Kinetic Gas Research Articles

Synergistic effect of sulfonated castor oil and porous medium on kinetics of gas hydrates formation

In recent years, interest in gas hydrates has increased as they represent a potential energy source and an alternative to the current environmentally friendly method of storing and transporting natural gas. In this study, the synergistic effect of a new promoting reagent – sulfonated castor oil (SCO) – and a porous medium on the formation and decomposition of methane and methane-propane hydrates was compared to that of sodium dodecyl sulfate (SDS) using the high-pressure differential scanning calorimetry (HP-μDSC) method. DSC tests demonstrated that water conversion in the presence of SCO in a porous substrate for methane hydrates reached 95% at high water saturation, which can be attributed to improved mass transfer in the presence of surfactants. However, this value did not exceed 60% for the hydrate of methane–propane mixture, indicating that the mechanism of promotion of the sI and sII hydrates differs. According to kinetic calculations based on the Avrami equation, both SDS and SCO accelerate the formation of hydrates, but for SCO, this is possible with less supercooling. The calorimetric measurements and kinetic parameter calculations demonstrated that SCO is comparable to the well-known reagent SDS in promoting activity in porous media with varying water saturation.

A multiscale model validated on local current measurements for understanding the solid oxide cells performances

A physical-based model has been developed and validated to unravel the complex relationships between the global solid oxide cells response and the reaction mechanisms taking place in the electrodes. This numerical tool combines three length-scales modules from the electrode microstructure up to the single repeat unit. This model allows computing the local distribution of reaction kinetic rates, current densities, and gas composition as function of the cell operating conditions. To validate the multiscale model, a special experimental setup has been developed to measure the local polarization curves along the cell length. For this purpose, a specific design of the interconnect has been proposed in order to probe the local current density on standard cells. A good agreement has been found between the experimental and simulated data for different operating conditions. The fully validated model has been used to analyze the cell operation in electrolysis and fuel cell modes. The activated reaction pathways associated with the elementary steps in the active layers have been investigated depending on the position along the cell length.

High Power‐ and Energy‐Density Supercapacitors through the Chlorine Respiration Mechanism

AbstractSupercapacitor represents an important electrical energy storage technology with high‐power performance and superior cyclability. However, currently commercialized supercapacitors still suffer limited energy densities. Here we report an unprecedentedly respiring supercapacitor with chlorine gas iteratively re‐inspires in porous carbon materials, that improves the energy density by orders of magnitude. Both electrochemical results and theoretical calculations show that porous carbon with pore size around 3 nm delivers the best chlorine evolution and adsorption performance. The respiring supercapacitor with multi‐wall carbon nanotube as the cathode and NaTi2(PO4)3 as the anode can store specific energy of 33 Wh kg−1 with negligible capacity loss over 30 000 cycles. The energy density can be further improved to 53 Wh kg−1 by replacing NaTi2(PO4)3 with zinc anode. Furthermore, thanks to the extraordinary reaction kinetics of chlorine gas, this respiring supercapacitor performs an extremely high‐power density of 50 000 W kg−1.

High Power- and Energy-Density Supercapacitors through the Chlorine Respiration Mechanism.

Supercapacitor represents an important electrical energy storage technology with high-power performance and superior cyclability. However, currently commercialized supercapacitors still suffer limited energy densities. Here we report an unprecedentedly respiring supercapacitor with chlorine gas iteratively re-inspires in porous carbon materials, that improves the energy density by orders of magnitude. Both electrochemical results and theoretical calculations show that porous carbon with pore size around 3 nm delivers the best chlorine evolution and adsorption performance. The respiring supercapacitor with multi-wall carbon nanotube as the cathode and NaTi2 (PO4 )3 as the anode can store specific energy of 33 Wh kg-1 with negligible capacity loss over 30 000 cycles. The energy density can be further improved to 53 Wh kg-1 by replacing NaTi2 (PO4 )3 with zinc anode. Furthermore, thanks to the extraordinary reaction kinetics of chlorine gas, this respiring supercapacitor performs an extremely high-power density of 50 000 W kg-1 .

