scholarly journals Inversion for Fire Heat-Release Rate Using Heat Flux Measurements

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Andrew J. Kurzawski ◽  
Ofodike A. Ezekoye
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fire Hazard ◽  
Computational Cost ◽  
Inversion Algorithm ◽  
Fire Dynamics ◽  
Oxygen Consumption Calorimetry ◽  
Flux Measurements

Abstract In fire hazard calculations, knowledge of the heat-release rate (HRR) of a burning item is imperative. Typically, room-scale calorimetry is conducted to determine the HRRs of common combustible items. However, this process can be prohibitively expensive. In this work, a method is proposed to invert for the HRR of a single item burning in a room using transient heat flux measurements at the walls and ceiling near the item. The primary device used to measure heat flux is the directional flame thermometer (DFT). The utility of the inverse method is explored on both synthetically generated and experimental data using two so-called forward models in the inversion algorithm: fire dynamics simulator (FDS) and the consolidated model of fire and smoke transport (CFAST). The fires in this work have peak HRRs ranging from 200 kW to 400 kW. It was found that FDS outperformed CFAST as a forward model at the expense of increased computational cost and that the error in the inverse reconstruction of a 400 kW steady fire was on par with room-scale oxygen consumption calorimetry.

scholarly journals Fire Behavior of Thermally Thin Materials in Cone Calorimeter

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1297
Author(s):  
Marouane El El Gazi ◽  
Rodolphe Sonnier ◽  
Stéphane Giraud ◽  
Marcos Batistella ◽  
Shantanu Basak ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Cone Calorimeter ◽  
Fire Hazard ◽  
Heat Of Combustion ◽  
Sample Weight ◽  
Effective Heat ◽  
Effective Heat Of Combustion

In this study, a representative set of thermally thin materials including various lignocellulosic and synthetic fabrics, dense wood, and polypropylene sheets were tested using a cone calorimeter at different heat fluxes. Time-to-ignition, critical heat flux, and peak of heat release rate (pHRR) were the main parameters considered. It appears that the flammability is firstly monitored by the sample weight. Especially, while the burning rate of thermally-thin materials does never reach a steady state in cone calorimeter, their pHRR appears to be mainly driven by the fire load (i.e., the product of sample weight and effective heat of combustion) with no or negligible influence of textile structure. A simple phenomenological model was proposed to calculate the pHRR taking into account only three parameters, namely heat flux, sample weight, and effective heat of combustion. The model allows predicting easily the peak of heat release rate, which is often considered as the main single property informing about the fire hazard. It also allows drawing some conclusions about the flame retardant strategies to reduce the pHRR.

scholarly journals Detailed Derivations of Formulas for Heat Release Rate Calculations Revisited: A Pedagogical and Systematic Approach

2019 ◽  
Vol 124 ◽  
Author(s):  
Jiann C. Yang
Keyword(s):  
Oxygen Consumption ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Chemical Engineering ◽  
Chemical Species ◽  
Flow Process ◽  
Generalized Framework ◽  
Oxygen Consumption Calorimetry ◽  
Engineering Practices

The derivations of the formulas for heat release rate calculations are revisited based on the oxygen consumption principle. A systematic, structured, and pedagogical approach to formulate the problem and derive the generalized formulas with fewer assumptions is used. The operation of oxygen consumption calorimetry is treated as a chemical flow process, the problem is formulated in matrix notation, and the associated material balances using the tie component concept commonly used in chemical engineering practices are solved. The derivation procedure described is intuitive and easy to follow. Inclusion of other chemical species in the measurements and calculations can be easily implemented using the generalized framework developed here.

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

Heat release rate: The single most important variable in fire hazard

1992 ◽  
Vol 18 (3) ◽  
pp. 255-272 ◽  
Author(s):  
Vytenis Babrauskas ◽  
Richard D. Peacock
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Fire Hazard ◽  
Important Variable ◽  
In Fire

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 INVESTIGATION THE FIRE HAZARD OF PLYWOODS USING A CONE CALORIMETER

Wood Research ◽  
2021 ◽  
Vol 66 (6) ◽  
pp. 933-942
Author(s):  
ZHIGANG WU ◽  
XUE DENG ◽  
LIFEN LI ◽  
LIPING YU ◽  
JIE CHEN ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Cone Calorimeter ◽  
High Efficiency ◽  
Fire Hazard ◽  
Mass Loss Rate ◽  
Fire Retardant ◽  
Safety Level

A high-efficiency fire retardant composition was prepared with dicyandiamide, phosphoric acid, boric acid, borax, urea and magnesium sulfate and it was used to process veneers which were then to prepare the plywood. Meanwhile, heat release and smoke release from combustion of plywood were tested by a cone calorimeter, including heat release rate, mass loss rate, CO yield, CO2 yield and oxygen consumption. Results showed that the plywood with this fire retardant treatment had the better flame-retardant performance and smoke suppression effect as well as the stronger char-forming capability compared to plywood without fire retardant treatment. The average heat release rate, total heat release, average effective heat of combustion, total smoke release, CO yield and oxygen consumption of the plywood with fire retardant treatment were decreased by 63.72%, 91.94%, 53.70%, 76.81%, 84.99% and 91.86%, respectively. Moreover, the fire growth index of plywood treated by fire retardant was relatively low (3.454 kW·m-2·s-1) and it took longer time to reach the peak heat release rate, accompanied with slow fire spreading. The fire performance index was relatively high (0.136 s·m2·kW-1) and it took longer time to be ignited, thus leaving a long time for escaping at fire accidents. The fire hazard of plywood with fire retardant treatment was low, and its safety level was high.

Fire Growth in Standard Tests and Railcars

2018 ◽  
Author(s):  
Charles Luo ◽  
Soroush Yazdani ◽  
Brian Y. Lattimer
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Large Scale ◽  
Growth Conditions ◽  
Standard Test ◽  
Fire Growth ◽  
Gas Temperature ◽  
Fire Dynamics ◽  
Room Corner Test

Large scale flammability performance of interior finish used on railcars has been evaluated in previous studies using the NFPA 286 room corner fire test, which has a cross-section similar to a railcar. In some studies, the wall containing the door was removed to account for the shorter length of the room compared to the railcar length. The focus of this study is to assess whether the NFPA 286 standard room-corner test with a door represents conditions that developed inside a railcar during a fire. Fire Dynamics Simulator (FDS) was used to model the fire growth in a NFPA 286 standard room-corner test with a door, NFPA 286 room without the wall containing the door, and railcar geometry with a single door open. All three cases had the same exposure fire in a corner and the same lining material. In predictions of the NFPA 286 room-corner test with a door, gas temperature, heat release rate, and time to flashover agreed well with available NFPA 286 standard test data. The simulation results of fire growth inside a railcar with one side door open produced similar conditions and fire growth compared with the standard NFPA 286 room with a door. For simulations on the NFPA 286 room with the wall containing the door removed, it was found that removal of the wall with the door resulted in non-conservative fire growth conditions with the gas temperature and heat release rate under-estimated compared to the standard NFPA 286 room with a door. These simulations indicate that the standard NFPA 286 room-corner test with a door is representative of conditions that would develop inside of a railcar.

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