Effects of fuel characteristics on horizontal spread rate and ground surface temperatures of smouldering duff

2020 ◽  
Vol 29 (9) ◽  
pp. 820
Author(s):  
Daniel A. Cowan ◽  
Wesley G. Page ◽  
Bret W. Butler ◽  
David L. Blunck
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Ponderosa Pine ◽  
Ground Surface ◽  
Spread Rate ◽  
Fuel Loading ◽  
Surface Temperatures ◽  
Inorganic Content ◽  
Fuel Characteristics ◽  
Horizontal Spread

The slow-moving flameless burning of wildland fuels (i.e. smouldering) can be difficult to detect and challenging to extinguish. Although previous research involving the smouldering of organic fuels (e.g. cotton, cellulose, peat) has investigated the influence of various fuel characteristics (e.g. moisture content, inorganic content, bulk density) on spread rate and surface temperatures, the smouldering behaviour of other common fuels is not well understood. This study expands on previous research to better understand how fuel characteristics influence the smouldering behaviour of duff from coniferous forests. Specifically, horizontal spread rates (0.5–19.5cm h−1) and ground surface temperatures (258–392°C) were measured on 52 duff samples collected from underneath mature ponderosa pine trees (Pinus ponderosa) from sites in the Pacific Northwest, USA, and evaluated in terms of their moisture content (6–113%), inorganic content (3–42%), bulk density (34–130kgm−3) and fuel depth (3.8–16.3cm). The data suggested that horizontal spread rates decrease when inorganic content, inorganic loading and/or moisture loading of the duff increases. Surface temperatures decrease when inorganic bulk density and/or fuel loading increases. Conversely, surface temperatures decrease when moisture content increases for shallow duff. Higher fuel loading increases the likelihood of smouldering below the surface.

scholarly journals Improving silvicultural practices for Mediterranean forests through fire behaviour modelling using LiDAR-derived canopy fuel characteristics

2019 ◽  
Vol 28 (11) ◽  
pp. 823 ◽  
Author(s):  
Brigite Botequim ◽  
Paulo M. Fernandes ◽  
José G. Borges ◽  
Eduardo González-Ferreiro ◽  
Juan Guerra-Hernández
Keyword(s):  
Bulk Density ◽  
Forest Type ◽  
Classification Tree ◽  
Airborne Lidar ◽  
Fuel Load ◽  
Mediterranean Forests ◽  
Fire Behaviour ◽  
Fuel Loading ◽  
Fuel Characteristics ◽  
Stand Height

Wildfires cause substantial environmental and socioeconomic impacts and threaten many Spanish forested landscapes. We describe how LiDAR-derived canopy fuel characteristics and spatial fire simulation can be integrated with stand metrics to derive models describing fire behaviour. We assessed the potential use of very-low-density airborne LiDAR (light detection and ranging) data to estimate canopy fuel characteristics in south-western Spain Mediterranean forests. Forest type-specific equations were used to estimate canopy fuel attributes, namely stand height, canopy base height, fuel load, bulk density and cover. Regressions explained 61–85, 70–85, 38–96 and 75–95% of the variability in field estimated stand height, canopy fuel load, crown bulk density and canopy base height, respectively. The weakest relationships were found for mixed forests, where fuel loading variability was highest. Potential fire behaviour for typical wildfire conditions was predicted with FlamMap using LiDAR-derived canopy fuel characteristics and custom fuel models. Classification tree analysis was used to identify stand structures in relation to crown fire likelihood and fire suppression difficulty levels. The results of the research are useful for integrating multi-objective fire management decisions and effective fire prevention strategies within forest ecosystem management planning.

scholarly journals Propagation probability and spread rates of self-sustained smouldering fires under controlled moisture content and bulk density conditions

2016 ◽  
Vol 25 (4) ◽  
pp. 456 ◽  
Author(s):  
Nuria Prat-Guitart ◽  
Guillermo Rein ◽  
Rory M. Hadden ◽  
Claire M. Belcher ◽  
Jon M. Yearsley
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Infrared Camera ◽  
Fire Spread ◽  
Spread Rate ◽  
Critical Moisture Content ◽  
Moisture Contents ◽  
Milled Peat ◽  
Critical Moisture ◽  
Smouldering Combustion

