scholarly journals Effect of Natural Aging on Oak Wood Fire Resistance

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2059
Author(s):  
Martin Zachar ◽  
Iveta Čabalová ◽  
Danica Kačíková ◽  
Tereza Jurczyková
Keyword(s):  
Activation Energy ◽  
Chemical Composition ◽  
Burning Rate ◽  
Fire Resistance ◽  
Ignition Temperature ◽  
Lignin Content ◽  
Spontaneous Ignition ◽  
Oak Wood ◽  
Elementary Analysis ◽  
Flame Ignition

The paper deals with the assessment of the age of oak wood (0, 10, 40, 80 and 120 years) on its fire resistance. Chemical composition of wood (extractives, cellulose, holocellulose, lignin) was determined by wet chemistry methods and elementary analysis was performed according to ISO standards. From the fire-technical properties, the flame ignition and the spontaneous ignition temperature (including calculated activation energy) and mass burning rate were evaluated. The lignin content does not change, the content of extractives and cellulose is higher and the content of holocellulose decreases with the higher age of wood. The elementary analysis shows the lowest proportion content of nitrogen, sulfur, phosphor and the highest content of carbon in the oldest wood. Values of flame ignition and spontaneous ignition temperature for individual samples were very similar. The activation energy ranged from 42.4 kJ·mol−1 (120-year-old) to 50.7 kJ·mol−1 (40-year-old), and the burning rate varied from 0.2992%·s−1 (80-year-old) to 0.4965%·s−1 (10-year-old). The difference among the values of spontaneous ignition activation energy is clear evidence of higher resistance to initiation of older wood (40- and 80-year-old) in comparison with the younger oak wood (0- and 10-year-old). The oldest sample is the least thermally resistant due to the different chemical composition compared to the younger wood.

Activation Energy of Teak and Oak Wood Spontaneous Ignition

2014 ◽  
Vol 1001 ◽  
pp. 262-266 ◽  
Author(s):  
Jozef Martinka ◽  
Tomáš Chrebet
Keyword(s):  
Activation Energy ◽  
Ignition Temperature ◽  
Ignition Time ◽  
Test Procedure ◽  
Thermodynamic Temperature ◽  
Tectona Grandis ◽  
Spontaneous Ignition ◽  
Oak Wood ◽  
Teak Wood ◽  
The Difference

This article deals with evaluation of the spontaneous-ignition activation energy of the Teak wood (Tectona grandis L.f.) and the Oak wood (Quercus robur L.). Spontaneous-ignition activation energy was calculated from dependence of ignition time to inverse value of thermodynamic temperature. This dependence was measured in the hot-air (Setchkin) furnace according to ISO 871:2006 standard by modification of the test procedure. The modifications of test procedure lay in measurement of the time to ignition of sample loaded by various temperatures (at spontaneous ignition temperature and at temperatures above this value). The mass of investigated samples was (3 ± 0.05) g and its moisture contents was 0 wt %. The dimensions of sample was (20 x 20) mm, the third dimension was adjust to achieve required mass of sample. The activation energy of spontaneous-ignition for Teak wood was 78.23 kJ.mol-1 and for Oak wood was 59.24 kJ.mol-1. The spontaneous-ignition temperature for Teak wood was 460 °C and for Oak wood was 450 °C. Thus despite slight difference between spontaneous-ignition temperatures of investigated materials the difference between activation energy of spontaneous-ignition is significant.

scholarly journals Study on the Risk Assessment of Spontaneous Ignition and of Perilla Oil Cakes Associated Activation Energy

2021 ◽  
Vol 35 (2) ◽  
pp. 1-8
Author(s):  
Sung-Ho Byun ◽  
Yu-Jung Choi ◽  
Jae-Hoon Jeong ◽  
Jae-Wook Choi
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Ignition Temperature ◽  
Ignition Delay Time ◽  
Fire Risk ◽  
Spontaneous Ignition ◽  
Maximum Temperature ◽  
Perilla Oil ◽  
Oil Cakes ◽  
Critical Ignition

