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A continuous flow metal‐free protocol for the synthesis of sulfonyl chlorides from thiols and disulfides in the presence of nitric acid, hydrochloric acid and oxygen was developed. The influence of the reaction parameters was investigated under batch and flow conditions. Online 19F NMR was successfully implemented to investigate different reaction conditions within a single experiment. The sulfonyl chlorides were isolated (mostly in 70–81 % yield) after performing a simple aqueous washing procedure. In particular, the protocol was successfully operated for >6 hours to convert diphenyl disulfide to its corresponding sulfonyl chloride, achieving a throughput of 3.7 g h−1. The environmental impact of the protocol was assessed and compared to an existing continuous flow protocol using 1,3‐dichloro‐5,5‐dimethylhydantoin (DCH) as reagent. The process mass intensity (PMI) for the newly‐developed flow protocol (15) compared favorably to the DCH flow process (20). [ABSTRACT FROM AUTHOR]

Recently, cryogenic fluids are widely transported via cargo ships as energy sources. The generation of boil-off gas (BOG) is inevitable in a cryogenic container due to the large temperature difference. Therefore, accurately analyzing the boil-off gas over time is essential to increase delivery efficiency and ensure tank safety. However, predicting the boil-off rate (BOR) is not a simple task, as both experiment and calculation require a significant amount of time. In this study, a simple predictive method is developed for simulating a 1/50 scaled model tank. The method consists of steady and quasi-unsteady calculations. Steady calculations are performed to establish a correlation between LN2 level and inner-wall temperature. Quasi-unsteady calculations simulate BOG over time by changing the inner-wall boundary conditions. This method can help engineers effectively evaluate the insulation performance of a cryogenic container in a short time and provide guidelines for simulating a real scale tank. [ABSTRACT FROM AUTHOR]

The reliable design of multiphase micro‐structured apparatus requires a precise knowledge of the internal flow regime. Previous research indicated that classifiers based on artificial neural networks (ANN) are relatively simple to develop and provide a reasonable accuracy when trained with data for specific inlet designs. This paper introduces advanced ANN classifiers capable of predicting all relevant flow regimes regardless of the inlet design with a recall of 94 % and above for Taylor, churn, dispersed, rivulet, and parallel flows, between 89 % and 94 % for annular and bubbly flows, and 83 % for Taylor‐annular flow. These classifiers were trained and validated by using more than 13,000 experimental data points extracted from 97 flow maps. [ABSTRACT FROM AUTHOR]

The effect of a transverse magnetic field on two-phase stratified flow in horizontal and inclined channels is studied. The lower heavier phase is assumed to be an electrical conductor (e.g., liquid metal), while the upper lighter phase is fully dielectric (e.g., gas). The flow is defined by prescribed flow rates in each phase, so the unknown frictional pressure gradient and location of the interface separating the phases (holdup) are found as part of the whole solution. It is shown that the solution of such a two-phase Hartmann flow is determined by four dimensionless parameters: the phases' viscosity and flow-rate ratios, the inclination parameter, and the Hartmann number. The changes in velocity profiles, holdups, and pressure gradients with variations in the magnetic field and the phases' flow-rate ratio are reported. The potential lubrication effect of the gas layer and pumping power reduction are found to be limited to low magnetic field strength. The effect of the magnetic field strength on the possibility of obtaining countercurrent flow and multiple flow states in concurrent upward and downward flows, and the associated flow characteristics, such as velocity profiles, back-flow phenomena, and pressure gradient, are explored. It is shown that increasing the magnetic field strength reduces the flow-rate range for which multiple solutions are obtained in concurrent flows and the flow-rate range where countercurrent flow is feasible. [ABSTRACT FROM AUTHOR]

