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Velocity string (VS) is one of the most common methods to unload water in gas-producing field. In order to understand the behavior affecting production rate, we obtained several parameters including well completion, gas well production data, gas liquid ratio (GLR) and pressure data at tubing and casing head pressure, flowing bottom hole pressure. We then explore the relationship between these parameters against reservoir pressure and perform sensitivity analysis using multiphase steady-state flow simulator to analyze the parameters are the most sensitive to gas production rate. The results show that: (1) at larger inner diameter of the VS, there is a certain increase trend of gas production of gas wells. However, the production rate does not show a linear increase relationship with the larger internal diameter. It will reach certain inflection point before it decreases; (2) the gas production of the VS well is mainly driven by the reservoir pressure, the higher the reservoir pressure, the greater the gas production; (3) the root cause of relatively low initial production rate after small inner diameter coiled tubing VS installation is categorized as an abnormal well startup. This study provides theoretical support for selecting the optimum size and depth of VS to maintain well productivity. [ABSTRACT FROM AUTHOR]

Predicting pressure drop in gas wells is one of the most important issues for designing deliquification technologies and optimizing gas production. Current pressure-drop prediction methods can be divided into analytical and empirical models. Although various models have been proposed to predict pressure drop in wellbores, no model has offered stable performance over wide liquid and gas flowrate ranges. Especially for gas wells with low liquid – gas ratios, very few models have been developed specifically. In this study, a simple and accurate three-point model is developed for predicting liquid holdup in wellbores. The model is based on the liquid holdups and gas velocities at the annular – churn, churn – slug and slug – bubble boundaries and is comprehensive for calculating the liquid holdup in vertical wellbores at different liquid/gas flowrates and pressures. The proposed method was verified with 39 collected laboratory and 182 field measured data points from the literature, which have wide parameter ranges. For comparison, some widely used models in the petroleum industry were also evaluated. In validation with the laboratory data with pipe diameters of 50.8 and 101.6 mm, although the new model has an average percentage error (E3) of 220.1% in the churn flow, ranking fourth of all the evaluated models, the other five indicators in the churn flow and six indicators in the annular flow are lowest of all these evaluated models, resulting in relative performance factors (RPFs) of 0.2 and 0, respectively. In the field measured data, gas and liquid productions range between 0.34 × 104 —77.6 × 104 m³/d and 1—347.8 m³/d, tubinghead pressure ranges from 0.7 to 84.7 MPa, which can cover most gas wells. The validation demonstrates that the new model still has good performance with five indicators being lowest. The RPF of the new pressuredrop model in the field measured data ranges is 0.29, still lowest of all these evaluated models, showing better performance than these widely used models in petroleum industry for vertical gas wells. This indicates that the new model can accurately predict pressure drop under different conditions in vertical gas wells. [ABSTRACT FROM AUTHOR]

This study, describes a method (SWASV) for measuring 2-mercaptobenzothiazole (2-MBT), a semi-volatile heteroaromatic pollutant compound present in water samples, was prepared using G-C3N4 nanosheets sensor. Although the other methods (gas or liquid chromatographic, electrophoresis, flow injection) for measuring 2-MBT have advantages such as excellent accuracy and reproducibility, it has limitations such as long-time measurement and high equipment cost. Here, we report the use of an electrochemical approach for analytical determination of 2-MBT that takes 100 s. The calibration curve was linear in the range of 0.02 to 20.0 µgL−1. The current response was linearly proportional to the 2-MBT concentration with an R2~0.998. We demonstrated a sensitivity of a limit of detection of 0.023 µg L−1. Finally, sensor nanosheets G-C3N4/CPE have been successfully applied for the determination of 2-MBT in different kinds of water samples. The method introduced to measure 2-MBT in real samples such as water samples was used and can be used for other samples. [ABSTRACT FROM AUTHOR]

The occurrence of pesticide residues, their metabolites and degradation products in 49 edible mushrooms (fresh, dried, canned and frozen) was investigated. Using QuEChERS extraction, followed by liquid and gas chromatography coupled with tandem mass spectrometry, the samples collected from Czech markets were tested for 427 analytes. A total of 21 pesticide residues, their metabolites and pesticide synergists were found in quantifiable concentrations. The most frequently detected pesticide residues included prochloraz and its metabolites, metrafenone and carbendazim. Two mushroom samples were found to be in violation of the maximum residue level. In addition, the fate of 13 pesticides during the processing of fresh mushrooms was investigated. The processing factors calculated from the data ranged from 6.0 to 12.3 for drying and from 0.3 to 1.3 for deep-freezing. The results showed that most of the pesticide residues tested were stable under the conditions of mushroom processing. [ABSTRACT FROM AUTHOR]

The Euler-Euler model is widely used in bubbly flow simulations up to industrial dimensions. The standard Euler-Euler model is based on the phase-averaging method. After averaging, the bubble forces in the field equations are functions of the local void fraction. In simulations, when the bubble diameter is larger than the computational cell spacing, the forces can transport the gas belonging to the same bubble in different directions. By contrast, a closure model for the bubble force is typically developed based on the assumption that the force is a resultant force that acts on the bubble's center of mass. This inconsistency can lead to a nonphysical gas concentration in the center of a channel or near the channel wall if the bubble diameter is larger than the cell spacing. The purpose of the present contribution is to develop an Euler-Euler model where the bubble force consistency is recovered for two-phase flow simulations where the diameter of the disperse phase can be larger than the cell spacing. Such an Euler-Euler model is developed by combining an existing particle-center-averaged Euler-Euler framework with a Gaussian convolution method. To validate this Euler-Euler approach, a comparison is made with experimental data for the bubbly flows in two different vertical pipes. The results show that the proposed Euler-Euler model recovers the bubble force consistency and alleviates the overprediction of the void fraction peak near the wall, while its simulation results in the axial gas and liquid velocity and the liquid turbulence kinetic energy are similar to the results of the standard Euler-Euler model. [ABSTRACT FROM AUTHOR]

