Gas Contact Research Articles

Surface interaction changes in minerals for underground hydrogen storage: Effects of CO2 cushion gas

Hydrogen (H2) offers a promising solution for the energy transition but storing it on a large scale at the surface poses significant technical and environmental challenges. Underground formations provide a practical alternative for large-scale H2 storage, yet understanding H2 behavior under various subsurface conditions is crucial for optimizing storage capacity and efficiency, which are influenced by rock properties such as wettability. This study addresses the gap in literature regarding the wettability of different minerals when CO2 was injected with H2 as a cushion gas. We examined the wettability of various mineral rocks in realistic subsurface circumstances. A series of wettability measurements were carried out using a captive drop instrument under high-pressure and high-temperature conditions, employing seven different minerals.Our findings reveal that mixed gas contact angles are significantly affected by temperature and pressure, with CO2 playing a crucial role in minimizing hydrogen trapping and enhancing CO2 capture in UHS and Carbon Capture, Utilization, and Storage (CCUS) projects. Higher CO2 mole fractions lead in increased contact angles due to the enhanced density and solubility of the gases, especially in basalt. Increasing the CO2 mole fraction from 25 % to 75 % at a constant pressure of 100 bar and temperature of 60 °C caused the contact angle of basalt with brine to rise from 54° to 86°. Pressure has a more pronounced effect on contact angle changes than temperature. For quartz rock in a 50 % H2 + 50 % CO2 mixture, the contact angle changes by 18° when the temperature increases from 20 °C to 80 °C at a constant pressure of 70 bar in distilled water. In contrast, the contact angle changes by 36° when the pressure increases from 10 bar to 100 bar at a constant temperature of 40 °C.These insights are essential for selecting suitable rock formations for underground gas storage, thereby supporting the advancement of hydrogen storage technologies. Furthermore, utilizing CO2 improves technical performance and environmental sustainability while also supporting international efforts to reduce greenhouse gas emissions. Overall, our results offer insightful information about the planning and operation of underground hydrogen storage systems, emphasizing the potential of CO2 to increase storage effectiveness and support carbon sequestration initiatives.

Estimation of gas diffusion coefficient for gas/oil-saturated porous media systems by use of early-time pressure-decay data: An experimental/numerical approach

This paper presented a novel numerical method for estimating the gas diffusion coefficient based on the early-time pressure-decay data. Experimentally, “flooding–soaking” procedures were developed to perform the gas diffusion in an oil-saturated tight core under different gas phase volume conditions. After flooding, the capillary bundle model was used to calculate the oil–gas contact area. The early-time pressure-decay data of the gas phase were monitored and recorded during the soaking process. Theoretically, a non-equilibrium inner boundary condition coupled with the characteristics of experimental early-time pressure had been incorporated to develop a diffusion model for a gas/oil-saturated tight core system. Based on gas-phase mass balance equations and gas equation of state, the diffusion coefficients were optimized once the discrepancy between experimental data and numerical solutions was minimized. According to the estimated results in this study, the CH4 diffusion coefficients were 3.74 × 10−11 and 3.86 × 10−11 m2/s in tight core saturated with crude oil, respectively. Moreover, the oil–gas contact area significantly impacts the diffusion flux in oil-saturated porous media. Specifically, an additional 10% contact area results in a 75% increase in CH4 diffusion mass. In addition, with the application of our proposed model to CH4/bitumen and CO2/bitumen systems, the diffusion coefficients were in close agreement with the results reported in previous literature, indicating that the proposed model was applicable to both gas/liquid and gas/liquid-saturated porous media systems.

Study Finds Compact Carbon-Capture Modules Feasible on Offshore Production Facilities

