; thus, the heat transfer and temperature distributions in a double-layered human–clothing–environment system in the presence of solar radiation are investigated as practical application in this study. A new heat transfer model modified from the previously proposed outdoor thermal model with single-layered clothing is developed. The new model integrates the radiative effects on clothing, the heat conduction within the air layer, and the heat convection on the outer surface of clothing. Radiation heat transfer is included as a source term for the clothing. Measurements of the temperature distributions are obtained under typical summer and winter atmospheric conditions with or without solar radiation to validate the model. A comparison confirms that the prediction model is valid. Subsequently, the effects of layered clothing are analyzed. Since insulation fundamentally influences the temperature distributions in the steady-state system, the temperatures at the boundary and air gap determine the slopes of the temperature distribution. Since the absorbed solar energy is more influential than the release of heat by conduction or even convection for clothing, the solar radiation and radiative properties are relatively dominant at the temperature distribution of clothing and consequently the entire system. Overall, the effects of solar radiation and the properties related to radiation are essential for evaluating the microclimate inside clothing.

Intelligent clothing: first and second generation clothing with adaptive thermal insulation properties

This paper deals with the idea that one of the inner thermal insulation layers of a garment may be replaced by expanding the air chambers in the form of an expanding thermal insert, which is inflated with air causing the chamber thickness and thermal insulation properties to change. The chambers are controllable so that the thermal insulation properties can be changed, and by connecting with an appropriate control, the architecture of an article of clothing can be designed such that it can independently monitor changes in its environment and change its thermal insulation properties in accordance with changes in its external and internal environment. In this way, it acquires the characteristics of intelligent clothing. The paper presents idea concepts, development, structural architecture and general characteristics of two generations of intelligent clothing with adaptive thermal insulation properties. The expanding thermal inserts are situated between the outer shell and the lining and are the key element of this type of new clothing. In the first generation of intelligent clothing the expanding inserts were designed in combination with three horizontal chambers that can be sealed in three horizontal layers, whereby it is possible to make six adaptable discontinuous levels of thermal insulation. In the second generation, ribbed expandable chambers were used. Their thickness is continuously changeable according to the pressure change in the chambers, whereby the value of thermal insulation of the chambers can be continuously adapted. The functioning of this clothing is based on the integration of sensors for internal and external temperature and air pressure in the chambers, on a microcontroller with regulation software and actuators to control the expanding insert. When wearing this kind of clothing, the microcontroller system monitors changes in ambient temperature and clothing microclimate depending on the wearer’s physical activity, compares them with the achieved thermal protection and makes autonomous decisions on the required increase or decrease in thermal protection. Since this clothing follows changes in its internal and external environment, estimates the real and necessary state, makes decisions and independently performs the adaptation of thermal insulation to a level that it ensures constant thermal comfort, it can be claimed that such a garment has the basic attributes of intelligent clothing. The paper describes the functioning of two types of thermal insulation chambers, the sensor system used, micropneumatic components, the microcomputer system, the flow chart of the algorithm of intelligent behavior, the complete built-in architecture of all technical subsystems, features of the first and second generation and the observed good and bad points of the conceptual approach to the development of intelligent clothing with adaptive thermal insulation properties.