Aflatoxins are one of the highly toxic secondary metabolites with high decomposition temperatures, ranging from 237 °C to 306 °C. Therefore, non-thermal treatments are preferred to ensure safe food while preserving food quality. High voltage atmospheric cold plasma (HVACP) is a novel non-thermal technology with the potential to reduce contaminants (e.g. mycotoxins) owing to reactive species such as ozone. Therefore, the aim of this study was to investigate the efficacy of HVACP to degrade Aflatoxin M1 (AFM1) in pure water. A dielectric barrier discharge HVACP was performed at 90 kV using modified air (MA65: 65% O2, 30% CO2, 5% N2) fill gas for 1, 3, and 5 min in a direct and indirect mode with no post-treatment or 4.0 h post-storage at room temperature. The chemical properties of water were evaluated. Ozone concentration in both gas and liquid phases was also measured. A 77% reduction of AFM1 was observed after 1 min of direct treatment with no post-treatment storage. The nitrate and peroxide contents after 1 min of direct treatment were 4.50 ± 0.70 and 9.5 ± 0.70 mg/L, respectively. Longer treatment time and direct mode of exposure resulted in a higher ozone concentration in either the gas or liquid phase. These results demonstrate the potential of HVACP as a non-thermal treatment for reducing AFM1 concentration. HVACP was capable of significantly degrading AFM1 using a very short treatment time and 4.0-h post-treatment storage. [ABSTRACT FROM AUTHOR]

Lump solutions are empirical rational function solutions found in all directions in space. One of the essential solutions to both linear and nonlinear partial differential equations is lump solutions. The current work studies a class of lump interaction phenomena to the generalized (3 + 1) -dimensional nonlinear-wave equation with time-dependent-coefficient. Variable-coefficient nonlinear partial differential equations offer us with more real aspects in the inhomogeneities of media and nonuniformities of boundaries than their counterparts constant-coefficient in many physical cases. The Hirota bilinear form is the fundamental concept that has been used to derive the novel lump-periodic and breather wave solutions. The acquired solutions are constructed using symbolic computations called Maple. The physical characteristics of the acquired solutions are shown with three-dimensional and contour plots in order to shed more light on the acquired novel solutions. [ABSTRACT FROM AUTHOR]

A bubbling reactor is an important type of gas scrubber to reduce SO2 emissions in maritime shipping. Both experiments and simulations were conducted to study the relationship between the periodic gas bubbling process and SO2 concentration at the outlet of the reactor, and the entrainment of liquid droplets on SO2 absorption. The accuracy of the model was verified by comparing the bubble size, the depth of bubbles injected into the water, and the SO2 concentration obtained in both experiments and simulations. The gas bubbling process is accompanied by bubble formation, rise, and collapse. The gas bubbling period is affected by the disturbance of the liquid level. The period of the SO2 concentration at the outlet of the gas bubbling reactor is smaller than that at the gas jar outlet which acts as the gas buffering region. The amounts of water carried out of the bubbling reactor by the gas bubbling process increase with the gas flow rates. The droplets and liquid film in the gas jar and the connecting tube play an important role in the absorption of SO2. This study encourages more research to reduce the fluctuation of SO2 concentration and consider droplet entrainment in the design of bubbling reactors. [ABSTRACT FROM AUTHOR]

Here is described a new approach for the simple and rapid detection of 2-chlorobenzylidene malonitrile (CS riot control agent) based on the reaction with isatin (1H-indole-2,3-dione) and, alternatively, with ninhydrin (2,2-dihydroxy-1H-indene-1,3(2H)-dione), both in an environment of ammonium acetate, dimethyl sulfoxide, and dimethylformamide. The method was designed for the preparation of detection tubes for air analysis, test strips for the analysis of liquid samples, and for spectrophotometric determination. The use of ninhydrin appears to be more sensitive, but isatin provides higher stability and practical applicability. [ABSTRACT FROM AUTHOR]

The accurate estimation of the water content of natural gas is the basis for proper equipment design in natural gas processing and transmission facilities. Methods for estimating the water content of natural gas have been reported based on pressure and temperature data, and the concentration of acid gases. This work aims to develop a predictive model based on artificial neural networks (ANN) to estimate the water content of natural gas, considering the contribution of heavier hydrocarbons than methane, commonly present in the rich gases, gas condensates, or liquefied petroleum gases. The novelty of the proposed model is the incorporation of natural gas richness (GPM) as an input parameter for calculating the water content of natural gas, in addition to temperature, pressure, and acid gas equivalent content. Experimental data from the literature is used in the ANN training and validation, with the help of the BigML machine learning platform to perform a multi-layer-feedforward neural network. The ANN performance showed the ability to accurately predict the water content for different gas mixtures (rich, lean, sweet, and sour gases). Comparisons with available models in the literature are performed, showing that the ANN model provides accurate estimations (AAD: < 10%). [ABSTRACT FROM AUTHOR]

The liquid film thickness seriously affects the distribution of temperature, velocity, and components near the interface for steam condensation in the presence of small concentration noncondensable gas. The liquid film thickness for H2O/CO2 forced convection condensation separation on vertical plate has not been studied numerically. Thus, volume of fluid model and a phase change model were used to study steam condensation in the presence of noncondensable gases. The calculations studied the effects of velocity, surface subcooling, and noncondensable gas mole fraction on the heat transfer for H2O/air or H2O/CO2 mixtures. The results show that the predicted heat transfer coefficients agree well with previous experimental data. The gas and liquid film thicknesses controlling the condensation heat transfer in the presence of a noncondensable gas become thicker as the mixture flows along the cooled wall. The condensate mass flow rate and the heat transfer coefficient are both seriously reduced by the noncondensable gas. The condensate heat transfer in the presence of noncondensable gases is mainly determined by the diffusion coefficient and the thermal conductivities of the components in the gas film layer. [ABSTRACT FROM AUTHOR]

The objectives of this study were to develop a novel analytical method for quantifying vinyl chloride (VC) emitted from aerosol products, to provide analytical data on VC in aerosol products, and to evaluate consumer VC exposure by aerosol products. Our quantitative method involves absorbing VC into dimethyl sulfoxide and analyzing it using headspace gas chromatography/mass spectrometry. The correlation coefficients of the VC calibration curves were ≥ 0.9994 in the range of 0.16–80 µg/mL VC standard gases, which were prepared under either nitrogen or emission gases containing dimethyl ether or liquid petroleum gas. VC concentrations in these emission gases were calculated using a VC calibration curve from standard gases prepared under nitrogen; they were within ± 10% of the actual concentrations. We analyzed 39 household aerosol products; VC concentrations of 0.095, 0.098, and 0.28 μg/L were detected in three polyvinyl chloride spray paints. Consumer VC inhalation exposure level was estimated through an exposure scenario, and the hazard quotient was confirmed to be very low when comparing the exposure level with a cancer risk level of 10−5 for inhaled VC. These results suggest that the human health risk from VC in spray paint was low. [ABSTRACT FROM AUTHOR]

