Prediction improvements of ignition characteristics of isolated coal particles with a one-dimensional transient model

2020 ◽  
Author(s):  
Wantao Yang ◽  
Bing Liu ◽  
Hai Zhang ◽  
Yang Zhang ◽  
Yuxin WU ◽  
...  
Keyword(s):  
Transient Model ◽  
One Dimensional ◽  
Coal Particles ◽  
Ignition Characteristics

scholarly journals Transient Model for CW and Pulsed Laser Machining of Ablating/Decomposing Materials—Approximate Analysis

1996 ◽  
Vol 118 (3) ◽  
pp. 774-780 ◽  
Author(s):  
M. F. Modest
Keyword(s):  
Three Dimensional ◽  
Pulsed Laser ◽  
Computer Time ◽  
Single Step ◽  
Laser Source ◽  
Laser Machining ◽  
Transient Model ◽  
One Dimensional ◽  
Cpu Time ◽  
Order Of Magnitude

Approximate, quasi-one-dimensional conduction models have been developed to predict the changing shape of holes, single grooves, or overlapping grooves carved by ablation into a thick solid that is irradiated by a moving laser source. For CW or pulsed laser operation a simple integral method is presented, which predicts shapes and removal rates with an accuracy of a few percent, while requiring one order of magnitude less CPU time than a three-dimensional, numerical solution. For pulsed operation a “full-pulse” model is presented, computing the erosion from an entire pulse in a single step, and reducing computer time by another order of magnitude.

Scaling Laws for Metering the Flow of Gas-Particle Suspensions Through Venturis

1982 ◽  
Vol 104 (1) ◽  
pp. 88-91 ◽  
Author(s):  
J. Lee ◽  
C. T. Crowe
Keyword(s):  
Pressure Drop ◽  
Scaling Laws ◽  
Stokes Number ◽  
Spherical Particles ◽  
Dimensional Model ◽  
Particle Suspensions ◽  
One Dimensional ◽  
Coal Particles ◽  
Scaling Parameters ◽  
Loading Ratio

An experimental investigation was undertaken to determine those scaling parameters applicable to measuring the mass flow rate of gas-particle suspensions through venturis. It was found that Stokes number and the particle/gas loading ratio are the two most important parameters. The results show that pressure drop increases linearly with loading ratio and decreases monotonically with increasing Stokes number. The results also indicate that β-ratio and orientation of venturi do not significantly affect the pressure drop. Data for irregularly shaped pulverized coal particles show higher pressure drop compared with those for spherical particles. A quasi one-dimensional numerical model overpredicts the pressure drop, but a two-dimensional model demonstrates improved agreement.

A Simple Model for Fluid Flow and Particle Motion Inside the Human Larynx

Volume 4 ◽  
2004 ◽  
Author(s):  
C. Ersahin ◽  
I. B. Celik ◽  
O. C. Elci ◽  
I. Yavuz ◽  
J. Li ◽  
...  
Keyword(s):  
Flow Field ◽  
Particle Deposition ◽  
Flow Distribution ◽  
Axial Direction ◽  
Correction Method ◽  
Accurate Solution ◽  
Two Dimensional ◽  
Transient Model ◽  
One Dimensional ◽  
Dimensional Flow

This study aims to develop a simple and quick, but sufficiently accurate solution method for calculating the air flow and tracking the particles in a complex tubular system, where the flow changes its magnitude and direction in a periodic manner. The flow field is assumed to be quasi-two-dimensional and a pressure-correction method is employed to calculate the spetio-temporal variation of the air velocity inside the larynx. Then, the calculated one-dimensional flow distribution is used to reconstruct a two-dimensional flow field is constructed based on the average velocity along the axial direction. The system geometry is taken as close as possible to the actual larynx for an average person with an average glottis opening. For the current study the walls of the larynx is approximated as rigid walls, but different ways to account for compliant walls are proposed within the context of the one-dimensional mode. The 1-D transient model is validated against a two-dimensional model using a verified commercial code. Particles are introduced into the system and tracked during every time fraction of the respiratory cycle. Then, the histograms of particles that come into contact with the larynx are calculated, and regions with a higher probability for particle deposition are identified.

Group Ignition of a Cloud of Coal Particles

1991 ◽  
Vol 113 (3) ◽  
pp. 677-687 ◽  
Author(s):  
W. Ryan ◽  
K. Annamalai
Keyword(s):  
Initial Conditions ◽  
Numerical Study ◽  
Ignition Time ◽  
Volatile Matter ◽  
Combustion Model ◽  
Ambient Conditions ◽  
Experimental Conditions ◽  
Coal Particles ◽  
Group Combustion ◽  
Ignition Characteristics

Ignition of an isolated single coal particle is known to occur either heterogeneously or homogeneously. While single-particle studies may be useful for dilute coal sprays, their application to burners is limited since ignition occurs in the vicinity of the burners where the spray is dense. Rather than considering an isolated particle, one must consider a collection of particles in order to determine the change in ignition characteristics resulting from particle interactions. Thus, group combustion models have been developed essentially to predict the ignition and combustion characteristics of a larger number of interacting drops/particles. This paper presents results of the ignition characteristics of a spherical cloud of uniformly distributed coal particles in quiescent surroundings using a simple group combustion model. For the conditions studied, the results are as follows: (1) Ignition is heterogeneous if the cloud is dilute and homogeneous if the cloud is dense under the same ambient conditions; (2) there is a minimum ignition time for a given set of initial conditions corresponding to a certain cloud denseness; (3) ignition time is less sensitive to the denseness of the cloud at higher ambient temperatures; and (4) decreased proximate volatile matter can result in either increased or decreased ignition time depending on the cloud denseness (ignition mode). Qualitative comparisons to experimental data are given; however, these comparisons should be approached with caution since the experimental conditions and geometries may be vastly different than those used in the numerical study presented here.

scholarly journals Low temperature combustion of organic coal-water fuel droplets containing petrochemicals while soaring in a combustion chamber model

2017 ◽  
Vol 21 (2) ◽  
pp. 1057-1066 ◽  
Author(s):  
Timur Valiullin ◽  
Pavel Strizhak ◽  
Sergey Shevyrev
Keyword(s):  
Combustion Chamber ◽  
Traditional Approach ◽  
Low Temperature Combustion ◽  
Fuel Droplets ◽  
Ignition Delay Times ◽  
Coal Particles ◽  
Integral Characteristics ◽  
Temperature Combustion ◽  
Ignition Characteristics ◽  
Thermocouple Junction

The paper examines the integral characteristics (minimum temperature, ignition delay times) of stable combustion initiation of organic coal-water fuel droplets (initial radius is 0.3-1.5 mm) in the oxidizer flow (the temperature and velocity varied in ranges 500-900 K, 0.5-3 m/s). The main components of organic coal-water fuel were: brown coal particles, filter-cakes obtained in coal processing, waste engine, and turbine oils. The different modes of soaring and ignition of organic coal-water fuel have been established. The conditions have been set under which it is possible to implement the sustainable soaring and ignition of organic coal-water fuel droplets. We have compared the ignition characteristics with those defined in the traditional approach (based on placing the droplets on a low-inertia thermocouple junction into the combustion chamber). The paper shows the scale of the influence of heat sink over the thermocouple junction on ignition inertia. An original technique for releasing organic coal-water fuel droplets to the combustion chamber was proposed and tested. The limitations of this technique and the prospects of experimental results for the optimization of energy equipment operation were also formulated.

Sign in / Sign up

Export Citation Format

Share Document