Pyrolysis and ignition delay time of poly(methyl methacrylate) exposed to ramped heat flux

2018 ◽  
Vol 36 (3) ◽  
pp. 147-163
Author(s):  
Chunjie Zhai ◽  
Fei Peng ◽  
Xiaodong Zhou ◽  
Lizhong Yang
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Methyl Methacrylate ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Ignition Time ◽  
Heat Fluxes ◽  
Critical Surface ◽  
Poly Methyl Methacrylate

Usually, the constant heat flux is used in the previous studies of polymeric pyrolysis. However, the ramped heat flux may be more realistic under a fire condition. For further understandings of polymer pyrolysis in the early stage of fire, the influences of ramped heat flux on pyrolysis of poly(methyl methacrylate) were experimentally and theoretically investigated. Linearly and quadratically ramped heat fluxes were controlled by the output power of a radiative heater. Surface temperature, mass loss rate, and ignition time were experimentally obtained to explore the thermochemical stability of poly(methyl methacrylate) under ramped heat fluxes. A one-dimensional model was used to predict the pyrolysis process, where kinetic parameters were evaluated by a genetic algorithm. Finally, ignition criteria including critical surface temperature and critical mass loss rate were revisited. We observed that the two ignition criteria give similar ignition time when the heat flux increases fast.

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.

scholarly journals Determination of Mass Loss Rate and Smoke Generated of Jordanian Hardwood Timber under Different Flaming Combustion and Limited Ventilation Environment

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Heat Flux ◽  
Mass Loss ◽  
Optical Density ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Heat Fluxes ◽  
Wood Products ◽  
Specific Optical Density ◽  
Flaming Combustion ◽  
Natural Wood

Natural wood has been used in structural applications for decades. Smoke from wood fires, additives and wood-protective coatings is a cause of death and serious injury in limited ventilation compartment. Ventilation restrictions in modern day designs complicate the combustion process and increase incomplete combustion products due to a reduction in the amount of oxygen available for fuel oxidation. Jordanian hardwood samples have been examined, tested and evaluated according to their mass loss rates, specific optical density, mass optical density, transmittance, and visibility using qualitative research used to realise the dynamics of fire phenomena. Four types of natural wood were tested under different heat fluxes with different Flaming combustion in a Smoke Density Chamber (SDC). The samples studied were Beech, Oak, Rhamnus, and Abies. The samples have been exposed to 25 and 50 kW/m2 heat fluxes in a limited ventilation compartment. Twelve samples were tested, each with dimensions of 75 x 75 mm and 10 mm thickness. An evaluation of the tested parameters, such as mass loss rate (MLR), specific optical density, transmittance, visibility and mass optical density (MOD have been carried out to determine their effectiveness as predictive parameters. Main results shows Beech has the lower values of specific optical density despite it has higher values of MLR% and MOD compared to other samples studied. Also, the mass loss rate (MLR %) increases with the heat flux even with different flaming conditions. In the opposite, there is a strong dependence for the mass optical density (MOD) on the heat flux and flaming conditions. Key conclusions have been drawn up that could be used in wood products and future works. The main objective of this work is to model the fire dynamic behavior in the pre-fire time. The results of this study can provide the bases for ventilation process and considerations of using natural woods in Jordan for different applications.

Experimental Study on the Factors Concerning the Ignition Time and Mass Loss Rate of Timber

2003 ◽  
Vol 21 (1) ◽  
pp. 29-39 ◽  
Author(s):  
Jing-Yan Zhang ◽  
Li-Zhong Yang ◽  
Zai-Fu Guo ◽  
Zhi-Hua Deng
Keyword(s):  
Experimental Study ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Ignition Time

scholarly journals An experimental study on crib fires in a closed compartment

2017 ◽  
Vol 21 (3) ◽  
pp. 1431-1441 ◽  
Author(s):  
Bhisham Dhurandher ◽  
Ravi Kumar ◽  
Amit Dhiman
Keyword(s):  
Heat Flux ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Flame Temperature ◽  
Great Influence ◽  
Gas Temperature ◽  
Compartment Pressure ◽  
Burning Behavior ◽  
Length Width

An experimental investigation on burning behavior of fire in closed compartments is presented. Fire experiments were performed in a closed compartment of interior dimensions 4 ? 4 ? 4 m (length ? width ? height) with ply board cribs as fire source. The parameters including the gas temperature, mass loss rate, heat flux, flame temperature, and compartment pressure were measured during the experiments. Experimental results indicated that the providing sudden ventilation to the closed compartment had great influence on the behavior of fire. The mass loss rate of the burning crib increased by 150% due to sudden ventilation which results in the increase in heat release rate by 198 kW. From the perspective of total heat flux, compartment pressure, and gas temperatures closed compartment with sudden ventilation were more hazardous.

