Liquid Flow Rate Research Articles

Epoxidation of Light Olefin Mixtures with Hydrogen Peroxide on TS-1 Catalyst

The direct epoxidation of mixed ethene and propene feedstocks using hydrogen peroxide over a titanium silicalite (TS-1) catalyst was investigated within a continuous trickle bed reactor operating in laboratory scale. Methanol was employed as the reaction solvent. This study aimed to streamline the epoxidation process by obviating the need for prior separation of alkenes, thereby enhancing process efficiency. An extensive array of operational parameters was explored in a trickle bed reactor, encompassing experimental parameters such as temperature, total pressure, hydrogen peroxide concentration, liquid flow rate, and gas composition. In contrast to prior investigations involving separate ethene and propene epoxidation, this study revealed a reduction in epoxide selectivity. The principal by-products observed were methoxy species, formed through the interaction between the epoxide and methanol, resulting in a ring-opening reaction. The influence of water on this ring-opening process was negligible. Notably, the tunability of the system was demonstrated, highlighting low temperature and elevated partial ethene pressure as pivotal factors for augmentingthe epoxide selectivity. The findings suggest that binary olefin mixtures exhibit diminished selectivity but improved stability. This behavior is potentially linked to the olefin solubility in methanol, or alterations in the surface species concentrations, typically associated with catalyst activity variations. These insights offer a valuable foundation for understanding and optimizing the direct epoxidation of mixed ethene and propene feedstock.Graphical

An experimental investigation on the influence of condenser bypass area for the transient and steady-state heat-transfer performance of heat pipes

Fundamentally, an effective method for improving the performance of transient and steady-state heat transfer is reducing the flow resistance at the phase-change interface based on the counter flow of vapor and liquid within a typical heat pipe. The flow resistance at such an interface is proportional to the volume flow rates of liquid and vapor. Therefore, the flow resistance at the interface can be reduced by limiting the mass flow rate of vapor or liquid. In this study, experiments were performed on a liquid bypass to improve the steady-state thermal performance of heat pipes. A separate bypass tube allowed some liquid to be subcooled in the condenser to bypass the evaporator without passing through the heat pipe. Three liquid-bypass ports were designed and fabricated in a condenser to experimentally investigate the influence of the bypass port area on the thermal performance of the heat pipe under steady-state operation. An on/off valve was attached to each bypass tube port in the condenser to control the bypass flow rate. The results showed that the thermal resistance, an evaluation index of the performance of steady-state heat transfer, generally decreased with an increase in the bypass port area of the condenser. The thermal resistance of a heat pipe with a horizontal tilt angle and one at an inclination angle of 50° decreased by up to 25.5% and 51.6%, respectively.

Downsizing Sustainable Aviation Fuel Production with Additive Manufacturing—An Experimental Study on a 3D printed Reactor for Fischer-Tropsch Synthesis

Sustainable aviation fuels (SAF) are needed in large quantities to reduce the negative impact of flying on the climate. So-called power-to-liquid (PtL) plants can produce SAF from renewable electricity, water, and carbon dioxide. Reactors for these processes that are suitable for flexible operation are difficult to manufacture. Metal 3D printing, also known as additive manufacturing (AM), enables the fabrication of process equipment, such as chemical reactors, with highly optimized functions. In this publication, we present an AM reactor design and conduct experiments for Fischer-Tropsch synthesis (FTS) under challenging conditions. The design includes heating, cooling, and sensing, among others, and can be easily fabricated without welding. We confirm that our reactor has excellent temperature control and high productivity of FTS products up to 800 kgC5+ mcat−3 h−1 (mass flow rate of hydrocarbons, liquid or solid at ambient conditions, per catalyst volume). The typical space-time yield for conventional multi-tubular Fischer-Tropsch reactors is ~100 kgC5+ mcat−3 h−1. The increased productivity is achieved by designing reactor structures in which the channels for catalyst and cooling/heating fluid are in the millimeter range. With the effective control of heat release, we observe neither the formation of hot spots nor catalyst deactivation.