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 34825, “Implementation of Compact Carbon-Capture Modules on Offshore Hydrocarbon Production Facilities,” by Jaime H. Tan and Rizal A. Hassan, Technip Energies, and Umberto Cornelis, KANFA, et al. The paper has not been peer reviewed. Copyright 2024 Offshore Technology Conference. _ Carbon capture and storage has been implemented onshore successfully by different industries, including utilities and waste treatment, to capture CO2 from flue gases after the combustion of fossil fuels. Duplicating this success for offshore hydrocarbon processing facilities can be challenging because of deck-space constraints and marine environmental conditions. The complete paper describes the development of a compact carbon-capture module design for post-combustion carbon capture and its potential implementation on typical offshore hydrocarbon production facilities. Solvent Absorption Technology for Post-Combustion Carbon Capture The process technology at the core of the compact carbon-capture module is based on a solvent-absorption technique and a proprietary amine-based solvent. First, feed gas is quenched and saturated in a circulated water prescrubber. The gas contacts the lean amine solution in a countercurrent mass-transfer packed absorption column, and CO2 is absorbed while the treated gas exits to the atmosphere. Midway through the column, partially loaded amine is removed from the tower, cooled, and reintroduced over a layer of mass-transfer packing. CO2-rich amine from the absorption column is pumped through a lean-rich amine heat exchanger and then to the regeneration column. The rising, low-pressure saturated steam in the column regenerates the lean amine solution. CO2 is recovered as a pure, water-saturated product. Lean amine is pumped from the stripper reboiler to the absorption column for reuse in capturing CO2. Finally, the CO2 is directed to byproduct-management systems. The pure CO2 streams produced from the system may be sequestrated or used for applications such as enhanced oil recovery. Design of Offshore Carbon-Capture Modules For offshore applications, the carbon-capture modules must be more compact and lighter compared with carbon-capture systems developed for onshore applications. The absorber column is the critical component of the carbon-capture module because of its weight, footprint, and height. To reduce the overall height of the absorber for offshore application, an innovative configuration has been adopted: The bottom section of the absorber is placed on top of the prescrubber/direct contact cooler (DCC), and the top section of the absorber and the wash-water section comprise the second column. With this arrangement, the maximum height of the columns is limited to approximately 25 m. Because the lower absorber section is placed on top of the prescrubber/DCC, the in-between chimney tray is designed to be totally leakage-free to avoid losses of amines into the DCC water loop. A patent-pending compact absorber column design has been developed. The column wall construction will be a part of the overall module support structure, with cantilevered platforms for supporting carbon-capture equipment. The equipment for compression, injection, and treatment of CO2 is placed on a separate submodule. This module design benefits from footprint and weight savings of potentially more than 20% compared with typical cylindrical absorber column designs.

Antimicrobial and Antifungal Effects of Essential Oils from Origanum vulgare, Lavandula officinalis, and Syzygium aromaticum on Bacterial Strains through Gaseous Contact

Background: Hospital-acquired infections, also known as nosocomial infections, affect thousands of patients worldwide. In Algeria, these infections raise significant concerns and give rise to numerous questions due to hygiene deficits and non-compliance with preventive measures. Objective: The main objective of this study was to investigate the antibacterial and antifungal properties of Origanum vulgare, Lavandula officinalis, and Syzygium aromaticum, as well as their combinations, to discover new antibacterial and antifungal agents to combat nosocomial infections related to hospital and medical care environments. Materials and Methods: Essential oils were obtained by a Clevenger-type apparatus and analyzed using GC and GC/MS. The antimicrobial and antifungal activity was tested against several bacteria responsible for nosocomial infections in in-vitro tests using the gas contact method in sealed containers. Results: The essential oil extracted from S. aromaticum buds was primarily composed of eugenol (59.4%), E-β-caryophyllene (16.5%), and eugenyl acetate (10.5%). The analysis of the chemical composition of L. officinalis essential oil identified 1,8-cineole (22.8%), β-pinene (12.4%), and linalool (8.5%) as the main compounds. As for O. vulgare essential oil, its major components were carvacrol (72.6%) and thymol (10.5%). The results revealed that the essential oils of L. officinalis, O. vulgare and S. aromaticum, as well as their combinations, used at a concentration of 1/10, had a remarkable effect on the E. coli, P. aeruginosa and K. pneumoniae strains. In contrast, they had a limited effect on the Gram-positive strain, S. aureus. The antifungal effectiveness of the essential oil of O. vulgare, as well as the combination of O. vulgare and S. aromaticum, has been remarkable against the C. albicans species, leading to a complete inhibition of yeast growth Conclusion: Our results indicate that our essential oils have a broad spectrum of antimicrobial activity, which makes them particularly useful as disinfectants in health facilities and could be used as a valuable medicine to control nosocomial infections and avoid infections acquired during a stay in a health facility such as respiratory tract infections and urinary tract infections.