Regression analysis techniques were employed to develop correlations for the average temperature shift of hydrates (ΔTav) as a function of seven thermophysical properties of the ILs. These predictors are; hydrogen bonding energy (EHB), Vander Waal's energy (EvdW), the energy of misfit (EMF), the energy of interaction (EINT), density (ρ), viscosity (μ), and molecular weight (MW). Multicollinearity effects among the variables were resolved by adopting the ridge regression approach. The regression models were developed from over 200 experimental data points involving 1-methyl-3-propyl-imidazolium ILs (PMIM-ILs), 1-(3-cyanopropyl)-3-methylimidazolium ILs (CPMIM-ILs), 1,3-dimethyl-imidazolium ILs (DMIM-ILs), 1-butyl-3-methylimidazolium ILs (BMIM-ILs), and 1-Ethyl-3-methylimidazolium ILs (EMIM-ILs). The predictive models were developed in three categories: Several ILs, BMIM-ILs, and the EMIM-IL models. Analysis shows that the prediction of ΔTav from models developed from the thermophysical data obtained from specific IL models is more accurate than those obtained from Several ILs models. Except for 1-Ethyl-3-methylimidazolium dicyanamide (EMIM-DCN) IL, the percentage accuracy of the models ranges between 81.56% and 99.91%. The new models present a significantly simpler and more accurate way to optimize the inhibitor synthesis, selection, and validation process for practical purposes. The synthesis, validation, and confirmation of ionic liquids (ILs) as potential gas hydrate inhibitors are arduous, costly, require sophisticated equipment, and involve labor-intensive experimental procedures. The development of mathematical models that can be used to automatically screen potential gas hydrate inhibitors such as the IL or deep eutectic solvent (DES) would drastically reduce the cost and extensive processes involved in the synthesis and validation of several prospective solvents. The percentage accuracy of the new mathematical models ranges between 81.56% and 99.91% for different classifications or groups of ILs. The application of the new models will facilitate quick screening of potential task-specific solvents, eliminate bias in the selection and ultimately reduce the time and cost associated with the screening and validation of the synthesized solvents. [ABSTRACT FROM AUTHOR]

In this study, the solvent effects are probed on the chemical reaction of the (E)-3-thiophene-2-yl-indoline-2-thione (I) and [20] fullerene, and the resulted complex (Ia) via the density functional theory (DFT). To characterize the synchronicity of the reaction and its correlation with activation energy, we estimated the energy barrier of transition states (ETS1≠ and ETS2≠) in the used solvents. The highest ETS1≠ and ETS2≠ value are found in water solvent, whereas the lowest ETS1≠ and ETS2≠ value are considered in the gas phase. Formation of the TS2 appears energetically less favorable due to the non-bonding electrostatic repulsion among the sulfur heteroatoms and C20, also the π–stacking between the thiophene ring and nanocage, which affects the stability of the TSs. The most thermodynamic stability, the adsorption energy difference among liquid phase and gas phase (ΔEl-g = El − Eg), and the most polarity (µ) belongs to stabilizing effect of water solvent on Ia, whereas the lowest thermodynamic stability, the lowest released ΔEl-g and the least polarity belongs to optimization of Ia in the gas phase. This stabilizing effect is attributed to the possibility of hydrogen bonding and dipole–dipole interaction in the water. The n→π* donation of N–C═S leads to a stronger interaction between sulfur heteroatom of I and fullerene. In contrast to the previous report on the produced thio-oxindoles in organic solvents, toluene was found to be the best solvent in terms of the highest yield and the shortest reaction time, in this case, adsorption takes place in water with no catalyst addition. Here, we have focused on chemical reaction of I and C20 to produce Ia complex via the optimized TSs in the gas phase, toluene, dichloromethane, methanol, acetonitrile, dimethyl sulfoxide and water, using DFT approach. [ABSTRACT FROM AUTHOR]

To improve the plunger gas lift efficiency, a modified plunger was developed by adding a check valve to the downhole positioner in the Changqing Gas Field. However, the transient flow behavior of the plunger lift with check valve is unclear owing to the lack of a reliable method. Therefore, in this study, a simplified transient mechanistic model based on the law of conservation of momentum and mass is proposed to simulate the comprehensive dynamic process of a plunger-lift system. The results of the proposed method exhibited a high coincidence with that of the accumulated gas and liquid production of gas Well-1 in one cycle, and the relative errors were 2.11% and 4.29%, respectively. The calculation results demonstrate that the plunger lift with check valve can effectively prevent the flow of liquid to the bottom of the well, reduce the bottom hole flow pressure, and increase the productivity of gas well during the shut-in period. The efficiency of the plunger lift with check valve was enhanced with an increase in the volume of the accumulated liquid unloaded from the bottom of gas wells. Additionally, for the plunger lift with check valve, the production peak value was higher and the instantaneous gas production peak value was lower in comparison with the conventional plunger. After the plunger reached the wellhead, the instantaneous fluid production of the conventional plunger was relatively unstable than that of the plunger lift with check valve. A certain distance should be maintained from the bottom of the well in the case of the positioner with check valve. If the positioner is placed at the bottom of the tubing, the difference between the lift efficiency of the plunger with check valve and conventional plunger is small, and lower than that of the conventional plunger. The installation position of the downhole positioner in a gas well should be below the accumulated liquids level and should maintain a certain distance between the positioner and bottom of the well (200 m). The results of this study enhance the understanding of the operation mechanism of the plunger lift with check valve, and unloading of the accumulated liquids from the bottom of gas wells. [ABSTRACT FROM AUTHOR]

