Clothing Assembly Research Articles

Optimization of multilayer clothing assemblies for thermal comfort in cold climate

This paper presents a theoretical study on the optimization of key material parameters of multilayer clothing assemblies for thermal comfort in cold climate. A mathematical model of heat and moisture transfer through a multilayer clothing assembly is established. The existence and uniqueness of the solution of the model are verified by using the fixed point theorem. The model predicts the optimum thicknesses and porosities of the two internal layers of the clothing assembly, with which the thermal comfort index will fall within the required intervals with the greatest probability. This study is significant for the optimum design of multilayer clothing assembly for thermal comfort.

Impact of ultraviolet radiation on thermal protective performance and comfort properties of firefighter protective clothing

In this study, the impact of ultraviolet radiation is studied on thermal protective performance and clothing comfort properties of firefighter protective clothing. Firefighter clothing assembly consists of the outer shell, moisture barrier and thermal barrier. In this research, two different outer shells were utilized. Outer shell O1 consists of inherently fire- retardant fibres mainly consisting of Conex (Nomex) and firefighter assembly having Conex as the outer shell was called specimen A. On the other hand, clothing arrangement which employed Proban coated outer layer (O2) was termed as specimen B. Both specimens were evaluated for tensile testing, air permeability, radiant heat transmission machine, bending moment and water vapour resistance before and after exposure to ultraviolet radiation. The tensile strength value of outer shell O2 was higher than that of O1 before and after exposure to UV radiation. Tensile strength values of both outer shells O1 and O2 decline after exposure to ultraviolet radiation. Air permeability values of both outer shell O1 and O2 increase after being exposed to ultraviolet radiation. It was noted that specimen A has better thermal protective performance as compared to specimen B, before and after exposure to UV radiation. Also, radiant heat transmission index RHTI 24 values were greater for specimen A as compared to specimen B, before and after exposure to UV radiation. Moreover, bending moment values for both outer shell O1 and O2 decline after being subjected to UV radiation. Furthermore, Water vapour resistance values of outer shell O1 and outer shell O2 enhance after exposure to ultraviolet radiation.

Warmth Property of Clothing Assembly - Part III: Theoretical Approach for Calculating the Warmth Parameters of Clothing Assembly. (Dept. T)

The present work deals with the theoretical prediction of warmth parameters of clothing assembly. Theoretical expressions are derived for calculating both air flow resistance and thermal resistance of clothing assembly. Three different cases which represent the most common wearing cases in winter season were selected for applying the theoretical expressions. The derived relations were found to be fairly close to those observed experimentally. Also an empirical relationship is fitted to the measured thermal resistance data of clothing assembly using stepwise multiple regression analysis. The regression analysis relates the thermal resistance of the clothing assembly to the parameters of weight per unit area, thickness and air resistance. This empirical relationship is shown to predict the thermal resistance of clothing assembly accurately.

Evaluation of the Moisture and Thermal Characteristics of Knitted Sport Wear Fabrics (Dept.T)

The main aim of this work was study the effect of fiber composition on the moisture and thermal properties for sport wear knitted fabrics. We also studied the effect of using single and double layer fabric on the moisture and thermal properties of these fabrics. To know how heat and water are transported through each fabric, measurements of their physical properties (thermal resistance, thermal conductivity, thermal absorptivity, heat flow, relative water vapor permeability and air permeability) were made in laboratories. The effects of fiber composition and the clothing assembly (one or two layers) have a highly significant effect on both moisture and thermal properties of sport wear knitted fabrics and also there were a high correlation between fabric thickness, fabric porosity, fabric air permeability, the relative water vapor permeability and fabric thermal properties

MATHEMATICAL MODELING OF THE HEAT AND MOISTURE TRANSFER IN A POROUS MEDIUM WITH STOCHASTIC EXTERNAL TEMPERATURE

A novel stochastic model that considers the fluctuations at the boundary and its propagation in the heat and moisture transfer simulation in a clothing assembly is presented. Randomness in terms of white Gaussian noise is input to the ambient temperature. The existence and uniqueness of a solution to the resulting system of stochastic differential equations is then analyzed. A computationally effective implicit splitting finite difference method is employed in the numerical validation of the problem. Numerical results show the fluctuations propagate to all the other dependent parameters − namely, vapor concentration, air concentration, and total concentration. Additionally, an insight into the insulating property of the fabric is given. Varying the fabric thickness is shown to have an impact on the adiabatic property of the porous medium, hence affecting the heat and moisture transfer.

