scholarly journals Regularity of Mine Gas Flow Disaster Induced by Gas Natural Ventilation Pressure after Coal and Gas Outbursts

ACS Omega ◽  
2021 ◽  
Author(s):  
Jingxiao Yu ◽  
Zongxiang Li ◽  
Yu Liu ◽  
Ziwen Dong ◽  
Yashengnan Sun
Keyword(s):  
Gas Flow ◽  
Natural Ventilation ◽  
Coal And Gas Outbursts ◽  
Mine Gas

Mine Gas Flow in the Porous Massif and CFD Tool

2015 ◽  
Vol 362 ◽  
pp. 38-46
Author(s):  
Pavel Staša ◽  
Oldřich Kodym
Keyword(s):  
Rock Mass ◽  
Gas Flow ◽  
Mining Activity ◽  
Flow Modeling ◽  
Coal Seams ◽  
The Past ◽  
Mining Conditions ◽  
Reduce Risk ◽  
Mine Gas ◽  
Numerical Flow Modeling

There is a still dangerous effect in the form of methane leakage from coal seams in areas where mining activity still continuing or took place in the past. The issue of mining gas flow is still a matter that is necessary to pay attention and try to find new ways to solve this set of phenomena, no matter if it is the mining corridors or the flow in the rock massif. The number of measures to gradually reduce risk has been taken to protect the population. Nevertheless, the current situation is generally rated as serious as those risks still remain valid. Leakage of mine gases depend on many natural and technical mining conditions. With the closure of mines and thus the end of the ventilation situation considerably worse. This paper deals with the flow of dangerous mine gas, methane, through the rock mass using numerical flow modeling using CFD program Fluent. Using CFD codes can gain insight on the phenomenon under review and the results to take appropriate measures in the form of active or passive intervention.

Regularities of Two-Phase Gas Flow under Coal and Gas Outbursts in Mines

2017 ◽  
Vol 53 (3) ◽  
pp. 533-543 ◽  
Author(s):  
A. T. Zhou ◽  
K. Wang ◽  
T. A. Kiryaeva ◽  
V. N. Oparin
Keyword(s):  
Gas Flow ◽  
Two Phase ◽  
Coal And Gas Outbursts

Experimental Study for the Energy Efficiency of Hot-Wall Kang

2010 ◽  
Author(s):  
Zongshan Wang ◽  
Lin Duanmu ◽  
Junliang Zhu ◽  
Yang Zhao
Keyword(s):  
Energy Efficiency ◽  
Heat Loss ◽  
Rural Areas ◽  
Gas Flow ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Total Heat ◽  
Gas Temperature ◽  
Low Velocity ◽  
Heating Efficiency

Chinese Kang with two thousand years’ history is a typical heating method using biomass in cold rural areas. It contributes to reducing the demands of coal and to optimizing the energy consumption structure, but its development is limited for low energy efficiency, poor indoor environment and etc. Therefore, we had a study based on experiment on a new reformed hot-wall Kang. The experimental results show that: the hot-wall Kang improved indoor thermal environment to a great extent. The radiation was the main way of heat elimination through the Kang’s surface, and took up about 65% of the total heat supply. The total heat carried by gas was gained by Kang body and chimney, 64.6% and 9.1% respectivley, and the remaining 26.3% was lost by discharged gas. Under the operation simulating residents’ living habit, the heating efficiency of Kang was up to 80.5% in the period of one testing day. The heat loss transferred to the ground through Kang cave and Hot-wall combustion space was 3.17% and 8.27% respectely. It also showed that the dust-ash layer filled in the cave weakened the ground heat loss and had same effect as that of insulation. Other discoveries: the mass flow rate of flue gas during the burning periods varied in the range of 0.04∼0.08 kg/s. It was turbulent flow at a low velocity, companied with two gas temperature layers. Based on the experiment, the thermal and operation character of hot-wall Kang were made clear. Furthermore, a guide for further optimization of the structure was put forward. And the results also supplied some proofs for the study of gas flow and heat transfer with natural ventilation.

scholarly journals A Fisher’s Criterion-Based Linear Discriminant Analysis for Predicting the Critical Values of Coal and Gas Outbursts Using the Initial Gas Flow in a Borehole

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Xiaowei Li ◽  
Chenglin Jiang ◽  
Jun Tang ◽  
Yujia Chen ◽  
Dingding Yang ◽  
...  
Keyword(s):  
Discriminant Analysis ◽  
Linear Discriminant Analysis ◽  
Spatial Data ◽  
Gas Flow ◽  
Prediction Method ◽  
Critical Value ◽  
Critical Values ◽  
Linear Discriminant ◽  
Coal And Gas Outbursts ◽  
Fisher’S Criterion

The risk of coal and gas outbursts can be predicted using a method that is linear and continuous and based on the initial gas flow in the borehole (IGFB); this method is significantly superior to the traditional point prediction method. Acquiring accurate critical values is the key to ensuring accurate predictions. Based on ideal rock cross-cut coal uncovering model, the IGFB measurement device was developed. The present study measured the data of the initial gas flow over 3 min in a 1 m long borehole with a diameter of 42 mm in the laboratory. A total of 48 sets of data were obtained. These data were fuzzy and chaotic. Fisher’s discrimination method was able to transform these spatial data, which were multidimensional due to the factors influencing the IGFB, into a one-dimensional function and determine its critical value. Then, by processing the data into a normal distribution, the critical values of the outbursts were analyzed using linear discriminant analysis with Fisher’s criterion. The weak and strong outbursts had critical values of 36.63 L and 80.85 L, respectively, and the accuracy of the back-discriminant analysis for the weak and strong outbursts was 94.74% and 92.86%, respectively. Eight outburst tests were simulated in the laboratory, the reverse verification accuracy was 100%, and the accuracy of the critical value was verified.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

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