Gas dispersion characteristics are of significant importance in froth flotation. Studies show that cyclonic static microbubble flotation column (FCSMC) is an efficient device to recover fine minerals. In the present study, the gas holdup distribution and the mean gas holdup in a laboratory gas-liquid FCSMC are first quantitatively measured by electrical resistance tomography (ERT). Different flowrates of gas and liquid are considered. Performed experiments show that when the air flowrate increases from 1.1 L/min to 2.3 L/min, the mean gas holdups on measured planes increase to about 4 ~ 5 times the original value. The gas dispersion along the radial direction is poor, which is dense in the center and rare in the periphery. This uneven bubble distribution aggravates as the amount of the supplying air increases. As the circulating liquid flux increases, the corresponding measured gas holdup gradually decreases and the bubble shrinks to the center along the radial direction. When the liquid flux increases from 1.5 m3/h to 1.8 m3/h, the averaged decline of the mean gas holdup on measured planes reduces to 54 ~ 65% of the original value. Finally, it is validated that the sieve plate packing effectively reduces non-uniform radial and axial distributions of the gas holdup. The obtained results might lead to more effective operating of FCSMC, provide a reference for further numerical study and ERT application in other complicated devices. [ABSTRACT FROM AUTHOR]

Stringent regulations and policies have prompted vessel operators and owners to direct the interests on developing greener vessels from oil-fuelled vessels to LNG-fuelled vessels. Consequently, the increasing demands for LNG, as the alternative fuel for vessels, have led to the booming development of LNG carriers or bunker vessels. LNG transfer operations, including loading and bunkering operations, are the major operations taking place on LNG carriers and bunker vessels. As these operations involve in between vessels (ship-to-ship) and terminals (shore-to-ship), compatibility issues should be anticipated and hence, proper compatibility studies should be performed prior to vessel construction stage. Since there are no standard guidelines and procedures of performing compatibility studies, it is the intent of the present article to provide an overview of performing shore-to-ship and ship-to-ship compatibility studies. [ABSTRACT FROM AUTHOR]

Acetaldehyde is one of the crucial gases with odor released during the early stage of spontaneous combustion of coal, and it is essential for predicting the spontaneous combustion tendency of coal. In this study, we systematically investigated the effects of coal metamorphic degree, coal temperature, coal particle size, and oxygen concentration on the release of acetaldehyde using three coal samples with different metamorphic degrees and a combination of oxidation and warming processes as well as gas and liquid chromatography. The results showed that with the increase in temperature, the amount of acetaldehyde released first increased and then stabilized or slightly decreased. The amount of acetaldehyde released at low temperatures was linearly related to oxygen consumption. The higher the degree of coal deterioration, the lower the amount of acetaldehyde released. As the particle size decreased, the amount of acetaldehyde released increased and then decreased. Finally, four warning levels were established based on the concentrations and trends of acetaldehyde together with other index gases. [ABSTRACT FROM AUTHOR]

A problem of satellite transitions induced in the vibration-rotation spectra of fastly rotating linear molecules by intermolecular interactions is explored. For this purpose, a dynamic, non-Markov perturbation theory is applied to the rotational Raman spectrum of liquid parahydrogen, where a weak satellite developing at the double S 0 (0) + S 0 (0) frequency was detected and extensively studied by Zoppi et al. (Phys. Rev. A. 53, 1395 (1996); Phys. Rev. B. 55, 12223 (1997)) on the basis of a static perturbation theory. The static approach is presently revised by means of the dynamic line-mixing theory, which gives a more realistic picture of intermolecular interactions. Our approach allows us to calculate all satellite spectral characteristics and shows the satellite-integrated intensity to be two-fold overrated by the static theory. Upon due corrections and with an account for the collision-induced (CI) polarisability terms, the agreement between simulated and measured intensities is cardinally improved. Arguments are given that, on going from gas to liquid, the satellite shape is materially affected by the translational motional narrowing. [ABSTRACT FROM AUTHOR]

In order to solve the problem that the wellbore liquid loading of low permeability horizontal wells can't be predicted accurately in previous studies, this article establishes a new matrix - natural fracture - wellbore horizontal gas well productivity equation considering stress sensitivity, starting pressure gradient and high speed turbulence effect. The method is used to judge whether there is liquid loading in a gas reservoir, and verified by the critical liquid carrying flow method. The results show that the accuracy rate of predicting liquid loading by productivity equation method is 80%, and the accuracy rate of predicting gas well productivity is 91.55%. Meanwhile, the influence rule of natural fracture parameters on productivity is given and it is found that the stress sensitivity coefficient has little effect on productivity. At the same bottom hole pressure, the gas production gradually decreases with the increase of high-speed nonlinear coefficient and gas production gradually increases with the increase of the number and width of natural fractures. The findings of this study can help for better understanding of the relationship between wellbore liquid loading and gas well productivity, and then better grasping the timing of gas well drainage and gas recovery. [ABSTRACT FROM AUTHOR]

In the past few years, research on the fabrication of deep eutectic solvents (DESs)-based supported liquid membranes (SLMs) is increasing tremendously due to their significant advantages such as low mass transport resistance, high performance, easy scale-up, low cost and simple operation. However, fabrication of DES-based SLMs is challenging and highly dependent on the fabrication parameters: DES properties and properties of membrane supports. Subsequently, the fabrication methods, immersion, pressure-based impregnation and vacuum filtration also affect the permeation performance of DES-based SLMs in liquids and gases separation. Furthermore, the SLM durability is influenced by the DES properties and process parameters including: temperature, pressure, and feed composition. Firstly, present work reviews the current progress and fabrication of DES-based SLMs. Subsequently, it presents a perspective on different strategies that use DESs as a unique tunable platform to design advanced SLMs for liquids and gases separation reported in the literature. In the next step, performances of the SLMs membranes for liquids and gases separation are described in details. The effects of process parameters on DES-based SLMs are also highlighted prior to the challenges. Lastly, challenges and future research opportunities are highlighted. [ABSTRACT FROM AUTHOR]

Transport and storage of liquefied natural gas (LNG) requires special double-walled cryogenic tanks. To provide a liquid state of LNG throughout entire storage time a temperature inside the tank should be equal −160 °C under the pressure of around 7 bar. Maintaining these parameters requires a vacuum insulation system and internal supports designed to minimize heat leakage into the tank. Additionally, the internal supports must be able to transfer complex mechanical loads that may occur during the operation of the tanker. Combinations and values of directional mechanical loads and thermal loads, to be accepted in designing mobile cryogenic tanks, are determined by proper vessels standards. In this article, we proposed the construction of internal supports for 25 m3 road tanker, which structure allows to reduce heat leakage into the internal tank, while transferring the complex mechanical loads. Tests of the presented solutions were carried out applying both mechanical and thermal finite element analysis using ANSYS software. [ABSTRACT FROM AUTHOR]

