Transient gas and particle emissions from smouldering combustion of peat

Hu, Yuqi; Christensen, Eirik G.; Restuccia, Francesco

doi:10.1016/j.proci.2018.06.008

Cited by 46 publications

(91 citation statements)

References 13 publications

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“…Converse to lateral spread, in-depth spread rate increases with MC, up to tripling the spread rate from 0 -140% MC ( Figure 8a). This agrees with results previously reported in the literature by Huang and Rein [28]. However, in-depth spread rates measured here are 2 to 3 times larger than Huang and Rein [23] at a depth of 5 cm.…”

Section: In-depth Spread Ratesupporting

confidence: 93%

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Influence of soil conditions on the multidimensional spread of smouldering combustion in shallow layers

Christensen

Fernandez-Añez

Rein

2020

Combustion and Flame

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Smouldering peatland fires are capable of burning vast amounts of organic soils, resulting in the release of greenhouse gases into the atmosphere, as well as a significant deterioration of air quality causing major regional crises known as haze events. Fundamental understanding of smouldering fire spread is essential for the development of mitigating technologies. In this paper, we have systematically conducted 63 experiments studying the individual and combined influence of two key factors affecting multidimensional smouldering spread in organic soils: moisture content (MC) and inorganic content (IC). Both lateral and in-depth smouldering spread were investigated using a novel shallow reactor. This shallow depth allows a greater number of experiments to be performed in a short period of time compared to deeper samples. Lateral spread was found to decrease linearly with moisture content (R 2 > 90%); while in-depth spread rate increased linearly up to 300% from moisture contents of 0% to 140%. Increased inorganic content linearly decreased the lateral spread rate but had little influence on in-depth spread in drier samples. Interestingly, in wetter samples, in-depth spread was in fact sensitive to inorganic content. A novel approach combining lateral and in-depth spread rates as vector components, revealed that the global spread is independent of moisture content, with an average spread rate of 8.7 and 8.4 cm/h for 2.5 and 40% IC, with changes in direction according to moisture content; going in-depth for wet soils, and laterally for dry soils. Similarly, increasing the IC encouraged downward spread for wet samples. We also report observations of a bifurcation of lateral spread, where spread would locally extinguish where the in-depth spread was greater than the lateral spread. These findings provide previously unknown insight into the relationship between lateral and in-depth spread in smouldering fires, ultimately improving the fundamental understanding of such fires.

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Section: In-depth Spread Ratesupporting

confidence: 93%

“…20 W were supplied to the sample through the coil for 30 min. This is a greater flux than used in literature, which is typically 100 W for 30 min across an 18 cm helical coil [21,27,28,30]. For this reason, the ignition protocol can be considered a reliable and strong ignition source, sufficient to ignite all samples studied.…”

Section: Methodsmentioning

confidence: 99%

Influence of soil conditions on the multidimensional spread of smouldering combustion in shallow layers

Christensen

Fernandez-Añez

Rein

2020

Combustion and Flame

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“…These practices can lead to widespread peat fires during prolonged dry spells, such as El Nino, and are often the cause of dramatic haze episodes, such as those regularly recorded in Indonesia (Page et al, 2002;Huijnen et al, 2016). Additionally, smouldering wildfire produces more toxic compounds per kilogram of fuel compounds than flaming Hu et al, 2019), and due to the low temperature causing weakly buoyant plumes, smoke can be blown into nearby cities, causing severe degradation of air quality and significant adverse health effects (World Health Organization, 2006;Hu et al, 2018). In 2015, the haze episode caused an economic loss of 16 billion US$ to Indonesia, not including economic losses to the other affected countries, such as Malaysia, Singapore, and Brunei Darussalam 1 .…”

