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Interaction of water droplets with pyrolyzing coal particles and tablets

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Defence Technology（防务技术） 2023年第12期30卷 1-12页

作者： Anastasia Islamova pavel Tkachenko pavel strizhak National Research Tomsk Polytechnic University Heat and Mass Transfer Laboratory30 Lenin AvenueTomsk634050Russia

The paper presents the experimental research findings for the patterns of collisions of water droplets with pressed tableted samples used as substrates and with small particles of a pyrolyzing solid *** coal samples were ***-substrate interactions were studied when varying the droplet diameter in the range from 1 to 4 mm and velocity from 0.5 to 4 m/*** corresponded to the Weber number range of *** coal tablet surface temperature was varied from 20 to 700℃.In the interactions of water droplets(0.7-1.5 mm in diameter,pre-collision velocity from 1 to 3 m/s)with coal particles(with a size of 0.2-1 mm,pre-collision velocity 0.7-2 m/s),the temperature of the latter was varied in the range of 330-480℃.The following regimes of the interaction of droplets with solid particles during chemical reactions and phase transformations were distinguished:spreading/agglomeration and break-up/*** in the characteristics of the interaction of water droplets with coal particles at varying temperatures were ***-particle interaction regime maps for B(We),We(Oh)and We(Ca)were *** collision regime boundaries were described using fitted curves that can be utilized to develop the existing mathematical models of droplet-particle collisions in *** was established that the gaseous volatile production in coal pyrolysis has a modest effect on the regimes and characteristics of the droplet destruction in the temperature range under consideration(20-700℃).

关键词： Droplet Particle solid substrate Collision Agglomeration separation

Thermogravimetric,kinetic study and gas emissions analysis of the thermal decomposition of waste-derived fuels

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Journal of Environmental sciences 2024年第3期137卷 155-171页

作者： Vadim V.Dorokhov Galina s.Nyashina pavel A.strizhak Heat and Mass Transfer Laboratory National Research Tomsk Polytechnic University30 Lenin AvenueTomsk 634050Russia

A wide range of wastes can potentially be used to generate thermal and electrical *** co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their *** this research,we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime,biomass,waste oils,and blends on their *** also analyze the concentrations of gaseous *** results show that biomass,oils,and coal slime significantly affect each other in the course of their co-combustion when added to slurry *** preparation of coal-water slurry based on slime and water reduced the ignition and burnout temperature by up to 16%.Adding biomass and waste oils additionally stimulated the slurry ignition and burnout,which occurred at lower *** to dry coal slime,threshold ignition temperatures and burnout temperatures decreased by 6%–9%and 17%–25%,***,the use of biomass and waste oils as part of slurries inhibited NOхand sO_(2)emission by 2.75 *** to the kinetic analysis,added biomass and waste turbine oil provide a 28%–51%reduction in the activation energy as compared to a coal-water slurry without additives.

关键词： Coal-water slurry Water-containing composite fuels Combustion Emission Kinetic TGA-DsC

Dissipation-induced instabilities and symmetry

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Acta Mechanica sinica 2011年第1期27卷 2-6页

作者： Oleg N.kirillov Ferdinand Verhulst Dynamics and Vibrations Group Department of Mechanical EngineeringTechnical University of Darmstadt Hochschulstr.1 Mathematisch Instituut University of Utrecht

The paradox of destabilization of a conservative or non-conservative system by small dissipation,or Ziegler’s paradox（1952）,has stimulated a growing interest in the sensitivity of reversible and Hamiltonian systems with respect to dissipative *** the last decade it has been widely accepted that dissipation-induced instabilities are closely related to singularities arising on the stability boundary,associated with Whitney’s *** first explanation of Ziegler’s paradox was given（much earlier）by Oene Bottema in *** aspects of the mechanics and geometry of dissipation-induced instabilities with an application to rotor dynamics are discussed.

关键词： Dissipation-induced instabilities Destabilization paradox Ziegler pendulum Whitney umbrella

Evaluation of the seismic hazard for 20 cities in Romania using Monte Carlo based simulations

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Earthquake Engineering and Engineering Vibration 2017年第3期16卷 513-523页

作者： Florin pavel Radu Vacareanu seismic Risk Assessment Research Center Technical University of Civil Engineering Bucharest Romania

This work focuses on the evaluation of the seismic hazard for Romania using earthquake catalogues generated by a Monte Carlo approach. The seismicity of Romania can be attributed to the Vrancea intermediate-depth seismic source and to 13 other crustal seismic sources. The recurrence times of large magnitude seismic events（both crustal and subcrustal）, as well as the moment release rates are computed using simulated earthquake catalogues. The results show that the largest contribution to the overall moment release for the crustal seismic sources is from the seismic regions in Bulgaria, while the seismic regions in Romania contribute less than 5% of the overall moment release. In addition, the computations show that the moment release rate for the Vrancea subcrustal seismic source is about ten times larger than that of all the crustal seismic sources. Finally, the Monte Carlo approach is used to evaluate the seismic hazard for 20 cities in Romania with populations larger than 100,000 inhabitants. The results show some differences between the seismic hazard values obtained through Monte-Carlo simulation and those in the Romanian seismic design code P100-1/2013, notably for cities situated in the western part of Romania that are influenced by local crustal seismic sources.