Perilla oil cakes are the residues of oil pressing processes, and used as fertilizers, feedstuff, food, etc. However, according to recent reports, perilla oil cakes often ignite spontaneously due to scorching heat, particularly in rice mills, general mills, and oil mills where large amounts of perilla oil cakes are stored. Thus, in this study, we attempted to elucidate the risk of spontaneous ignition of perilla oil cakes. For this purpose, thermogravimetry/differential thermal analysis (TG-DTA) was performed to identify thermal properties like weight reduction and heat generation, and spontaneous ignition was conducted for sample vessels of different thicknesses. The results showed that the ignition temperature of perilla oil cakes was 115 ℃ for the small (20 cm × 20 cm × 3 cm) vessel. The apparent activation energy associated with the critical ignition temperature was 60.74 kJ/mol. The ignition delay time and the time to reach maximum temperature were both found to increase with increasing vessel thickness. It was concluded that proper protection against heat must be in place because fire risk increases and spontaneous ignition can occur when large amounts of perilla oil cakes are accumulated.

Application of thermal ignition theory to determination of spontaneous ignition temperature limits of hydrocarbon-oxygen mixtures

1977 ◽  
Vol 355 (1681) ◽  
pp. 153-165 ◽  
Keyword(s):  
Heat Transfer ◽  
Activation Energy ◽  
Rayleigh Number ◽  
Ignition Temperature ◽  
Spontaneous Ignition ◽  
Thermal Ignition ◽  
Temperature Changes ◽  
Critical Boundary ◽  
Rate Of Heat Release

Measurements of temperature changes in decane-air mixtures near the critical boundary for spontaneous ignition indicate that, under conditions where heat transfer in the reacting gases takes place solely by conduction, temperature limits for ignition are in excellent agreement with predictions according to the conductive theory of thermal ignition. It is shown, however, that, by use of a derived relation between the dimensionless rate of heat release and the Rayleigh number, thermal ignition theory can be extended to the prediction of temperature limits under conditions where considerable convective heat transfer also takes place. Furthermore, the overall activation energy of the initial reactions involved in the oxidation of other alkanes has been shown to be a useful parameter for the prediction of the corresponding spontaneous ignition temperature limits.

scholarly journals Influence of the precursor chemical composition on heavy metal adsorption properties of hemp (Cannabis Sativa) fibers based biocarbon

2017 ◽  
Vol 82 (12) ◽  
pp. 1417-1431 ◽  
Author(s):  
Marija Vukcevic ◽  
Biljana Pejic ◽  
Ivana Pajic-Lijakovic ◽  
Ana Kalijadis ◽  
Mirjana Kostic ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Chemical Composition ◽  
Surface Area ◽  
Active Sites ◽  
Cannabis Sativa ◽  
Lignin Content ◽  
Area Measurement ◽  
Bet Surface Area ◽  
Homogeneous Distribution ◽  
Hemp Fibers

Waste hemp (Cannabis sativa) fibers were used as sustainable and renewable raw materials for production of low-cost biocarbon sorbent for heavy metals removal. Carbon precursors of different chemical composition were obtained by oxidative and alkaline treatments of hemp fibers. Influence of lignocellulosic precursor chemical composition on hemp fibers-based biocarbon (HFB) characteristics was examined by BET surface area measurement, scanning electron microscopy and mass titration. It was found that lignin content and polymorphic transformation of cellulose increase the SBET of microporous HFBs, while hemicelluloses induce more homogeneous distribution of adsorption active sites. Heavy metal ions adsorption onto HFBs is primarily influenced by the amount of surface oxygen groups, while specific surface area plays a secondary role. Equilibrium data obtained for lead ions adsorption were analyzed by different nonlinear adsorption isotherms, and the best fitting model was chosen using standard deviation and Akaike information criterion (AICC). The maximum adsorption capacities of HFBs ranged from 103.1 to 116.3 mg Pb/g. Thermodynamic parameters showed that Pb2+ adsorption onto HFBs is a spontaneous and complex endothermic process, suggesting the coexistence of physisorption and chemisorption mechanisms.

scholarly journals Effects of the Harvest Stage of Maize Hybrids on the Chemical Composition of Plant Fractions: An Analysis of the Different Types of Silage