A numerical study on fluid flow and heat transfer characteristics of oily wastewater falling film outside an elliptical tube

Falling film heat exchangers have recently been widespread as a heat transfer technique for oily wastewater. Researching the characteristics of fluid mechanism for heat transmission is crucial. In this research, numerical models are applied to simulate the heat transmission and flow of falling film outside ellipse tube. In order to emulate fluid flow and heat transmission, the oily wastewater falling film is analyzed utilizing the VOF approach under circumstances of constant thermal flow. On the flow properties and heat transfer coefficient distribution of liquid film, the impacts of the input height, contact angle, liquid film flow rate, and oil content are examined. These computational outcomes are attained: (1) More so than film thickness, according to the simulation results, increasing liquid film flow significantly affects velocity;(2) One of the main causes of how oil concentration affects heat transmission is the complex disturbance process of liquid film and the force change around tube structure;(3) Around 40°, inlet height has the greatest impact on local heat transfer coefficient;(4) The overall heat transmission will deteriorate due to the hydrophobic impact brought on by increased contact angle.

Green citrate-based binary diluents for blood oxygenation membranes with high gas permeability

The diluent significantly influences the structure and properties of the oxygenated membrane prepared via thermally induced phase separation (TIPS). With the increasing concern of damage to human body and environment from diluents, non-toxic and environmental-friendly diluents are gradually gaining more attention. In this study, green binary diluents acetyl trioctyl citrate (ATOC) and acetyl tributyl citrate (ATBC) are used to prepare poly-4-methyl-1-pentene (PMP) flat sheet membranes and hollow fiber membranes (HFMs) via TIPS. Firstly, the effects of ATOC/ATBC mass ratio on the morphology, gas permeability, mechanical properties, and crystallization behaviors of flat sheet membranes are investigated. When the ATOC/ATBC mass ratio is 6/4, the membrane has high gas permeability and mechanical properties. Furthermore, the optimal polymer-diluent composition is applied to the preparation of HFMs. The effects of spinning parameters (flow rate of core liquid, and spinning speed) on morphology, gas permeability, and blood oxygenation performance of PMP HFMs are studied. Under optimized preparation conditions, the PMP HFM exhibits high gas permeability (the permeability of O2 is 39.4 ± 2.1 mL min−1 cm−2 bar−1 and the permeability of CO2 is 42.3 ± 2.3 mL min−1 cm−2 bar−1), which is higher than the results reported in previous research. The PMP HFM also shows excellent blood oxygenation performance. This study may contribute to the green preparation of PMP oxygenated membranes for artificial membrane lungs.

Expressing variable mass transfer coefficients for gas fermentation in trickle bed reactor

Gasification of lignocellulosic biomass and syngas biomethanation are promising technologies for producing biomethane. Trickle bed reactors (TBR) are efficient for syngas fermentation allowing for higher concentration of microbial cells and high surface area for mass transfer. Optimized scaling up and dimensioning of the reactor is crucial when it comes to industrial applications. The first step towards this goal and the scope of the present study is to develop a model able to simulate the mass transfer of gases to the liquid phase as a function of the operating conditions and reactor geometry. Experiments were performed in a lab scale TBR with co-current flow of syngas and water, representing the growth medium, to determine the volumetric mass transfer coefficient (kLa) of each gas compound and its dependence on the flowrate of syngas and water and reactor structural characteristics. The kLa achieved were in the range of 6.18–13.6 hr−1 for H2, 2.6–5.79 hr−1 for CO and 1.53–3.43 hr−1 for CO2. A dimensionless equation was fitted to the experimental data and a model was developed to predict kLa of a specific gas at various gas and liquid flowrates, and reactor configurations. A kinetic model was also developed to simulate the concentrations of syngas in gas phase and liquid phase by applying the kLa values predicted by the dimensionless correlation. Finally, the model was validated using experimental data obtained by mass transfer coefficient determination in pilot scale TBR with pure argon gas and literature data where the predicted kLa had a coefficient of variance of ± 15% and ± 25% respectively within a realistic range of liquid and gas flowrates.