Jet slipping mechanism and fabricating of composite fiber by multiple field coupling

AbstractThe rotary jet spinning process involves the joint action of centrifugal force, gravity, temperature, humidity, and flow fields on the spinning solution. The solution is ejected through the nozzle after flowing from the storage container and stretched in the air to form a composite fiber. At present, the investigation of rotary jet composite spinning primarily focused on the dynamics and kinematics of the spinning solution and jet within the container. However, there is still a lack of comprehensive exploration into the motion and slip phenomena exhibited by the composite spinning solution in air. This article investigates the slip phenomenon between the polymer and the gas contact surface after the spinning solution leaves the spinneret aperture. A slip model is established to analyze the motion and force of the polymer in air. Meanwhile, a mathematical model for the evaporation rate of composite spinning solution motion under the influence of multi‐field coupling is established through theoretical analysis. A numerical simulation of the rotary jet spinning process was conducted to obtain clouds of jet exit velocity. The morphology of composite fibers produced by rotary jet spinning was analyzed using scanning electron microscopy, enabling a comparison of diameter distribution and surface quality under different environmental and equipment parameters. This study provides a certain reference for the preparation of high‐quality composite fibers.

Multi-channel capillary bioreactor for hydrophobic VOC and CO2 abatement – Process intensification through silicone oil addition

A multi-channel capillary bioreactor devoted to the continuous abatement of hydrophobic volatile organic compounds (VOCs) by a bacterial and bacterial/microalgae consortium was investigated for 200 days. Toluene, α-pinene and hexane removal in the capillary bioreactor was up to 99 %, 98 %, and 55 %, respectively, which is remarkably high considering the low gas contact time of less than 1 second. Addition of silicone oil increased the removal efficiency (RE) of α-pinene within two days from 45 ± 6 % to 98 ± 2 %, probably through alleviation of biokinetic inhibition provided by the oil acting as buffer for the α-pinene and/or its metabolites. The RE of toluene increased after silicone oil addition over a period of about eight weeks from 81 ± 3 % to 99 ± 1 %, most likely via microbial adaptation. On the contrary, the removal of hexane did not increase following silicone oil addition, potentially due to the inhibition of hexane or its metabolites as the bioreactor was deliberately operated without replenishing the recirculation liquid. Interestingly, biomass adhered to the silicone oil phase rather than residing in the water phase. The bacterial diversity was substantially enhanced, and probably contributed to the observed stable performance of the capillary bioreactor. After the introduction of microalgae on day 150, lower CO2 concentrations at the outlet compared to the inlet were observed immediately. A net CO2 consumption was recorded, achieving complete carbon sequestration from the removed VOCs, along with additional CO2 removed from the inlet ambient air.

Natural Structural Transition of Gas Hydrates From sI to sII in the Deep Seafloor

AbstractThe evolution of gas hydrates influenced by the seawater environment is unknown. We present a model of structural transformation from sI hydrate to sII hydrate due to the influence of seawater environment and vent fluid in nature through in situ experiments of gas hydrate formation in the Haima cold seep area. The in situ experimental results indicate that gas hydrates preferentially form as sI hydrates even in cold seep environments where C2+ hydrocarbons are present. During subsequent evolution, the sI hydrates could restructured at the effect of seawater environment and vent fluid, causing transformation to sII hydrates under the influence of hydrate stability. The supply of gas and direct contact with seawater environment are critical factors for structural transformation. Such structural transformation is the result of gas hydrates seeking thermodynamic stability and may be common in active cold seep areas.

Research on Resource Recovery and Disposal of Copper-Containing Sludge.

