In-depth temperature and smoke production of charring wood under a constant external heat flux

2021 ◽  
pp. 073490412110578
Author(s):  
Yumi Matsuyama ◽  
Fumiaki Takahashi
Keyword(s):  
Ponderosa Pine ◽  
Strong Correlations ◽  
Fire Dynamics ◽  
Oxidative Pyrolysis ◽  
Temperature Trends ◽  
Gasification Rate ◽  
Time Variations ◽  
Smoke Chamber ◽  
Infrared Gas Analyzer ◽  
External Heat Flux

The combustion characteristics of charring wood have been studied experimentally in a well-ventilated environment of a smoke chamber. A numerical simulation has also been performed for a limited case, with the Fire Dynamics Simulator, to estimate the burning environment. A horizontally placed specimen (ponderosa pine) with a moisture content of 0% or 20% is exposed to a radiant flux (25 kW/m2), with or without flaming ignition. Simultaneous measurements of the specimen’s in-depth temperature and the mass loss determine the charring front (rate) at 300 °C and the gasification rate, respectively. These condensed-phase conditions relate directly to real-time variations of gas-phase quantities: the specific optical density of smoke and the concentrations of toxic gases measured by a Fourier transform infrared gas analyzer. In-depth temperature trends are similar whether the flame exists, whereas the smoke and toxicants’ concentrations are substantially different. After the charring front moves through the specimen, the oxidative pyrolysis continues under the irradiation at high temperatures (up to ∼550 °C). Carbon monoxide and acrolein are produced continuously throughout the test, and the results indicate strong correlations. Although char formation of wood is favorable for fire safety, consequent incomplete combustion produces smoke and toxicants.

Space and time variations of temperature trends in the Arctic stratosphere

2005 ◽  
Vol 67 (15) ◽  
pp. 1388-1394
Author(s):  
Yu.P. Koshelkov ◽  
G.R. Zakharov ◽  
B.M. Kiryushov
Keyword(s):  
The Arctic ◽  
Space And Time ◽  
Temperature Trends ◽  
Time Variations

Effects of elevated CO2 and N fertilization on soil respiration from ponderosa pine (Pinusponderosa) in open-top chambers

1995 ◽  
Vol 25 (8) ◽  
pp. 1243-1251 ◽  
Author(s):  
James M. Vose ◽  
Katherine J. Elliott ◽  
Dale W. Johnson ◽  
Roger F. Walker ◽  
Mark G. Johnson ◽  
...  
Keyword(s):  
Ponderosa Pine ◽  
Root Biomass ◽  
N Fertilization ◽  
Early Spring ◽  
Open Top Chambers ◽  
Coarse Root ◽  
Treatment Variation ◽  
Flow Through ◽  
Sulfate Soils ◽  
Infrared Gas Analyzer

We measured growing season soil CO2 evolution under elevated atmospheric CO2 and soil nitrogen (N) additions. Our objectives were to determine treatment effects, quantify seasonal variation, and determine regulating mechanisms. Elevated CO2 treatments were applied in open-top chambers containing 3-year-old ponderosa pine (Pinusponderosa Dougl. ex Laws.) seedlings. Nitrogen applications were made annually in early spring. The experimental design was a replicated factorial combination of CO2 (ambient, + 175, and + 350 μL•L−1 CO2) and N (0, 10, and 20 g•m−2 N as ammonium sulfate). Soils were irrigated to maintain soil moisture at >25%. Soil CO2 evolution was measured over diurnal periods (20–22 h) in April, June, and October 1993 using a flow-through, infrared gas analyzer measurement system. To examine regulating mechanisms, we linked our results with other studies measuring root biomass with destructive sampling and root studies using minirhizotron techniques. Significantly higher soil CO2 evolution was observed in the elevated CO2 treatments in April and October; N effects were not significant. In October, integrated daily values for CO2 evolution rang ed from 3.73 to 15.68 g CO2•m−2•day−1 for the ambient CO2 + 0 N and 525 μL•L−1 CO2 + 20 g m−2 N, respectively. Soil CO2 flux among treatments was correlated with coarse root biomass (r2 = 0.40; p >F = 0.0380), indicating that at least some of the variation observed among treatments was related to variation in root respiration. Across all sample periods and treatments, there was a significant correlation (r2 = 0.63; p >F = 0.0001) between soil CO2 evolution and percent fungal hyphae observed in minirhizotron tubes. Hence, some of the seasonal and treatment variation was also related to differences in heterotrophic activity.

THE AGING OF AMMONIUM CHLORIDE SMOKES

1951 ◽  
Vol 29 (2) ◽  
pp. 201-216 ◽  
Author(s):  
T. Gillespie ◽  
G. O. Langstroth
Keyword(s):  
Ammonium Chloride ◽  
Satisfactory Agreement ◽  
Direct Measurement ◽  
Mass Concentration ◽  
Particle Number ◽  
Critical Evaluation ◽  
Critical Value ◽  
Wide Range ◽  
Time Variations ◽  
Smoke Chamber

In an extension of earlier work, studies have been made of the time variations in the particle number and size and mass concentration of 'still' ammonium chloride smokes having a wide range of initial mass concentration. Direct measurement of losses to chamber surfaces was an important feature of the experiments since it provided an additional quantity to be satified by theory and permitted a more critical evaluation of the coagulation and loss constants than was previously possible. Satisfactory agreement was found between theory and observation. The dependence of the loss constant on smoke chamber dimensions was found to be in accordance with expectation. The coagulation constant was 4.3 × 10−8 cc. per min. for the least dense, but tended to a larger value for the more dense smokes. A revision of the constants obtained from earlier data indicated that the coagulation constant was little affected by turbulent air motion below a more or less critical value.

