Gas Mixture Research Articles

Optimizing the pore environment in biological metal-organic frameworks through the incorporation of hydrogen bond acceptors for inverse ethane/ethylene separation.

Optimizing the pore environment in biological metal-organic frameworks through the incorporation of hydrogen bond acceptors for inverse ethane/ethylene separation.

The membranes of V–Pd alloys: study of ultrapure hydrogen extraction from gas mixtures

The membranes of V–Pd alloys: study of ultrapure hydrogen extraction from gas mixtures

Catalytic sensor-based software-algorithmic system for the detection and quantification of combustible gases in complex mixtures

Catalytic sensor-based software-algorithmic system for the detection and quantification of combustible gases in complex mixtures

Casuarina seed-packed biofilter for the treatment of gaseous mixture: Performance, optimization, synergistic effects, neural model analysis, and kinetics

Casuarina seed-packed biofilter for the treatment of gaseous mixture: Performance, optimization, synergistic effects, neural model analysis, and kinetics

Thermodynamic properties of natural gas mixture in the pre-salt layer: A molecular dynamics approach

Thermodynamic properties of natural gas mixture in the pre-salt layer: A molecular dynamics approach

Study on the pressure characteristics and flame dynamics behavior of methane-hydrogen gas mixtures under the influence of multiple factors

Study on the pressure characteristics and flame dynamics behavior of methane-hydrogen gas mixtures under the influence of multiple factors

A data-driven study on viscosity estimation of hydrogen-containing gas mixtures using machine learning

A data-driven study on viscosity estimation of hydrogen-containing gas mixtures using machine learning

Advancements in the simulation of environmentally friendly gas mixtures for Resistive Plate Chambers

Advancements in the simulation of environmentally friendly gas mixtures for Resistive Plate Chambers

Impact of hydrogen addition, up to 20 % (mol/mol), on the thermodynamic (p, ρ, T) properties of a reference high-calorific natural gas mixture with significant ethane and propane content

Impact of hydrogen addition, up to 20 % (mol/mol), on the thermodynamic (p, ρ, T) properties of a reference high-calorific natural gas mixture with significant ethane and propane content

Mid-infrared acetone gas sensors using substrate-integrated hollow waveguides augmented by advanced preconcentrators

The identification of volatile organic compounds (VOC) such as acetone, a relevant biomarker for diabetes mellitus in exhaled human breath has become essential for early disease diagnostics, prognosis, and monitoring of metabolic responses to pharmacological interventions. Gas chromatography coupled with mass spectrometry (GC–MS) is considered as the gold standard for breath analysis. However, its inability to offer point-of-care monitoring limits its applicability in clinical environments. Optical techniques based on absorption in the mid-infrared range (2.5 to 25 μm) appear as promising alternatives due to their inherent selectivity, potential for miniaturization, portability, and direct analysis with rapid response. Relevant biomarkers present in exhaled breath, are usually observed in the ppb to ppm (v/v) concentration regime. For sensitivity enhancement of optical sensing techniques, appropriate preconcentration schemes are required prior to the optical detection. The present study describes a method combining a multi-channel substrate-integrated preconcentration module (a.k.a., muciPRECON) for enhancing and optimizing the detection of acetone via a mid-infrared photonic sensing system. The sensor system comprises a compact Fourier Transform Infrared (FTIR) spectrometer, a technique that enables detailed infrared spectral analysis, coupled to a substrate-integrated hollow waveguide (iHWG) simultaneously acting as a gas cell and as a photon conduit. Preconcentation experiments were from acetone/nitrogen gas mixtures in the concentration range of 5–100 ppm at − 10 °C followed by desorption at a temperature of 100 °C and direct injection into the IR sensing system Thus obtained acetone spectra were quantified evaluating a molecule-specific vibrational absorption peak area in the spectral window 1260–1170 cm−1. After extensive screening, Tenax was identified as superior sorbent material providing an enrichment factor of up to 153-times, a limit of detection (LOD) of 0.118 ppm, and a limit of quantification (LOQ) of 0.393 ppm. These results are indeed promising for practical applications, especially since acetone concentrations usually vary between 0.3 and 0.9 ppmv within the exhaled breath of healthy individuals, and in individuals with diabetes, acetone concentrations are typically around 1.7 to 3.0 ppmv. Consequently, the developed systems have the necessary sensitivity and accuracy to detect acetone levels that are in the relevant physiological range indicating their potential use in future real-world scenarios.