Critical heat flux and mass loss rate for extinction of flaming combustion of timber

2017 ◽  
Vol 91 ◽  
pp. 252-258 ◽  
Author(s):  
Richard Emberley ◽  
Tam Do ◽  
Jessica Yim ◽  
José L. Torero
Keyword(s):  
Heat Flux ◽  
Mass Loss ◽  
Critical Heat Flux ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Flaming Combustion

scholarly journals Research on combustion performance of PVC foam in fire propagation apparatus

2019 ◽  
Vol 118 ◽  
pp. 01034
Author(s):  
Guoan Zhang ◽  
Lingling Wei ◽  
Junhao Gao ◽  
Tingting Qiu ◽  
Rongnan Yuan ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
High Speed ◽  
Mass Loss Rate ◽  
Ignition Time ◽  
Combustion Characteristics ◽  
Heat Fluxes ◽  
Fire Propagation

Polyvinyl chloride foam (PVC) is widely used as the wall materials of the high-speed train. The combustion characteristics of PVC foam under the heat fluxes of 20-60 kW/m2 are investigated by fire Propagation Apparatus (FPA). The results show that the ignition time of PVC foam decreases with the increase of heat flux. The peak of heat release rate, mass loss rate and smoke production rate increase with the increase of heat flux. Under the condition of 60 kW/m2, the heat release rate has the peak value of 109.10 kW/m2. The research on the combustion characteristics of the PVC can be used to analyse the fire risk of the train and guide the formulation of safety measures.

Experimental Study on Ignition and Combustion Characteristics of Fibre-Reinforced Phenolic Composite

2016 ◽  
Vol 707 ◽  
pp. 13-22
Author(s):  
Rui Yu Chen ◽  
Shou Xiang Lu ◽  
Chang Hai Li ◽  
Siu Ming Lo
Keyword(s):  
Carbon Dioxide ◽  
Heat Flux ◽  
Carbon Monoxide ◽  
Mass Loss ◽  
Peak Concentration ◽  
Mass Loss Rate ◽  
Ignition Time ◽  
Combustion Characteristics ◽  
Ignition And Combustion ◽  
Phenolic Composite

The ignition and combustion characteristics of the fibre-reinforced phenolic composite were studied experimentally employing cone calorimeter. Various parameters, including the ignition time, the mass loss and mass loss rate (MLR), the heat release rate (HRR) and the concentration of the carbon dioxide and carbon monoxide were measured and presented. Linear correlations of the transformed ignition time (1/tig)0.55 and 1/tig, the first and second peak MLR, the average MLR and the peak HRR with the heat flux were demonstrated. Based upon the correlations and theoretical analyses, flammability properties including the critical heat flux (CHF) and the minimum heat flux, the ignition temperature, the heat of gasification and the heat of combustion were calculated. The specimen with the thickness of 3 mm was prone to be thermally thin material. The peak concentration of the carbon dioxide increased with the heat flux. However, the peak concentration of the carbon monoxide declined with an increase in the applied heat flux.

Influence of model assumptions on charring polymer decomposition in the cone calorimeter

2018 ◽  
Vol 36 (3) ◽  
pp. 181-201 ◽  
Author(s):  
Luc Murer ◽  
Sarah Chatenet ◽  
Gaelle Fontaine ◽  
Serge Bourbigot ◽  
Olivier Authier
Keyword(s):  
Heat Flux ◽  
Mass Loss ◽  
Cone Calorimeter ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Constant Volume ◽  
Radiative Heating ◽  
Gaseous Products ◽  
Time To Extinction ◽  
Polymer Decomposition

This article addresses the one-dimensional modeling of a charring polymer decomposition in the cone calorimeter used to reproduce at bench scale the radiative heating from a fire. The rate-controlling phenomena are first discussed in a preliminary analysis of dimensionless numbers. Then, the role of three critical assumptions is highlighted by simulations: (1) transport of the gaseous products within the material or instantaneous release of gaseous products, (2) volume variation or constant volume, and (3) absorption of applied heat flux at the exposed face or through the thickness. Their influence in thermally thick regime is shown in particular on mass loss rate and time to extinction. Under the conditions tested, the influence of internal transport by convection on mass loss rate and time to extinction is minor. The assumption of constant volume appears to have a moderate influence on the mass loss rate and time to extinction. Variations of optical properties affect the numerical results by an increase of the maximum peak of mass loss rate and a decrease of time to extinction. Finally, the effects of applied heat flux and initial material thickness on the mass loss rate and time to extinction are important. With a higher heat flux or a smaller thickness, the decomposition is earlier, faster, and more intense.

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