Modeling of a Clothing Assembly line through the Identification Process

Nowadays, a new concept called fast fashion emerged worldwide. In order to remain efficient, companies need to keep their logistics under control. For that purpose, they need to control their manufacturing and decrease their delays and costs. To achieve that, industries need to make a lot of experiments before optimizing their supply chains. This may lead to unnecessary costs and it is contrary to the company’s policy. To overcome this situation, modeling and simulating could provide the best economical solution. The aim of this work is to obtain a mathematical model of an assembly line in the textile and clothing industry. The system will be represented by a black box with a real set of data collected from the industry. This model will have to reflect as faithfully as possible the studied system.

The physical and qualitative analysis of fluctuations in air and vapour concentrations in a porous medium.

This work presents the development and physical analysis of a sweat transport model that couples the fluctuations in air and vapour concentrations, and temperature, in a one-dimensional porous clothing assembly. The clothing is exposed to inherent time-varying conditions due to variations in the body temperature and ambient conditions. These fluctuations are governed by a coupled system of nonlinear relaxation–transport–diffusion PDEs of Petrovskii parabolic type. A condition for the well-posedness of the resulting system of equations is derived. It is shown that the energy of the diffusion part of the system is exponentially decreasing. The boundedness and stability of the system of equations is thus confirmed. The variational formulation of the system is derived, and the existence and uniqueness of a weak solution is demonstrated analytically. This system is shown to conserve positivity. The difficulty of obtaining an analytical solution due to the complexity of the problem, urges for a numerical approach. A comparison of three cases is made using the Crank–Nicolson finite difference method (FDM). Numerical experiments show the existence of singular coefficient matrices at the site of phase change. Furthermore, the steady-state profiles of temperature, air and vapour concentrations influence the attenuation of fluctuations. Numerical results verify the analytical findings of this work.

4788 Thermal Manikin Measurements of Protective Clothing Assemblies

The thermal comfort of a foundry worker is very important and related to many factors, i.e., the structure of the protective clothing assembly, the number of layers and their thickness, as well as the distance between the body and appropriate underwear. The research undertaken aimed at checking thermal insulation for assemblies consisting of aluminized protective clothing and appropriate underwear in two sizes and without underwear. Measurements of the clothing thermal insulation were conducted using a thermal manikin dressed in two-layer protective clothing and three kinds of underwear products covering the upper and lower parts of the manikin. The first part of the paper presents a comparison of results of thermal insulation measurement of two kinds of protective clothing: a traditional one made of aluminised glass fabrics and a new one made of aluminised basalt fabrics. Each of the protective clothing was worn on three kinds of underwear products in m and s sizes. The influence of the underwear size was noted. In the second part of paper, measurements were made for two aluminized basalt clothing variants: commercial and a prototype with modifications in static and dynamic conditions. The results were discussed.

The Central American Clothing Assembly Industry and China's Producers for the U.S. Market

This is a descriptive paper on the export performance of clothing industries in Central America and the Caribbean Basin to the U.S. market. A brief summary of the history of the region’s garment export industry in the face of evolving trade liberalization is provided. Attention is given to the evolution of CAFTA–DR’s apparel export industry according to changing US preferential trade programs. The importance of China’s membership in the World Trade Organization, and the elimination of Multi-Fiber Agreement quotas are highlighted in the fortunes of Central American clothing exporters’ attempts to expand their shares in the US market.

Fundamental Aspects on Conductive Textiles Implemented in Intelligent System

Conductive fibers, which are electrically conductive elements having the structure of a fiber, have a fairly long history and have been used for applications in electronic textiles as well as for aesthetics, anti-static and shielding purposes. Electrically conducting textile fibers, such as gold-coated threads, were produced in antiquity for aesthetic purposes, before the discovery of electricity, using various manufacturing methods. The textile intelligent systems, which comprise conducting textile structures (electroconducting wires or structures), present a dynamic behavior which favors the self regulation of the thermal insulation and vapor permeability with the purpose to maintain the thermo-physiological balance; the clothing assembly aims at monitoring the biologic potential, used only in critical situation (ex. accidents, falling down in a precipice etc.).