Microscopic nature of macroscopic nonlinearity: analytical calculation of gas susceptibilities

An analytical formula for the non-resonant nonlinear susceptibility of an arbitrary order in a gaseous medium is obtained by successive quantum-mechanical calculation of the response of an atom in the laser field and summation of these response fields from all atoms in a coherent manner. Based on this formula, the transition from domination of a single nonlinear susceptibility term at a given harmonic to comparable contributions of multiple high-order susceptibilities at mid-infrared wavelengths is observed. It occurs at the accessible laser intensities (1010-1012 W/cm2), which decreases with the laser wavelength. The proposed composite approach can be used to find promising gaseous media, including gas mixtures, with improved harmonic generation efficiency.

A Comprehensive Study of Various Types of Combustion Models for Simulation of Secondary Combustion Chamber of Ducted Rocket Using CFD

ABSTRACT The secondary combustion chamber is a critical issue in the design, development, and efficiency of solid-propellant ducted rocket engines. In these engines, the propellant, which is fuel-rich, is incompletely combusted in the first chamber. This incomplete combustion produces a hot gas mixture containing solid particles. These solid particles, after mixing with the hot air stream entering from the air intake in the secondary chamber, complete their combustion, and the final combustion products create thrust by passing through the nozzle. Due to the very short residence time in the secondary combustion chamber, it is essential to study the exact combustion kinetics of the gas-phase fuel and solid particles, as well as the interaction of reaction mechanisms with turbulent flow. In this article, for the first time, the Eddy Dissipation Concept (EDC) approach has been studied to simulate the two-phase reactive flow field in the secondary combustion chamber of a ducted rocket. This approach helps solve the interaction of reactive mechanisms and turbulent flow more accurately and provides a more precise estimate of the combustion chamber’s performance. In this approach, a chemical reaction is considered not only for the gas phase but also for the solid particle phase (DPM), and the chemical reactions of both phases are solved simultaneously and coupled. A 9-step mechanism is used for chemical reactions, including solid carbon particles and 7 gaseous species. Additionally, radiative heat transfer phenomena are considered. The simulation based on the EDC-DPM approach is compared with simulations based on three other combustion approaches: One-stream Non-Premixed (One-stream), Two-stream Non-Premixed (Two-stream), and Finite Rate/Eddy Dissipation Model (EDM/FR). The results show that the simulation based on the EDC-DPM approach is a better match with the experimental data. The estimated temperature, pressure, and engine thrust exhibit only small prediction errors of 3.2%, 3.25%, and 4.78%, respectively. Moreover, the predicted reactive flow field is closer to reality. In contrast, the prediction errors for the One-stream, Two-stream, and EDM/FR combustion models for chamber temperature are 12.54%, 18.56%, and 4.2%, chamber pressure is 3.47%, 17.03%, and 1.48%, respectively, and engine thrust is 4.81%, 22.2%, and 2%, respectively.

Superior Hydrogen Separation in Nanofluidic Membranes by Synergistic Effect of Pore Tailoring and Host-Guest Interaction.

High-purity H2 production accompanied by precise decarbonization paves the way for a carbon-neutral society. Hydrogen-bonded organic frameworks (HOFs) are promising materials for advanced gas separation membranes, but their broad nanoscale pores limit selective separation. High-quality carboxylic acid-based HOF membranes (HOF-S, HOF-M, HOF-L) with pore sizes of 6.2, 16, and 24 Å were synthesized using an innovative pore-tailoring strategy. Under optimized conditions, H2 can pass through while CO2 is blocked by the size-exclusion principle. Abundant carboxylic acid groups in pores hinder the mobility of CO2 via electrostatic interaction, integrating adsorption and molecular sieving to enable excellent H2 transport and separation. The HOF-S membrane combines size exclusion and HOF-CO2 interactions, exhibiting excellent selectivity for H2/CO2 (164) and a ternary gas mixture (H2/CO2 selectivity: 154; H2/CH4 selectivity: 201). It also displays long-term stability under both dry and wet conditions. This strategy opens new possibilities for customizing nanofluidic membranes for advanced gas separation technologies.

