An Efficient Method for Modeling Radiative Transfer in Multicomponent Gas Mixtures With Soot

2000 ◽  
Vol 123 (3) ◽  
pp. 450-457 ◽  
Author(s):  
Vladimir P. Solovjov ◽  
Brent W. Webb
Keyword(s):  
Carbon Dioxide ◽  
Radiative Transfer ◽  
Narrow Band ◽  
Gas Mixtures ◽  
Distribution Functions ◽  
Individual Species ◽  
Gas Mixture ◽  
Weighted Sum ◽  
Multicomponent Gas ◽  
The Individual

An efficient approach for predicting radiative transfer in high temperature multicomponent gas mixtures with soot particles is presented. The method draws on the previously published multiplication approach for handling gas mixtures in the spectral line weighted-sum-of-gray-gases (SLW) model. In this method, the gas mixture is treated as a single gas whose absorption blackbody distribution function is calculated through the distribution functions of the individual species in the mixture. The soot is, in effect, treated as another gas in the mixture. Validation of the method is performed by comparison with line-by-line solutions for radiative transfer with mixtures of water vapor, carbon dioxide, and carbon monoxide with a range of soot loadings (volume fractions). Comparison is performed also with previously published statistical narrow band and classical weighted-sum-of-gray-gases solutions.

scholarly journals Molecular Simulations of CO2/CH4, CO2/N2 and N2/CH4 Binary Mixed Hydrates

2021 ◽  
Vol 83 (3) ◽  
pp. 372-378
Author(s):  
A. A. Sizova ◽  
S. A. Grintsevich ◽  
M. A. Kochurin ◽  
V. V. Sizov ◽  
E. N. Brodskaya
Keyword(s):  
Carbon Dioxide ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Gas Hydrates ◽  
Molecular Simulations ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
Grand Canonical Monte Carlo ◽  
Multicomponent Gas ◽  
Grand Canonical

Abstract Grand canonical Monte Carlo simulations were performed to study the occupancy of structure I multicomponent gas hydrates by CO2/CH4, CO2/N2, and N2/CH4 binary gas mixtures with various compositions at a temperature of 270 K and pressures up to 70 atm. The presence of nitrogen in the gas mixture allows for an increase of both the hydrate framework selectivity to CO2 and the amount of carbon dioxide encapsulated in hydrate cages, as compared to the CO2/CH4 hydrate. Despite the selectivity to CH4 molecules demonstrated by N2/CH4 hydrate, nitrogen can compete with methane if the gas mixture contains at least 70% of N2.

SLW-1 Modeling of Radiative Heat Transfer in Non-Isothermal Non-Homogeneous Gas Mixtures With Soot

2010 ◽  
Author(s):  
Vladimir P. Solovjov ◽  
Denis Lemonnier ◽  
Brent W. Webb
Keyword(s):  
Radiative Heat ◽  
Gaseous Medium ◽  
Good Accuracy ◽  
Radiation Transfer ◽  
Gas Mixtures ◽  
Optimal Choice ◽  
Distribution Functions ◽  
Gas Absorption ◽  
Individual Species ◽  
Benchmark Solutions

The Spectral Line Weighted-sum-of-gray-gases (SLW) model consisting only of a single gray gas and of one clear gas is developed as an efficient spectral method for modeling radiation transfer in gaseous medium. The model is applied here in prediction of radiative transfer in non-isothermal and non-homogeneous gas mixtures with non-gray soot. The absorption spectrum of the gas mixture and soot particles is treated as a spectrum of a single effective gas reducing the problem to the simplest case of the SLW model with a single gray gas. Good accuracy can be achieved by the optimal choice of the model’s gray gas absorption coefficient and its weight by application of the Absorption-Line Blackbody Distribution Functions of individual species in the mixture calculated with a high-resolution spectral database. The SLW-1 model is validated by comparison with benchmark solutions using the Line-by-Line method, the SLW method with a large number of gray gases, and the SNB model.