Rationale Behind EU-DEMO Limiter’s Plasma-Facing Component Design Under Material Phase Change

The protection strategy adopted for the European DEMOnstration (EU-DEMO) fusion power reactor foresees the use of sacrificial components–referred to as limiters–dealing with plasma-wall contacts. Their aim is to protect the first wall (FW) against the huge amount of plasma energy (up to GigaJoules) released in a few milliseconds during disruptive events, which might lead to melting and/or vaporization of the foreseen plasma-facing tungsten armor. The current limiter design concepts rely on actively water-cooled plasma-facing components (PFCs) made of tungsten. As water is not allowed inside the main chamber, limiter’s PFCs must be designed to preserve the cooling system integrity under any scenario, therefore the estimate of the thickness of material undergoing any phase change is crucial. Given the initial assessment of plasma magnetic configurations during off-normal events, this article describes the procedure followed for designing the limiter’s PFC, which includes a novel approach for estimating the molten thickness of material under high heat flux. A simplified 1-D model has been implemented in MATLAB, which deals with multiphase moving boundary problems, hence its name Thermal Analysis foR Tracking InterFaces under meLting&vaporizaTion-induced plasma Transient Events (TARTIFL&TTE). This model takes its inspiration from the way phase change interface tracking problems are tackled in food industry (i.e., freeze-drying processes) and solute concentration diffusion-controlled problems. It overcomes the complexity of solving a strongly coupled non-linear system of partial and ordinary differential equations in moving spatial domains by adopting a change of coordinate system based on the Landau transformation. As a result, an equivalent and fixed spatial coordinate system is defined where the spatial domain boundaries of the different phases are constrained, and the systems of governing equations are easy to solve. Both the solid and liquid phases are modeled, while the vapor is assumed to be removed once formed. Its benchmark against computational results found in the literature has shown a very good agreement, which paves the way to further development of it. For phase change interface tracking problems in 2-D/3-D and more complex geometries, a commercial Multiphysics software adopting the Lagrangian–Eulerian approach in moving mesh frames will be used for tackling problems where material is removed following a phase change. Although the vapor domain is not simulated, a set of gas kinetics boundary conditions couples the interface between vapor and liquid phases, driving its position over time. This will be detailed described in a future companion article.

Controlled Covalent Functionalization of ZIF-90 for Selective CO2 Capture & Separation.

Mixed Matrix Membranes (MMM) with enhanced selectivity and permeability are preferred for gas separations. The porous metal-organic frameworks (MOFs) materials incorporated in them play a crucial part in improving the performance of MMM. In this study, Zeolitic imidazolate frameworks (ZIF-90) are selected to fabricate Polyetherimide (PEI) MMMs owing to their lucrative structural and chemical properties. This work reports new controlled post-synthetic modifications of ZIF-90 (50-PSM-ZIF-90) with ethanolamine to control the diffusion and uptake of CO2. Physical and chemical properties of ZIF-90, such as stability and presence of aldehyde functionality in the imidazolate linker, allow for easy modulation of the ZIF-90 pores and window size to tune the gas transport properties across ZIF-90-based membranes. Effects of these materials were investigated on the performance of MMMs and compared with pure PEI membranes. Performance of the MMMs was evaluated in terms of permeability of different gases and selective separation of CO2 and H2 gas. Results presented that the permeability of all membranes was in the following order, i.e., P(H2) > P(CO2) > P(O2) > P(CH4) > P(C2H6) > P(C3H8) > P(N2), demonstrating that kinetic gas diffusion is the predominant gas transport mode in these membranes. Among all the membranes, permeability of pure PEI membrane was highest for all gases due to the uniform porous morphology. The pure PEI membrane showed highest permeability of H2, which is 486.5 Barrer, followed by 49 Barrer for O2, 29 Barrer for N2, 142 Barrer for CO2, 41 Barrer for CH4, 40 Barrer for C2H6 and 39.6 Barrer for C3H8. Results also confirm the superiority of controlled PSM-ZIF-90-PEI membrane over the pure PEI and ZIF-90-PEI membranes in CO2 and H2 separation performance. The 50-PSM-ZIF-90 PEI membrane exhibited a 20% increase in CO2 separation from methane and a 26% increase over nitrogen compared to the ZIF-90-PEI membrane. The 50-PSM-ZIF-90 PEI membrane showed 15% more H2/O2 separation and 9% more H2/CH4 separation than ZIF-90 PEI membrane. Overall, this study represents the role of controlled PSM in enhancing the property of new materials like ZIF and its application in MMMs fabrication to develop a promising approach for the CO2 capture and separation.

