Analysis of Fire Characteristics based on the Thickness and Incident Heat Flux of Wood

This study tested the wood used in building interiors; each type had various incident heat fluxes based on their thickness. The combustion characteristics measured were effective heat of combustion, heat release rate peak and arrival time, maximum average rate of heat emission, and piloted ignition temperature. The wood specimens used in the experiment were 4.8 to 18 mm thick. 25, 35, 50, and 60 kW/m² were applied to the incident heat flux that the wood specimens were exposed to. The wood specimens tested were two types of medium-density fiberboard (each with a different density), treated red pine, particle board, and plywood. A comprehensive comparison of different fire characteristics was conducted to analyze the fire patterns corresponding to each type of wood in this way, the risk of fire was studied. The risk of fire was particularly high for particle board. The results of quantifying the fire characteristics of the types of wood studied could function as important input data with which to calculate the fire load of composite combustibles.

Improving Fire Retardancy of Beech Wood by Graphene

The aim of this paper was to improve the fire retardancy of beech wood by graphene. Six fire properties, namely time to onset of ignition, time to onset of glowing, back-darkening time, back-holing time, burnt area and weight loss were measured using a newly developed apparatus with piloted ignition. A set of specimens was treated with nano-wollastonite (NW) for comparison with the results of graphene-treated specimens. Graphene and NW were mixed in a water-based paint and brushed on the front and back surface of specimens. Results demonstrated significant improving effects of graphene on times to onset of ignition and glowing. Moreover, graphene drastically decreased the burnt area. Comparison between graphene- and NW-treated specimens demonstrated the superiority of graphene in all six fire properties measured here. Fire retardancy impact of graphene was attributed to its very low reaction ability with oxygen, as well as its high and low thermal conductivity in in-plane and cross-section directions, respectively. The improved fire-retardancy properties by the addition of graphene in paint implied its effectiveness in hindering the spread of fire in buildings and structures, providing a longer timespan to extinguish a fire, and ultimately reducing the loss of life and property. Based on the improvements in fire properties achieved in graphene-treated specimens, it was concluded that graphene has a great potential to be used as a fire retardant in solid wood species.

Numerical study on the effect of oxygen concentration on the piloted ignition of PMMA in reduced pressure atmospheres

Purpose This study aims to investigate the controlling mechanisms of ambient oxygen and pressure on piloted ignition of solid combustibles under external radiant heating. Design/methodology/approach The numerical simulation method was used to model the influence of ambient oxygen concentration on the piloted ignition of a thermally irradiated solid sample in reduced pressure atmospheres. The solid phase decomposition and gas phase kinetics were solved simultaneously. Findings It was determined that the elevated oxygen atmospheres resulted in a higher flame temperature and a thicker temperature profile over the solid surface. Also, increasing oxygen and reducing pressure had a similar effect in the decrease of the ignition delay time. The shorter ignition time in reduced pressure was mainly because of the decreasing of convective heat losses from the heated solid. As oxygen was reduced, however, ignition occurred later and with a greater mass loss rate because more volatiles of solid fuel at transient ignition were required to sustain a complete reaction under an oxygen-poor condition. Research limitations/implications The results need to be verified with experiments. Practical implications The results could be applied for design and assessment of fire-fighting and fire prevention strategies in reduced pressure atmosphere. Originality/value This paper shows the effect mechanism of ambient oxygen and pressure on piloted ignition of solid combustibles.