In this work, the equation-of-state data for liquid nitrogen shock compressed to 43 GPa along the principal Hugoniot and reflected-shock data up to 91 GPa were reported. A cryogenic target was used to liquefy the gas that was then further compressed by high-speed impactors. The first- and second-shock states were observed by a high-precision Doppler pin system (DPS). Optical wavefrom of DPS resulted in the first-shock velocity from which other derivative quantities i.e. particle-velocity, specific-volume, internal-energy, and Grüneisen-parameter, were determined. Our results and published equation-of-state data were used to extrapolate the principal Hugoniot. Their comparison showed softening above 27 GPa, attributed to the absorption of thermal energy that dissociates the molecular nitrogen. Our single-shock data provided a good match to available Hugoniot data. The reduced velocity profiles allowed us to detect optical reflectance of the dissociated liquid phase, and the apparent shock-velocity was used to determine the true shock-velocity in dissociation threshold. [ABSTRACT FROM AUTHOR]

Given a number of marine vessels treating the liquefied natural gas either as cargo or fuel, this paper examined the regulatory gaps of two different international Codes – the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk and the International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels – from the regulatory standpoint. Results of the gap analysis have identified and discussed the key areas encountered with regulatory discrepancies or ambiguities that might interrupt the proper design, construction and operation of LNG carrier and LNG fuelled ship. A systematic investigation and harmonisation process across the Codes was proposed to mitigate the potential issues that may arise from the discordant regulations. Also, the International Maritime Organization was suggested to take proactive action to improve such dissonances while a general insight into the importance of filling those gaps was provided for rule-makers and stakeholders. [ABSTRACT FROM AUTHOR]

The primary concern of PM2.5 (particle size of an aerodynamic diameter 2.5 micrometers or less) is its adverse health effects. As not all PM2.5 particles are equally toxic, a uniform PM2.5 mass control across the emitting sources may not provide the maximum health benefits. A new approach that apportions PM2.5 constituents, based on their toxicity and further realigns them into the sources, is developed and applied to Delhi city. In PM2.5, concentrations of 81 constituents in 11 apportioned sources were derived. Fourteen carcinogen constituents (Pb, Cr, Ni, Cd, As, Co and eight PAHs) were considered. The USEPA's CompTox was used to obtain the cancer threshold concentration (Cca) of the constituents. A product of constituent concentration and the inverse of Cca yielded constituent-wise cancer potential (CCPca). The source-wise cancer potential was 20% for diesel, 19% for road dust, 16% for coal power plant, 13% for municipal solid waste burning and 8% for gasoline vehicles. Among 14 carcinogen constituents, Cr accounted for 20% of mass but showed the maximum CCPca. The net incremental lifetime cancer risk (NILCR) for all sources was 4.2 × 10−4. Diesel showed the maximum NILCR at 8.5 × 10−5 and liquid petroleum gas lowest at 8.8 × 10−6. [ABSTRACT FROM AUTHOR]

The analysis in this paper was performed before the disastrous and unsolicited invasion of Russia to Ukraine. The paper aims to identify if the biggest Russian gas exporter Gazprom used market power to decouple its gas prices from European gas hub benchmarks. The empirical analysis is based on pairwise price convergence between the Russian pipeline and European gas hubs. The main finding shows that Gazprom takes advantage of its market position. The proposed model does not support the company's claims of pipeline price tightness to liquid European gas hubs, and rather proves fluctuating and unstable price convergence between pipelines and hubs from 2016 to March 2020, right before the COVID-19 pandemic. Notably, a robust and trendy-stable price convergence is observed between the Russian pipeline gas and Brent benchmark. Methodologically, the paper contributes with a modified convergence model compliant with gas market fundamentals and suggests a time-expanding concept missed in previous studies. Ongoing political and European gas market developments of 2022 (during the paper review) support the conclusions. [ABSTRACT FROM AUTHOR]

We study a liquid droplet moving inside a rarefied gas. In other words, we consider a two-phase flow with liquid and rarefied gas phases and an interface between the two phases which deforms with respect to time and space. The gas phase is modelled by the Bhatanager–Gross–Krook (BGK) model of the Boltzmann equation. The liquid phase is modelled by the incompressible Navier–Stokes equations. Interface boundary conditions for the liquid and gas phases are presented. The BGK model is solved by a semi-Lagrangian scheme with a meshfree reconstruction procedure. A similar meshfree particle method is used to solve the incompressible Navier–Stokes equations for the liquid phase. In 1D the solutions of the BGK-Navier-Stokes equations and the Boltzmann-Navier-Stokes equations are compared, where the Boltzmann equation is solved by a direct simulation Monte Carlo method. Results in 1 D and 2 D physical spaces are presented. [ABSTRACT FROM AUTHOR]

Isothermal absorption of components from dilute gaseous mixtures by falling film of liquids in irrigated plane-parallel channels for co-current laminar flows of liquid and gas were modeled taking into account the processes occurring at the gas entrance. A solution was obtained in the form of analytical expression and reduced to the solution of particular limited problems for the cases when the resistance is concentrated within the gas or the liquid. For visual representation of fluxes the plane of hydrodynamic parameters was suggested. The calculations can be carried out inside of a limited area of the plane. Outside of the area, some simplifications can be adopted: (a) mass transfer resistance is concentrated in a gas or in a liquid and (b) the concentration changes in transversal directions can be neglected or there is a boundary diffusion layer in the gas or the liquid. It was shown that in calculating of the process of gas cooling by the transversal temperature gradients in the liquid can be neglected. The restrictions on temperature difference at the entrance were found, according to them the corresponding thermophysical coefficients can be assumed to be constants and the heat exchange can be calculated using the relationships derived for isothermal absorption. The method can be applied to a wide class of problems which can be reduced to solving of convection diffusion equations with more difficult interphase boundary conditions. Compared to existing numerical and analytical methods, our approach advantage is in its simplicity, visual representation, and shorter computation time. [ABSTRACT FROM AUTHOR]