RETRACTION NOTICE: Pareto-based allocations of multi-type flexible AC transmission system devices for optimal reactive power dispatch using Kinetic Gas Molecule Optimization algorithm

RETRACTION NOTICE: Pareto-based allocations of multi-type flexible AC transmission system devices for optimal reactive power dispatch using Kinetic Gas Molecule Optimization algorithm

Influence of Pyrolysis Gas Composition and Reaction Kinetics on Leaf-Scale Fires

ABSTRACT The impact of pyrolysis gas composition and the underlying reaction kinetics on the burning characteristics of a leaf was computationally investigated. The computational configuration resembled a previous experimental setup where vertically oriented manzanita (Arctostaphylos glandulosa) leaves were burned. Different compositions and reaction kinetics for the pyrolysis gas released during the leaf thermal decomposition were examined. The most detailed composition included , , , and , which was suggested by the previous experimental study of pyrolysis products of different plant species. The least involved compositions only included either or . In all considered compositions, in addition to pyrolysis gas, the release of the heavy gas, i.e. tar, was accounted for. Tar breakdown was represented by a single-step reaction with the light gases above and soot as the products where the stoichiometric coefficients were determined by an optimization technique for consistency with the measurements for the tar molecule. The burning simulation results agreed best with the previous experimental data when a mixture of , , was used. The least agreement was noted when pyrolysis gas was represented by only . Inclusion of tar breakdown reaction appreciably increased the overall heat release due to combustion of its products above the leaf.

Changes in metabolic gas kinetics on exposure to heat stress

Objectives: Heat stress is one of the major stressors in military aviation with the potential to adversely affect the efficiency of the aircrew and hence flight safety. Metabolic rate (MR) increases on exposure to heat and metabolic gases are considered as a proxy for MR. This study examined the influence of heat stress on metabolic gas kinetics in healthy Indian males and assessed the duration of attaining normal baseline values of metabolic gases post-exposure. Materials and Methods: In 16 healthy male volunteers, cardiorespiratory variables, including metabolic gases (oxygen uptake [VO2], carbon dioxide output [VCO2], minute ventilation [VE], breathing frequency [BF], and heart rate [HR]), were recorded before and approximately 2 h after a standard meal. The subjects were then exposed to a simulated temperature of 40°C with a relative humidity of 70% for 1 h in the environmental chamber. Same physiological parameters were recorded at the end of 30 min and 60 min during heat exposure and up to 90 min following exposure to heat stress at an interval of 30 min. Results: A significant increase (P < 0.001) in mean VO2 (ml/Kg/min) was observed post-meal (1.49 ± 0.95) as well as at 30 min (1.17 ± 0.96) and at 60 min (2.14 ± 1.19) of heat exposure. A similar increase (P < 0.05) in mean VCO2 was observed post-meal and following heat exposure. VE (L/min) increased by 12.12% post-meal (P = 0.01), 16.16% (P < 0.001) at 30 min, and 19.65% (P < 0.001) at 60 min of heat exposure. There was a significant increase in mean BF (per min) during heat exposure (2.31 ± 1.24 at 30 min and 3.53 ± 1.05 at 60 min) and till 60 min of the recovery period compared to baseline (P < 0.001). HR (bpm) increased by 14 bpm at 30 min and 17 bpm at 60 min of exposure and till 30 min after elimination of heat stress (P < 0.001). Conclusion: A statistically significant increase was observed in VO2, VCO2, VE, BF, and HR on exposure to heat stress. Optimal recovery was observed after 30 min of eliminating the heat stress for VO2 and VCO2. Similar recovery was observed after 60 min of eliminating the heat stress for HR and following 90 min for VE and BF. Hence, if the crew is required to continue to operate in the heat stress environment, a minimum period of 90 min of a break in between the sorties must be ensured in a relatively cooler environment.

Programming xenon diffusion in maltose-binding protein

Protein interiors contain void space that can bind small gas molecules. Determination of gas pathways and kinetics in proteins has been an intriguing and challenging task. Here, we combined computational methods and the hyperpolarized xenon-129 chemical exchange saturation transfer (hyper-CEST) NMR technique to investigate xenon (Xe) exchange kinetics in maltose-binding protein (MBP). A salt bridge ∼9 Å from the Xe-binding site formed upon maltose binding and slowed the Xe exchange rate, leading to a hyper-CEST 129Xe signal from maltose-bound MBP. Xe dissociation occurred faster than dissociation of the salt bridge, as shown by 13C NMR spectroscopy and variable-B1 hyper-CEST experiments. “Xe flooding” molecular dynamics simulations identified a surface hydrophobic site, V23, that has good Xe binding affinity. Mutations at this site confirmed its role as a secondary exchange pathway in modulating Xe diffusion. This shows the possibility for site-specifically controlling xenon protein-solvent exchange. Analysis of the available MBP structures suggests a biological role of MBP’s large hydrophobic cavity to accommodate structural changes associated with ligand binding and protein-protein interactions.