Transient simulation of the oscillatory injection of water–ethanol mixtures into an inductively-coupled radio frequency thermal plasma

Abstract This study investigates the effects of oscillatory water–ethanol injection on the temperature, velocity, and species distributions within an inductively-coupled radio frequency (RF) thermal plasma, using a transient 2D-axisymmetric computational fluid dynamics model. The simulation models a TEKNA PL-35 RF plasma torch, operated with an argon–oxygen gas mixture, accounting for various species such as electrons, atoms, molecules, and ions. The water–ethanol solution is injected through a probe into the plasma core with sinusoidal velocity, replicating the effects of a peristaltic pump. Validation of the model is performed through comparison with previously published numerical data, demonstrating good conformity. The study explores the influence of frequency and molar concentration of the injected water–ethanol mixture, and operating pressure on key plasma characteristics, including electron density and temperature distribution. Results indicate that applying an oscillatory velocity pattern for central fluid injection into the plasma reduces the overall plasma temperature, particularly near the probe outlet. Additionally, it leads to a more uniform temperature distribution by decreasing sharp temperature gradients at the torch outlet. Furthermore, higher operating pressures increase electron density, which enhances energy transfer through mechanisms such as electron impact reactions. This improved energy transfer promotes a more uniform temperature distribution, leading to greater plasma uniformity. These results suggest that the oscillatory injection can promote more uniform heating of precursor materials, which is vital for applications such as coating deposition and powder synthesis.

Numerical Simulation of The Operation of Natural Gas Treatment

Natural gas will remain a transitional fuel for many years to come. However, the exploitation of deposits also brings water particles associated with them (with a decrease in their pressure). Therefore, drying natural gas becomes a main activity in providing them as an energy source. In this material, we present a numerical model of the behavior of water in the natural gas mixture and provide data on the use of molecular sieves impregnated with alumina, silica gel, activated carbon, and hygroscopic salts.

Model Test on the Detonation of Hydrogen–Air Mixture Gas in a Closed Cylindrical Tube

Abstract Hydrogen is becoming one of the prospective energy resources, and there are high demands for transporting and storing hydrogen by ships. The safety of transporting hydrogen is one of the very important topics. However, experimental data on hydrogen explosion are still not enough. The purpose of the present study is to obtain experimental data of hydrogen–air mixture gas explosion as well as to investigate the mechanism of “detonation.” Especially, main focus is laid on the visualization of detonation phenomena of hydrogen–air mixture gas using the latest high-speed camera. In order to make a movie of detonation, a transparent cylindrical tube is adopted. Moreover, the structural response of a steel plate subjected to detonation pressure is also investigated. In the present study, a series of detonation experiments is carried out where hydrogen–air mixture gas is stored in a transparent acrylic cylindrical tube and ignited. A steel plate is set at one end of the cylindrical tube in order to investigate structural response due to hydrogen explosives. The shock wave front of detonation is captured using high-speed cameras. The results of the experiment including the form of the shock wave front are discussed in detail.

Atmospheric Pressure Glow Discharge in a Mixture of Carbon Dioxide and Methane

ABSTRACTThe electrical characteristics, emission spectra, and composition of gas products in a DC discharge mixture of CO2 and CH4 at different polarities of the applied voltage and an AC discharge (50 Hz) at atmospheric pressure and different ratios of CO2 and CH4 flow rates have been investigated. The best degree of CH4 decomposition is about 95%. The degree of CO2 decomposition ranges from 85%−95% at a CO2/CH4 consumption ratio equal to one. The best characteristics of the decomposition process are obtained in a direct current discharge under conditions when the cathode is located in the part of the discharge tube opposite to the point of introduction of the gas mixture.