Optimization of CO2 Capture Efficiency in a Flue Gas Treatment System: Assessing the Impact of Flow Rates, Absorbent Concentrations, Nanoparticles, and Temperature

This study focuses on improving the efficiency of flue gas purification systems for carbon dioxide (CO2) capture. The researchers investigated various factors, including flow rates, absorbent concentrations, nanoparticles, and temperature, to optimize the CO2 capture process. They conducted experiments using a polytetrafluoroethylene (PTFE) hollow fiber membrane contactor to separate CO2 from nitrogen. The presence of titanium dioxide and silica nanoparticles in a potassium carbonate solution facilitated the separation process. The findings indicate that optimizing flow rates and absorbent concentrations can enhance CO2 capture efficiency. The use of nanoparticles in the absorbent solution was found to improve material capture effectiveness. The study also revealed that higher temperatures contribute to increased CO2 capture efficiency. The research aims to advance CO2 capture techniques to mitigate the release of industrial greenhouse gases, particularly in flue gas treatment systems. The researchers determined optimal settings for CO2 capture in these systems, emphasizing the importance of absorbent concentration for stability and absorption, as well as the role of nanoparticles in enhancing reaction kinetics and CO2 collection. The objective of the analysis is to maximize removal efficiency, although specific lower and upper bounds and a target value were not provided. The proposed solution suggests specific values for the independent variables, including temperature, gas flow rate, liquid flow rate, and the concentrations of K2CO3, PZ, SiO2, and TiO2, to optimize CO2 capture.

Assessment of Machine Learning Algorithms for Predicting Air Entrainment Rates in a Confined Plunging Liquid Jet Reactor

A confined plunging liquid jet reactor (CPLJR) is an unconventional efficient and feasible aerator, mixer and brine dispenser that operates under many operating conditions. Such operating conditions could be challenging, and hence, utilizing prediction models built on machine learning (ML) approaches could be very helpful in giving reliable tools to manage highly non-linear problems related to experimental hydrodynamics such as CPLJRs. CPLJRs are vital in protecting the environment through preserving and sustaining the quality of water resources. In the current study, the effects of the main parameters on the air entrainment rate, Qa, were investigated experimentally in a confined plunging liquid jet reactor (CPLJR). Various downcomer diameters (Dc), jet lengths (Lj), liquid volumetric flow rates (Qj), nozzle diameters (dn), and jet velocities (Vj) were used to measure the air entrainment rate, Qa. The non-linear relationship between the air entrainment ratio and confined plunging jet reactor parameters suggests that applying unconventional regression algorithms to predict the air entrainment ratio is appropriate. In addition to the experimental work, machine learning (ML) algorithms were applied to the confined plunging jet reactor parameters to determine the parameter that predicts Qa the best. The results obtained from ML showed that K-Nearest Neighbour (KNN) gave the best prediction abilities, the proportion of variance in the Qa that can be explained by the CPLJR parameter was 90%, the root mean square error (RMSE) = 0.069, and the mean absolute error (MAE) = 0.052. Sensitivity analysis was applied to determine the most effective predictor in predicting Qa. The Qj and Vj were the most influential among all the input variables. The sensitivity analysis shows that the lasso algorithm can create an effective air entrainment rate model with just two of the most crucial variables, Qj and Vj. The coefficient of determination (R2) was 82%. The present findings support using machine learning algorithms to accurately forecast the CPLJR system’s experimental results.

Closed loop liquid cooling of high-powered CPUs: A case study on cooling performance and energy optimization

This case study presents an experimental investigation of closed loop liquid cooling of CPUs. The cooling system implements a pumped liquid supplying a cold plate fixed to the emulated CPU heat source and a remote Air-Cooled Heat Exchanger (ACHE). The Hybrid Liquid-Air (HLA) system employs 25% v/v Arteco-Freecor with distilled water solution as the primary coolant, and air as the secondary coolant. The thermal-hydraulic performance of the system is characterized over a range of operating conditions, including CPU heat loads (12–72 W/cm2), water volumetric flow rates (0.5–8 L/min), and air velocities (1–3 m/s). In order to provide a performance frame of reference, evaluations were also conducted with a conventional air-based fan-fin CPU cooling system. The results indicate that the HLA system significantly outperforms the traditional air-cooled fan-fin system, with much lower CPU temperatures and feasible power levels exceeding 300 W. Additionally, the study highlights the importance of the liquid flow rate and fan speed on the overall cooling performance. Finally, an optimal combination of liquid and air flow rates is identified for minimum energy consumption. Overall, these findings support the conclusion that conventional air-cooling is reaching its theoretical limit and closed loop liquid cooling has the potential keep pace with the escalating power levels of modern CPUs. However, the additional energy cost of the cooling system should be carefully managed in order to maximize overall system Coefficient of Performance.

