Numerical simulation of the dynamic formation process of fog-haze and smog in transport tunnels of a hot mine

2016 ◽  
Vol 26 (8) ◽  
pp. 1062-1069 ◽  
Author(s):  
Sheng-hua Zou ◽  
Kong-qing Li ◽  
Qiao-yun Han ◽  
Chuck Wah Yu
Keyword(s):  
Wind Speed ◽  
Numerical Modelling ◽  
Coal Mine ◽  
Aerosol Particles ◽  
Geometric Mean ◽  
Particle Diameter ◽  
Monte Carlo Algorithm ◽  
Hunan Province ◽  
Air Conditioner

Fog-haze and smog can be formed in transport tunnels during artificial cooling by air-conditioner, under hot and high humidity conditions inside a coal mine. The processes of coagulation, condensation, nucleation, crushing and evaporation, which can occur at the same time, can be simulated by a dynamic model. The relationship between the particle size distribution over time and environmental parameters such as wind speed, temperature and relative humidity, during smog formation in transport tunnels in a coal mine was characterised by our numerical modelling and in-situ study of a coal mine in Hunan Province, China. The development and dissipation of fog-haze and smog when under cooling inside a deep coal mine were modelled using multiple Monte Carlo algorithm method validated by our experiment using a 1 m3 wooden chamber. Our numerical modelling was confirmed by our in-situ measurement results, indicating that (1) the bigger the condensation coefficient would lead to a faster formation of aerosol particles giving larger number and sizes of particles; (2) faster wind speed would reduce the number of aerosol particles and increase the geometric mean of the particle diameter. (3) When cooling in the tunnels, 2 m/s would be the lowest wind speed that could disperse the haze in the transport tunnels in the mine. The findings of our research should provide the theoretical basis for artificial cooling and controlling of the formation of haze in transport tunnels for mining.

scholarly journals The ATAL within the 2017 Asian Monsoon Anticyclone: Microphysical aerosol properties derived from aircraft-borne in situ measurements

2021 ◽  
Author(s):  
Christoph Mahnke ◽  
Ralf Weigel ◽  
Francesco Cairo ◽  
Jean-Paul Vernier ◽  
Armin Afchine ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Asian Summer Monsoon ◽  
Aerosol Particles ◽  
Potential Temperature ◽  
Particle Diameter ◽  
Aerosol Layer ◽  
Mixing Ratio ◽  
Detection Range ◽  
Particle Mixing

Abstract. The Asian summer monsoon is an effective pathway for aerosol particles and precursor substances from the planetary boundary layer over Central, South, and East Asia into the upper troposphere and lower stratosphere. An enhancement of aerosol particles within the Asian monsoon anticyclone (AMA) has been observed by satellites, called the Asian Tropopause Aerosol Layer (ATAL). In this paper we discuss airborne in situ and remote sensing observations of aerosol microphysical properties conducted during the 2017 StratoClim field campaign within the region of the Asian monsoon anticyclone. The aerosol particle measurements aboard the high-altitude research aircraft M55 Geophysica (reached a maximum altitude of about 20.5 km) were conducted by a modified Ultra High Sensitivity Aerosol Spectrometer Airborne (UHSAS-A; particle diameter detection range from 65 nm to 1 µm), the COndensation PArticle counting System (COPAS, for detecting total aerosol densities of submicrometer sized particles), and the Cloud and Aerosol Spectrometer with Detection of POLarization (NIXE-CAS-DPOL). In the COPAS and UHSAS-A vertical particle mixing ratio profiles, the ATAL is evident as a distinct layer between 15 km (≈ 370 K) and 18.5 km altitude (≈ 420 K potential temperature). Within the ATAL, the maximum detected particle mixing ratios (from the median profiles) were 700 mg−1 for diameters between 65 nm to 1 µm (UHSAS-A) and higher than 2500 mg−1 for diameters larger than 10 nm (COPAS). These values are up to two times higher than previously found at similar altitudes in other tropical locations. The difference between the particle mixing ratio profiles measured by the UHSAS-A and the COPAS indicate that the region below the ATAL at potential temperatures from 350 to 370 K is influenced by the fresh nucleation of aerosol particles (diameter

scholarly journals Concept for an electrostatic focusing device for continuous ambient pressure aerosol concentration

2019 ◽  
Vol 12 (6) ◽  
pp. 3395-3402
Author(s):  
Joseph L. Woo ◽  
Neha Sareen ◽  
Allison N. Schwier ◽  
V. Faye McNeill
Keyword(s):  
Continuous Flow ◽  
Ambient Pressure ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Aerosol Concentration ◽  
Submicron Particles ◽  
Virtual Impactors ◽  
Unipolar Charger ◽  
Prototype Design

Abstract. We present a concept for enhancing the concentration of charged submicron aerosol particles in a continuous-flow stream using in situ electrostatic focusing. It is proposed that electrostatic focusing can enable the continuous, isothermal concentration of aerosol particles at ambient pressure, without altering their chemical composition. We model this approach theoretically and demonstrate proof of concept via laboratory measurements using a prototype. The prototype design consists of a nozzle-probe flow system analogous to a virtual impactor. The device was tested in the laboratory using submicron, monodisperse stearic acid particles. Particles were charged using a unipolar charger then concentrated using a cylindrical electrostatic immersion lens to direct the charged submicron particles into the sample probe. Under applied lens voltages ranging from 0 V to 30 kV, aerosol concentration increased up to 15 %. Observed particle enrichment varied as a function of voltage and particle diameter. These results suggest that an imposed electric field can be used to increase aerosol concentration in a continuous flow. This approach shows promise in increasing the effective enriched size range of virtual impactors or other continuous-flow methods of collection.

