scholarly journals Ignition Properties of Thermally Thin Plastics: The Effectiveness of Non-Competitive Char Formation in Reducing Flammability

2002 ◽  
Vol 6 (3) ◽  
pp. 155-181 ◽  
Author(s):  
M. I. Nelson ◽  
J. Brindley ◽  
A. C. Mcintosh
Keyword(s):  
Activation Energy ◽  
Heat Flux ◽  
Steady State ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Critical Mass ◽  
Single Step ◽  
Maximum Heat ◽  
Char Formation

The retardancy effect of char formation upon the flammability of thermally thin products is investigated. The char is formed in a single-step non-competitive scheme and is assumed to be thermally stable. The criterion for ignition is that of a critical mass flux of volatiles from the solid into the gas phase. Both steady-state and transient formulations of the model are considered. In the high activation energy limit the critical heat flux efficiency in the steady-state model is proportional to c/(1−c), where c is the fraction of char formed. In the transient model the efficiency in reducing the maximum heat release rate, average heat release rate, and total heat released is given by c and is independent of activation energy and heat flux. The specific application that we have in mind for our model is piloted ignition in the cone calorimeter.

Retardant Properties of Nanosilica/PTFE Nanoparticals-Reinforced Polypropylene

2014 ◽  
Vol 1004-1005 ◽  
pp. 77-84 ◽  
Author(s):  
Zhen Lu Zhang ◽  
Dong Li Li ◽  
Wen Cai Xu ◽  
Ya Bo Fu ◽  
Rui Juan Liao
Keyword(s):  
Mass Loss ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Thermoplastic Polymer ◽  
Maximum Heat ◽  
Average Mass ◽  
Melting Characteristics

This work reports the flammability properties of Nanocomposites reinforced with silica and PTFE nanoparticles and toughened with an elastomeric ethylene-vinyl acetate (EVA). Through trial and simulation study of the flame retardant thermoplastic polymer and melting characteristics of PP in the combustion process.The study found that modified PP composites have good flame retardancy compared to PP in case of fire relatively.In the study,the melting characteristics of the thermoplastic polymer affected the mass loss rate in the combustion stage.Nanocomposites experienced low plastic mass loss compared with PP, this has been related to pyrolysis mechanism of polymer.In general,The polymers undergoing depolymerization will lead to a rapid volatilization and therefore experienced much less melting.The results showed that:total heat release of nanocomposites was higher than polypropylene, while the average heat release rate, the maximum heat release rate, the average effective heat of combustion, the average mass loss rate, the average specific extinction area, and other indicators were lower than polypropylene.

DNS of Flame-Wall Interaction and Heat Transfer in a Constant Volume Vessel

2010 ◽  
Author(s):  
Akihiko Tsunemi ◽  
Yoshihiro Horiko ◽  
Masayasu Shimura ◽  
Naoya Fukushima ◽  
Seiji Yamamoto ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Burning Velocity ◽  
Fluid Velocity ◽  
Pressure Rise ◽  
Kinetic Mechanism ◽  
Constant Volume ◽  
Wall Interaction

Direct numerical simulations of turbulent hydrogen/air and methane/air premixed flames in a rectangular constant volume vessel have been conducted with considering detailed kinetic mechanism to investigate flame behaviors and heat losses. For the hydrogen cases, since heat release rate increases with pressure rise due to dilatation during combustion in the constant vessel, heat flux on a wall also increases. For the methane cases, the pressure increase does not raise wall heat flux significantly because of the decrescence of heat release rate caused by thermo-chemical reaction near a wall. Pressure waves caused by wall reflection fluctuate flame propagation for the hydrogen flames. Flame displacement speed decreases remarkably at the moment when the pressure wave passes through flame fronts from unburnt side to burnt side. However, the turbulent burning velocity at that time does not decrease because of increases of fluid velocity normal to the flame fronts.

A Comparison of the Behaviour of Spruce Wood and Polyolefins during the Test on the Cone Calorimeter

2013 ◽  
Vol 726-731 ◽  
pp. 4280-4287 ◽  
Author(s):  
Jozef Martinka ◽  
Emília Hroncová ◽  
Tomáš Chrebet ◽  
Karol Balog
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Cone Calorimeter ◽  
Lower Sensitivity ◽  
Average Heat ◽  
Fire Propagation ◽  
Spruce Wood

This article deals with comparison of the behaviour of spruce wood and polyolefins (polyethylene PE and polypropylene PP) during the test on the cone calorimeter. Samples were tested on the cone calorimeter at heat flux of 20 and 40 kW/m2. An evaluation of the behaviour of examined materials was based on the determination of the maximum and the average heat release rate, yield of carbon monoxide (CO), and relative comparison of tendency to fire propagation in a flashover phase. The tendency of materials to fire propagation in the flashover phase was evaluated based on the Pearson ́s correlation, the Spearman ́s correlation and the Kendall ́s correlation coefficient of HRR-CO and CO2-CO. Spruce wood showed better properties in comparison with PE and PP in all evaluated parameters (the maximum and the average heat release rate, the yield of CO, and also the resistance to fire propagation in the flashover phase. Additionally, spruce wood showed significantly lower sensitivity of dependence of the maximum and also the average heat release rate on external heat flux.