Protective performance of thermal protective clothing assemblies exposed to different radiant heat fluxes

Three layered clothing assemblies were constructed from commercial heat protective textile clothing materials for outer, middle and inner layers. Thermal liners, used as middle layer, were prepared from Nomex fibres of two different fineness keeping other parameters constant. Different three layered combinations of fabrics were compared for radiant heat protective performance based on the estimate of burn injury time using Stoll’s curve. Analysis of experimental results showed that characteristics of the outer layer fabric and its interaction with applied heat flux are important factors that affect thermal response of the clothing assemblies. Fineness of the constituent fibres of nonwoven thermal liner was found to significantly affect the protective performance. Thermal properties, porosity, optical properties of the clothing layers found to affect heat protection provided by clothing assembly.

Analysis of Moisture Evaporation from Underwear Designed for Fire-Fighters

Abstract In this study we analysed the effect of moisture on the thermal protective performance of fire-fighter clothing in case of routine fire-fighting conditions. In the first stage of this research we investigated simultaneous heat and moisture transfer through a single-layer fabric, used as underwear for fire-fighters, at different moisture conditions. In the second stage of the study, the underwear in dry and wet state was tested together with protective clothing systems for fire-fighter consisting of three or four layers. It was found that during the evaporation of the moisture, a temperature plateau appeared during which temperatures hardly rose. The energy consumption used for the phase change of moisture located in the assembly dominated the heat transfer process as long as there was moisture present. As soon as all water had evaporated, the temperatures approached the temperatures measured for dry samples. The moisture within the clothing assembly did not lead to increased temperatures compared with the measurements with dry samples. This research has confirmed that moisture can positively affect the thermal protection of a clothing system.

Heat and sweat transport in fibrous media with radiation

The paper is concerned with heat and sweat transport in porous textile media with a non-local thermal radiation and phase change. The model, based on a combination of these classical heat transfer mechanisms (convection, conduction and radiation), is governed by a nonlinear, degenerate and strongly coupled parabolic system. The thermal radiative flow is described by a radiation transport equation and characterized by the thermal absorptivity and emissivity of fibre. A conservative boundary condition is introduced to describe the radiative heat flux interacting with environment. With the conservative boundary condition, we prove the global existence of positive/non-negative weak solutions of a nonlinear parabolic system. A typical clothing assembly with a polyester batting material sandwiched in two laminated covers is investigated numerically. Numerical results show that the contribution of radiative heat transfer is comparable with that of conduction/convection in the sweating system.

Physiological cost and thermal envelope: A novel approach to cycle garment evaluation during a representative protocol

This study aimed to examine thermoregulation in different clothing assemblies during a representative cycling exercise protocol. Six men undertook cycling exercise simulating representative thermal exchange challenges while wearing low (LOW), intermediate (INT1 and INT2), or high (HI) amounts of clothing. Exercise was conducted at 14.5 °C, 46.8% relative humidity and included a "flat" [45 min at 35% peak power output (PPO), wind speed 8.3 m/s], "uphill" (30 min at 55% PPO, wind speed 3.6 m/s), and "downhill" (20 min at 50 W, wind speed 16.7 m/s) stage. Rectal temperature changed with the exercise stage and was independent of clothing assembly. In contrast, an "envelope" was evident for mean body temperature, resulting from differences in mean skin temperature between the LOW and HI conditions. The elevated mean body temperature in HI was associated with increased physiological "cost," in the form of increased sweat production and heart rate. Physiological cost provides a better index of clothing performance than deep body temperature in the "thermoregulatory zone," as a consequence sports clothing should attempt to optimize the balance between comfort and reduced physiological cost.

Near-infraed scattering method for fabric thermal comfort

Wetting behavior of a clothing assembly plays an important role in thermophysiological body comfort. The instruments and methods utilised for testing purposes should adequately quantify wetting parameters of fabric thermal comfort. The surface conductivity method has been used to for moisture management testing in fabrics, but that method cannot give the detailed information for fiber-liquid interaction. With the new near-infrared scattering method, the wetting mechanism is introduced and interpreted through liquid transfer process from an infinite liquid reservoir. Wetting results from two kinds of fabrics show the difference in fabric thermal comfort.

