Secondary Fire Induced by Mine Methane Explosions

2012 ◽  
Vol 518-523 ◽  
pp. 1325-1333
Author(s):  
Yu Long Duan
Keyword(s):  
Numerical Simulation ◽  
Oxygen Concentration ◽  
Conservation Of Energy ◽  
Diffusion Velocity ◽  
Combustion Limit ◽  
Great Danger

The mechanism of fire induced by methane explosions was studied to know about the great danger of induced fire. Firstly, from the point of heat ignition to study it, then the especial heat environment after explosions was studied. Lastly, from the point of characteristics of gas separated from fuel to judge whether fire to be induced. The part of heat ignition was based on conservation of energy. And the special heat environment was studied by using CFD software Fluent to do some numerical simulation. As to gas separated from fuel, mainly from three aspects to discuss it: yields of gas and relating conversion, diffusion velocity, minimum combustion supporting oxygen concentration. And the research shows that, if the gas separated out from fuel could diffuse to satisfy the minimum combustion limit before the temperature of environment reduce to its fire induced temperature, and there is enough oxygen, sub-fire could be induced. This research could provide some technique support to prevent and cure such kind of accident, and has great significance.

Numerical simulation and application of micro-nano bubble releaser for irrigation

2021 ◽  
Vol 11 (6) ◽  
pp. 1007-1015
Author(s):  
Yubin Zhang ◽  
Zhengying Wei ◽  
Jing Xu ◽  
Huafeng Wang ◽  
Huomei Zhu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Oxygen Concentration ◽  
Structural Parameters ◽  
Average Particle Size ◽  
Utilization Rate ◽  
Average Particle ◽  
Low Oxygen ◽  
Oxygen Utilization ◽  
Bubble Generation ◽  
Release Device

In oxygenated irrigation, there are problems of large oxygenated bubble particles, low oxygen concentration in water, and mismatch with current irrigation systems. In this paper, numerical simulation of micro-nano bubble releaser was carried out and the development of oxygenated irrigation equipment was studied. The release method of dissolved gas was selected to generate micro-nano bubbles after comparing different micro-nano bubble generation methods. The basic structure of the core-component releaser of generating micro-nano bubbles was initially determined. Effects of different structures of the release device on water aeration performance were studied by CFD analysis method. An optimal structure of the releaser was determined with orthogonal experiments based on a single factor experiment. The structural parameters included a throat of a 3 mm diameter, a 2 mm thick turbulent cavity, a six-degree exit angle, and two outlets. Optimal inlet and outlet pressure difference of the release device was 0.3 MPa. The bubble had an average particle size of 373.1 nm as measured. The release device was fabricated by 3D printing technology and the micro-nano bubble aeration irrigation device was developed. The system function test was carried out. Under the standard state, the performance parameters of the micro-nano bubble aerator included the maximum oxygen concentration of 11.4 mg/L, a total oxygen transfer coefficient of 0.4139 min-1, 0.0114 kg/h oxygenation capacity, and 60.81% oxygen utilization rate. The device had advantages of a high oxygen-increasing efficiency and a small volume, making it quite prospective in the field of oxygenated irrigation.

Dissolved Oxygen Convection and Diffusion Numerical Simulation of Water and Air Mixture Flow in Circular Pipe

2011 ◽  
Vol 383-390 ◽  
pp. 6651-6656
Author(s):  
Ze Gao Yin ◽  
Xian Wei Cao ◽  
Dong Sheng Cheng ◽  
Le Wang
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Pipe Flow ◽  
Concentration Distribution ◽  
Dissolved Oxygen Concentration ◽  
Mixture Flow ◽  
Velocity Pressure ◽  
And Diffusion

In Fluent, the 3-D RNG k–ε mathematical model is employed to compute water and air mixture pipe flow. The dissolved oxygen convectionaεnd diffusion model is established to simulate the concentration distribution of dissolved oxygen with user defined scalar method. Velocity, pressure and dissolved oxygen concentration are computed. Then, dissolved oxygen concentration and pressure are compared with the data of physical model, and they agree with each other approximately, showing it is valid and reliable to compute the mixture pipe flow and dissolved oxygen concentration with the model .Furthermore, under a specific condition, velocity, pressure and dissolved oxygen concentration of water and air mixture pipe flow are computed and their characteristics are analyzed.

Numerical simulation of effects of cusp magnetic field on oxygen concentration of 300 mm CZ-Si

Rare Metals ◽  
2012 ◽  
Vol 31 (5) ◽  
pp. 494-499 ◽  
Author(s):  
Yongtao Wang ◽  
Wenting Xu ◽  
Xiaolin Dai ◽  
Qinghua Xiao ◽  
Shujun Deng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Oxygen Concentration ◽  
Cusp Magnetic Field

Numerical Simulation of Flow and Thermal Behavior of Radiating Gas Flow in Plane Solar Heaters

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Mohammad Foruzan Nia ◽  
Seyyed Abdolreza Gandjalikhan Nassab ◽  
Amir Babak Ansari
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Thermal Efficiency ◽  
Gas Flow ◽  
Simple Algorithm ◽  
Outlet Section ◽  
Gas Temperature ◽  
Conservation Of Energy ◽  
Solid Media ◽  
Solar Heater