Copper-containing sludge is a common by-product of industrial activities, particularly electroplating and metal processing. This type of sludge contains high concentrations of heavy metals such as copper, which can pose a potential threat to the environment. Therefore, its treatment and disposal require special attention. Due to its efficient mass and heat transfer characteristics, the suspended state technology has shown significant potential for application in a number of key processes, including the drying, decomposition, and reduction of copper-containing sludge. This paper presents an in-depth analysis of the current status of the application of the suspended state technology in the treatment of copper-containing sludge. Based on this analysis, a device for the treatment of copper-containing sludge in the suspended state was designed, through which the characteristics of copper-containing sludge in the oxidative decomposition and reduction phases are investigated. The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were initially employed to investigate the relationship between the influencing factors and the conversion rate of copper oxides. This was followed by a single-factor influence study, which led to the determination of the optimal process parameters for the decomposition experiments of the Cu-containing sludge in an oxidizing atmosphere. The 100 μm Cu-containing sludge was reacted with 10% O2 gas at a flow rate of 1 m/s for 3 min under the condition of 900 °C. The process parameters were then determined as follows: The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were employed to investigate the relationship between the influencing factors and the copper conversion rate. This was followed by a single-factor influence study, which determined the optimal process parameters for the copper-containing sludge reduction experiments. The 200 μm copper-containing sludge was reacted for 5 min at a flow rate of 7% carbon monoxide at a flow rate of 1.5 m/s under the condition of 800 °C.

MASSTRANSFER FEATURES IN THE APPARATUSES WITH A MOVING NOZZLE IN A THREE-PHASE FOAM LAYER

The improvement of heat and mass exchange equipment for sorption processes in the countercurrent contact of gas and liquid in combined block elements with a weighted spherical nozzle, as well as a more in-depth study of this process, is an urgent task of chemical technology. A fundamentally new type of ball-shaped three-dimensional mesh fluidized nozzle was developed and researched, the bodies of which are made of polymer layers with holes, and a freely coiled metal or polymer mesh is located inside. The nozzle has a high specific surface area, developed free volume and low bulk density. The study of mass transfer in the liquid and gas phases was carried out and the corresponding calculation equations were obtained. Dependencies for the calculation of the mass transfer coefficients and the efficiency of the combined block element on the mode and design parameters are established. The results of calculations based on the obtained dependencies show a sufficient correlation with the experimental data. The proposed model of the desorption process of carbon dioxide from water, which allows predicting the values of the efficiency indicators of the decarbonization process. It was established that the use of a combined block element with a ball-shaped nozzle allows to increase the mass transfer coefficients compared to the failure plate. The industrial implementation of absorption processes in the foam layer and the use of the gas-liquid layer stabilization method significantly expands the scope of application of foam apparatuses and opens up new opportunities for intensifying technological processes. Previously expressed assumption about the perspective of using mesh materials for the manufacture of nozzle bodies was confirmed by experiments, but the peculiarity of the operation of devices with similar nozzles should be emphasized.

Destabilizing surface bubbles with excessive bulk oversaturation

The response and dynamics of surface-attached bubbles in gas-oversaturated environments have practical implications for industrial processes such as photocatalytic water splitting. Surprisingly, the behavior of microbubbles and nanobubbles depends rather strongly on the nucleation techniques, e.g., solvent exchange gives rise to stable bubbles, while other methods like electrochemical water splitting produce unstable ones. By experimentally investigating a prototypical system of bubble nucleation, we show how these outcomes are determined by a competition between gas oversaturation and contact line friction. We derive a stability line in the oversaturation-radius parameter space, which not only agrees with our experiments but also correctly predicts the outcome of previous experiments across five orders in oversaturation and bubble radius.

Real-time application and modelling of the NOx-sorption reaction on a particulate calcium carbonate surface-flow filter exposed to combustion exhaust.

Of major interest, especially in city environments, and increasingly inside vehicles or industrial plants, is the drive to reduce human exposure to nitrogen oxides (NOx). This trend has drawn increasing attention to filtration, which has developed remarkably owing to the capabilities of recently developed mathematical models and novel filter concepts. This paper reports on the study of the kinetic modelling of adsorption of nitrogen dioxide (NO2), collected from the tailpipe of a diesel engine, reacting to calcium nitrate salt (Ca(NO3)2) on a surface flow filter consisting of a coating of fine ground limestone or marble (CaCO3) in combination with micro-nanofibrillated cellulose (MNFC) acting as binder and humectant applied onto a multiply recycled newsprint substrate. The coating and substrate are both porous, but on different pore size scales, with the coating having significantly lower permeability. To maximise gas-coating contact, therefore, the coating deposition is pixelated, achieved by pin coating. An axially dispersed gaseous plug flow model (dispersion model) was used to simulate the transport within the coating pore network structure, following earlier flow modelling studies, and a kinetic reaction model was used to examine NO2 to NO3- conversion in correlation with experimental results. Modelling results indicate a 60.38% conversion of exposed NO2 gas to Ca(NO3)2 under the specific conditions applied, with an absolute relative error between the predicted and experimentally estimated value being 0.81%. The model additionally enabled a prediction of effects of changing parameters over a limited perturbation range, thus assisting in predicting filter element consumption, with attention given to the active component CaCO3 surface as a function of particle size in relation to the gas contact exchange, promoting the reaction over time. It is intended that the Ca(NO3)2 formed from the reaction can go on to be used as a value-added fertiliser, thus contributing to circular economy.

