scholarly journals Ignition of Fuel Beds by Cigarettes: A Conceptual Model to Assess Fuel Bed Moisture Content and Wind Velocity Effect on the Ignition Time and Probability

Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 35
Author(s):  
Domingos Xavier Viegas ◽  
Ricardo Oliveira ◽  
Miguel Almeida ◽  
Donghyun Kim
Keyword(s):  
Moisture Content ◽  
Flow Velocity ◽  
Conceptual Model ◽  
Ignition Time ◽  
Ambient Conditions ◽  
Ambient Flow ◽  
Model Predictions ◽  
Time To Ignition ◽  
Velocity Effect ◽  
Extinction Model

A conceptual model based on the balance of energy in a system composed of a burning cigarette, ambient flow and a porous fuel bed is proposed to study the burning of a single cigarette and the process of fuel bed dehydration, pyrolysis and its eventual ignition or combustion extinction. Model predictions of time to ignition and of the probability of ignition as a function of fuel bed moisture content and ambient flow velocity are compared with results obtained in laboratory ignition tests of straw fuel beds for various ambient conditions. According to this study, the main parameters influencing the models developed are the fuel bed and tobacco moisture content, as well as the flow velocity.

Experimental study of moisture content effects on horizontal flame spread over thin cotton fabric

2018 ◽  
Vol 89 (15) ◽  
pp. 3189-3200 ◽  
Author(s):  
Yunji Gao ◽  
Guoqing Zhu ◽  
Hui Zhu ◽  
Weiguang An ◽  
Yu Xia
Keyword(s):  
Moisture Content ◽  
Cotton Fabric ◽  
Flame Spread ◽  
Extreme Values ◽  
Ignition Time ◽  
Convective Heat Transfer Coefficient ◽  
Flame Height ◽  
Spread Rate ◽  
Untreated Cotton ◽  
Flame Spread Rate

In this paper, moisture content effects on horizontal flame spread were experimentally investigated using 0.245 mm thick, 28 cm tall and 28 cm wide untreated cotton fabric sheets with various moisture contents varying from 0 to 34%. The pyrolysis spread rates, flame heights and ignition times were obtained and analyzed. The corresponding results are as follows: as moisture content increases, the flame height and spread rate first increase and then decrease. In contrast, the ignition time shows an opposite trend with moisture content. The extreme values are observed in cases of 2% moisture content samples. Moreover, the flame spread rate in the warp direction is larger than that in the weft direction. For horizontal flame spread, the moisture content has the effect of consuming part of the heat feedback, which can play a role in reducing the flame spread rate; simultaneously, the moisture content can enlarge flame size and increase the convective heat transfer coefficient, thereby resulting in an increase in flame spread rate. The non-monotonous trend in pyrolysis spread rate is the result of competition between these effects.

scholarly journals Characteristics of Woody Cutting Waste Briquette with Paper Waste Pulp as Binder

2020 ◽  
Vol 190 ◽  
pp. 00030
Author(s):  
Qurrotin Ayunina Maulida Okta Arifianti ◽  
Azmi Alvian Gabriel ◽  
Syarif Hidayatulloh ◽  
Kuntum Khoiro Ummatin
Keyword(s):  
Moisture Content ◽  
Ignition Time ◽  
Combustion Process ◽  
Calorific Value ◽  
Volatile Matter ◽  
Proximate Analysis ◽  
Hydraulic Press ◽  
Combustion Characteristic ◽  
Paper Waste ◽  
Iron Mold

The current research aimed to increase the calorific value of woody cutting waste briquette with paper waste pulp as binder. There were three different binder variation used in this study, they are 5 %, 10 %, and 15 %. To create a briquette, a cylindrical iron mold with diameter of 3.5 cm and height of 3 cm and a hydraulic press with 2 t power were applied. The physical characteristics of the combination woody waste briquette and paper waste pulp, such as moisture content, ash content, volatile matter and carbon fix were examined using proximate analysis. The calorific value of briquetted fuel was tested by bomb calorimeter. The combustion test was performed to determine the combustion characteristic of briquettes, for example initial ignition time, temperature distribution, and combustion process duration. The general result shows that the calorific value of briquette stood in the range of 4 876 kCal kg–1 to 4 993 kCal kg–1. The maximum moisture content of briquette was 5.32 %. The longest burning time was 105 min.

scholarly journals Processing of Wild Sunflower with Different Moisture Contents into Solid Bio Fuel

2021 ◽  
pp. 1-9
Author(s):  
Fabie T. Dummapi ◽  
Jacqueline I. Liniasan ◽  
Marvin T. Valentin ◽  
Milagros B. Onalan ◽  
Leonardo D. Dumalhin ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Moisture Content ◽  
Physical Properties ◽  
Ignition Time ◽  
Volume Density ◽  
Ash Content ◽  
Burning Time ◽  
Wild Sunflower ◽  
Average Mass ◽  
Moisture Contents