Active control methods are commonly employed in droplet-based microfluidics. While passive methods of droplet generation face limitations, active methods, including flow rate pulsations provide an avenue for precise control. We investigate the influence of sinusoidal pulsations of dispersed phase flow rate on the plug flow dynamics in a T-junction microchannel. The study covers a range of fluid sets, including gas-liquid and liquid-liquid systems. In the absence of pulsations, distinct regimes of plug formation were identified, and plug length, velocity, and natural frequency of formation were determined. Introducing flow rate pulsations at frequencies proportional to the natural ones f = fpulse/fplug, we observed distinct plug length distributions, including double- or triple-mode, drop-on-demand mode, and multi-mode distribution. The influence of pulsations on plug length was particularly notable at low dimensionless frequencies (f < 1), especially for fluid combinations with higher viscosity ratios. The model was proposed to explain plug length distribution patterns under pulsatile conditions. Micro-PIV measurements provided insights into the velocity fields within plugs, revealing the stretching of streamlines without altering plug length. Our findings contribute to the understanding of active control methods in droplet-based microfluidics and suggest potential applications for precise control over microfluidic processes.

In view of the close relationship between gas-liquid mass transfer performance and flow regime, the coaxial mixer was selected as the research object, and the effects of rotation mode, inner impeller diameter, gas flow rate, and viscosity on flow regimes were experimentally investigated. The results showed that the main growth interval of the mass transfer coefficient was the loading regime, and the critical complete dispersion regime was an efficient and economic operation condition. In this state, the co-rotation mode had a low-power advantage compared to the counter-rotation mode. The anchor speed and gas flow rate could improve mass transfer performance, but at the expense of higher power consumption. Although it was easier to achieve the complete dispersion regime with a larger diameter impeller, the mass transfer performance was reduced at this time. The viscosity had a significant negative influence on gas-liquid dispersion and mass transfer performance. In terms of impeller combinations, PBTD+Anchor and RT+Anchor performed well in low and high viscous systems, respectively. In addition, applying the artificial neural network model to estimate the N cd for the coaxial mixer correlated with the studied parameters to recognize the complete dispersion regime. [Display omitted] • The critical complete dispersion regime was the most efficient operating condition. • Effects of rotation mode, inner diameter impeller, gas flow rate, and liquid viscosity were investigated. • PBTD+Anchor and RT+Anchor performed well in low- and high-viscous systems, respectively. • Mathematical model for accurate estimation of the N cd of the coaxial mixer were established. [ABSTRACT FROM AUTHOR]

Micro‐packed beds have the advantages of excellent heat and mass transfer efficiency and high safety, which have been successfully applied to hydrogenation and oxidation reactions. The dispersion behavior of multiphase flow is closely related to mass transfer and reaction performance. However, the study of dispersion law in micro‐packed beds is not sufficient. This work investigated the dispersion behavior of gas–liquid/liquid–liquid two‐phase flow in micro‐packed beds. The average size and distribution of droplets/bubbles were measured in different systems. Key parameters that affect the dispersion characteristics of the two phases were observed experimentally, including gas/liquid phase flow rate, size of the packing, and physical parameters of the systems. The experimental results showed that gas–liquid and liquid–liquid dispersion processes exhibited different characteristics due to the different physical parameters of liquid and gas as the dispersed phase. The fracture driving force of the gas–liquid process was mainly from the continuous liquid phase, while the fracture driving force of the liquid–liquid process came from both the dispersed phase and the continuous phase. [ABSTRACT FROM AUTHOR]

Flooding is a condition where gas rises vertically upwards from the sparger and through the stirrer region. The flooding point, the impeller speed at which flooding is overcome, is usually considered the minimum operating condition for gas-liquid mixing processes in stirred tanks. Most previous studies on flooding have been performed using low viscosity fluids in the turbulent regime. The present study shows that the flooding point does not change significantly when the viscosity increases (and therefore the Reynolds number decreases) by three orders of magnitude. • The flooding point, N F , can be reliably obtained from shaft torque measurements. • N F is independent of liquid viscosity down to a Reynolds number of approx. 300. • N F estimated using turbulent correlations or data are valid in transitional flow. [ABSTRACT FROM AUTHOR]