Effects of cathode gas diffusion layer porosity and contact angle distributions along through-plane direction on the performance of polymer electrolyte membrane fuel cell

In the present work, a numerical model for polymer electrolyte membrane fuel cell (PEMFC) has been employed to investigate the effects of porosity and contact angle distributions of the porous layer on the performance of PEMFC. The three-dimensional, two-phase, and non-isothermal flow solver considers heat transfer, electrochemical reaction, and liquid water saturation. Various cases with different cathode gas diffusion layer (GDL) porosities are performed. The results showed that a better performance is achieved when the GDL porosity is increased because of the reduced mass transport resistance of oxygen. The effects of the porosity distributions on the PEMFC performance were examined by comparing the predictions from the cases with non-uniform porosity and uniform porosity in the cathode GDL. It was shown that the current density of the cases with non-uniform porosity is higher than that of the uniform porosity case when the operation voltage is low. This is due to the fact that non-uniform porosity distributions in the cathode GDL enhance the reactant transport. When the operation voltage is high, the current densities of the cases with non-uniform porosity and uniform porosity are almost the same. Moreover, the influence of contact angle distributions in cathode GDL was explored. Various cases with gradient-decreasing, gradient-increasing, and uniform constant contact angles from GDL/channel interface to GDL/catalyst layer interface were studied. It was found that the case with gradient-increasing contact angle has a better performance due to the larger capillary pressure difference to remove more water. The poor performance of the case with gradient-decreasing contact angle is related to the phenomenon of flooding in the catalyst layer.

The Use of Chitosan and Beeswax Coatings on Berangan Banana (Musa Paradisiaca) in Different Maturity Stages

The coating is a method of giving a thin layer on the surface of the fruit to inhibit the release of gas, water vapor, and direct contact with oxygen. Coatings can create modified atmospheric conditions that slow fruit ripening, browning and prevent water loss, which in turn delays spoilage. The purpose of this study was to quantify the effect of the type of coating material (chitosan and beeswax) and the maturity stages of bananas (full green skin, 25% yellow skin, and 50% yellow skin) on changes in the quality of barangan bananas during storage. Coating significantly affected weight loss, soluble solids concentration (SSC), titratable acidity (TA), and firmness. Bananas with chitosan coating had higher SSC and titratable acidity than bananas with beeswax coating, but had lower weight loss. The maturity stages of bananas had a significant effect on weight loss, total dissolved solids, total acid, and firmness, which also affected the storage time of barangan bananas. Bananas with a yellow maturity level of 50% had higher weight loss and total dissolved solids than bananas with full green maturity and 25% yellow maturity. The barangan bananas with full green maturity had a shelf life of up to 12 days, bananas with 25 % yellow skin had a shelf life of up to 8 days, and bananas with 50% yellow skin had a shelf life of 4 days at room temperature.

Pore surface engineering of FeNC for outstanding power density of alkaline hydrazine fuel cells

In alkaline hydrazine fuel cells (AHFCs), the rapid kinetics of hydrazine oxidation contribute to their superior power density compared to other liquid fuel cells. However, the optimization of oxygen reduction reaction (ORR) electrodes in AHFCs has received limited attention, despite the potential importance of ORR as a rate-determining step. The wettability and pore structure of ORR catalysts are critical factors in facilitating reactant supply (O2 and H2O) and improving catalyst utilization. In this study, we synthesized a hierarchical pore structure in a FeNC catalyst by excess iron incorporation and steam activation, and adjusted its water/oxygen gas contact property by oxalic acid treatment. The modified catalyst exhibited improved wettability and optimized triple-phase boundaries. Remarkably, utilizing a 25 cm2 electrode size and non-noble electrocatalysts, the resulting AHFC achieved a significant power density improvement from 630 to 1240 mW cm−2, setting a new record for AHFCs. This research highlights the importance of pore structure and surface engineering, including the role of excess iron, in enhancing the performance of ORR electrodes in AHFCs.