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 786
Author(s):  
Egon Henrique Horst ◽  
Valter Harry Bumbieris Junior ◽  
Mikael Neumann ◽  
Secundino López
Keyword(s):  
Chemical Composition ◽  
Lignin Content ◽  
Neutral Detergent Fiber ◽  
Maturity Stage ◽  
Important Distinction ◽  
Maize Hybrids ◽  
Acid Detergent Lignin ◽  
Whole Plant ◽  
Grain Formation ◽  
Early Harvest

The chemical composition of plant components of three maize hybrids harvested at the beginning of six reproductive stages of maturity was compared. The hybrids evaluated included Maximus VIP3, Defender VIP and Feroz VIP, which were evaluated at each of following stages: R1 (grain formation), R2 (milky grain), R3 (pasty grain), R4 (floury grain), R5 (hard grain) and R6 (ripe grain). The advancement in maturation was linearly related to the crude protein (CP) content of the stem, whole plant, and leaves, and there was a difference among the hybrids. Between R4 and R5 stages, Maximus and Defender presented the highest CP contents for husk (6.58 and 5.42% for Maximus; 5.54 and 5.17% for Defender). The neutral detergent fiber (NDF) of the leaves showed a quadratic relationship with the advancement of maturation but did not differ among the hybrids. For all the hybrids, the NDF content in the husk and cobs increased linearly during the reproductive stages (>77 and 78%, respectively, for the three hybrids in R6). Defender had the lowest NDF content of the cob in R3. The acid detergent lignin contents did not differ among stages in the stems, and showed a linear decrease throughout the whole plant, though the contents did not differ among the hybrids. Due to the differences observed, recommendations for harvest based on the maturity stage for each hybrid should be taken into consideration. There seems to be no important distinction among hybrids for harvesting and use of straw. Despite the reduction in grain yield, an early harvest for earlage or snaplage can provide lower lignin content in husk and cob, as well as higher protein content in the husk, favoring the nutritional value of the vegetative fraction (husk and/or cob).

scholarly journals The nutritional quality of feedstuffs used in dairy goat nutrition in Vojvodina

2019 ◽  
Vol 35 (2) ◽  
pp. 163-178
Author(s):  
Snezana Paskas ◽  
Jelena Miocinovic ◽  
Branislav Vejnovic ◽  
Zsolt Becskei
Keyword(s):  
Chemical Composition ◽  
Medicago Sativa ◽  
Protein Content ◽  
Nutritional Quality ◽  
Lignin Content ◽  
Dairy Goat ◽  
Crude Fibre ◽  
Significant Difference ◽  
Medicago Sativa L

The study was to conduct to evaluate the chemical composition and nutritive values of feedstuffs (forages and concentrate mixtures) used for dairy goats nutrition in Vojvodina. Samples were collected from six farms, including one organic farm. The results showed that the relative feed values of analyzed forages were in the range of good, medium to lower quality. Average protein content from lowest to highest for investigated forages was: corn silage (Zea Mays) (65.37-82.57g kg??DM), alfalfa haylage (Medicago sativa L.) (159.99-184.17g kg??DM), pasture (185.30g kg?? DM), and alfalfa hay (Medicago sativa L.) (167.48-203.60g kg??DM). The non-fibre carbohydrates and protein content most varied in organic hay samples (cv: 29.25% and 19.09%, respectively). Generally, feedstuffs used in organic nutrition, including organic concentrate, were of lower nutritional quality and moreover contained higher amounts of crude fibre and lignin. Especially, a high source of variation was observed in investigated concentrate mixtures for the crude protein content (p<0.0001), ranged from 135.32 to 209.87g kg??DM. Corn silages also varied substantially in their chemical composition and significant difference (p<0.05) was observed in regard to acid detergent fibre (ADF) and lignin content (ranged: ADF: 242.20-319.24g kg??DM; ADL: 27.98-52.54g kg??DM, respectively). Furthermore, pasture contained the most soluble materials during May and June and their content was related inversely to crude fibre amount. This survey highlights that investigated farms still pay insufficient attention to the quality of the feedstuff. For the development of intensive goat farming, greater emphasis should be placed on using higher quality feedstuffs, as well, standards for feed quality must be considered and established.

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