The effect of a transverse magnetic field on two-phase stratified flow in horizontal and inclined channels is studied. The lower heavier phase is assumed to be an electrical conductor (e.g., liquid metal), while the upper lighter phase is fully dielectric (e.g., gas). The flow is defined by prescribed flow rates in each phase, so the unknown frictional pressure gradient and location of the interface separating the phases (holdup) are found as part of the whole solution. It is shown that the solution of such a two-phase Hartmann flow is determined by four dimensionless parameters: the phases’ viscosity and flow-rate ratios, the inclination parameter, and the Hartmann number. The changes in velocity profiles, holdups, and pressure gradients with variations in the magnetic field and the phases’ flow-rate ratio are reported. The potential lubrication effect of the gas layer and pumping power reduction are found to be limited to low magnetic field strength. The effect of the magnetic field strength on the possibility of obtaining countercurrent flow and multiple flow states in concurrent upward and downward flows, and the associated flow characteristics, such as velocity profiles, back-flow phenomena, and pressure gradient, are explored. It is shown that increasing the magnetic field strength reduces the flow-rate range for which multiple solutions are obtained in concurrent flows and the flow-rate range where countercurrent flow is feasible.

In this work, a visualization experiment for rectangular channels was carried out to explore gas–liquid two-phase flow characteristics. Typical flow patterns, including bubble, elastic and mixed flows, were captured by direct imaging technology and the corresponding measurements with fluctuation characteristics were recorded by using an electrical conductivity sensor. Time-domain and frequency-domain characteristics of the corresponding electrical conductivity measurements of each flow pattern were analyzed with a probability density function and a power spectral density curve. The results showed that the feature vectors can be constructed to reflect the time–frequency characteristics of conductivity measurements successfully by introducing the quantized characteristic parameters, including the maximum power of the frequency, the standard deviation of the power spectral density, and the range of the power distribution. Furthermore, the overall recognition rate of the four flow patterns measured by the method was 93.33% based on the support vector machine, and the intelligent two-phase flow-pattern identification method can provide a new technical support for the online recognition of gas–liquid two-phase flow patterns in rectangular channels. It may thus be concluded that this method should be of great significance to ensure the safe and efficient operation of relevant industrial production systems. [ABSTRACT FROM AUTHOR]

The pressure drop for air-water two-phase flow in pipeline systems with S-shaped and vertical risers at various inclinations (−1°, −2°, −4°, −5° and −7° from horizontal) was predicted using an artificial neural network (ANN). In the designing of the ANN model, the superficial velocity of gas and liquid as well as the inclination of the downcomer were used as input variables, while pressure drop values of two-phase flows were determined as the output. An ANN network with a hidden layer containing 14 neurons was developed based on a trial-and-error method. A sigmoid function was chosen as the transfer function for the hidden layer, while a linear function was used in the output layer. The Levenberg-Marquardt algorithm was used for the training of the model. A total of 415 experimental data points reported in the literature were collected and used for the creation of the networks. The statistical results showed that the proposed network is capable of calculating the experimental pressure drop dataset with low average absolute percent error (AAPE) of 3.35% and high determination coefficient (R2) of 0.995. [ABSTRACT FROM AUTHOR]

The simulation of gas-liquid two-phase flow through a porous media by using multiple GPUs have performed. The ideal parallel efficiency of the weak scaling is achieved by applying weakly compressible method, which can avoid to solve Poisson's equation. We can calculate a wide range of parameters by introducing weakly compressible method. The conservative Allen-Cahn equation is solved to capture the gas-liquid interface by using the finite volume method to conserve the total mass of each phase. The simulations of gas-liquid two-phase flow through two-dimensional porous medium are performed by using our solver by using multi GPUs. Ideal parallelization efficiency is achieved by overlapping computation and communication time. [ABSTRACT FROM AUTHOR]