In this study, the thermal and hydraulic performances of six different printed circuit heat exchanger (PCHE) configurations with supercritical liquefied natural gas as the working fluid are studied by a numerical method. Firstly, the thermal and hydraulic performances of the PCHE with airfoil fins are investigated at different operating pressures, which indicate that the PCHE with airfoil fins has better thermal performance but worse hydraulic performance when it operates at higher pressure condition. Furthermore, the effects of different PCHE configurations on the thermal and hydraulic performances are analyzed in detail. The results show that delta vortex generators (VGs) arranged upstream the airfoils can provide better thermal performance than VGs arranged downstream the airfoils, and the thermal performance of the common-flow-up configuration is not always better than the common-flow-down configuration. Finally, the overall heat transfer performance of PCHEs is evaluated by the volume goodness criterion under the same mass flow rate. The results show that the straight channel PCHE with front common-flow-up delta VG and airfoil fins has the best volume goodness factor among the six PCHE configurations. [ABSTRACT FROM AUTHOR]

The existing rate-based modeling of monoethanolamine (MEA) solvent for CO2 capturing has been improved using different kinetic models. Different models obtained from a combination of 15 kinetic models and 4 mass transfer correlations have been applied. The results show that the mass transfer correlation is instrumental for a reliable rate-based model. The resulting framework predicts the temperature and composition profiles at both liquid and gas phases with good accuracy. Overall, this allowed for improved prediction of (i) the CO2 capture performance, (ii) the CO2 partial pressure in output gas, and (iii) the temperature and CO2 composition profiles in the liquid. [ABSTRACT FROM AUTHOR]

In this current study, an apparatus called air–water interface generator was investigated for oxygen transfer enhancement by increasing a contact area between air and water. The effect of this apparatus and its optimal installation condition were investigated. The total volumetric oxygen transfer coefficient (kLaT) in this study was divided into volumetric oxygen transfer for the bubble transfer (kLaB), volumetric oxygen transfer for the inner interface transfer inside the apparatus (kLaI), and volumetric oxygen transfer for the free water surface transfer (kLaS). The experimental results show that the apparatus installed near the water surface could increase the oxygen transfer 18% due to the presence of an inner interface. Additionally, the effect of the number and the position of apparatus on bubble dispersion should also be taken into consideration since the bubble transfer makes the most significant contribution to total oxygen transfer in the diffused aeration system. [ABSTRACT FROM AUTHOR]

This paper is a sequel to the authors' article on a full-scale fire testing to collapse of a steel stiffened plate structure without passive fire protection (PFP) under lateral patch loading (Paik JK, Ryu MG, He KH, Lee DH, Lee SY, Park DK, Thomase G. 2020. Full-scale fire testing to collapse of steel stiffened plate structures under lateral patch loading (Part 1) – without passive fire protection. Ships Offshore Struc. doi:). The test structure represents steel plate panels of a 1900 TEU containership in compliance with test facility in a maximum size and capacity. The aim of this paper is to experimentally examine the effects of PFP application on the fire collapse of steel stiffened plate structures. For this purpose, two transverse frames (primary strength members) of the test structure were insulated by cerawool which is a fire protection material. A fire test was conducted in a furnace burnt by liquefied petroleum gases. Structural collapse was monitored at discrete time intervals from when the fire started until the test structure entirely collapsed. The effect of fire-protected transverse frames on the structural collapse was investigated by comparison with test results on the structure that was unprotected from the fires. [ABSTRACT FROM AUTHOR]

Previous studies have found difficulties in reconciling mass transfer between membrane contactors of different geometries, which has been attributed to differences in fluid mixing. In this study, we compare the two most commonly adopted geometries (parallel and transverse flow) and use residence time distribution (RTD) analysis to verify the influence of geometry on fluid mixing in addition to developing a generalized correlation that can collectively describe mass transfer for both geometries. Lumen-side mass transfer was well described by the Lévêque solution in well-developed laminar conditions for both parallel and transverse flow modules. However, considerably lower mass transfer was identified for shell-side flow in the parallel fiber configuration, with RTD analysis providing confirmation that this was due to shell-side bypass which reduced mean fluid residence time τ = v / L in the contactor to below that of the theoretical residence time. The mean residence time calculated from RTD analysis enabled reconciliation of mass transfer data between both geometries, such that mass transfer could be adequately described for both configurations using: S h s = 1.27 R e 0.793 S c 0.33 d h / L . The Reynolds number exponent indicated transitional mass transfer despite operation firmly within the laminar regime, which would indicate an enhancement in mass transfer provided by secondary flow effects within tightly packed fiber bundles. Whilst previously observed, for example in heat transfer analogies, such dependencies are generally more closely associated with parallel flow rather than 'classical' cross-flow modules in which fluid flow is explicitly perpendicular to the fiber bundle, and indicates that mass transfer in transverse flow may be better described as parallel flow, which confirms previous assumptions. Importantly, this study demonstrates the capability to reconcile mass transfer between modules of different geometries and permits the opportunity to project process design and scale-up between the two most commonly applied membrane contactor module geometries. [ABSTRACT FROM AUTHOR]

This paper is a sequel to the authors' earlier article Paik et al. [2020a. Full-scale collapse testing of a steel stiffened plate structure under cyclic axial-compressive loading, Structures, ]. The aim of the paper was to present a test data on the ultimate compressive strength characteristics of a full-scale steel stiffened plate structure at cryogenic condition which may be due to unwanted release of liquefied gases. The test structure was fabricated in a shipyard using exactly the same welding technology as used in today's shipbuilding industry. It is observed that the test structure reaches the ultimate limit states triggered by brittle fracture, which is totally different from typical collapse modes at room temperature. Details of the test database are documented as they can be used to validate computational models for the structural crashworthiness analysis involving brittle fracture at cryogenic condition. [ABSTRACT FROM AUTHOR]

Experimental data and detailed numerical modelling are presented on the burning characteristics of a model gasoline/biofuel mixture consisting of n-heptane and iso-butanol. A droplet burning in an environment that minimises the influence of buoyant and forced convective flows in the standard atmosphere is used to promote one-dimensional gas transport to facilitate numerical modelling of the droplet burning process. The numerical model includes a detailed combustion kinetic mechanism, unsteady gas and liquid transport, multicomponent diffusion inside the droplet, variable properties, and non-luminous radiative heat transfer from the flame. The numerical simulation was validated by experimental measurements in the standard atmosphere which showed good agreement with the evolutions of droplet and flame diameters. The iso-butanol concentration had a strong effect on formation of particulates. Above ~20% (volume) iso-butanol, flame luminosity was significantly diminished anddecreased with increasing iso-butanol concentration, while CO2 emissions as a representative greenhouse gas were not strongly influenced by the iso-butanol loading. The soot shell was located near a 1350 K isotherm for concentrations up to 20% (volume) iso-butanol, suggesting this value as a possible soot inception temperature for the mixture droplet. The combustion rate decreased with increasing iso-butanol concentration which was attributed to iso-butanol's higher liquid density. No evidence of a low temperature burning regime, or of extinction, was found (in experiments and simulations) for the small droplet sizes investigated. [ABSTRACT FROM AUTHOR]