Abstract In this paper, the radiating effect of working gas on thermal performance of plane solar heaters is investigated. In the numerical simulation of gas flow, the continuity and momentum equations are solved using the finite volume method (FVM) in which the pressure–velocity coupling is handled by the SIMPLE algorithm. To obtain the temperature distribution, the conservation of energy in the fluid and solid media is solved by the finite difference technique. The distribution of radiating intensity which is needed to calculate the radiative term in the gas energy equation is computed by numerical solution of the radiative transfer equation (RTE) using the discrete ordinate method (DOM). The effect of the variation of different parameters on the predicted thermal efficiency of plane solar heater is investigated by presenting the performance plot. The obtained results show that when the gas medium participates in radiation, the gas temperature at the outlet section increases considerably, especially at high optical thicknesses. Also, the temperature difference between the absorber plate and flowing gas decreases, and more uniform temperature distribution takes place inside the solar heater, which leads to a considerable increase in thermal efficiency. Comparison between the present numerical results and the experimental data published in literature shows good agreement.

scholarly journals Исследование взаимосвязи механических напряжений, оптической неоднородности и концентрации кислорода в кристаллах германия

2022 ◽  
Vol 56 (3) ◽  
pp. 285
Author(s):  
А.Ф. Шиманский ◽  
Е.Д. Кравцова ◽  
Т.В. Кулаковская ◽  
А.П. Григорович ◽  
С.А. Копыткова ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Structural Analysis ◽  
Mechanical Stress ◽  
Oxygen Concentration ◽  
Radial Distribution ◽  
Thermoelastic Stress ◽  
Czochralski Method ◽  
Optical Inhomogeneity ◽  
X Ray

The radial distribution of mechanical stress, optical inhomogeneity and oxygen concentration in Sb-doped germanium crystals grown by the Czochralski method with diameter of 200 mm and resistivity from 10.5 to 18.5 Ω·cm were studied. It was found that residual stress calculated from the data of X-ray structural analysis correlates with results of numerical simulation of thermoelastic stress and interrelates with optical inhomogeneity and concentration of oxygen presented in the atomically dispersed state in germanium.

scholarly journals Analysis of the Effect of a Vertical Magnetic Field on Melt Convection and Oxygen Transport During Directional Solidification of Multi-Crystalline Silicon by Numerical Simulation

Crystals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 8
Author(s):  
Botao Song ◽  
Yufeng Luo ◽  
Senlin Rao ◽  
Fayun Zhang ◽  
Yun Hu
Keyword(s):  
Magnetic Field ◽  
Numerical Simulation ◽  
Directional Solidification ◽  
Oxygen Concentration ◽  
Crystalline Silicon ◽  
Vertical Magnetic Field ◽  
Silicon Melt ◽  
Average Oxygen Concentration ◽  
Melt Convection ◽  
The Magnetic Field

Melt convection during the directional solidification process of multi-crystalline silicon plays a critical role in the transport of impurities. The utilization of a static magnetic field is an effective way to control the melt convection pattern. Studying the effect of the Lorentz force induced by the vertical magnetic field (VMF) on the melt convection of silicon in detail is beneficial to optimize the magnetic field parameters in the production process. Based on the numerical simulation method of multi-physics coupling, this paper explores the effects of different VMF intensities on the convection of silicon melt and the transport of oxygen in the melt during the directional solidification of polycrystalline silicon. The results show that in the first 125 minutes of the crystallization stage, the melt convection velocity is affected significantly by the magnetic field intensities. When different convection circulations are present in the silicon melt, the upper circulation easily transports oxygen to the furnace atmosphere, and the subjacent circulation easily lead to the retention and accumulation of oxygen. Enhancing the VMF intensity to a certain extent can reduce the size of the oxygen retention region in the silicon melt, and the time of the first disappearance of the subjacent circulation near the sidewall of the crucible is shortened. Then the average oxygen concentration in the silicon melt can be reduced. However, a larger vertical magnetic field intensity can result in greater average oxygen concentration in the oxygen retention region.

Numerical Simulation and Study of the Effect between "Three-Zone" Distribution in Goaf and Air Volume in Working Face

2014 ◽  
Vol 962-965 ◽  
pp. 1158-1164
Author(s):  
Yan Zhao ◽  
Yan Chuan Li
Keyword(s):  
Numerical Simulation ◽  
Oxygen Concentration ◽  
Large Scale ◽  
Oxidation Zone ◽  
Small Scale ◽  
Air Leakage ◽  
Exponential Relationship ◽  
Air Volume ◽  
Working Face ◽  
Result Show

We conducted a numerical simulation of oxygen concentration in goaf using Comsol4.3b when the air volume in working face ranges from 500 m3/min to 900m3/min. The result show that with the air volume increasing the oxygen concentration boundary of 18% move to deep goaf in a small scale, while the boundary of 8% move to deep goaf in a large scale and show an exponential relationship, in other words air volume change greatly affect the 8% boundary. The boundary of maximum air leakage and air leakage 0.004% all display an exponential relationship with air volume. But the movement scale of air leakage boundary 0.004% is small. The width of oxidation zone increases obviously with air volume increasing and the relations formula is Lmax= 100.4ln (Q)-25.55ln (Q)-410.4. Draw a conclusion that in ventilation management air volume should be reduced appropriately in order to reduce the width of oxidation zone and slow the speed of moving to deep goaf, thus control spontaneous combustion in goaf.

Sign in / Sign up

Export Citation Format

Share Document