Continuous reductive amination of carbonyl compounds with ammonia to synthesize secondary amines with high selectivity

Secondary amines are important compounds in the field of drug development. Applying reductive amination can conveniently synthesize secondary amines from carbonyl compounds. In this work, we propose an economical method for selective synthesis of secondary amines by using ammonia as a nitrogen source. A promising Pt/SiO2 (Pt loading 1 wt%) catalyst was designed for the continuous reductive amination of benzaldehyde (benchmark reaction), and effects of catalyst, solvent, temperature, the molar ratio of ammonia to benzaldehyde, pressure, concentration, liquid flow rate and gas flow rate are investigated. With the optimal reaction conditions, a high yield of dibenzylamine (95.5%) is obtained under very mild reaction temperature (30 ℃) and extremely short reaction times. Furthermore, a kinetic model for the formation of dibenzylamine is established, and corresponding kinetic parameters are obtained. Besides, many substrates, including aromatic aldehydes, biomass derivative furfural and even ketone, can all be smoothly converted into secondary amines.

Catalytic Hydrogenation of Nitrate over Immobilized Nanocatalysts in a Multi-Phase Continuous Reaction System: System Performance, Characterization and Optimization

Nitrate catalytic reduction in a continuous system was studied in the presence of Pd-Cu macrostructured catalysts synthesized through a novel washcoating methodology of the pre-formed bimetallic powder catalyst. The present work aims to understand the behavior of the macrostructured bimetallic catalyst in the presence of different reaction conditions in order to achieve the design of an optimized facility that can produce the best catalytic results: maximum NO3− conversion with enhanced N2 selectivity. The residence time of the inlet solution and the catalyst concentration in the reactor proved to be the parameters that most influenced the conversion and selectivity due to the important role that these parameters play in the hydrodynamic conditions of the reactor. A higher loading of catalyst and lower inlet flow rates allow promoting a higher contact time between the three phases that participate in the reaction (G-L-S). The most efficient reaction conditions (three pieces of the macrostructured catalyst, liquid flow rate of 10 mL min−1, and a total gas flow rate of 200 Ncm3 min−1 (1:1 H2:CO2)) allowed obtaining an NO3− conversion of 51% with a corresponding N2 selectivity of 23%. Also, the conversion results strongly depended on the total gas flow rate used during the reaction since this assists the mixing between the three phases and promotes a greater contact that will contribute to enhanced catalytic results.

Phase volume fraction measurement of vertical oil–water-gas flow using integrated optical-electrical coaxial cross-modal probe sensor

Measuring phase volume fraction is an essential part of petroleum exploration and development. According to the problems that the common sensors are unable to obtain the phase volume fraction of oil–water-gas flow, an integrated optical-electrical coaxial cross-modal probe sensor (IOECCMPS) is designed, and a phase volume fraction system based on IOECCMPS is developed for different oil–water-gas flow. Specifically, the electrical and optical mathematical models of the IOECCMPS were established, and theoretical analysis of electric field distribution and ray tracing results. We also analyzed the sensitivity distribution of the electrical measurement module (EMM). Based on the above results, the effects of structural parameters on its performance are discussed, including the electrode length, electrode thickness, the angle of the monitoring tip, and insulating tube structure. In addition, we also studied the response characteristics of the IOECCMPS in oil–water-gas flow. Furthermore, the IOECCMPS circuit was designed and experimented with on the oil–water-gas flow measurement platform. Experimental results show: the developed IOECCMPS can realize multi-phase measurement under oil–water-gas flow such as liquid flow rate range (0.42–2.92 m3/h), liquid water volume fraction range (50–90%), gas flow rate range (0.21–1.67 m3/h), etc., and the measurement error is within 5%. In the research work of this paper, the developed IOECCMPS can simultaneously accomplish the accurate measurement of phase volume fraction of oil–water-gas flow, which provides a reference for the development of oil production monitoring technology.