The influence of impellers system, baffles system and type of liquid on gas hold-up in a vessel has been presented in this paper. The analysis of gas hold-up was conducted on the basis of the data obtained in the vessel. The vessel used in the study was of inner diameter D = 0.288 m, and it was filled with liquid up to a height of H = 0.576 m. The vessel used in the study was equipped in four planar standard baffles or 24 vertical tubular baffles located on the circuit. A high-speed impellers system, consisting of two impellers located on the shaft, was used to agitate the liquid. The six gas–liquid systems were tested. The gas used in the study was air. The liquids were distilled water, aqueous solutions of NaCl (concentration c = 0.4 kmol/m3 or 0.8 kmol/m3), aqueous solution of sucrose (concentration c = 2.5% mass., 5% mass.), 5% mass. aqueous solution of sucrose and yeast suspension concentration ys = 1% mass. The obtained set of over 1600 experimental points allowed to derive the equations describing the effect of gas flow number Kg, Weber number We and parameter Y (for air–water and air–aqueous solution of NaCl) and Kg, We, c and ys (for air–water, air–aqueous solution of sucrose and air–yeast suspension–aqueous solution of sucrose) on gas hold-up. These equations do not have equivalents in the literature. [ABSTRACT FROM AUTHOR]

Gas-liquid fluid dynamics and mass transfer are crucial aspects of aerobic fermentation and robust methodologies for their determination in industrial bioreactors are expected to provide significant improvements in many production processes. In this work, a gas-liquid stirred tank of high aspect ratio, that replicates the geometry of typical industrial aerated fermenters, is investigated. In particular, the liquid phase homogenization dynamics and the gas phase spatial distribution are determined. The selected methodology is based on the analysis of the conductivity measurements obtained by Electrical Resistance Tomography. The gas-liquid flow regimes and the mixing time are identified at various gas flow rates and impeller speeds, thus covering different gas-liquid regimes. Data collected with vertical and horizontal arrangements of the electrodes allow to obtain a detailed picture of the equipment working mode and to gain insight into the gas-liquid flow dynamics under optically inaccessible conditions. Quantitative evaluation of the reliability of the collected data is attempted by comparing the results obtained with the vertical and horizontal arrangements in the same locations. [Display omitted] • Liquid homogenization and gas distribution in gas-liquid system are investigated. • ERT is applied to measure the mixing characteristics in opaque stirred vessels. • Comparison between different ERT electrodes arrangement has been performed. • The effect of different flow regimes on gas distribution has been quantified. [ABSTRACT FROM AUTHOR]

This paper investigates a CFD‐based analysis for gas–liquid and liquid–liquid Taylor flows through a circular axisymmetric microchannel with a sudden enlargement. A series of simulations are conducted by exploring the influence of different superficial velocity ratios, apparent viscosities, and channel expansion on the hydrodynamics of slug flow. A concentric junction introduces dispersed airflow into a continuous flow of water for gas–liquid flow, and the junction introduces dispersed water into a continuous flow of dodecane for liquid–liquid flow. The air‐bubble and water‐slug evolution processes, slug breakup, and slug expansion are investigated. In all cases, the lengths of air bubbles and water slugs increase with increasing superficial velocity ratio, particularly before the expansion. For gas–liquid flow, the apparent viscosity ratio causes a fluctuating interface over the uniform film region. However, the water slug length is shorter and the film region is slightly thicker in liquid–liquid compared to gas–liquid flow. The numerical analysis developed in this paper is in good agreement with the existing correlations and experimental data in the literature. [ABSTRACT FROM AUTHOR]

Operating efficiency and reliability are major problems that restrict gas-liquid multiphase pumps, which are core pieces of equipment used in deep-sea oil and gas exploration and transportation. In this paper, a 100-20x helical axial-flow gas-liquid pump is taken as the research object. The Euler multiphase flow model and SST k-ω turbulent model are used to model the multiphase pump. By exploring the airfoil composite position and the maximum thickness composite scheme, a mathematical model for the head coefficient and efficiency of the multiphase pump with respect to the relative thickness is established, and the external and internal flow characteristics of the modified multiphase pump are analyzed. We explore the influence of the composite position and the maximum thickness variation law of the composite airfoil on the performance of the mixed pump and determine the final airfoil composite scheme. We found that a change in the maximum thickness of the composite airfoil gives the external curve of the multiphase pump a “hump"-like characteristic, which shows that the head coefficient and efficiency increase first and then decrease with the increase in the maximum thickness of the composite airfoil. When the composite position is in the middle of the airfoil, the airfoil maximum thickness is 1.25 mm and the gas-phase volume fraction is 70%. Moreover, the head coefficient and efficiency of the multiphase pump reach their maximum values; the head coefficient and efficiency increase by 2.4% and 1.16%, respectively, compared with the basic model.

