scholarly journals Experimental study on moisture transfer through firefighters' protective fabrics in radiant heat exposures

2017 ◽  
Vol 21 (4) ◽  
pp. 1665-1671 ◽  
Author(s):  
Meng Chen ◽  
Fanglong Zhu ◽  
Qianqian Feng ◽  
Kejing Li ◽  
Rangtong Liu
Keyword(s):  
Heat Flux ◽  
Moisture Transfer ◽  
Radiant Heat ◽  
Positive Influence ◽  
Heat Radiation ◽  
Radiant Heat Flux ◽  
Thermal Protective Performance ◽  
Protective Fabrics ◽  
Protective Performance ◽  
Radiation Time

The effects of absorbed moisture on thermal protective performance of fire-fighters? clothing materials under radiant heat flux conditions were analyzed in this paper. A thermal protective performance tester and temperature sensor were used to measure the temperature variations for the facecloth side of four kinds of commonly used flame retardant fabrics in several radiant heat exposures, which varied in moisture content. Experimental results showed that, all of the temperature profiles of these four kinds of moistened fabrics under different radiant heat flux conditions presented the same variation trend. The addition of moisture had a positive influence on the thermal protective performance during the constant temperature period when heat radiation time was more than 60 seconds. As the heat radiation time increased beyond 500 seconds, the thermal protective performance of moistened fabrics became worse than that of dried fabrics in general.

scholarly journals Analysis of thermal properties, water vapor resistance and radiant heat transmission through different combinations of firefighter protective clothing

2019 ◽  
Vol 69 (06) ◽  
pp. 458-465
Author(s):  
NAEEM JAWAD ◽  
ADNAN MAZARI ◽  
AKCAGUN ENGIN ◽  
HAVELKA ANTONIN ◽  
KUS ZDENEK
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Flux Density ◽  
Heat Flux Density ◽  
Protective Clothing ◽  
Radiant Heat ◽  
Thermal Protective Performance ◽  
Firefighter Protective Clothing ◽  
Protective Performance ◽  
Different Levels

This experimental work is an effort to seek the possibility of improvement in thermal protective performance of firefighter protective clothing at different levels of heat flux density. Improvement in thermal protective performance means enhancement in the time of exposure against the heat flux, which will provide extra time to firefighters to perform their duties without suffering from severe injuries. Four different multilayer combinations of firefighter protective clothing were investigated. Each combination consists of outer shell, moisture barrier and thermal liner. Aerogel sheet was also employed as a substitute to thermal barrier. Initially, properties like thermal resistance, thermal conductivity, and water vapor resistance of multilayer fabric assemblies were investigated. Later on these combinations were exposed to different levels of radiant heat flux density i.e. at 10, 20 and 30 kW/m2 as per ISO 6942 standard. It was noted that those combinations in which aerogel blanket was used as thermal barrier acquire greater thermal resistance, water vapor resistance and have less transmitted heat flux density values.

scholarly journals Review: Radiation Heat Transfer Through Fire Fighter Protective Clothing

2017 ◽  
Vol 25 (0) ◽  
pp. 65-74 ◽  
Author(s):  
Jawad Naeem ◽  
Adnan Ahmed Mazari ◽  
Antonin Havelka
Keyword(s):  
Heat Flux ◽  
Thermal Insulation ◽  
Protective Clothing ◽  
Radiant Heat ◽  
Fire Fighter ◽  
Radiation Heat ◽  
Thermal Protective Performance ◽  
Firefighter Protective Clothing ◽  
Protective Performance ◽  
Different Levels

A fire fighter garment is multilayer protective clothing with an outer shell, moisture barrier and thermal barrier, respectively. Fire fighters encounter different levels of radiant heat flux while performing their duties. This review study acknowledges the importance and performance of fire fighter protective clothing when subjected to a low level of radiation heat flux as well as the influence of air gaps and their respective position on the thermal insulation behaviour of multilayer protective clothing. Thermal insulation plays a vital role in the thermal comfort and protective performance of fire fighter protective clothing (FFPC). The main emphasis of this study was to analyse the performance of FFPC under different levels of radiant heat flux and how the exposure time of fire fighters can be enhanced before acquiring burn injuries. The preliminary portion of this study deals with the modes of heat transportation within textile fabrics, the mechanism of thermal equilibrium of the human body and the thermal protective performance of firefighter protective clothing. The middle  portion is concerned with thermal insulation and prediction of the physiological load of  FFPC. The last section deals with numerical models of heat transmission through firefighter protective clothing assemblies and possible utility of aerogels and Phase Change Materials  (PCMs) for enhancing the thermal protective performance of FFPC.