Study on the Effects of Heat Flux Levels on Heat Release Rate of Wood

2003 ◽  
Vol 21 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Jingwei Ji ◽  
Liz-Hong Yang ◽  
Xiaojun Chen ◽  
Weicheng Fan
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate

The Increase in the Maximum Heat-Release Rate and Apparent Flame Strength of Opposed-Jet Diffusion Flames Under Impressed Electric Fields

1966 ◽  
Vol 88 (2) ◽  
pp. 157-164
Author(s):  
Bernard J. Rezy ◽  
Robert J. Heinsohn
Keyword(s):  
Electric Field ◽  
Heat Release ◽  
Electric Fields ◽  
Heat Release Rate ◽  
Release Rate ◽  
Field Experiments ◽  
Diffusion Flames ◽  
Maximum Heat ◽  
Jet Diffusion Flames ◽  
Opposed Jet

This paper is concerned with a study of the behavior of opposed-jet diffusion flames subjected to electrostatic fields. A theory for an idealized diffusion flame is presented which predicts an increase in the maximum volumetric heat-release rate when a flame is subjected to an electric field. Experiments reveal that the maximum mass flow into the flame increases with the application of an electric field.

scholarly journals Estimation of Magnitude and Heat Release Rate of Fires Occurring in Historic Buildings-Taking Churches as an Example

2021 ◽  
Vol 13 (16) ◽  
pp. 9193
Author(s):  
Wen-Yao Chang ◽  
Chieh-Hsin Tang ◽  
Ching-Yuan Lin
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Water Mist ◽  
Smoke Detector ◽  
Fire Dynamics ◽  
Historical Building ◽  
Maximum Heat ◽  
Improvement Measures ◽  
Maximum Heat Release

Historical buildings often fail to meet today’s building and fire protection regulations due to their structure and space restrictions. For this reason, if such buildings encounter fire, serious damage will be resulted. The fire of the Notre-Dame Cathedral in Paris (Notre-Dame de Paris) in April 2019 highlights the seriousness of this problem. In this study, the historical building of “Tamsui Church” was selected as an example. The Fire Dynamics Simulator (FDS) was adopted to analyze the scale of damage and possible hazards when the wooden seats in the church are on fire, and improvement measures were proposed to ensure that such buildings can be used under safer conditions. It was found that the existing seat arrangement will cause the spreading of fire, and the maximum heat release rate is 2609.88 kW. The wooden roof frame above the fire source will also start to burn at 402.88 s (6.6 min) after the fire, which will lead to a full-scale fire. To maintain the safety of the historical building, it is necessary to add active firefighting equipment (smoke detector and water mist system).

scholarly journals A Numerical Study on the Effect of Volume Change in a Closed Compartment on Maximum Heat Release Rate

2017 ◽  
Vol 31 (5) ◽  
pp. 19-27
Author(s):  
Hong-Seok Yun ◽  
◽  
Dong-Gun Nam ◽  
Cheol-Hong Hwang ◽  
◽  
...  
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Volume Change ◽  
Release Rate ◽  
Numerical Study ◽  
Maximum Heat ◽  
Maximum Heat Release

scholarly journals Differences between Free and Compartment Burning of Furniture Part 2 Maximum Heat Release Rate and Fire Growth Rate

2007 ◽  
Vol 26 (4) ◽  
pp. 523-527
Author(s):  
Akihide Jo ◽  
Takayuki Orito ◽  
Norichika Kakae ◽  
Yoshifumi Ohmiya ◽  
Kaoru Wakatsuki
Keyword(s):  
Growth Rate ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fire Growth ◽  
Maximum Heat ◽  
Maximum Heat Release

scholarly journals Flammability Characteristics of Green Roofs

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 126
Author(s):  
Nataliia Gerzhova ◽  
Pierre Blanchet ◽  
Christian Dagenais ◽  
Sylvain Ménard ◽  
Jean Côté
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Green Roof ◽  
Fire Risk ◽  
Green Roofs ◽  
Fuel Load ◽  
Growing Media ◽  
Maximum Heat ◽  
Flammability Characteristics

Assessing the fire risk of vegetated roofs includes the determination of their possible contribution to fire. Green roof components such as plants and growing media are organic materials and present a fuel that can catch and support the spread of fire. The flammability characteristics of these components were analyzed and compared to a typical roof covering. Growing media with 15% of organic matter were tested using cone calorimeter apparatus. The fuel load and heat release rate of the growing media were measured in both moist (30%) and dry conditions. It was observed that growing media in a moist condition do not present a fire risk, reaching a maximum heat release rate of 33 kW/m2. For dry substrates, a peak heat release rate of 95 kW/m2 was recorded in the first minute, which then rapidly decreased to 29 kW/m2 in the second minute. Compared to a typical bitumen roof membrane, the green roof showed a better fire performance. The literature data report more severe results for plant behavior, reaching peak heat release rates (HRRs) of 397 kW/m2 for dried and 176 kW/m2 for a green material. However, a rapid decrease in HRR to much lower values occurs in less than 2 min. The results also show that extensive and intensive types of green roofs present 22% and 95% of the additional fire load density when installed on a modified bitumen membrane, 19.7 and 85.8 MJ/m2, respectively.

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