Prediction of Radiative Transport in Nonhomogeneous Combustion Gas Mixtures With a Wide Band G(K) Model

2013 ◽  
Author(s):  
Liping Liu ◽  
Jing He
Keyword(s):  
Radiative Transfer ◽  
Narrow Band ◽  
Gaussian Quadrature ◽  
Wide Band ◽  
Gas Mixtures ◽  
Source Distribution ◽  
Distribution Model ◽  
Band Model ◽  
Radiative Transport ◽  
Combustion Gas

A wide band cumulative absorption coefficient distribution, g(k), model is adopted to predict radiative transport in combustion gas mixtures. Prior research has demonstrated similar accuracy of the model to the statistical narrow-band model and superiority to the exponential wideband model under isothermal and homogeneous conditions. This study aims to assess its usefulness in nonhomogeneous media. Sample calculations are performed in a 1D planar slab containing H2O/CO2 mixtures. The six-flux discrete ordinate method (S6-DOM) is employed to solve the radiative transfer equation (RTE), followed by an eight-point Gaussian quadrature of moments with zeroth-order fit. Predictions on the radiative source distribution along the slab and the net radiative flux at the walls are compared to the benchmark line-by-line calculation (LBL) and the statistical narrow-band correlated-k distribution model using the 7-point Gauss-Lobatto quadrature scheme (SNBCK-7). The differences between the g(k) model and LBL are below 5% for a large domain of the layer, with a CPU reduction by a factor of over 30 compared to SNBCK-7 and on the order of 104∼105 compared to LBL. The wide band g(k) model shows significant promise as an accurate and efficient tool to predict radiative transfer in nonhomogenerous media for combustion and fire simulations.

scholarly journals Dobór wydajności gazów propan-butan dodawanych w celu wspomagania efektywnego spalania gazu ziemnego niskometanowego z użyciem flary

Nafta-Gaz ◽  
2021 ◽  
Vol 77 (1) ◽  
pp. 26-32
Author(s):  
Paweł Budak ◽  
◽  
Tadeusz Szpunar ◽  
Keyword(s):  
Carbon Dioxide ◽  
Flow Rate ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
Gas Reservoirs ◽  
Empirical Relationships ◽  
Complete Combustion ◽  
Toxic Gases ◽  
Butane Mixture ◽  
Propane Butane

The paper discusses the problems related to the burning of gas mixtures containing flammable and non-flammable gases using a flare. Before being burned, such a gas mixture must be “enriched” with other flammable gases before it can be directed to the flare. In the case of some Polish gas reservoirs such as Cychry or Sulęcin, the composition of the gas mixture doesn’t make it possible to burn it using the flare because the content of inflammable components is too high and the gas mixture is inflammable. The gas from the reservoirs mentioned above contains above 90 percent of nitrogen and small percentages of flammable components. Sometimes, besides nitrogen, the gas mixture contains other inflammable gases like carbon dioxide, helium, and oxygen. Usually, the propane/butane is used for that purpose. The possibility of burning the gas mixture using the flare is particularly important if the toxic gases are present in the mixture – hydrogen sulfide in particular. The propane/butane gases are added to the stream of gas mixture meant for burning using a special appliance. The typical arrangement of a gas-burning installation (i.e. the flare) is shown and the destination of its components is discussed. The empirical formula is provided which allows us to recognize if the gas mixture is flammable or not. The composition of the gas mixture must be known to calculate the propane/butane flow rate, including percentages of flammable and inflammable components. The algorithm constructed for calculating the propane/butane flow rate is presented, which must be maintained to assure the flammability of the gas mixture destined for burning using the flare. The results of the calculations for four gas mixtures from the Polish gas reservoirs are provided. The presented method of determining the flammability of gas mixtures (or its inability to be burned) and the flow rate of the propane/butane mixture required for complete combustion is based on empirical relationships, which are provided in the paper and may be helpful in planning the assisted combustion of low methane gases (not suitable for further use) using a flare.

scholarly journals Diffusion Mechanisms for the Occurrence of the Instability of Mechanical Equilibrium of a Ternary Gas Mixture Containing Carbon Dioxide

Fluids ◽  
2021 ◽  
Vol 6 (5) ◽  
pp. 177
Author(s):  
Vladimir Kossov ◽  
Olga Fedorenko ◽  
Adilet Kalimov ◽  
Aiym Zhussanbayeva
Keyword(s):  
Carbon Dioxide ◽  
Gas Mixture ◽  
Mechanical Equilibrium ◽  
Significant Difference ◽  
Pressure Area ◽  
Multicomponent Gas ◽  
Diffusion Mechanisms ◽  
The Difference ◽  
Diffusion Convection ◽  
Kinetic Features