The consumption of large areas of peat during wildfires is due to self-sustained smouldering fronts that can remain active for weeks. We studied the effect of peat moisture content and bulk density on the horizontal propagation of smouldering fire in laboratory-scale experiments. We used milled peat with moisture contents between 25 and 250% (mass of water per mass of dry peat) and bulk densities between 50 and 150 kg m–3. An infrared camera monitored ignition, spread and extinction of each smouldering combustion front. Peats with a bulk density below 75 kg m–3 and a moisture content below 150% self-sustained smouldering propagation for more than 12 cm. Peat with a bulk density of 150 kg m–3 could self-sustain smouldering propagation up to a critical moisture content of 115%. A linear model estimated that increasing both moisture content and bulk density significantly reduced the median fire spread rate (which ranged between 1 and 5 cm h–1). Moisture content had a stronger effect size on the spread rate than bulk density. However, the effect of bulk density on spread rate depends upon the moisture content, with the largest effect of bulk density at low moisture contents.

Influences of moisture content, mineral content and bulk density on smouldering combustion of ponderosa pine duff mounds

2011 ◽  
Vol 20 (4) ◽  
pp. 589 ◽  
Author(s):  
Emily C. Garlough ◽  
Christopher R. Keyes
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Mineral Content ◽  
Prescribed Burning ◽  
Klamath Mountains ◽  
Root Mortality ◽  
Decision Support Models ◽  
Smouldering Combustion

When applying prescribed fire to long-unburned but fire-adapted ecosystems, fuels managers require better decision-support models to determine appropriate conditions for achieving desired effects. Prolonged combustion in duff accumulations at the base of large conifers may lead to fine root mortality, cambial injury, enhanced susceptibility to bark beetle attack, and possibly tree death. A laboratory experiment was conducted to investigate how moisture content, mineral content, and bulk density affect smouldering combustion in ponderosa pine (Pinus ponderosa C. Lawson) duff mound fuels of the south-eastern Klamath Mountains, California, USA. Samples were divided between upper and lower duff for a total of 100 burn tests. Moisture content was adjusted to observe the transition through the ignition and spread limit. Bulk density, mineral content and percentage consumption were recorded for each burn. The moisture content threshold for smouldering combustion was 57 and 102% respectively for upper and lower duff. Percentage consumption was inversely related to moisture content for both layers of duff, and partially dependent on mineral content for lower duff. Bulk density was a non-significant factor in either ignition or percentage combustion for the conditions examined here. Results from this study identify important attributes of duff that control the burning process in order to inform prescribed burning decisions.

scholarly journals Downward spread of smouldering peat fire: the role of moisture, density and oxygen supply

2017 ◽  
Vol 26 (11) ◽  
pp. 907 ◽  
Author(s):  
Xinyan Huang ◽  
Guillermo Rein
Keyword(s):  
Bulk Density ◽  
Carbon Emission ◽  
Oxygen Supply ◽  
Emission Flux ◽  
Computational Simulations ◽  
Spread Rate ◽  
One Dimensional ◽  
Peat Fire ◽  
Horizontal Spread

Smouldering fires in peatland are different from the flames in wildland fires. Smouldering peat fire is slow, low-temperature and more persistent, releasing large amounts of smoke into the atmosphere. In this work, we experimentally and computationally investigate the vertical downward spread of smouldering fire in a column of 30cm-tall moss peat under variable moisture content (MC) and bulk density. The measured downward spread rate decreases with depth and wet bulk density, and is ~1cmh−1 equivalent to a carbon emission flux of 200 tonnesday−1ha−1. We observe that downward spread increases as MC increases substantially at least inside the range from 10 to 70%, which is not intuitive and goes against the trend observed for the horizontal spread in the same peat. We also conduct one-dimensional computational simulations to successfully reproduce the experimental observations. The analysis shows that the spread rate increases with MC and decreases with density because smouldering spread is controlled by the oxygen supply. The volume of the porous peat expands when absorbing water, which reduces the density of organic matter and decreases the heat release rate. This shows that the widely assumed conclusion that the spread rate of wildfire decreases with MC is not universal when applied to smouldering fires.

scholarly journals Comparative Study of the Properties of Wood Flour and Wood Pellets Manufactured from Secondary Processing Mill Residues

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2487
Author(s):  
Geeta Pokhrel ◽  
Yousoo Han ◽  
Douglas J. Gardner
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Raw Materials ◽  
Wood Flour ◽  
The United States ◽  
Red Maple ◽  
Wood Pellets ◽  
Secondary Processing ◽  
Material Costs ◽  
Mill Residues

