Numerical modeling of flexible polyurethane foam combustion under two ignition modes

A sequence of experiments were conducted in a cone calorimeter to measure the flammability properties of 4050# lubricating oil and 15# hydraulic oil. Meanwhile, the heat release rate, mass loss rate and ignition time were used to investigate the combustion characteristics of the two kinds of oil with varying external radiant heat fluxes. The results show that the 15# oil is easier to be ignited than the 4050# oil and -0.55 power of the ignition time is linear with the external radiant heat flux, which agrees with the previous studies.

Laponite-based inorganic-organic hybrid coating to reduce fire risk of flexible polyurethane foams

Numerical modeling of endothermic pyrolysis and ignition delay of composite materials exposed to an external radiant heat flux

The window glass ignition temperature is one of the main factors that determine the Heat Release Rate (HRR) of passenger rail car. In order to reveal the influence of window glass ignition temperature on the HRR of China Railways High-speed (CRH) passenger rail car, the HRR, ignition temperature and other thermal parameters of the individual materials and component assemblies of the CRH passenger rail car, are measured with the Cone Calorimeter, burning temperature tester and other instruments, as the input parameters of Fire Dynamics Simulator (FDS), and according to the different window glass ignition temperatures ,4 fire scenarios have been designed to obtain the HRR vs. time curves of CRH passenger rail car. The comparison results show that the window glass ignition temperature exerts a significant influence on the HRR of passenger rail car; if the ignition temperature is lower than 415°C, during the fire process the windows near the ignition source will be broken, and the back draft phenomenon will take place, resulting in the extremely high second peak HRR, about 22.6MW; if the ignition temperature is higher than 470°C, during the fire process all the windows will not be broken; and so it is suggested that the window glass ignition temperature in the passenger rail car should be higher than 520°C.

Rates of heat release and related fire parameters for silicones

Analysis of entrainment phenomenon near mechanical exhaust vent and a prediction model for smoke temperature in tunnel fire

Functionalizing Ti3C2Tx for enhancing fire resistance and reducing toxic gases of flexible polyurethane foam composites with reinforced mechanical properties

Synthesis and characterization of MnO2 nanosheets based multilayer coating and applications as a flame retardant for flexible polyurethane foam

Modelling thermal degradation of woody fuel particles

Experimental research on radiation blockage of the fuel vapor and flame in pool fires

Numerical study on the impact of wall thermal inertia on maximum smoke temperature and longitudinal attenuation in long channel fires

Accidental leakage of automobile oils is of great inclination to initiate pool fires in engine compartment, with threats to induce the flashover of other components and flame penetration into the passenger compartment. This paper presents experimental results of the ignition and burning behaviors of a kind of automobile oils (automatic transmission oil) using a cone calorimeter. Measurements of oil temperature, ignition time, mass loss and heat release rate are performed at different external heat fluxes and initial fuel depths. The comparison between experimental and numerical oil temperature evolutions shows that the variations of the ignition time at different experimental conditions depend on the heat dissipation process inside the liquid phase. The steady mass burning rate is nearly independent of initial fuel depth and has a linear relation with external heat fluxes. In addition, the results indicate an increase in peak heat release rate by a large margin initially, followed by a relatively small margin under thicker initial fuel depths, while its variations are proportional to external heat fluxes. Correlations are also developed to determine the peak heat release rate as a function of the initial fuel depth.

EcoSmartFire is a Windows program that models heat damage and piloted ignition of structures from radiant exposure to discrete landscaped tree fires. It calculates the radiant heat transfer from cylindrical shaped fires to the walls and roof of the structure while accounting for radiation shadowing, attenuation, and ground reflections. Tests of litter burn, a 0.6 m diameter fire up to 250 kW heat release under a Heat Release Rate (HRR) hood, with Schmidt-Boelter heat flux sensors in the mockup wall receiving up to 5 kW/m2 radiant flux, in conjunction with Fire Dynamic Simulator (FDS) modeling verified a 30% radiant fraction, but indicated the need for a new empirical model of flame extinction coefficient and radiation temperature as function of fire diameter and heat release rate for use in ecoSmartFire. The radiant fluxes predicted with both ecoSmartFire and FDS agreed with SB heat flux sensors to within a few percent errors during litter fire growth. Further experimental work done with propane flame heating (also with 30% radiant fraction) on vertical redwood boards instrumented with embedded thermocouples validated the predicted temperature response to within 20% error for both models. The final empirical correlation for flame extinction coefficient and temperature is valid for fire diameters between 0.2 and 7.9 m, with heat release rates up to 1000 kW. From the corrected radiant flux the program calculates surface temperatures for a given burn time (typically 30 s) and weather conditions (typically dry, windy, and warm for website application) for field applications of many trees and many structural surfaces. An example was provided for a simple house exposed to 4 burning trees selected on a Google enhanced mapping that showed ignition of a building redwood siding. These temperatures were compared to damage or ignition temperatures with output of the percentage of each cladding surface that is damaged or ignited, which a homeowner or a landscaper can use to optimize vegetation landscaping in conjunction with house exterior cladding selections. The need for such physics-based fire modeling of tree spacing was indicated in NFPA 1144 for home ignitability in wildland urban interface, whereas no other model is known to provide such capability.

Passive houses are becoming more and more popular due to energy efficiency requirements. An important aspect is their airtightness, i.e., they have a very low leakage. The present paper describes a preliminary numerical study on fire-induced pressure variations in a structure that resembles a passive house compartment. The configuration without ventilation system is considered in this paper. The fire source used in the experiment consists of wood cribs that have been simulated in the Fire Dynamics Simulator (FDS), version 6.5.2, as a cube with a prescribed heat release rate (HRR) curve (based on experimental measurements). The grid sensitivity study is conducted by using different mesh cell size and comparing the results of pressure variation. A cell size of 0.1 m is considered sufficient in this preliminary study. The maximum over-pressure obtained without ventilation reached up to 870 Pa in the experiment. Such high over-pressure will definitely hinder the escape of occupants. The structural integrity may also be affected by the over-pressure. Using a constant leakage area, which is the default option, the pressure difference without ventilation rises up to 2027 Pa in the simulation. A good agreement with the experimental data can only be achieved if the simulated leakage area is not kept constant when the room pressure rises. Tuning the leakage pressure exponent in FDS significantly reduces the deviation between the simulation and experimental results. The default setting of reference pressure difference in FDS is used to examine the influence of this parameter on the pressure prediction. When applying the default reference pressure difference, a smaller leakage pressure exponent is needed to reproduce experimental results. Therefore, the reference pressure difference has a certain influence on leakage area and should be set according to the pressure used in determining the reference leakage area during experiments. The overall pressure evolutions are qualitatively well captured in the FDS simulations, as these strongly depend on the fire heat release rate evolution, which was prescribed to match the experimental profile. However, in order to improve the current level of accuracy and address the general validity of the observations made in the present study, more experimental and numerical work need to be carried out.

A computer model was developed to calculate the heat release rate of aircraft cabin panels in the OSU calorimeter based on their thermophysical, thermochemical and geometrical properties. It calculates the temperature profile through the panel as a function of time and uses the measured kinetic constants of the individual materials to deduce the mass loss rate. The mass loss rate is multiplied by the heat of combustion of the volatiles to obtain the heat release rate which would be measured in the Cone calorimeter. This heat release rate is used in an energy balance at the surface of the specimen to calculate the rise in enthalpy of the flue gases in the OSU calorimeter and thus the specimen's heat release rate in that apparatus. The calculated heat release rates are in reasonable agreement with measurements in the Cone and OSU calorimeters.