Functionalized Zn-based desulfurizer with ordered mesoporous structure based on insights into sulfur-release mechanism during hot coal gas desulfurization

Sulfur-release effect impedes the engineering application of hot coal gas desulfurization. However, the related mechanism is not clear. This study aims to clarify the aforementioned effects and directionally design/fabricate ordered mesoporous Zn-based sorbents with function of inhibiting sulfur-release behavior. The results reveal that COS is mainly formed via R-1 (reaction between CO and H2S) before the reaction gas contacts Zn-based sorbents. R-2 (reaction between CO2 and H2S) catalyzed by ZnS is more kinetically favorable than its non-catalytic process. Furthermore, R-1 and R-2 contribute almost equally to the overall amount of released COS during desulfurization process. Then, considering the composition of coal gas, the strategy of promoter (with function of catalytic hydrogenolysis of COS) modification was proposed to inhibit sulfur-release behavior. A series of functionalized sorbents with four Zn/Me (Me: Mo, Ni) molar ratios (88:12–97:3) were constructed. The sorbents exhibit ordered pore-arrangement structure. Compared to unmodified sorbents, Mo- and Ni-doping both result in significant decline (by 98 %−99 %) in the amount of released COS before H2S-breakthrough. Moreover, the doping of Mo/Ni into ZnO generally produces positive effects on H2S-uptake activity. However, regeneration leads to notable deterioration of performance for Mo-doped sorbents. It is ascribed to the inadequate conversion of ZnS and structure destruction of sorbents. On the contrast, Ni-doped sorbents with Zn/Ni molar ratio of 90:10 could not only greatly suppress the sulfur-release effect and but also maintain 92 %−95 % of initial sulfur capacity during five sulfidation-regeneration cycles.

Investigation of the Water-Invasion Gas Efficiency in the Kela-2 Gas Field Using Multiple Experiments

Although improving the recovery of water-invaded gas reservoirs has been extensively studied in the natural gas industry, the nature of the efficiency of water-invaded gas recovery remains uncertain. Low-field nuclear magnetic resonance (NMR) can be used to clearly identify changes in water saturation in the core during high-pressure water-invasion gas. Here, we provide four types of water-invasion gas experiments (spontaneous imbibition, atmospheric pressure, high-pressure approximate equilibrium, and depletion development water-invasion gas) to reveal the impact of the water-invasion gas efficiency on the recovery of water-invasion gas reservoirs. NMR suggested that imbibition mainly occurs in medium to large pores and that residual gas remains mainly in large pores. The amount of gas driven out from the large pores by imbibition was much greater than that driven out from the small pores. Our findings indicate that the initial gas saturation, contact surface, and permeability are the main factors controlling the residual gas saturation, suggesting that a reasonable initial water saturation should be established before the water-invasion gas experiments. Additionally, the water-invasion gas efficiency at high pressures can be more reliably obtained than that at normal pressures. After the high-pressure approximate equilibrium water invasion for gas displacement, a large amount of residual gas remains in the relatively larger pores of the core, with a residual gas saturation of 42%. In contrast to conventional experiments, the residual gas saturation and water displacement efficiency of the high-pressure approximate equilibrium water invasion for gas displacement did not exhibit a favorable linear relationship with the permeability. The residual gas saturation ranged from 34 to 43% (avg. 38%), while the water displacement efficiency ranged from 32 to 45% (avg. 40%) in the high-pressure approximate equilibrium water invasion for gas displacement. The residual gas saturation in the depletion development water-invasion gas experiment was 26–40% (average: 33%), with an efficiency ranging from 45 to 50% (average: 48%), indicating that the depletion development experiment is closer to the actual development process of gas reservoirs. Our findings provide novel insights into water-invasion gas efficiency, providing robust estimates of the recovery of water-invasion gas reservoirs.