Quantitative Estimation of Micro-sized Particle Deposition in Tracheobronchial Airways

IntroductionAssessment and prediction of health risks caused by exposure to dust particles in ambient air is a relevant task the contemporary healthcare has to tackle. To do it, it is necessary to develop mathematical models that make it possible to estimate introduction of dust particles into the human body.PurposeThe present study focuses on quantification of particles that are deposited in the tracheobronchial (TB) airways (G0–G5) as well as particles able to reach the lungs. We investigate deposition of particles with various sizes and density that are present in ambient air in a large industrial center.MethodsInhaled air is considered a multiphase mixture of a homogenous gas and solid dust particles. We considered non-stationary airflow during light, moderate and vigorous activity.ResultsWe quantified a share of deposited particles (SDP) with various dispersed structure (between 0.5 and 20 µm) and density (1000, 2000, 2700, 4000 kg m–3) in the TB airways; the article provides computed motion paths of particulate matter.Conclusions Particle density mostly influences differences in deposition of micro-sized particles (2.5–20 µm). Deposition of small particles (PM1) slightly depends on particle density and intensity of breathing. Larger particles (2.5–20 µm) are governed primarily by inertial impaction and gravitational settling. As particle sizes and mass go down, SDP in the airways decreases and accordingly there is a growth in the share of particles able to penetrate small airways and reach the lungs. As the micro-sized particles (2.5–20 µm) density increases, the SDP increases, which is typical for all breathing modes. As respiratory intensity increases, SDP grows.Graphical abstract

Исследование влияния фазового состава наночастиц диоксида циркония, осажденных с помощью дугового разряда низкого давления, на фотолюминесцентные свойства

The paper studies zirconium dioxide nanoparticles obtained by arc deposition at low pressure with variable oxygen content in the gas mixture. The phase composition, structural characteristics, and chemical state of zirconium in the samples are confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, and electron paramagnetic resonance. The modification of the phase composition of the samples, which is accompanied by a change in the photoluminescent properties, is discussed. ZrO2 nanopowder in the tetragonal phase demonstrates intense luminescence (λmax = 417 nm) when excited by light with a wavelength of 270 nm. As the phase composition of the nanoparticles changes to the prevailing monoclinic modification, the broad peak in the PL spectra is replaced by three pronounced peaks at 376, 407, and 479 nm. For all samples, the nature of the radiation is associated with impurity states in the band gap. New energy levels are formed by oxygen vacancies and surface defects.

Studying the Sintering Behavior of H2-Reduced Bauxite Residue Pellets Using High-Temperature Thermal Analysis.

Treating bauxite residue as an alternative source of metals for iron and aluminum industry is an approach to promote circular economy in metal industries. Reduction of metal oxides with a H2-based process is an important step for the decarbonization of metal industry. In this study, bauxite residue (BR) pellets were prepared and were reduced with different H2-H2O gas compositions at different temperatures, which yielded with various degrees of reduction. The bauxite residue pellets were made from a mixture of bauxite residue and Ca(OH)2 powders and sintered at 1150 °C. Hydrogen reduction was carried out on the oxide pellets using a resistance furnace at elevated temperatures in controlled reduction atmosphere of H2-H2O gas mixtures, which resulted in the reduction of iron oxides in the pellets. Unreduced and reduced pellets were subsequently heated to 1400 °C to study their sintering behavior during H2 reduction using differential thermal analysis (DTA) and thermogravimetric analysis (TGA) techniques to investigate the evolution of phases related to slag formation. Equilibrium module of Factsage™ was utilized to analyze results of thermal analysis. Both chemical and physical changes that occurred during the sintering process of the H2-reduced BR pellets were successfully detected by TG-DTA analysis, and the initial slag- and gas-phase formation were detected to occur from 900 °C and 1180 °C, respectively. One of the most notable chemical reactions to occur during the analysis was formation of mayenite at 810 °C, which is easily leachable, providing potential for recovery of alumina.