Physical and reactive absorption of CO2 in capillaries: Mass transfer, modelling and produced chemical species

In a circular economy and sustainability context, CO2 utilization is key. For photochemical or electrochemical transformations, CO2 absorption in liquids has become crucial and even a limiting step. This work aimed to establish an average mass transport coefficient (k̅La) characteristic of the CO2 absorption in water and in alkaline solutions in capillary absorbers (2–4 mm) under Taylor flow and recirculation mode. A correlation among prevailing dimensionless numbers (Sh, Re, Ca and Sc) was also established. To achieve so, the absorption of CO2 was conducted in both, water and NaOH solutions (0.5 mol/dm3), and its concentration was monitored by measuring total inorganic carbon and pH. The gas and liquid flowrates used for the tests were 1.66×10−4 L/s and 2.5×10−4 L/s, respectively. The effect of temperature was investigated in the range of 283 and 308 K. The highest k̅La was found to be 12 × 10−2 and 2.1 × 10−2 s−1, for water and NaOH solutions, respectively. The modelling and simulation of the carbon species formation and production was also conducted and a determination coefficient (R2) of 0.99 was found.

Analytical first-principles-based model for sprays-based CO2 capture

CO2 removal from flue gases or air is directly proportional to the overall contact area between the solvent and gas flow. Spraying the solvent offers possibilities for large area/volume ratios resulting from the small size of solvent droplets. The overall mass transfer (KGAv) is a crucial indicator of the performance of the system and indicates the overall CO2 capture rate per unit volume at given working pressure. The maximum capture rate of spray systems considered in this study is 608 kmol/m3-hr. This study develops an analytical model to predict mass transfer in spray-based systems for CO2 capture by evaluating KGAv and capture efficiency. Model predictions are validated using two experimental studies for a range of liquid flow rate, inlet solvent loading, different nozzle types, and inlet CO2 partial pressure. The relative importance of the incorporation of equilibrium partial pressure of CO2 (P*) into amine with respect to CO2 partial pressure is also studied. It is found that its effect on KGAv is prominent in high liquid flow rate and low solvent loading regimes where the overall CO2 capture is high. Finally, the variation of key parameters such as KGAv, total mass transfer coefficient (KG), effective area (Av), solvent loading (α), and mole fraction of CO2 in the gas stream (XCO2) along the channel height is studied, which gives insights on optimization of the channel height for specified operating conditions.

Parametric Reduced-Order Modeling of Battery Thermal Management Systems for Varying Rates of Cooling Liquid Flow

The thermal management system in battery packs for electrical/hybrid electric vehicles plays an important role in maintaining good performance and health of battery cells. In order to optimize the thermal management system design, computational fluid dynamics (CFD) simulations are often used. The CFD is a powerful tool that can accurately simulate the thermal behavior of the system using numerical computation techniques such as finite volume method. However, the days-long computational expense means that the CFD-based simulations are still unsuitable for situations when rapid results are required, for example for online predictive control or fast-pace optimization design.A new method of reduced-order modeling of battery thermal management systems (BTMS) was presented in [1]. Given a CFD model, the algorithm based on projection on Krylov-subspace yields a reduced-order model (ROM). The ROM accurately predicts the system’s transient response to arbitrary internal heating of individual batteries and temperature of cooling liquid at inlet. Unlike conventional Krylov-subspace approaches, the algorithm does not require the system matrix of the CFD model. Therefore, the method is more suitable for use with commercial CFD software which does not allow access to such internal information. The ROM uses a drastically reduced number of degrees of freedom requiring drastically reduced simulation time.This paper extends our ROM by including the mass flow rate of cooling liquid as a model parameter. The task is accomplished by interpolating the system matrices after several local reduced-order models are constructed at discrete mass flow rates (MFR). In order to interpolate the local ROMs, we first need to transform the local ROMs onto a common subspace. The transformation matrix is obtained by applying the singular value decomposition (SVD) to the local projection matrices. In this paper, three local ROMs are built at 3 different MFRs. After these local ROMs are transformed according to the above procedure, a parametric reduced-order model (pROM) is constructed via quadratic interpolation.The constructed pROM is tested against the new MFRs different from those used for building the local ROMs. For each new MFR, the pROM produced a transient response that is almost indistinguishable from that of the CFD model (e.g., see Figure 1). The several thousand core-hour computational time needed for CFD simulations is replaced by a few tens of seconds using the pROM on a personal computer. The low computing load of the pROM is deemed adequate for on-board applications. Reference [1] Xiang L, Lee CW, Zikanov O, Hsu C-C. Efficient reduced order model for heat transfer in a battery pack of an electric vehicle. Applied Thermal Engineering. 2022; 201:117641.Figure 1 Figure 1