scholarly journals Concept for an electrostatic focusing device for continuous ambient pressure aerosol concentration

2019 ◽  
Author(s):  
Joseph L. Woo ◽  
Neha Sareen ◽  
Allison N. Schwier ◽  
V. Faye McNeill
Keyword(s):  
Continuous Flow ◽  
Ambient Pressure ◽  
Aerosol Particles ◽  
Particle Diameter ◽  
Aerosol Concentration ◽  
Submicron Particles ◽  
Virtual Impactors ◽  
Unipolar Charger ◽  
Prototype Design

Abstract. We present a concept for enhancing the concentration of charged submicron aerosol particles in a continuous flow stream using in situ electrostatic focusing. It is proposed that electrostatic focusing can enable the continuous, isothermal concentration of aerosol particles at ambient pressure, without altering their chemical composition. We model this approach theoretically and demonstrate proof-of-concept via laboratory measurements using a prototype. The prototype design consists of a nozzle-probe flow system analogous to a virtual impactor. The device was tested in the laboratory using submicron, monodisperse stearic acid particles. Particles were charged using a unipolar charger, then concentrated using a cylindrical electrostatic immersion lens to direct the charged submicron particles into the sample probe. Under applied lens voltages ranging from 0 V to 30 kV, aerosol concentration increased up to 15 %. Observed particle enrichment varied as a function of voltage and particle diameter. These results suggest that an imposed electric field can be used to increase aerosol concentration in a continuous flow. This approach shows promise in increasing the effective enriched size range of virtual impactors or other continuous-flow methods of collection.

scholarly journals The Interaction Features of the Multi-Level Retaining Walls with Soil Mass

2017 ◽  
Vol 26 (3) ◽  
pp. 179-190
Author(s):  
Igor Boyko ◽  
Liudmyla Skochko ◽  
Veronica Zhuk
Keyword(s):  
Numerical Modelling ◽  
Numerical Simulations ◽  
Variable Stiffness ◽  
Retaining Walls ◽  
Soil Mass ◽  
Soil Base ◽  
Deep Foundation ◽  
Multi Level ◽  
Horizontal Displacements

Abstract The interaction features of multi-level retaining walls with soil base were researched by changing their geometric parameters and locality at the plan. During excavation of deep foundation pits it is important to choose the type of constructions which influences on the horizontal displacements. The distance between the levels of retaining walls should be based on the results of numerical modelling. The objective of this paper is to present a comparison between the data of numerical simulations and the results of the in-situ lateral tests of couple piles. The problems have been solved by using the following soil models: Coulomb-Mohr model; model, which is based on the dilatation theory; elastic-plastic model with variable stiffness parameters.

Principle of Well-Net Design for Coalbed Methane Exploitation in Coal Mine Area

2014 ◽  
Vol 543-547 ◽  
pp. 3967-3973
Author(s):  
Bao Shan Han
Keyword(s):  
Coal Mining ◽  
Coal Mine ◽  
Coalbed Methane ◽  
Design Theory ◽  
Surface Condition ◽  
Coal Pillar ◽  
Negative Influence ◽  
In Situ Stress ◽  
Well Location

There are abundant CBM (Coalbed Methane) in China. These CBM has caused a remarkable problem to the coal-mining in China. In order to improve the structure of Chinese energy and eliminate the risk of coal mine gas, the relevant industries and sections have implemented many explorations in CBM enriched areas. With great achievements, there are many important problems in the actions of CBM exploitation. The disadvantageous interaction of the surface CBM well and the later coal mining has been ignored at all. There are many disadvantages and defects. To solve these problems and eliminate or weaken the disadvantageous, the scientific and reasonable design of surface CBM well location is an important step. With the thinking of surface condition, coal mining plan, the arrangement of coal mine laneway, the direction and scale of the in-situ stress, and thinking more about the negative influence to and of surface CBM well, according to the theories of mining dynamics, mining engineering, mining geomechanics, and the CBM engineering, the design theory of the surface CBM well net can be studied. Finally, the arrangement principle of CBM product well in coal field is presented. The existing or future coal pillar will be a critical location for the surface CBM well location.

scholarly journals Field test of a new snow-particle counter (SPC) system

1993 ◽  
Vol 18 ◽  
pp. 149-154 ◽  
Author(s):  
Takeshi Sato ◽  
Tadashi Kimura ◽  
Taminoe Ishimaru ◽  
Toshisuke Maruyama
Keyword(s):  
Wind Speed ◽  
Mass Flux ◽  
Particle Trajectory ◽  
Particle Diameter ◽  
Blowing Snow ◽  
Fraunhofer Diffraction ◽  
Wind Speed Profile ◽  
Particle Counter ◽  
Sampling Volume ◽  
Snow Particle

The optical system of the snow-particle counter (SPC), which was developed by Schmidt in 1977, has been improved. A laser diode is used as a light source, achieving uniform sensitivity to a blowing snow particle regardless of the location of particle trajectory within a sampling volume. The light entering a slit, which may be affected by a blowing snow particle, is perfectly detected by use of a piano-cylindrical lens and a dual-type photodiode. A signal processor has been developed to get output voltage proportional to the mass flux of blowing snow.From the estimates based on blowing snow characteristics and wind speed profile, the new SPC system can accurately detect all the particles of effective sizes at least at a height above 0.1 m when the wind speed at a height of 1 m is less than 15 m s−1.Considering the Fraunhofer diffraction by both the wire and the particle, the relation between a particle diameter and sensor output of the new SPC system is derived from the calibration with spinning wires.Mass flux obtained with the new SPC system was found to be close to that with a snow trap. The system was operated continuously for at least nine days using two 35 A h lead batteries.

scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

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