Section: Characteristics Smouldering Flamingmentioning

confidence: 99%

Review of the Transition From Smouldering to Flaming Combustion in Wildfires

et al. 2019

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Wildfires are uncontrolled combustion events occurring in the natural environment (forest, grassland, or peatland). The frequency and size of these fires are expected to increase globally due to changes in climate, land use, and population movements, posing a significant threat to people, property, resources, and the environment. Wildfires can be broadly divided into two types: smouldering (heterogeneous combustion) and flaming (homogeneous combustion). Both are important in wildfires, and despite being fundamentally different, one can lead to the other. The smouldering-to-flaming (StF) transition is a quick initiation of homogeneous gas-phase ignition preceded by smouldering combustion, and is considered a threat because the following sudden increase in spread rate, power, and hazard. StF transition needs sufficient oxygen supply, heat generation, and pyrolysis gases. The unpredictable nature of the StF transition, both temporally and spatially, poses a challenge in wildfire prevention and mitigation. For example, a flaming fire may rekindle through the StF transition of an undetected smouldering fire or glowing embers. The current understanding of the mechanisms leading to the transition is poor and mostly limited to experiments with samples smaller than 1.2 m. Broadly, the literature has identified the two variables that govern this transition, i.e., oxygen supply and heat flux. Wind has competing effects by increasing the oxygen supply, but simultaneously increasing cooling. The permeability of a fuel and its ability to remain consolidated during burning has also been found to influence the transition. Permeability controls oxygen penetration into the fuel, and consolidation allows the formation of internal pores where StF can take place. Considering the high complexity of the StF transition problem, more studies are needed on different types of fuel, especially on wildland fuels because most studied materials are synthetic polymers. This paper synthesises the research, presents the various StF transition characteristics already in the literature, and identifies specific topics in need of further research.

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“…Peat land is a source of atmospheric methane (CH4) and a source of carbon (C) in the form of dissolved organic carbon (DOC) [19], [20]. Greater use of peat moss has been shown to damage the environment [21], [22]. Peat moss extraction is a significant source of greenhouse gases as well as a user of large amounts of land for its growth [23], [24].…”

Section: The Effects Of Watering Rates Using the Drip Irrigation Methods On The Root Mass Growth Of Bird's Nest Ferns 1 Introductionmentioning

confidence: 99%

The Effects of Watering Rates Using the Drip Irrigation Method on the Root Mass Growth of Bird’s Nest Ferns

Pimsuwan¹

2020

GEOMATE

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The increasing demands of gardeners have made peat moss a popular option as a planting material. However, the price of peat moss has increased recently. Therefore, alternative substances for use as a planting material need to be studied. The root of the bird's nest fern offers a cheaper, easier to produce and more readily available source for a planting material than peat moss. The objective of this research was to increase root mass growth by using drip irrigation. With an experimental design using CRD, two-year old bird's nest ferns with root mass sizes of 5 inches were watered by means of a drip irrigation method at rates of 200, 400, 600, 800 and 1,000 ml every 3 days. The data measured were root mass height, root mass diameter, leaf length, leaf width and canopy width. The data were analyzed by ANOVA and the differences between the means of treatment were compared by DMRT. The research found that the ferns which received water at a rate of 800 ml produced a root mass height of 11.06 cm and a root mass diameter of 11.93 cm. They were significantly different (p<0.05). The ferns which received water at a rate of 200 ml produced a leaf length of 29.52cm and a leaf width of 9.55 cm. The amount of water causes fern growth to significantly different (p<0.01). The 800 ml rate of drip irrigation also produced the largest canopy width of 48.12 cm.

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Transient gas and particle emissions from smouldering combustion of peat

Cited by 46 publications

References 13 publications

Influence of soil conditions on the multidimensional spread of smouldering combustion in shallow layers

Influence of soil conditions on the multidimensional spread of smouldering combustion in shallow layers

Review of the Transition From Smouldering to Flaming Combustion in Wildfires

The Effects of Watering Rates Using the Drip Irrigation Method on the Root Mass Growth of Bird’s Nest Ferns

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