Selective adsorption and separation of light hydrocarbon gases in VI/IV dipeptide crystals

The separation of propane/propylene mixtures remains a subject under intensive research because designing cheaper, greener and sustainable processes is of paramount importance to industry. Dipeptides crystallize into several lattices displaying a variety of porosities that enable the separation of species with approximate size. In this study, we show that microporous crystals of L-Isoleucyl–l-Valine (IV) and L-Valyl-l-Isoleucine (VI) are able to distinguish between methane, propane and propylene. Adsorption equilibrium isotherms were determined and coupled with Molecular Dynamics simulations for computing diffusion and loading of binary mixtures of relevant gases in the dipeptide frameworks to obtain kinetic and equilibrium gas mixtures selectivities. It was found that although the pore diameters in both dipeptide crystals are similar, VI has a higher permselective separation of propane/propylene mixtures displaying a maximum ideal permselectivity of αP(C3H6)/C3/H8) = 1.3.

Local Average Based Kinetic Gas Molecular (LA-KGMO) Optimized MR Brain Image Segmentation Using Modified Self Organizing Map (MSOM)

Local Average Based Kinetic Gas Molecular (LA-KGMO) Optimized MR Brain Image Segmentation Using Modified Self Organizing Map (MSOM)

Free expansion of an ideal gas by kinetic gas theory

We consider the adiabatic free expansion of an ideal gas. According to classical thermodynamics, the internal energy of the gas is not affected by the expansion, but kinetic gas theory predicts an average energy difference between escaping and remaining gas. This difference is transient if the gas escapes into a finite volume, consistent with the equilibrium prediction of classical thermodynamics. For escape into an infinite volume, classical thermodynamics is not applicable. Numerical calculations of the magnitude of the predicted effect are provided.

Tropical Plant Phytonutrient Improves the Use of Insect Protein for Ruminant Feed

This work aimed to examine the effects of binding proteins from Gryllus bimaculatus with Sesbania grandiflora phytonutrient on gas dynamics, in vitro digestibility, and ruminal fermentation characteristics. For rumen fluid sources, two dairy bulls with permanent cannulas were used as donors. G. bimaculatus and S. grandiflora powder were combined in the following ratios: 100:0, 99:1, 98:2, 97:3, 96:4, 95:5, 94:6, and 93:7. As 7% of S. grandiflora and 3% of G. bimaculatus were combined, the rumen undegradable protein increased by 45.8% when compared to the control group (p < 0.05). All gas kinetics were not substantially different across treatments, except for cumulative gas output during 96 h of incubation (p < 0.05). Comparing the G. bimaculatus powder to S. grandiflora at a ratio of 95:5 to 93:7 revealed an increase in cumulative gas production (p < 0.05), compared to the other groups. Reduction of G. bimaculatus resulted in a linear increase of in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD) at 24 h after incubation. The lowest level of G. bimaculatus—93% with 7% S. grandiflora—showed the greatest IVDMD and IVOMD (p < 0.05) when compared with the control group. Ruminal pH in all treatments remained constant after 4 and 8 h of in vitro incubation (p > 0.05). However, as the quantity of S. grandiflora in the sample increased, the concentration of ammonia-nitrogen (NH3-N) linearly decreased (p < 0.05). Compared to the control group, the NH3-N concentration at 4 h of incubation was decreased by 47% when 7% S. grandiflora and 93% G. bimaculatus were mixed. The alteration in the G. bimaculatus to S. grandiflora ratio did not affect the levels of acetic acid or butyric acid. However, when 93% of G. bimaculatus was combined with 7% of S. grandiflora at hour 4 of incubation, propionic acid concentration was moderately increased (p < 0.01) by 6.58 mmol/L. In conclusion, combining 93% G. bimaculatus with 7% S. grandiflora powder enhanced protein utilization, in vitro digestibility, propionate concentration, and cumulative gas production.