关键词： seismic sources uncertainty seismic moment GMPE percentile

Prognosis of residual coal gas capacity made by the ‘Express' method

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International Journal of Minerals,Metallurgy and Materials 2011年第2期18卷 127-131页

作者： pavel Prokop pavel Zapletal Ivo Pěgímek Technical University of Ostrava

An easy, reliable, and inexpensive method, called ＇Express＇ method, was described to determine the residual gas capacity of deep mines using results from an air and gas balance. Air and gas balances are common elements of mine management and must be performed periodically. Using the process described here to obtain balance results, it is straightforward to obtain the residual gas capacity, which is an important parameter for decision-making in current mine operations. After a mine is closed, the residual gas capacity becomes a dominant factor used to select methods to protect against gas emissions from the closed underground area or perhaps to provide information for the use of gas reserves. The proposed ＇Express＇ method is a much simpler method to obtain the residual gas capacity than other procedures used for this purpose to date.

关键词： coal mines gas storage methane ventilation degassing

Transonic Instability in Entrance Part of Mixing Chamber of High-speed Ejector

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Journal of Thermal science 2005年第3期14卷 258-263,271页

作者： Vaclav Dvorak pavel safarik Technical University of Liberec Faculty of Mechanical Engineering Division of Power Engineering Halkova 6 461 17 Liberec Czech Republic Ph.DCzech Technical University in Prague Faculty of Mechanical Engineering 207- Institute of Fluid Dynamics and Power Engineering Division of Fluid Dynamics and Thermodynamics. Technicka 4 166 07 Praha 6 Czech Republic

The paper deals with experimental and numerical study of flow structure in two-dimensional model of supersonic ejector. schlieren pictures of flow structure were taken, static pressure distributions on side wall were measured and Fluent software to calculate the flow structure in supersonic ejector was used. For certain region of back pressure ratio pb/p02 and stagnation pressure ratio of both streams p01/p02 the terminal shock wave is close to the trailing edge of the primary flow nozzle and a transonic instability occurs. The instability causes the movement of position of boundary layer separation, the structure of shock waves changes and all flow structure oscillates. The movie of these regimes during schlieren experiments was taken and relevant numerical modelling was performed.

关键词： transonic instability ejector shock waves

Comparison of three methods for natural gas dehydration

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Journal of Natural Gas Chemistry 2011年第5期20卷 471-476页

作者： Michal Netusil pavel Ditl Department of Process Engineering Czech Technical University

This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.

关键词： gas reservoir underground gas storage natural gas gas dehydration

Investigation on regional attenuation of Vrancea (Romania) intermediate-depth earthquakes

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 501-509页

作者： Florin pavel Radu Vacareanu seismic Risk Assessment Research Center Technical University of Civil Engineering

This paper aims at investigating possible regional attenuation patterns in the case of Vrancea（Romania） intermediate-depth *** 500 pairs of horizontal components recorded during 13 intermediate-depth Vrancea earthquakes are employed in order to evaluate the regional attenuation *** recordings are grouped according to the azimuth with regard to the Vrancea seismic source and subsequently,Q models are computed for each azimuthal zone assuming similar geometrical ***,the local soil amplification which was disregarded in a previous analysis performed for Vrancea intermediate-depth earthquakes is now clearly *** results show minor differences between the four regions situated in front of the Carpathian Mountains and considerable differences in attenuation of seismic waves between the forearc and backarc regions（with regard to the Carpathian Mountains）.Consequently,an average Q model of the type Q（f） = 115×f^1.25 is obtained for the four forearc regions,while a separate Q model of the type Q（f） = 70×f^0.90 is computed for the backarc *** results highlight the need to evaluate the seismic hazard of Romania by using ground motion models which take into account the different attenuation between the forearc/backarc regions.

关键词： Fourier amplitude spectrum azimuth dependency source-to-site distance Q model local soil conditions

Temperature Profiles of a Vertical, 7-Element Bundle Cooled with supercritical Freon-12

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Journal of Energy and Power Engineering 2013年第2期7卷 207-218页

作者： Graham Richards Igor Pioro Glenn Harvel Alexsei shelegov pavel kirillov Faculty of Energy systems and Nuclear science University of Ontario Institute of Technology Ontario L1H 7K4 Canada Institute of Physics and Power Engineering Obninsk 249033 Russia

A set of experimental data obtained at the Institute of Physics and Power Engineering in a vertical bundle cooled with supercritical R-12 was analyzed. The test section was a 7-element bundle installed in a hexagonal flow channel with three grid spacers. Data was collected at pressures of approximately 4.65 MPa for several different combinations of wall and bulk-fluid temperatures that were below, at, or above pseudocritical conditions. Analysis of the data has confirmed that there are three distinct heat-transfer regimes for forced convention in supercritical fluids：（1） normal heat transfer, （2） deteriorated heat transfer, and （3） enhanced heat transfer. It was also confirmed that the effects of spacers are evident which was previously observed in sub-critical experimental data. This work compares the wall and bulk fluid temperature data of the experiments to predictions based upon current 1-D correlations for heat transfer in supercritical fluids.

关键词： Heat transfer fluid properties supercritical pressures Freon-12 temperature profiles.