Heat and sweat transport through clothing assemblies with phase changes, condensation/evaporation and absorption

The paper is concerned with the heat and sweat transport in porous textile media with complex phase changes, which is described as a non-isothermal, multi-phase and multi-component fluid flow and governed by a nonlinear, degenerate and strongly coupled parabolic system. The phase change, condensation/evaporation and fibre absorption, play an important role in the design of functional clothing. In this paper, we present some more precise formulations on condensation/evaporation, fibre absorption and heat capacity to maintain the physical conservation of mass and energy. A typical clothing assembly with a hydrophobic batting material and two different types of cover is investigated numerically. Numerical results show that for the hydrophobic material, the evaporation and condensation zones arise simultaneously in the batting area and that the proposed formulations are more realistic to describe the phase change. Existence and uniqueness of a classical positive solution for the incompressible model are also proved.

Quasi-steady-state and steady-state models for heat and moisture transport in textile assemblies

Heat and moisture transport plays an important role in many engineering areas. In many sweat transport systems, such as clothing assembly, the moisture concentration (or sweat) is relative small and the air concentration reaches a steady state quickly. In this paper, a quasi-steady-state multi-component and multi-phase model for heat and moisture transport in porous textile materials with phase change is proposed. An analytic form of the air concentration is obtained in terms of the mixture gas (vapour and air) concentration and temperature. The new model is described in the form of a single-component flow with an extra air resistance (permeability), involving only the vapour concentration (or pressure), temperature and water content. The existence of the classical positive solutions of the corresponding steady-state model is proved. Two types of clothing assemblies are investigated numerically. The comparisons among the experimental measurements and numerical results of the fully dynamic model, the proposed quasi-steady-state model and steady-state model are also presented. Numerical results show that the proposed quasi-steady-state model is realistic and less complicated.

MOISTURE TRANSMISSION THROUGH TEXTILES

Abstract The moisture transmission behaviour of a clothing assembly plays a very important role in influencing its efficiency with respect to thermophysiological body comfort. This paper is in two parts. Part I deals with the processes involved in moisture transmission and the factors at play. Part II is concerned with selecting the measurement techniques which are of great importance in determining fabric factors that influence comfort. The instruments and methods used for testing purposes should adequately simulate the exact conditions for which the fabric will be used, in order to determine the effectiveness of that fabric for a particular wearing situation and environmental condition. The testing methods used and the apparatus developed by different researchers for determining moisture transmission through textiles by different mechanisms are discussed in this paper. Moreover, this part of the paper deals with the mathematical models of liquid and vapour transport through textile materials developed by several scientists in order to understand the exact phenomena involved and to predict the factors affecting the transmission under a particular condition.

The Effect of Clothing on the initial Responses to Cold Water Immersion in man

The protection provided by three clothing assemblies against the cold shock response was investigated. Nine healthy male volunteers each undertook three two minute head-out immersions into stirred water at 10 degrees C. The subjects wore a different clothing assembly for each immersion, these were: a) Swimming trunks only; b) Conventional clothing (equivalent to RN No 8s); c) Conventional clothing plus windproof/shower-proof clothing (RN foul-weather clothing Mk III). The cardiac, ventilatory and thermal responses of the subjects were examined before and during the immersions. No significant differences were found between the magnitude of the responses recorded on immersion when conventional clothing or foul-weather clothing were worn. Mean skin temperature was lower (P less than 0.05) and respiratory frequency and minute ventilation were higher (P less than 0.05) on immersion in swimming trunks compared to the other two conditions. It is concluded that when policies for the use of immersion protective clothing are being formulated, consideration should be given to all of the potentially hazardous responses associated with cold water immersion.

The effect of clothing on "diving bradycardia" in man during submersion in cold water.

Eighteen healthy male volunteers undertook three seated submersions into stirred water at 5 degrees C. Whilst submerged, the subjects attempted to hold their breath for 20 s. They wore a different clothing assembly for each submersion, viz: a cotton overall assembly, a "wet suit" assembly and a "dry suit" assembly. During the experiments the breath-hold time, heart rate, skin and rectal temperatures of the subjects were recorded. The results showed that significantly (P less than 0.05) more subjects developed a diving bradycardia--defined as five or more consecutive R-R intervals of over 1.2 s--when wearing the dry suit. It is concluded that increasing the cold stress experienced by individuals during cold-water submersion decreases the incidence of diving bradycardia but not the magnitude of the bradycardia when it occurs.