3D heat transfer modeling and parametric study of a human body wearing thermal protective clothing exposed to flash fire

This paper presents an experiment-based, multi-medium heat transfer model to study thermal responses of multi-layer protective clothing with an air gap exposed to thermal radiation and hot contact surface. The model considers the dynamical changes of air gap, each layer’s fabric thickness, and air content contained in the fabric due to the pressure applied. The fabric heat transfer model developed from this study was incorporated into a human skin burn model in order to predict skin burn injuries. The predicted results from the model were well in agreement with the experimental results. A parametric study was conducted using various contact temperatures and applied pressures and design variables of firefighting protective clothing, such as physical properties of fabric layers and air gap sizes. It was concluded from the parametric study that resistance to transmission of injurious levels of heat decreases as the test temperature and contact pressure increase, and the contact heat transfer can weaken the importance of air gap under radiant heat flux(8.5 kW/m2) for 60 s and compression (pressure: 3 kPa, temperature: 316℃) for 60 s. The findings obtained in this study can be used to engineer fabric systems that provide better protection for contact heat exposure.

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Effect of Compression on Contact Heat Transfer in Thermal Protective Clothing Under Different Moisture Contents

Clothing and Textiles Research Journal ◽

10.1177/0887302x19863104 ◽

2019 ◽

Vol 38 (1) ◽

pp. 19-31 ◽

Cited By ~ 1

Author(s):

Yun Su ◽

Rui Li ◽

Jie Yang ◽

Guowen Song ◽

Jun Li

Keyword(s):

Heat Transfer ◽

Moisture Content ◽

Protective Clothing ◽

Transfer Efficiency ◽

Protective Level ◽

Contact Heat ◽

Contact Heat Transfer ◽

Heat Transfer Efficiency ◽

Skin Contact ◽

Thermal Protective Clothing

Contact burns pose a serious threat on firefighters’ health, safety, and job performance. The objective of the study was to analyze the effects of compression and moisture content on thermal protective performance of clothing. Skin-simulant sensor and Pennes bio-heat transfer model were used to predict time to cause skin contact burn. A new index (heat transfer efficiency) was proposed to examine the effects of applied pressure and moisture level on the contact heat transfer in the thermal protective clothing. It was demonstrated that the addition of moisture nonlinearly decreased the thermal protective level of clothing. The fabric thickness was greatly decreased by the compression, but the thermal protective level presented no significant difference between two kinds of pressures. The heat transfer efficiency was an effective index for evaluating the contact heat transfer, which was determined by the basic properties of fabric, the moisture content, and the pressure level. The conclusions from this study could contribute to understanding the effects of compression and moisture on the contact heat transfer, thus providing the principle of thermal protection against skin contact burns.

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Application of Nanofiber Technology to Nonwoven Thermal Insulation

Journal of Engineered Fibers and Fabrics ◽

10.1177/155892500700200204 ◽

2007 ◽

Vol 2 (2) ◽

pp. 155892500700200 ◽

Cited By ~ 20

Author(s):

Phillip W. Gibson ◽

Calvin Lee ◽

Frank Ko ◽

Darrell Reneker

Keyword(s):

Heat Transfer ◽

Thermal Insulation ◽

Radiative Heat Transfer ◽

Protective Clothing ◽

Radiative Heat ◽

Glass Fibers ◽

Small Diameter ◽

Cold Environments ◽

Thermal Protective Clothing ◽

Biological Protection

Nanofiber technology (fiber diameter less than 1 micrometer) is under development for future Army lightweight protective clothing systems. Nanofiber applications for ballistic and chemical/biological protection are being actively investigated, but the thermal properties of nanofibers and their potential protection against cold environments are relatively unknown. Previous studies have shown that radiative heat transfer in fibrous battings is minimized at fiber diameters between 5 and 10 micrometers. However, the radiative heat transfer mechanism of extremely small diameter fibers of less than 1 micrometer diameter is not well known. Previous studies were limited to glass fibers, which have a unique set of thermal radiation properties governed by the thermal emissivity properties of glass. We are investigating the thermal transfer properties of high loft nanofiber battings composed of carbon fiber and various polymeric fibers such as polyacrylonitrile, nylon, and polyurethane. Thermal insulation battings incorporating nanofibers could decrease the weight and bulk of current thermal protective clothing, and increase mobility for soldiers in the battlefield.

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Simulations of Heat Transfer through Multilayer Protective Clothing Exposed to Flame

Autex Research Journal ◽

10.2478/aut-2020-0041 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Adam K. Puszkarz ◽

Waldemar Machnowski

Keyword(s):

Heat Transfer ◽

Computer Aided Design ◽

Protective Clothing ◽

Three Dimensional ◽

Woven Fabrics ◽

Nonwoven Fabrics ◽

Thermal Protective Clothing ◽

Simulation Results ◽

Multilayer Assemblies ◽

The Individual

AbstractIn this paper, the safety and thermal comfort of protective clothing used by firefighters was analyzed. Three-dimensional geometry and morphology models of real multilayer assemblies used in thermal protective clothing were mapped by selected Computer-Aided Design (CAD) software. In the designed assembly models, different scales of the resolution were used for the particular layers – a homogenization for nonwoven fabrics model and designing the geometry of the individual yarns in the model of woven fabrics. Then, the finite volume method to simulate heat transfer through the assemblies caused by their exposure to the flame was applied. Finally, the simulation results with experimental measurements conducted according to the EN ISO 9151 were compared. Based on both the experimental and simulation results, parameters describing the tested clothing protective features directly affecting the firefighter’s safety were determined. As a result of the experiment and simulations, comparable values of these parameters were determined, which could show that used methods are an efficient tool in studying the thermal properties of multilayer protective clothing.

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