Natural resource agencies need effective strategies to control the spread of aquatic invasive species (AIS) such as invasive fish, which can expand their range using rivers as hydrological pathways to access new areas. Lock and dam structures within major rivers are prospective locations to deploy techniques, such as carbon dioxide (CO2) infusion into lock water, that could impede upstream AIS migration without disrupting vessel passage and lock operation. The current pesticide label for CO2 in the United States allows injections of 100–150 mg/LCO2 as a behavioral deterrent treatment for invasive carps. This research describes the first operationalizing and testing of a CO2 injection and manifold distribution system at a 1,548,000-L navigation lock chamber on the Fox River near Kaukauna, Wisconsin, USA. Two chemical distribution manifolds located on the floor and wall of the chamber were independently tested to quantify mixing time, mixing homogeneity, injection efficiency, and operational power requirements under a range of operating parameters. Both manifold configurations were able to meet most performance benchmarks established during previous fish behavior studies. Certain limitations were exhibited and quantified for both manifold configurations in terms of mixing homogeneity and operational power. This research details the design and performance of CO2-to-water infusion systems that could be used to deter the spread of AIS at navigation pinch-points. These results may inform future CO2 system designs and operating conditions to support natural resource management plans to limit the spread of AIS. [ABSTRACT FROM AUTHOR]

• Population balance predictions are analyzed in gas–liquid Stirred Tanks (ST). • Different flow regimes are investigated starting from validated flow fields. • Current limitations and modeling challenges of the PBM are identified and discussed. • Common coalescence and breakup kernels fail in predicting DSD in the impeller zone. • A workflow for simulating gas-–liquid ST in different flow regimes is proposed. In this work we analyze the challenges of the adoption of a population balance approach in aerated stirred tanks operating at high gas volume fractions, in different flow regimes and when segregation of the phases is present, i.e. due to the formation of aerated cavities behind flat blades. A decoupled solution of the equations governing the fluid flow and of the population balance equation (PBE) is adopted to obtain preliminary information on the bubble size distribution and to identify the specific issues that need to be addressed to extend the applicability of the population balance model to different regimes. A workflow is proposed for the simulation of aerated stirred tanks with geometries for which established correlations for the estimation of bubble size are not available and a simplified approach to determine whether a coupled CFD PBE solution may be required is presented. [ABSTRACT FROM AUTHOR]

In this paper, an Artificial Neural Network soft matrix correlation to estimate the pressure drop of air-water two-phase flow is developed. The applicability of the model is extended by using dimensionless physical numbers as inputs (Air-Reynolds number, Water-Reynolds number, and the ratio of Air Inertial Forces to Water Inertial Forces), so the model can be implemented for vertical pipes with the proper combination of diameter-velocity-density-viscosity allowing estimations of dimensional numbers within the range of: Air-Reynolds numbers (430–6100), Water-Reynolds number (2400–7200), and Air-Water-Inertial forces ratio (1.6–1834), including the diameter range from 3 to 28 mm. Experimental measurements of frictional pressure drop of water-air mixtures are determined at different conditions. A search of the most suitable density, viscosity, and friction models was conducted and used in the model. The performance of the proposed ANN correlation is compared against published expressions showing good approximation to experimental data; results indicate that the most used correlations are within a mean relative error (mre) of 23.9–30.7%, while the proposed ANN has a mre = 0.9%. Two additional features are discussed: i) the applicability and generality of the ANN using untrained data, ii) the applicability in laminar, transitional, and turbulent flow regimen. To take the approach beyond a robust performance mapping, the methodology to translate the ANN into a programmable equation is presented. [ABSTRACT FROM AUTHOR]