Mixing of carbon dioxide dissolved in a multicomponent gas mixture at different pressures was researched. It was found that the mechanical equilibrium of the ternary gas mixture 0.4163H2 (1) + 0.5837CO2 (2) − N2 (3) is violated at a pressure of p = 0.7 MPa and structured flows appear in the system. The pressure area (from 0.7 to 1.5 MPa) at which the conditions of priority transfer of components with the highest molecular weight in the mixture are realised in the system is fixed. To analyse the effect of pressure on the process of changing “diffusion–convection” modes, a mathematical model, which takes into account the kinetic features of multicomponent mixing, was applied. It was shown that the change in the modes of mass transfer is associated with a significant difference in the diffusion ability of the components. It is noted that the difference in the diffusion coefficients of components results in the nonlinearity of the concentration distribution, which leads to the inversion of the density gradient of the gas mixture, which is the cause of convective flows.

Removal of Carbon Dioxide from a Multicomponent Gas Mixture by Absorption Using a Y-Type Microreactor

2021 ◽  
Author(s):  
Sarah Natacha de Oliveira Almeida Morais ◽  
Ciro Evandro da Silva Lobo ◽  
Carlos Eduardo de Araújo Padilha ◽  
Domingos Fabiano de Santana Souza ◽  
José Roberto de Souza ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Mixture ◽  
Multicomponent Gas ◽  
Multicomponent Gas Mixture

scholarly journals A crossover trial investigating the atmospheric content of improvised respirators

2021 ◽  
pp. 175114372098871
Author(s):  
Paul R Greig ◽  
Clarissa Carvalho ◽  
Suniel Ramessur ◽  
Jan Schumacher ◽  
Kariem El-Boghdadly
Keyword(s):  
Carbon Dioxide ◽  
Crossover Study ◽  
Crossover Trial ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
Moisture Exchange ◽  
Carbon Dioxide Concentrations ◽  
Full Face ◽  
Heat And Moisture ◽  
Oxygen Concentrations

Introduction This study was designed to determine the respiratory safety of improvised respirators based on modified full-face snorkel masks, making comparisons with a purpose-designed mask Methods This is a prospective crossover study conducted on ten recruits. Volunteers wore snorkel masks mated to an anaesthetic heat and moisture exchange filter. The system was worn at rest then during exercise. Gases were sampled from the mask at 5-min intervals. Results The modified snorkel was satisfactory in seven participants. For three carbon dioxide concentrations were >1%. Two participants exposed to excessive CO2 also experienced oxygen concentrations <19%. All participants exposed to unsatisfactory gas mixtures were non-white. Conclusions Modifying snorkel masks changes the way that gases circulate through the system. These modifications increase the risk of rebreathing in some users, which may yield an unsafe gas mixture. These improvised masks cannot be recommended as a substitute for purpose-designed equipment.

scholarly journals One-step ethylene production from a four-component gas mixture by a single physisorbent

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jian-Wei Cao ◽  
Soumya Mukherjee ◽  
Tony Pham ◽  
Yu Wang ◽  
Teng Wang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Binding Sites ◽  
Selective Adsorption ◽  
Diphenyl Ether ◽  
Gas Mixtures ◽  
Single Step ◽  
Gas Mixture ◽  
One Step ◽  
Breakthrough Experiments ◽  
Insight Into

AbstractOne-step adsorptive purification of ethylene (C2H4) from four-component gas mixtures comprising acetylene (C2H2), ethylene (C2H4), ethane (C2H6) and carbon dioxide (CO2) is an unmet challenge in the area of commodity purification. Herein, we report that the ultramicroporous sorbent Zn-atz-oba (H2oba = 4,4-dicarboxyl diphenyl ether; Hatz = 3-amino-1,2,4-triazole) enables selective adsorption of C2H2, C2H6 and CO2 over C2H4 thanks to the binding sites that lie in its undulating pores. Molecular simulations provide insight into the binding sites in Zn-atz-oba that are responsible for coadsorption of C2H2, C2H6 and CO2 over C2H4. Dynamic breakthrough experiments demonstrate that the selective binding exhibited by Zn-atz-oba can produce polymer-grade purity (>99.95%) C2H4 from binary (1:1 for C2H4/C2H6), ternary (1:1:1 for C2H2/C2H4/C2H6) and quaternary (1:1:1:1 for C2H2/C2H4/C2H6/CO2) gas mixtures in a single step.

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