scholarly journals Лучистый тепловой поток от возбужденных атомов в высокочастотном ионном двигателе

2021 ◽  
Vol 47 (4) ◽  
pp. 45
Author(s):  
В.К. Абгарян ◽  
М.В. Абгарян ◽  
А.Б. Надирадзе ◽  
В.В. Нигматзянов ◽  
А.А. Семенов
Keyword(s):  
Heat Flux ◽  
Radio Frequency ◽  
Spontaneous Emission ◽  
Discharge Plasma ◽  
Radiant Heat ◽  
Numerical Calculations ◽  
Radiant Heat Flux ◽  
Ion Thrusters

The radiant heat flux coming from the discharge plasma on the surfaces of radio frequency ion thrusters is considered. Spontaneous emission of photons is formed when the excitation of plasma atoms and ions is removed. The distributions of the densities of the heat flux brought by radiation to the surface in the thrusters are calculated. The distributions can be used in numerical calculations of temperatures in thrusters design.

Development of a pyrolysis model for oriented strand board: Part II—Thermal transport parameterization and bench-scale validation

2021 ◽  
pp. 073490412110366
Author(s):  
Junhui Gong ◽  
Hongen Zhou ◽  
Hong Zhu ◽  
Conor G McCoy ◽  
Stanislav I Stoliarov
Keyword(s):  
Heat Flux ◽  
Mass Loss ◽  
Loss Rate ◽  
Oriented Strand Board ◽  
Mass Loss Rate ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Controlled Atmosphere ◽  
Radiant Heat Flux ◽  
Pyrolysis Model

Oriented strand board is a widely used construction material responsible for a substantial portion of the fire load of many buildings. To accurately model oriented strand board fire response, kinetics and thermodynamics of its thermal decomposition and combustion were carefully characterized using milligram-scale testing in part I of this study. In the current work, Controlled Atmosphere Pyrolysis Apparatus II tests were performed on representative gram-sized oriented strand board samples at a range of radiant heat fluxes. An automated inverse analysis of the sample temperature data obtained in these tests was employed to determine the thermal conductivities of the undecomposed oriented strand board and condensed-phase products of its decomposition. A complete pyrolysis model was formulated for this material and used to predict the mass loss rates measured in the Controlled Atmosphere Pyrolysis Apparatus II experiments. These mass loss rate profiles were predicted well with the exception of the second mass loss rate peak observed at 65 kW m−2 of radiant heat flux, which was underpredicted. To further validate the model, cone calorimeter tests were performed on oriented strand board at 25 and 50 kW m−2 of radiant heat flux. The results of these tests, including both mass loss rate and heat release rate profiles, were predicted reasonably well by the model.

Radiant heat flux modelling for wildfires

2020 ◽  
Vol 175 ◽  
pp. 62-80 ◽  
Author(s):  
James E. Hilton ◽  
Justin E. Leonard ◽  
Raphaele Blanchi ◽  
Glenn J. Newnham ◽  
Kimberley Opie ◽  
...  
Keyword(s):  
Heat Flux ◽  
Radiant Heat ◽  
Radiant Heat Flux

Radiant heat flux to external surfaces from escaping and extrusive flashover flames

2003 ◽  
Vol 217 (2) ◽  
pp. 247-256 ◽  
Author(s):  
A Chen ◽  
J Francis
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Current Practice ◽  
Radiant Heat ◽  
Vertical Surface ◽  
Radiant Heat Flux ◽  
Hot Gas

Current practice when predicting safe separation distances between buildings is to assess the radiant hazard posed by flames and hot gas visible across the vent. The vent is treated as a radiating vertical surface with a representative temperature. A method is proposed for calculating the radiant heat flux to external surfaces from hot gas and extrusive flame emerging from a vent in a compartment wall containing post-flashover fire. An experimental study has been made to examine the validity of the method for extrusive flames unaffected by wind.

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