The generation of secondary processing mill residues from wood processing facilities is extensive in the United States. Wood flour can be manufactured utilizing these residues and an important application of wood flour is as a filler in the wood–plastic composites (WPCs). Scientific research on wood flour production from mill residues is limited. One of the greatest costs involved in the supply chain of WPCs manufacturing is the transportation cost. Wood flour, constrained by low bulk densities, is commonly transported by truck trailers without attaining allowable weight limits. Because of this, shipping costs often exceed the material costs, consequently increasing raw material costs for WPC manufacturers and the price of finished products. A bulk density study of wood flour (190–220 kg/m3) and wood pellets (700–750 kg/m3) shows that a tractor-trailer can carry more than three times the weight of pellets compared to flour. Thus, this study focuses on exploring the utilization of mill residues from four wood species in Maine to produce raw materials for manufacturing WPCs. Two types of raw materials for the manufacture of WPCs, i.e., wood flour and wood pellets, were produced and a study of their properties was performed. At the species level, red maple 40-mesh wood flour had the highest bulk density and lowest moisture content. Spruce-fir wood flour particles were the finest (dgw of 0.18 mm). For all species, the 18–40 wood flour mesh size possessed the highest aspect ratio. Similarly, on average, wood pellets manufactured from 40-mesh particles had a lower moisture content, higher bulk density, and better durability than the pellets from unsieved wood flour. Red maple pellets had the lowest moisture content (0.12%) and the highest bulk density (738 kg/m3). The results concluded that the processing of residues into wood flour and then into pellets reduced the moisture content by 76.8% and increased the bulk density by 747%. These material property parameters are an important attempt to provide information that can facilitate the more cost-efficient transport of wood residue feedstocks over longer distances.

scholarly journals Parameters of Trucks and Loads in the Transport of Scots Pine Wood Biomass Depending on the Season and Moisture Content of the Load

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 223
Author(s):  
Grzegorz Trzciński ◽  
Łukasz Tymendorf ◽  
Paweł Kozakiewicz
Keyword(s):  
Moisture Content ◽  
Bulk Density ◽  
Load Capacity ◽  
Wood Chips ◽  
Total Weight ◽  
Wood Biomass ◽  
Four Seasons ◽  
Gross Vehicle Weight ◽  
Bulk Volume ◽  
Average Quantity

Transport of wood biomass is one of the key operations in forestry and in the wood industry. An important part is the transport of shredded wood, where the most common forms are chips and sawdust. The aim of the research was to present the variability of the total weight of trucks (gross vehicle weight, GVW), the weight of the empty trucks (tare), and loads of chips and sawdust in different periods of the year. Changes in specific parameters were analyzed: GVW; tare weight; trailer capacity; use of the trailer load capacity; bulk volume and bulk density of wood biomass loads; solid cubic meter (m3) and weight of 1m3 of the load; and load weight depending on the season, with simultaneous measurements of wood chips and sawdust moisture. More than 250 transports from four seasons of the year were analyzed in the research. It was found that the total weight of trucks (GVW) was at a comparable level, on average from 39.42 to 39.64 Mg with slight differences (with SD 0.29 and 0.39). The weight of empty trucks was 16.15 Mg for chip-bearing trucks and 15.93 Mg for sawdust-bearing trucks (with SD 0.604 and 0.526). The type of wood material has an influence on the transported volume. The average quantity of load in the bulk cubic meter was 64.783 m3 for wood chips (SD 3.127) and 70.465 m3 (SD 2.516) for sawdust. Over 30% differences in the volume of transported wood chips and approximately 18% for sawdust were observed. The use of the loading capacity of the trailer was on average 72.58% (SD 5.567) for the transport of wood chips and 77.42% (SD 3.019) for the transport of sawdust. The sawdust bulk density was from 0.3050 to 0.4265 Mg⋅m−3 for wood chips and 0.3200 to 0.3556 Mg⋅m−3 for sawdust. This parameter is significantly dependent on moisture content, and the determined correlation functions can be used for estimating and predicting bulk density. The abovementioned absolute moisture content of chips and sawdust also depends on the season, which also affects the selected parameters of wood biomass loads.

Measuring the Thermo-Technical Parameters of Autoclaved Aerated Concrete

2016 ◽  
Vol 824 ◽  
pp. 100-107 ◽  
Author(s):  
Alena Struhárová
Keyword(s):  
Thermal Conductivity ◽  
Moisture Content ◽  
Physical Properties ◽  
Bulk Density ◽  
Capillary Absorption ◽  
Measuring Device ◽  
Technical Parameters ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Technical Properties

Bulk density and moisture content are factors that significantly affect the physical properties of autoclaved aerated concrete (AAC) including thermal conductivity and other thermo-technical characteristics. This article shows the results of measurements of compressive strength, capillary absorption, water absorption and porosity of AAC (ash on fluidized fly ash) at different bulk density and also the results of thermal conductivity of AAC at different bulk density and variable moisture content of the material. The thermo-technical properties were measured using the Isomet 2104, a portable measuring device. Acquired results demonstrate dependence of physical properties including thermal conductivity of AAC on bulk density and moisture content. The reliability and accuracy of the method of measuring was also shown.