Gas kinetics of galactic disks explains rotation curves of S-type galaxies without a need for dark matter

In this paper, I show that the generally accepted methods of classical mechanics are not applicable for calculating the outer parts of the rotation curves (RCs) of galaxies, where the influence of collisions on gas dynamics becomes dominant. In addition, the hydrodynamic approach cannot be used for this purpose due to an extreme rarefaction of the gas. I develop a new approach for describing the gas dynamics in outer regions of galactic disks, where the gas dynamics is determined mainly by collisions. Equations (free from restrictions imposed on hydrodynamics) are obtained that describe the dynamics of rarefied gas. The resulting equation [Formula: see text] (14) relates two quantities: the tangential velocity of the gas as a function of the distance from the center of a galaxy (RC) and the radial distribution of the gas density. It is shown that if the physical properties of the rarefied gas are properly taken into account, then dark matter (DM) is not required, and the “nonphysical” (non-Keplerian) RCs of the outer parts of the galactic disks are tailwinds that can be described within the framework of conventional gas kinetics. To illustrate the correctness of the obtained model, two galaxies with flat RCs (NGC7331 and NGC3198) are considered. From the observed RCs, using Eq. ( 14 ), the radial densities of the gas are calculated. An excellent agreement was obtained between the calculated gas densities and their observed values, which is a serious argument in favor of the developed model. Thus, the nonphysical RCs of spiral galaxies represent the tailwinds of gas, the dynamics of which is naturally described by the kinetic equation without involving the concept of DM. Total masses of two galaxies NGC7331 and NGC3198 have been calculated. Implications for cosmology are discussed.

Low-pressure ozone injection system: relationship between reaction kinetics and physical properties of grains.

The ozonation of grains in a closed system at low pressure is a strategy with the potential for treating packaged products. Research is necessary to characterize the reaction kinetics of ozone in this type of injection system so that it is possible to design chambers and determine the ozone concentrations suitable for commercial-scale applications. The objective of this study was therefore to characterize the low-pressure ozone injection system in relation to the physical properties of the grains and determine possible changes in their quality. Samples (5 kg each) of common beans, cowpea beans, corn, popcorn kernels, paddy rice, and polished rice were exposed to ozone in a 70 L hypobaric chamber. Initially, the internal pressure of the chamber was reduced to 500 hPa. Then, ozone was injected at a concentration of 32.10g m-3 at a volumetric flow rate of 1L min-1 until reaching a pressure of 1000 hPa. To relate the decomposition of ozone to the grains that were being evaluated, different physical properties were determined, and quality analysis was conducted. Ozone gas half-life outside and inside the package depended on the grain type. Ozone decomposition was quickest in polished rice and slowest in common beans. The half-life of the different grains ranged from 17.8 to 52.9 and 16.4 to 52.9min, outside and inside the package, respectively. Considering the physical properties, specific surface (Ss), surface area (SA), and sphericity (φ) exhibited a significant correlation with the decomposition rate constant (k) of ozone. However, the variables volume (V), permeability (K), porosity (ε), and specific mass (ρ) showed no correlation with k. The physical properties of grain influenced the reaction kinetics of ozone gas during the low-pressure injection process. Ozone gas injection at low pressures did not alter the quality attributes of the grains under study. © 2022 Society of Chemical Industry.

Kinetic Modeling for the Gas-Phase Hydrogenation of the LOHC γ-Butyrolactone–1,4-Butanediol on a Copper-Zinc Catalyst

Liquid organic hydrogen carriers (LOHCs) are an interesting alternative for hydrogen storage as the method is based on the reversibility of hydrogenation and dehydrogenation reactions to produce liquid and safe components at room temperature. As hydrogen storage involves a large amount of hydrogen and pure compounds, the design of a three-phase reactor requires the study of gas and liquid-phase kinetics. The gas-phase hydrogenation kinetics of LOHC γ-butyrolactone/1,4-butanediol on a copper-zinc catalyst are investigated here. The experiments were performed with data, taken from the literature, in the temperature and pressure ranges 200–240 °C and 25–35 bar, respectively, for a H2/γ-butyrolactone molar ratio at the reactor inlet of about 90. The best kinetic law takes into account the thermodynamic chemical equilibrium, is based on the associative hydrogen adsorption and is able to simulate temperature and pressure effects. For this model, the confidence intervals are at most 28% for the pre-exponential factors and 4% for the activation energies. Finally, this model will be included in a larger reactor model in order to evaluate the selectivity of the reactions, which may differ depending on whether the reaction takes place in the liquid or gas phase.

