Radiant, convective and heat release characterization of vegetation fire

Abstract

Fire spread across forest fuel is usually characterized by the rate of spread or the fireline intensity.The determination of the fireline intensity represents an essential aspect for understanding the behaviour of the fire and the involved combustion processes. The heat released during fire spread cannot be a-priori estimated from the fundamental properties of the fuel material and experiments need to be carried out to determine it. This paper presents a global characterization of horizontal fire spread in still air across fuel beds in terms of heat release, rate of spread, flame geometry and radiant and convective fractions. The influence of the fuel load on these main fire properties is investigated.A series of experiments was conducted using a Large Scale Heat Release apparatus. The fire tests were carried out on a combustion table located on a load cell. The fuel consisted in a 2 m long and 1 m wide bed of pine needles. The fireline intensity was accurately estimated by means of oxygen consumption calorimetry and some other methods to assess this quantity were also tested.Combustion efficiency and effective heat of combustion were discussed. The heat fluxes emitted during the fire spread were also investigated. In the studied configuration, radiation was the dominant heat transfer mechanism in the preheating zone; whereas some transfers combining

Combustion of forest litters under slope conditions: Burning rate, heat release rate, convective and radiant fractions for different loads

“…The variations observed among a same fuel configuration can be explained by the difference of the fuel moisture content and in a lesser extent by a slight variation in the experimental protocol (ignition, fuel distribution or fuel bed height). An average of these values is reported in Table 2, where the mean data obtained for no slope [32] are reported to facilitate the comparison between no slope and upslope fire spread experiments. A brief discussion of these results is presented in the following to facilitate the understanding of the phenomena.…”

“…For horizontal fire spread, the data have already been published [32]. Only a short summary of results is performed hereafter.…”

“…A second study was devoted to the evaluation of the fireline intensity based on the mass burning rate [31]. A third work concerned the characterization of fires spreading under no slope condition from a point of view of heat release and radiant and convective fractions [32]. Recently, a preliminary study to this work was conducted to investigate the effect of slope on the rate of spread, the heat release rate and the combustion efficiency [33].…”

Particulate Matter Emission Factors for Biomass Combustion

“…There are more studies on residential burners and laboratory burning simulations because these two are less complex, less expensive, and emissions can be collected more easily than in burning conducted in the field. In addition, variables that could influence the combustion process can be controlled in laboratory burning experiments [47].…”

Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score

“…Due to rising importance of reliable vegetation flammability information numerous researchers worked on quantifying it with studies ranging from field burning experiments [17,18] and burning tables/benches [19][20][21][22] to individual leaf testing [16,23]. In this effort a high number of testing procedures and measured parameters were associated with vegetation flammability.…”