Wild sunflower with moisture contents of 16%, 12% and 8% was densified without the addition of binding agent. The physical properties of the formed briquettes such as mass, dimensions, volume, density and shattering resistance were evaluated. Thermal properties like ignition time, burning time, ash content, and thermal fuel efficiency by means of boiling test were also evaluated. Wild Sunflower stems were gathered and shredded using locally fabricated biomass shredder available at the Research Office of Benguet State University, and were processed into the desired size and moisture contents. Right after the briquetting operation, the physical properties of the briquette were measured and then stored in a zip bag for 24 hours. After the storage, same measurement was conducted. Results show that the influence of moisture contents on the average mass, dimension, shattering resistance, volume and density was statistically insignificant. The wild sunflower with moisture content of 16% had the highest shattering resistance of 88.85%. Furthermore, the influence of moisture content on the thermal properties like ignition time, burning time and ash content are statistically insignificant. Among the moisture contents, the fastest ignition time of 43.75 sec with longest burning time was recorded under 12%. Ash content was also lowest at 12%.

scholarly journals Chilled Aeration to Control Pests and Maintain Grain Quality during Summer Storage of Wheat in the North Central Region of Kansas

2019 ◽  
Vol 35 (4) ◽  
pp. 657-688
Author(s):  
Alejandro Morales-Quiros ◽  
Carlos Campabadal ◽  
Dirk E. Maier ◽  
Sonia M.N. Lazzari ◽  
Flavio A. Lazzari ◽  
...  
Keyword(s):  
Moisture Content ◽  
Grain Quality ◽  
Insect Pest ◽  
Reproduction Rate ◽  
Ambient Conditions ◽  
Flour Quality ◽  
The North ◽  
Chilling Temperatures ◽  
Steel Silos ◽  
Grain Temperature

Abstract.Chilled aeration allows grain to be cooled, independent of ambient conditions, to “safe” temperatures at which insects, fungi, and spoilage development are reduced to a minimum. The objective of this research was to evaluate the advantages of using grain chilling to preserve the quality of grain and reduce post-harvest losses caused by insects and fungi, compared to the conventional aeration and storage strategies used during summer storage in central Kansas. The research trials were developed at a farmer’s cooperative in central Kansas in 2015 and 2016 on low-moisture wheat harvested during the summer of 2015 and 2016, respectively, and stored in two 1,350 metric ton (t) steel silos in which one was chilled and the other was used as a control managed by the cooperative. Temperature of the grain inside each silo was monitored with temperature cables. Variables evaluated were: moisture content (MC), grain and flour quality, insect-pest development and reproduction rate, insect fragments per 500 g of grain, and fungi presence. In 2015, the chilling treatment reduced the grain temperature from 28°C to 17°C in approximately 175 h, while in 2016 it took 245 h to reach about the same temperature with an initial grain temperature of 39°C. Grain temperatures below 25°C were not achieved in the control silo during the summer using ambient aeration. Minimum variation of MC was observed in the Chilled silo while ambient aeration reduced the moisture content by 0.5%. Reproduction rates of the red flour beetle and lesser grain borer were significantly reduced by chilling temperatures lower than 17°C. Lower temperatures also reduced insect populations detected in probe traps and insect damaged kernels. Insect fragments and fungi presence had no significant increase throughout the trials in either of the silos. No clear evidence of flour quality being better preserved at lower temperatures was detected. The energy cost of running the grain chiller was between 0.26-0.32 $/t higher than ambient aeration. Keywords: Ambient aeration, Grain chilling, Grain quality, Stored-product fungi, Stored-product insects, Summer storage, Wheat.

scholarly journals Experimental and Mathematical Tools to Predict Droplet Size and Velocity Distribution for a Two-Fluid Nozzle

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 231
Author(s):  
Sadegh Poozesh ◽  
Nelson K. Akafuah ◽  
Heather R. Campbell ◽  
Faezeh Bashiri ◽  
Kozo Saito
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Droplet Size Distribution ◽  
Integral Form ◽  
Accurate Estimation ◽  
Ambient Conditions ◽  
Computational Tools ◽  
Model Predictions ◽  
Model Fluids ◽  
Two Fluid

Despite progress in laser-based and computational tools, an accessible model that relies on fundamentals and offers a reasonably accurate estimation of droplet size and velocity is lacking, primarily due to entangled complex breakup mechanisms. Therefore, this study aims at using the integral form of the conservation equations to create a system of equations by solving which, the far-field secondary atomization can be analyzed through predicting droplet size and velocity distributions of the involved phases. To validate the model predictions, experiments are conducted at ambient conditions using water, methanol, and acetone as model fluids with varying formulation properties, such as density, viscosity, and surface tension. Droplet size distribution and velocity are measured with laser diffraction and a high-speed camera, respectively. Finally, an attempt is made to utilize non-scaled parameters to characterize the atomization process, useful for extrapolating the sensitivity analysis to other scales. The merit of this model lies in its simplicity for use in process control and optimization.