A computational study of a two-fluid atomizing coaxial jet: Validation against experimental back-lit imaging and radiography and the influence of gas velocity and contact line model

Numerical simulations of liquid atomization in a two-fluid coaxial geometry have been performed using a geometric Volume-of-Fluid method. Experimental measurements have been obtained using visible light back-lit imaging and X-ray radiography. Simulations are validated against experiments, using the same geometry and fluid injection rates of air and water, by showing excellent agreement in quantities such as liquid mass distribution in the spray formation region and the liquid jet length statistics and temporal dynamics. At the nozzle exit, the coflowing liquid and gas streams are separated by a cylindrical splitter plate. The liquid is laminar and modeled using a Poiseuille flow while the gas inflow model and the contact line model are varied. For the gas velocity models, the vorticity thickness is shown to have a strong influence on the downstream liquid distribution; the difficulty of its modeling and routes to overcome them are discussed. For the contact line model, pinning the interface to the inner wall of the splitter plate leads to an initial increase in the diameter of the liquid jet just downstream of the nozzle exit. In contrast, pinning to the outer wall of the splitter plate or allowing for a free moving contact line results in a monotonic decrease in the diameter of the liquid jet as the downstream distance is increased, in agreement with the experimental observations and measurements. A sub-grid scale contact line model based on a static contact angle is introduced. The static contact angle is varied in the model, showing that the liquid remains intact longer as the static contact angle is increased.

Hydrophobic air pollutants removal at one second gas contact in a multi-channel capillary bioreactor

Biological processes are increasingly applied for gas purification as a sustainable and economical alternative to conventional physical-chemical processes (chemical absorption, incineration, adsorption). Although biological gas treatment is accepted as an economical, safe, and reliable air pollution control technology, it faces important limitations when applied for the treatment of poorly water-soluble compounds due to mass transfer limitations. A twenty-five capillary channels bioreactor was studied to characterize mass transfer coefficients and the removal of hydrophobic air pollutants under segmented gas-liquid flow pattern. The removal efficiency of hexane, toluene and α-pinene vapors reached values up to about 75%, 99% and 75%, respectively, at a gas contact time of less than 1 s, which is at least one, but closer to two orders of magnitude shorter than conventional biological gas purification systems. The bioreactor displayed stable operation for 100 days and was robust against common upsets, which opens the new opportunities for expanding the application field of biological processes for air pollution control and the mitigation of greenhouse gases in dilute air streams. SynopsisThis study breaks through existing barriers of gas treating biotechnologies which allows expansion of the application field of more sustainable processes for air pollution control.

Tan's Two-Body Contact in a Planar Bose Gas: Experiment versus Theory.

We determine the two-body contact in a planar Bose gas confined by a transverse harmonic potential, using the nonperturbative functional renormalization group. We use the three-dimensional thermodynamic definition of the contact where the latter is related to the derivation of the pressure of the quasi-two-dimensional system with respect to the three-dimensional scattering length of the bosons. Without any free parameter, we find a remarkable agreement with the experimental data of Zou etal. [Tan's two-body contact across the superfluid transition of a planar Bose gas, Nat. Commun. 12, 760 (2021).NCAOBW2041-172310.1038/s41467-020-20647-6] from low to high temperatures, including the vicinity of the Berezinskii-Kosterlitz-Thouless transition. We also show that the short-distance behavior of the pair distribution function and the high-momentum behavior of the momentum distribution are determined by two contacts: the three-dimensional contact for length scales smaller than the characteristic length ℓ_{z}=sqrt[ℏ/mω_{z}] of the harmonic potential and, for length scales larger than ℓ_{z}, an effective two-dimensional contact, related to the three-dimensional one by a geometric factor depending on ℓ_{z}.

Mass transfer of chemical absorption of CO2/N2 mixed gas in a microchannel

In the chemical industry, the gas phase is not always pure gas generally. The mass transfer (MT) of mixed gas in a microchannel was investigated by using organic amine aqueous solution to absorb CO2/N2 mixed gas. MT in the bubble formation stage was calculated, and the influence of operating conditions on it was investigated. When the gas contacts the liquid, the CO2 in the bubble is continuously absorbed. Combined with the reduction of bubble volume, the instantaneous MT driving force of the bubble along the microchannel is calculated. On this basis, the MT coefficient of the mixed gas is obtained. The results show that after mixed gas in a certain concentration enters the microchannel, the instantaneous MT driving force and instantaneous MT coefficient are constantly decreased during the bubble moves along the microchannel.