Two-phase flow measurement is a key issue in the natural gas industry. Among the many different flow meters available, the swirl meter stands out for its reliability, ease of maintenance, large measurement range, and strong output signal. In this study, computational fluid dynamics (CFD) simulations were conducted, using RNG k-e turbulence and Eulerian multiphase models, to investigate the gas–liquid two-phase flow characteristics in swirl meters. The CFD simulation results were then validated against the tested precession frequency of our experiment, and a satisfactory match was found between the outcomes. A detailed analysis was then conducted to generate profiles for velocity, pressure, etc. Based on examinations of the flow field distributions, it was found that gas flow inside swirl meters is sensitive to the presence of the liquid phase; the influence increased with the volume fraction of the liquid present. Further investigation indicated that the vortex precession was attenuated in the presence of the liquid phase. This led to the variation of the entire field; the pressure fluctuations at the end of the throat, in particular, resulted in metering errors of the gas flows. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ecofriendly catalytic route for combining oleic acid with CO 2 was proposed. • The absorption behaviours of CO 2 and its cycloaddition kinetics was estimated. • Carbonate kinetics of methylated oleic acid and cottonseed oil were compared. • Models for gas–liquid mass transfer and carbonation kinetics were developed. The cycloaddition of CO 2 to epoxidized molecules is an ecofriendly strategy for synthesizing aliphatic carbonates. In this study, heterogeneous catalytic synthesis of carbonated methyl oleate was performed. Influences of reaction parameters such as reaction temperature (403.15–443.15 K), pressure (1–3 MPa), concentration of functional groups (1.22–2.88 mol·L−1) and catalyst loading (0.025–0.042 g·mL−1) on the kinetics were evaluated. Gas-liquid mass transfer of CO 2 in the methylated oleic acid system was investigated, and a mathematical model was developed. The dissolution of CO 2 was found to be exothermic, and the dissolution capacity decreases with increasing temperature and decreasing pressure. The solubility of CO 2 follows an order of methylated form > epoxidized form > carbonated form. A high conversion rate (68.45 %) of epoxides was achieved in 6 h at 443.15 K and 3 MPa with a catalyst loading of 0.042 g·mL−1. These results show a potential route for synthesizing aliphatic carbonates by combining methyl oleate with CO 2. [ABSTRACT FROM AUTHOR]

In this paper, 3D dual impeller stirring tank was used as a model to simulation combine with experiments to explore the acid leaching kinetics of high-calcium and -silicon manganese ores. The effects of stirring speed, temperature, and aeration rate on the spatial distribution of gas and liquid phases were investigated, and the influence of the gas phase on the flow state was further explored by using CFD (Computational Fluid Dynamics). Meanwhile, the effects of stirring speed, temperature, and aeration rate on the leaching rate of target element manganese were studied by experiments. According to simulations and experiments, stirring speed at 500 rpm perfectly. The aeration rate was 7 m/s, the suitable leaching temperature was 140 °C by experiments. These results also showed that the leaching of high-calcium and -silicon manganese ores follows the control of Interface chemical reaction.The apparent activation energy of the reaction was 43.4 kJ.mol−1. [ABSTRACT FROM AUTHOR]

• Multi-scale entropy was used to characterize gas-liquid chaotic mixing characteristic. • Relative power demand (P g / P 0) in gas-liquid mixing system can be enhanced by fractal impeller. • Mass transfer coefficient can be improved by fractal impeller. • Dispersion coefficient (σ) in gas-liquid mixing system can be reduced by fractal impeller. Gas-liquid mixing characteristics in fractal impeller stirred tank were experimentally investigated by measuring multi-scale entropy (MSE), relative power demand (RPD), local gas holdup, bubble size, and mass transfer coefficient (K L a). Results showed that fractal impeller could enhance 21.69% of MSE and 11.94% of RPD on the basis of pitched-blade impeller. Fractal impeller can enhance the local gas holdup, decrease the bubble size, reduce the dispersion coefficient (σ) and improve the gas-liquid dispersion performance. Meanwhile, the regression based on d 32 − for pitched-blade impeller and fractal impeller were obtained. In addition, fractal impeller can also increase 11.07% of volume mass transfer coefficient (K L a) compared with pitched-blade impeller in the gas-liquid mixing process. The results can provide theoretical guidance for the optimal design of gas-liquid stirred tank. Fractal impeller could create a longer turbulence production region and higher turbulence intensities over a wider spatial extent to reduce the impeller trailing vortex and improve the gas-liquid chaotic mixing degree. [Display omitted] [ABSTRACT FROM AUTHOR]