Experimental study on non-isothermal oxidative characteristics and kinetics of methane in accelerating rate calorimetry tests

The non-isothermal oxidative characteristics and kinetics of natural gas have important effects on performance of gas reservoir combustion, which directly determines temperature distribution, playing a significant role in hydrogen generation boundary. In this paper, the non-isothermal oxidation of methane, as main component of natural gas, is in depth analysis, which is rarely studied. At first, the non-isothermal oxidative characteristics at different pressure, oxygen/methane ratio, and debris were investigated by accelerating rate calorimetry (ARC). Afterwards, the non-isothermal oxidation kinetic parameters were analyzed and calculated. The difference of onset self-exothermic, ignition temperature, and kinetics parameters under different conditions were extraordinarily emphasized, aiming achieving successful and stable gas reservoir combustion for high efficiency hydrogen production. The results indicated that there is no even self-exothermic phenomenon at depleted reservoir condition (7.1–9.8 MPa and 100–150 °C), and the minimum starting self-exothermic temperature ignition temperature of methane oxidation are 220.6 °C and 312.7 °C. The pressure did not have effect on oxidation temperature in methane oxidation while did in catalytic oxidation. It was observed that rock debris has catalytic effect on methane oxidation suggested by obviously lower onset self-exothermic temperature detected and significantly smaller activation energy calculated in oxidation process of methane with debris. Moreover, the oxidation reaction rate of methane with debris is lower than that of methane, assisting more methane undergoes a more thorough HTO reaction conducive to combustion and decreasing the possibility of explosion in the injection air ignition process. According to the results obtained by ARC tests, we suggested that the near-wellhole places of gas reservoirs should be better heated over 313 °C for successfully achieving stable combustion. Some new knowledge got from this study is conducive to achieve rapid and stable combustion, thus achieving high-efficiency hydrogen generation.

A novel model of reaction specific surface area via depressurization and thermal stimulation integrating hydrate pore morphology evolution in porous media

Reaction specific surface area (RSSA) of hydrate is essentially important for hydrate kinetic dissociation and gas production from hydrate-bearing sediment. Models of RSSA available in literatures neglecting hydrate pore morphology evolution and methods induced hydrate dissociation could not capture the characteristic of RSSA evolution accurately. In this study, a novel model using logistic function to link microscale hydrate pore morphology evolution with macroscale RSSA variations was proposed, and verified by different published laboratory data and compared with other models. The introduced critical hydrate saturation and transitional intensity of hydrate pore morphology were optimized by genetic algorithm. Results indicated that the critical hydrate saturation and transitional intensity of hydrate pore morphology dominated the characteristics of RSSA evolution. The RSSA evolution was orderly divided into four stages named ‘high Sh pore wall coating dominated’, ‘high Sh pore filling dominated’, ‘low Sh pore filling dominated’ and ‘low Sh pore filling only’ in both method of hydrate dissociation by depressurization and thermal stimulation. In addition, the RSSA for depressurization was lower than that of thermal stimulation at the same hydrate saturation due to annulus hydrate by thermal stimulation. Grain size and arrangement factor significantly influenced RSSA, which showed a negative correlation. The proposed model brings reliable predictions and mechanistic understandings of the RSSA evolution in hydrate-bearing sediment, and builds fundamental theory for development of natural gas hydrate in safety and efficiency.

Off-Gas System Scale-Up of HIsarna Iron-Making Process: A CFD-Based Approach

For all industrial applications, predicting system characteristics and behavior plays a vital role before constructing costly and complex multi-physic systems. Correct and reliable predictions become even more important once the aim is to go from small- to large-scale processes to establish an industrial demonstrations. In this study, a CFD-based scale-up of HIsarna off-gas system based on the Eulerian–Lagrangian approach is investigated and detailed step in scale-up procedure is discussed. A three-dimensional CFD model is developed and validated based on the available pilot scale data and used to design and scale up the post-combustion chamber (also known as reflux chamber). Detailed kinetics for volumetric and gas–solid reactions are incorporated in validated CFD model with a special attention to the wall boundary condition and modeling. The effect of reflux chamber geometry, oxygen injection ports, oxygen injection flowrate, isolation wall thickness, and inlet flue gas composition on different system characteristics such as heat loss through the wall, CO–H2–carbon mixture conversion, flue gas, and wall temperature are investigated. The aim of the scaled up geometry, like pilot scale, is to achieve full combustion of unwanted species inside the reflux chamber to assure zero emissions from the off-gas system. Compared to the pilot scale, the scaled up reflux chamber is capable of handling and removing higher amount of unwanted species coming from the main reactor and therefore lower CO–H2 and carbon particle emissions, mainly due to a larger size which provides larger volume and residence time for volumetric and gas–solid reaction to proceed.