In this study, hydrodynamic parameters such as minimum liquid phase fluidization velocity (U lmf) , semifluidization velocity (U sfm) , pressure drop (Δ P) , and height of top packed bed formation of a co-current gas-liquid -solid multiphase semifluidized bed were studied using the liquid as the continuous phase and air as the dispersed phase. Air, water, and acrylic beads of various sizes were used to represent the gas, liquid, and solid phases, respectively. The experiments were conducted in a vertical perspex column. The liquid and gas was co-currently fed into the column with varying flow rate. The column has three sections comprising of gas-liquid release section, main section, and gas-liquid distributor section, respectively. The significant outcomes of this study are reduced minimum fluidization velocity ranging from 0.004 to 0.01 m/s and minimum semifluidization velocity of 0.032–0.006 m/s compared to reported high values. Maximum bed pressure drop was found to be 5.6 kPa. Empirical mathematical correlations that represent the hydrodynamic and bed characteristics were developed from the experimental data which are also a new aspect of this study. Model results fitted well to the experimental values and the values obtained are quite useful for the various industrial application. [ABSTRACT FROM AUTHOR]

NMR spectroscopy of quadrupolar noble gases, 21Ne (spin 3/2), 83Kr (9/2), 131Xe (3/2), dissolved in thermotropic liquid crystals enables the derivation of versatile information about the physical properties of the materials. The spectra display fine structures, triplets and nonets, which reveal quadrupole couplings. These, in turn, can be used in the determination of electric field gradients (EFG), orientational order parameters, and tilt angles. Comparison of 129Xe and 131Xe chemical shifts reveals second-order quadrupole shifts (SOQS) in circumstances where the ratio of quadrupole coupling and magnetic flux density is suitable. The 131Xe SOQS is shown to distinguish between uniaxial and biaxial nematic phases. Both 83Kr and 131Xe NMR spectra may display asymmetry around the central transition because of the SOQS, which can be used to identify biaxiality in nematic phases. As a curiosity, the effect of possible hexadecapole coupling on the 83Kr NMR transitions of krypton in liquid crystals is discussed. [ABSTRACT FROM AUTHOR]

Ionic liquids (IL) are considered viable alternative solvents for CO2 capture. Because of this and the unlimited number of possible combinations between cations and anions, it is important to develop a systematic approach based on a reliable model for defining the best combinations to promote natural gas sweetening by enabling the most efficient CO2 capture accompanied by minimal hydrocarbons losses. Hence, in this study, the conductor-like screening model for real solvents (COSMO-RS) model was employed to predict the solubility of CO2, CH4, C2H6, and C3H8 in eight selected ILs with varying combinations of cations and anions. All predictions have been compared against experimental data from the literature which was obtained at the same conditions. The model and experimental data show similar trends and moderate agreement for each of the selected ILs. The observed deviations were 8–62%, 8–40%, 1–37%, and 29–35%, for CO2, CH4, C2H6, and C3H8, respectively. Both the experimental data and predictions confirm that [hmim][TCB] IL is more suitable for natural gas sweetening because of its higher CO2 solubility and selectivity than that of other ILs. Finally, the experimentally determined solubilities of these gases in ILs and conventional amine solvents are compared with highlight the greater efficiency of ILs. [ABSTRACT FROM AUTHOR]

In this paper, the generalized (3+1)-dimensional nonlinear wave in liquid with gas bubbles is investigated. It describes the dynamics of nonlinear waves in hydrodynamics. On the one hand, we construct a class of special N-wave solutions by applying the linear superposition principle, resonant multiple wave solutions and complexiton solutions are derived. On the other hand, the rational breather wave and rogue wave solutions of the equation are also obtained by employing the extended homoclinic test method. Finally, all these solutions are presented via 3-dimensional plots and density plots with choices some special parameters to show the dynamic characteristics. [ABSTRACT FROM AUTHOR]

Twenty-six key odourants were found in Hongxin and Shatian pomelo peel oils using aroma extraction dilution analysis (AEDA). trans-2-Dodecenal was identified to be the most potent key odourant, with a flavour dilution value of 100000 in Hongxin and 10000 in Shatian. Hongxin peel oil was found to be more floral while Shatian was green and peely. Gas chromatography coupled with quadrupole time-of-flight mass spectrometry (GC-QTOF/MS) revealed 22 volatiles that were undetected by the less sensitive GC-MS detector. Non-volatile compounds in the peel oils were identified and quantified using liquid chromatography (LC)-QTOF/MS. Besides organic acids, naringin and bergamottin were, concentration-wise, the dominant non-volatile compounds identified in the juices and peel oils, respectively. Pomelo juices had higher antioxidant capacities than their peel oils, and Shatian pomelos possessed higher antioxidant activities than Hongxin. The use of high-resolution detectors allowed for improved compound detection and identification in citrus, and may be applied to other complex natural products. [ABSTRACT FROM AUTHOR]

This work studied the gas–liquid–liquid (G–L–L) reaction system of CO2 absorption into K2CO3/KHCO3 buffer solution enhanced by organic phase in a rotor–stator reactor (RSR). The effects of volume fraction of organic phase, type of organic phase, rotational speed of RSR, gas and liquid volumetric flow rate, and temperature on CO2 absorption percentage were investigated. Results indicate that the addition of the organic phase with a volume fraction of 1.3–1.6% had significant promoting effect on CO2 absorption. CO2 absorption percentage increased with increase in the rotational speed of the RSR but decreased with rise in liquid temperature and gas–liquid ratio. This work demonstrates that RSR can significantly enhance liquid–liquid mixing and gas–liquid mass transfer processes in the G–L–L system. [ABSTRACT FROM AUTHOR]