Interrelationships of factors of social development are more complex than Life History Theory predicts

2019 ◽  
Vol 42 ◽  
Author(s):  
Boris Kotchoubey
Keyword(s):  
Life History ◽  
Social Development ◽  
Life History Theory ◽  
Strong Correlations ◽  
Behavioral Features

Abstract Life History Theory (LHT) predicts a monotonous relationship between affluence and the rate of innovations and strong correlations within a cluster of behavioral features. Although both predictions can be true in specific cases, they are incorrect in general. Therefore, the author's explanations may be right, but they do not prove LHT and cannot be generalized to other apparently similar processes.

Dielectronic Recombination in the Average-Atom Model

1988 ◽  
Vol 102 ◽  
pp. 215
Author(s):  
R.M. More ◽  
G.B. Zimmerman ◽  
Z. Zinamon
Keyword(s):  
Detailed Balance ◽  
Systematic Errors ◽  
Dielectronic Recombination ◽  
Rate Equations ◽  
Strong Correlations ◽  
Dense Plasmas ◽  
Atom Model ◽  
New Feature ◽  
Average Atom Model ◽  
Attachment Process

Autoionization and dielectronic attachment are usually omitted from rate equations for the non–LTE average–atom model, causing systematic errors in predicted ionization states and electronic populations for atoms in hot dense plasmas produced by laser irradiation of solid targets. We formulate a method by which dielectronic recombination can be included in average–atom calculations without conflict with the principle of detailed balance. The essential new feature in this extended average atom model is a treatment of strong correlations of electron populations induced by the dielectronic attachment process.

Saturn's E, G and F rings: modulated by the plasma sheet

1984 ◽  
Vol 75 ◽  
pp. 597
Author(s):  
E. Grün ◽  
G.E. Morfill ◽  
T.V. Johnson ◽  
G.H. Schwehm
Keyword(s):  
Solar Wind ◽  
Direct Contact ◽  
Transport Processes ◽  
Time Variable ◽  
Dust Particles ◽  
Spatial Diffusion ◽  
Drag Forces ◽  
Orbit Perturbation ◽  
Time Variations ◽  
F Ring

ABSTRACTSaturn's broad E ring, the narrow G ring and the structured and apparently time variable F ring(s), contain many micron and sub-micron sized particles, which make up the “visible” component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. It is suggested that the extent of the E ring and the braided, kinky structure of certain portions of the F rings as well as possible time variations are a result of plasma induced electromagnetic perturbations and drag forces. The G ring, in this scenario, requires some form of shepherding and should be akin to the F ring in structure. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 102to 104years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.

Innovation of Natural Preservation of Mackerel (Rastrelliger kanagurta) Using Coconut Coconut Ashes with Drying Time Variations on Hedonics

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Rika Agustina ◽  
Rita Sunartaty ◽  
Teuku Makmur
Keyword(s):  
Research Design ◽  
Block Design ◽  
Drying Time ◽  
Basic Ingredient ◽  
Randomized Block Design ◽  
Salt Substitute ◽  
Long Time ◽  
Time Variations ◽  
Rastrelliger Kanagurta

Coconut frond ash is one of the wastes from coconut trees which has not been maximally utilized. Coconut frond ash contains MgCl2 and KCl so that it can be used as a salt substitute in the process of preserving fish. In this study coconut frond ash was used as a basic ingredient for making dried mackerel with a long time of drying to storage. The purpose of this study was to determine the effect of drying time on mackerel storage. The research design used was a Randomized Block Design (RCBD) with 2 factors studied. The first factor is the drying time consists of 3 levels, namely P1 = 3 days, P2 = 4 days, P3 = 5 days. The second factor is storage which consists of 3 levels, namely S1 = 30 days, S2 = 60 days, S3 = 90 days. Each treatment was repeated 2 times to obtain 18 experimental units to observed hedonic tests. From the results of the study it can be stated that the treatment has a very significant effect (P≥0.01) on the hedonic test which includes (color, aroma, taste and texture).

Holocene diatom assemblages from Dunderbukhta sediments, West Svalbard

2019 ◽  
pp. 242-245
Author(s):  
Ksenya V. Poleshchuk ◽  
Zinaida V. Pushina ◽  
Sergey R. Verkulich
Keyword(s):  
Environmental Changes ◽  
Ecological Groups ◽  
Diatom Assemblages ◽  
Diatom Analysis ◽  
Diatom Flora ◽  
Sediment Samples ◽  
Ecological Zones ◽  
Middle Holocene ◽  
Temperature Trends

The diatom analysis results of sediment samples from Dunderbukta area (Wedel Jarlsberg Land, West Svalbard) are presented in this paper. The diatom flora consists of four ecological groups, which ratio indicates three ecological zones. These zones show environmental changes of the area in early–middle Holocene that is demonstrating periods of regression and temperature trends.

Sign in / Sign up

Export Citation Format

Share Document