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A continuous flow metal-free protocol for the synthesis of sulfonyl chlorides from thiols and disulfides in the presence of nitric acid, hydrochloric acid and oxygen was developed. The influence of the reaction parameters was investigated under batch and flow conditions. Online 19 F NMR was successfully implemented to investigate different reaction conditions within a single experiment. The sulfonyl chlorides were isolated (mostly in 70-81 % yield) after performing a simple aqueous washing procedure. In particular, the protocol was successfully operated for >6 hours to convert diphenyl disulfide to its corresponding sulfonyl chloride, achieving a throughput of 3.7 g h -1 . The environmental impact of the protocol was assessed and compared to an existing continuous flow protocol using 1,3-dichloro-5,5-dimethylhydantoin (DCH) as reagent. The process mass intensity (PMI) for the newly-developed flow protocol (15) compared favorably to the DCH flow process (20)., (© 2024 Wiley-VCH GmbH.)

A computational study based on unsteady Reynolds-averaged Navier-Stokes that resolves the gas-liquid interface was performed to examine the unsteady multiphase flow in a liquid-ring pump as a function of its inlet pressure (10, 40, and 80kPa) and its impeller's rotational speed (1150, 1450, and 1750rpm). Results obtained show the shape of the liquid ring to play a critical role in creating the expansion ratio needed to draw air into the pump and the compression ratio needed to expel air out of the pump. The dominant processes that determine the shape of the liquid ring was found to be the centrifugal force from rotation, the acceleration and deceleration due to the difference in pressure at the pump's inlet and outlet, and the eccentricity of the impeller relative to the pump's housing. Results are presented to show how the rotational speed of the impeller and the pressure at the pump's inlet affect the nature of the multiphase flow in the pump as well as the pump's effectiveness in creating a vacuum. The effects of heat transfer on the gas phase during the compression and expansion processes were found to be approximated well by polytropic processes. This computational study was validated by comparing computed with measured volumetric flowrates ingested through the suction port and the torque exerted on the pump's impeller. [ABSTRACT FROM AUTHOR]

The use of gases as reagents in organic synthesis can be very challenging, particularly at a laboratory scale. This Concept takes into account recent studies to make the case that gases can indeed be efficiently and safely formed from relatively inexpensive commercially available reagents for use in a wide range of organic transformations. In particular, we argue that the exploitation of continuous flow membrane reactors enables the effective separation of the chemistry necessary for gas formation from the chemistry for gas consumption, with these two stages often containing incompatible chemistry. The approach outlined eliminates the need to store and transport excessive amounts of potentially toxic, reactive or explosive gases. The on‐demand generation, separation and reaction of a number of gases, including carbon monoxide, diazomethane, trifluoromethyl diazomethane, hydrogen cyanide, ammonia and formaldehyde, is discussed. [ABSTRACT FROM AUTHOR]

• Experimental k L a data for pilot-plant and laboratory fermenters are presented. • Experimental k L a data for several impeller types in the coalescent batch are presented. • Using several impeller types for various diameters in coalescent batch. • k L a correlation shapes are suggested for fermenters design. Volumetric mass transfer coefficient (k L a), is the critical transport characteristic in the design of mechanically agitated contactors. Prediction of k L a is nowadays mostly based on literature correlations. Our aim is to establish suitable k L a correlations for different types of devices that would be based on the experimental data set. In our previous work, the correlation for k L a prediction in coalescent batch were described only for Rushton turbines (Petříček et al., 2019). Now, we aim at the description of one universal correlation that would be viable for mechanically agitated contactors in coalescent batch for several impeller types with different diameters and their combinations on a common shaft. The measured transport characteristics were summarized into correlations. This correlation shape can be used to predict transport characteristics in industrial-scale vessels under a wide range of operational conditions. [ABSTRACT FROM AUTHOR]