Ignition and burning of fibreboard exposed to transient irradiation
| Autor: | Marcos Chaos, Izabella Vermesi, Franz Richter, Guillermo Rein |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Mass flux
Technology Materials science Materials Science Engineering Multidisciplinary 020101 civil engineering Materials Science Multidisciplinary 02 engineering and technology WOOD Civil Engineering 09 Engineering 0201 civil engineering law.invention Experiment Engineering 020401 chemical engineering law General Materials Science Irradiation 0204 chemical engineering Safety Risk Reliability and Quality Flameout Smouldering MODELING PYROLYSIS Science & Technology Mechanics Fire Ignition TIME Ignition system Heat flux Extinction (optical mineralogy) DENSITY HEAT-FLUX WET Transient (oscillation) SPREAD Pyrolysis |
| Popis: | Natural materials like wood are increasingly used in the construction industry, making the understanding of their ignition and burning behaviour in fires crucial. The state of the art of wood flammability is based mostly on studies at constant heating. However, accidental fires are better represented by transient heating. Here, we study the piloted ignition and burning of medium density fibreboard (MDF) under transient irradiation. Experiments are conducted in a Fire Propagation Apparatus under parabolic heat flux pulses with peak irradiation ranging from 30 to 40 kW/m2 and time-to-peak irradiation from 160 to 480 s. The experimental results reveal that the critical conditions for ignition of fibreboard vary over wide ranges: mass flux between 4.9 to 7.4 g/m2-s, surface temperature between 276 to 298°C, and heat flux between 29 to 40 kW/m2. Flameout conditions are studied as well, with observations of when it leads either to extinction or to smouldering combustion. We explored the experiments further with a one-dimensional pyrolysis model in Gpyro and show that predictions are accurate. Assuming a non-uniform density profile (a realistic assumption) improves the predictions in comparison to a uniform density profile by increasing the mass loss rate by 12%, decreasing the temperatures by 45%, and increasing the ignition time by 20 s. These results further support previous findings that a single critical condition for igntion or flameout established under constant irradiation does not hold under transient irradiation which indicates that ignition and extinction theories need improvements. |
| Databáze: | OpenAIRE |
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