The departure from ideal gas behavior is described by several known equations of state (EoS), developed from a combination of theoretical considerations and experimental correlations. In this work, a different approach, in the framework of kinetic theory, is proposed: from a pairwise potential of the Lennard–Jones type, the interaction between molecules is accounted for by means of a self-consistent force field. The propagation of a perturbation wave in the dense gas or liquid of unperturbed density n 0 is described and the isothermal propagation velocity is determined. An EoS is derived and compared to the van der Waals EoS, of which it is found to reproduce the main features. [ABSTRACT FROM AUTHOR]

The speed of an excavation and suction rescue vehicle (ESRV) can be adjusted by adjusting the opening position/diameter of the vertical suction component in the gas-liquid flow field within the pipe. In this study, changes in gas-liquid flow in a vertical suction pipe were observed using computational fluid dynamics (CFD) in ANSYS Fluent software. A total of 95 geometric models were established for analysis. The opening diameter is found to substantially affect the gas-liquid two-phase flow within the pipe; a larger opening diameter results in a larger vortex by the gas phase within the pipe at the initial stage, which in turn increases the deformation of the liquid phase. An optimal suction scheme was designed with an opening of 5 mm diameter in any position of the pipe. In this case, the mass flow of liquid at the suction port is about 93.5 kg/s when stable. Openings in the upper part of the pipe are preferable when other opening diameters are used. [ABSTRACT FROM AUTHOR]

Instantaneous gas–liquid flow and distribution have an important influence on the performance of a multiphase pump, especially under the high gas content conditions. How to accurately simulate the complete working cycle of a multiphase pump and reflect the transient oil-gas flow inside the pump cavity are the main difficulties of the study. A three-dimensional whole-cycle numerical simulation has been conducted to predict the void fraction waves of the reciprocating multiphase pumps under the high gas rates and to evaluate the effects of multi-case parameters on its pulsation characteristics. The instantaneous two-phase distribution and fluctuation characteristic accompanying the movement of the piston and the valves during each process of the multiphase pump are innovatively obtained under the high gas rates. Five different ideal gas model and real gas models used in this simulation are compared and optimized first, and then validated by the experimental results. Void fraction wave signals in the time and frequency domains are obtained from multiple working cycles of the multiphase pump, and the pulsation rates, propagation speeds, amplitudes, and power spectral densities are analyzed in great detail under different inlet gas contents, pressure ratios, crank speeds, and stroke lengths. [ABSTRACT FROM AUTHOR]

This project is primarily aimed at determining the effect of phase inversion on oil-water dispersion from a three-phase mixture comprising of an oil-water emulsion at different oil percentages and air at varying liquid and gas flowrates through a horizontal pipe. Parameters affected by phase inversion were investigated such as liquid-side pressure drop, viscosity and flow regimes. The liquid-side pressure drop was estimated and predicted from existing as well as developed correlations. The results obtained were tabulated and represented graphically. Viscosity measurements were taken at different oil percentages. At inversion, the mixture's continuous phase switched from water to oil as indicated by the increase in viscosity and pressure drop. A significant change in pressure drop was noted for all correlations used beyond the point of phase inversion. The viscosity of the liquid phase was tried to be related with oil percentage empirically to get a Reynolds's no of laminar or turbulence. However, that did not influence the prediction significantly. It was also found that tghe occurrence of phase inversion affected the flow regimes of the mixture causing a shift from a plug dominant flow to a more slug-type flow pattern. [ABSTRACT FROM AUTHOR]

Three ionic liquids (ILs), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and 1-ethyl-3-methylimidazolium tetrafluoroborate, were used for the development of electrochemical NO2 sensors and electrochemical transistors. NO2 sensors with a solid electrolyte containing an IL showed good stability, reversibility, and sensitivity up to 365 pA/ppb. The output characteristics of the transistors exhibited suitable properties with respect to the drain-source current vs. the drain-source voltage and the gate-source modulation. Concerning the dynamic characteristics, the fastest response of the drain-source current from ION to IOFF was ∼2 ms. The time constant depends on the type of the cations and the material of the source and drain electrodes. [ABSTRACT FROM AUTHOR]

Upgrading of waxy Mumbai High vacuum residue was carried out at four different temperatures, viz. 430, 445, 460, and 475 °C in an autoclavable reactor. The temperature difference between the material at the wall and at the centre of the reactor was found to be as low as 0οC and as high as 10οC depending upon rate of coke formation at different severities. Maximum coke formation (23.31 wt%) was found at 475 °C and for the reaction time of 60 min. Maximum liquid and gas yield was found to be 55.96 wt% and 16.9 wt%, respectively at 475 °C and for the reaction time of 90 min. [ABSTRACT FROM AUTHOR]

The article talks about the economic aspects of the liquefied natural gas (LNG). With the increasing value and demand of natural gas, countries such as Abu Dhabi, Algeria, Indonesia, Iran, Libya, Nigeria, and the Soviet Union have entered or are planning to enter the market for imported natural gas in Japan, U.S. and Western Europe. The most economic method to transport natural gas across oceans is to ship it in LNG form. The safety of LNG as a source of energy, the reliability of its supply, and its pricing are discussed.

In the early 2000s, developing liquefied natural gas (LNG) was declared a priority by the Russian state-controlled energy company Gazprom. As Gazprom had limited experience of LNG production, a logical solution was to establish partnerships with foreign companies. Despite ambitious goals, no major Gazprom-led LNG projects have emerged so far. While this can mainly be explained by market fall-out, scholars have also pointed to weaknesses in Gazprom’s approach to foreign partners. This article analyses the partnership dynamics between Gazprom, Total, and Statoil in Russia’s most ambitious LNG production project, the Shtokman field in the Barents Sea. The three companies established a partnership to develop the field in 2008, but only four years later the project was shelved. In addition to objective parameters, this paper finds that some of the challenges to the partnership resulted from differing norms, ideas, and world-views. These difficulties might, however, have been overcome had the field been commercially viable. [ABSTRACT FROM AUTHOR]

The polyimide films PM-A were investigated by X-ray diffractometry after deformation at temperatures of liquid nitrogen and liquid helium. As a result of deformation the temperature of liquid nitrogen in the films two regions with different densities were formed. It was found that the deformation of films at liquid-helium temperatures, does not lead to significant changes in the structure of the film. Assuming that the film consists of quasi-linear chain molecules, two «mechanism» has been proposed. These «mechanisms» are qualitatively describe the processes taking place in the polyimide films PM-A after deformation at low temperatures. [ABSTRACT FROM AUTHOR]