Characterisation of the fuel and fire environment in southern Ontario’s tallgrass prairie

2015 ◽  
Vol 24 (8) ◽  
pp. 1118 ◽  
Author(s):  
Susan Kidnie ◽  
B. Mike Wotton
Keyword(s):  
Moisture Content ◽  
Tallgrass Prairie ◽  
Prescribed Burning ◽  
Fire Spread ◽  
Fuel Load ◽  
Prairie Restoration ◽  
Prescribed Burn ◽  
Spread Rate ◽  
Prescribed Burns ◽  
Tallgrass Prairie Restoration

Prescribed burning can be an integral part of tallgrass prairie restoration and management. Understanding fire behaviour in this fuel is critical to conducting safe and effective prescribed burns. Our goal was to quantify important physical characteristics of southern Ontario’s tallgrass fuel complex prior to and during prescribed burns and synthesise our findings into useful applications for the prescribed fire community. We found that the average fuel load in tallgrass communities was 0.70 kg m–2. Fuel loads varied from 0.38 to 0.96 kg m–2. Average heat of combustion did not vary by species and was 17 334 kJ kg–1. A moisture content model was developed for fully cured, matted field grass, which was found to successfully predict moisture content of the surface layers of cured tallgrass in spring. We observed 25 head fires in spring-season prescribed burns with spread rates ranging from 4 to 55 m min–1. Flame front residence time averaged 27 s, varying significantly with fuel load but not fire spread rate. A grassland spread rate model from Australia showed the closest agreement with observed spread rates. These results provide prescribed-burn practitioners in Ontario better information to plan and deliver successful burns.

Physical Quality of Turmeric Powder (Curcuma longga Linn) Result of Foam-mat Drying Method Using Microwave

2021 ◽  
pp. 57-65
Author(s):  
Dhinar Patliani ◽  
Dian Purbasari
Keyword(s):  
Grain Size ◽  
Moisture Content ◽  
Water Absorption ◽  
Bulk Density ◽  
Oil Absorption ◽  
Drying Method ◽  
Physical Quality ◽  
Average Grain Size ◽  
Two Factors

Turmeric (Curcuma longa L) in Indonesia is widely known as a herbal medicinal plant, food coloring, and food flavoring. The high water content of turmeric will shorten the storage time and the quality of the ingredients. The need for drying which is the process of removing the moisture content of the material with the aim of prolonging the shelf life. The use of the foam-mat drying method with the addition of adhesives aims to speed up the drying process and maintain the quality of a material. The result of drying turmeric obtained is turmeric powder product. This study used a completely randomized design (CRD) with two factors, namely the variation of the microwave oven power and the composition of the developer agent (ovalet). The research procedure was divided into two stages, namely the manufacture of powder and continued with the measurement of physical quality. The stages of making powder begin with the preparation of raw materials, stripping, size reduction, addition of developer, drying, then grinding. The second stage is measuring physical quality, namely fineness modulus, average grain size, powder moisture content, color, water absorption, oil absorption, and bulk density. The power variations used are 420 watts, 535 watts, and 680 watts, while the composition of the developer is 1%, 2%, and 4%. Data analysis using two-way ANOVA statistical test with two factors that affect the variation of power and composition of the developer (ovalet). FM values ​​ranged from 0.364 – 1.576, D values ​​ranged from 0.005 – 0.0012 mm, final moisture content values ​​ranged from 7.60 – 9.59%, powder moisture content values ​​ranged from 9.47 – 11.43%ww , L values ​​ranged from 61.46 – 65.96, a values ​​ranged from 13.54 – 16.05, b values ​​ranged from 48.21 – 52.42, DSA values ​​ranged from 2.78 – 3.54 ml/ g, DSM values ​​ranged from 1.22 – 1.60 ml/g, and DC values ​​ranged from 0.38 – 0.44 g/cm3. The combination treatment of drying power with developer is influenced by the drying power of the parameters, namely the value of moisture content, fineness modulus, average grain size, brightness level, redness level, yellowness level, oil absorption, water absorption, and bulk density. While the developer affects the finenes modulus, average grain size, yellowness level, and bulk density.

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