scholarly journals Modeling Indoor Relative Humidity and Wood Moisture Content as a Proxy for Wooden Home Fire Risk

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 5050 ◽  
Author(s):  
Torgrim Log
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Moisture Sorption ◽  
Fire Risk ◽  
Cold Weather ◽  
Indoor Climate ◽  
Ambient Conditions ◽  
Wood Panel ◽  
Fire Disaster ◽  
Strong Winds

Severe wooden home conflagrations have previously been linked to the combination of very dry indoor climate in inhabited buildings during winter time, resulting in rapid fire development and strong winds spreading the fire to neighboring structures. Knowledge about how ambient conditions increase the fire risk associated with dry indoor conditions is, however, lacking. In the present work, the moisture content of indoor wooden home wall panels was modeled based on ambient temperature and relative humidity recorded at meteorological stations as the climatic boundary conditions. The model comprises an air change rate based on ambient and indoor (22 °C) temperatures, indoor moisture sources and wood panel moisture sorption processes; it was tested on four selected homes in Norway during the winter of 2015/2016. The results were compared to values recorded by indoor relative humidity sensors in the homes, which ranged from naturally ventilated early 1900s homes to a modern home with balanced ventilation. The modeled indoor relative humidity levels during cold weather agreed well with recorded values to within 3% relative humidity (RH) root mean square deviation, and thus provided reliable information about expected wood panel moisture content. This information was used to assess historic single home fire risk represented by an estimated time to flashover during the studied period. Based on the modelling, it can be concluded that three days in Haugesund, Norway, in January 2016 were associated with very high conflagration risk due to dry indoor wooden materials and strong winds. In the future, the presented methodology may possibly be based on weather forecasts to predict increased conflagration risk a few days ahead. This could then enable proactive emergency responses for improved fire disaster risk management.

Analysis of underwater thruster model with ambient flow velocity using CFD

2013 ◽  
Vol 6 (3) ◽  
pp. 163-168
Author(s):  
Han-Kyo Chung ◽  
Jinhyun Kim
Keyword(s):  
Flow Velocity ◽  
Ambient Flow

Storing Peanuts in Trailer-Sized Containers1

1996 ◽  
Vol 23 (1) ◽  
pp. 43-45
Author(s):  
F. S. Wright ◽  
S. H. Deck ◽  
J. S. Cundiff
Keyword(s):  
Moisture Content ◽  
Arachis Hypogaea ◽  
The Other ◽  
Mold Growth ◽  
Ambient Conditions ◽  
Foreign Material ◽  
Handling System ◽  
Quality Degradation ◽  
Arachis Hypogaea L ◽  
The Hours

Abstract A containerized handling system is envisioned whereby peanuts (Arachis hypogaea L.) are placed in containers in the field and remain in these containers until they are shelled. This would reduce the foreign material, loose shelled kernels, and pod damage that result from handling as peanuts move through the buying point and into storage. Two naturally ventilated containers (half-trailer size) were stored in 1993. One container had a shed cover and the other an A-frame cover. In 1994 four containers were stored, two with shed covers and two with A-frame covers. One shed and one A-frame had a 1.7 m3/min fan that operated daily between the hours of 10 a.m. and 6 p.m. Top layer peanuts were at 12% moisture content at the beginning of storage in 1993 and ranged 10 to 11% moisture content after 16 wk. In 1994, the peanuts were over-dried and top layer peanuts entered storage at 6% moisture content. After 12 wk, moisture content was 7%. No mold growth or quality degradation was observed either year. The results indicated top layer peanuts absorb or desorb very little moisture when peanut moisture content is in the range of 6 to 12% at the beginning of storage. Containers were successful for storage at the ambient conditions in Tidewater, VA during 1993 and 1994.

Experimental Study on Heat and Mass Transfer of Millet in a Fixed Furnace

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Conghui Gu ◽  
Zhulin Yuan ◽  
Yaming Yan ◽  
Dengshan Luo ◽  
Bin Li ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Flow Velocity ◽  
Heat And Mass Transfer ◽  
Wall Temperature ◽  
Air Flow ◽  
Significant Drop ◽  
Drying Characteristics ◽  
Series Of Experiments ◽  
Air Flow Velocity

Abstract A series of experiments on the heat and mass transfer of millet particles are conducted in order to demonstrate the effects on drying characteristics of particles in this work. Experimental results illustrate that thermal conductivity between particles is significantly influenced by temperature and moisture content of millet particles. The temperature of particles in axial and radial direction increases because of the increase of inner wall temperature and decreases with the increase of air flow velocity. Moreover, the moisture content of particles near the inner wall has experienced a significant drop with the increase of inner wall temperature. As a consequence, the increase of air flow velocity results from the decrease of particles moisture content and drying rate of particles increases due to the increase of air flow velocity. Furthermore, the accumulated height of particles has barely influenced on the drying characteristics of millet particles.

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