Thermal performance analysis of 18,650 battery thermal management system integrated with liquid-cooling and air-cooling

The growing emphasis on developing high-performance battery thermal management systems to maintain optimal temperatures in lithium-ion batteries makes it a key priority in the electric vehicle industry. Therefore, this study aims to explore a composite thermal management system that leverages both air and liquid cooling. The study investigates the thermal effects of varying liquid flow rates and air flow rates in a computational fluid dynamics model for an 18,650 battery pack discharged at 2C. A three-dimensional model is built in ANSYS SCDM, and the mesh is generated using Fluent Meshing. Subsequently, the model is imported into Fluent to solve the turbulent flow using the k-ε model. The obtained results provide a temporal characterization of the battery thermal management system. Research indicates that the utilization of the composite thermal management system can reduce the temperature difference of the battery pack to a minimum of 3.73 K. Increasing air and liquid flow rates also decrease the highest temperature to 317.38 K. Moreover, increasing air and liquid flow rates reduce entropy production in the thermal management system. Notably, air flow affects entropy production in both air and fluid regions, making it a more effective means to reduce entropy production. In conclusion, the proposed composite thermal management system improves the cooling performance of traditional thermal management systems and provides guidance for efficient battery thermal management design.

A Pressure-Based Multiphase Flowmeter: Proof of Concept.

Multiphase flowmeters (MPFMs) measure the flow rates of oil, gas, and brine in a pipeline. MPFMs provide remote access to real-time well production data that are essential for efficient oil field operations. Most MPFMs are complex systems requiring frequent maintenance. An MPFM that is operationally simple and accurate is highly sought after in the energy industry. This paper describes an MPFM that uses only pressure sensors to measure gas and liquid flow rates. The design is an integration of a previously developed densitometer with an innovative Venturi-type flowmeter. New computing models with strong analytical foundations were developed, aided by empirical correlations and machine-learning-based flow-regime identification. A prototype was experimentally validated in a multiphase flow loop over a wide range of field-like conditions. The accuracy of the MPFM was compared to that of other multiphase metering techniques from similar studies. The results point to a robust, practical MPFM.

SIMULATION OF THERMAL STUDIES IN A WELL ON THE SIMULATOR DRILLSIM

The paper presents the results of studies in the well conducted specifically for testing the technique of restoring the equilibrium temperature of rocks by measured transient temperature distributions in the well. The technique is based on numerical simulation of heat exchange processes during flushing of a long-idle well and subsequent solution of the inverse problem. A depth temperature measurement was carried out in an idle well (geothermal distribution) and a series of depth temperature measurements were carried out immediately after washing after 3, 6, 9 and 12 hours. After the experiment, numerical simulation of the temperature recovery process after flushing was carried out. To do this, a simulator was developed that takes into account the thermophysical properties of rocks and mudliquid, the design of the well, as well as the history of the well. Based on the developed simulator, it is proposed to implement a solution to the inverse problem of determining the equilibrium temperature of rocks from the measured non-stationary distributions after its perturbation. As shown in the paper, the developed algorithm makes it possible to determine not only the geothermal temperature distribution, but also the flow rate of the mud liquid in the borehole during the flushing process.

Integrated high-gravity process for HCl removal and CO2 capture using carbide slag slurry in a rotor-stator reactor: Experimental and modeling studies

The treatment of flue gas containing HCl and CO2 has garnered significant attention. This study proposes an integrated high-gravity process based on a rotor-stator reactor (RSR) for HCl removal and CO2 capture through mineralization using carbide slag slurry (CSS), an industrial waste. Experimental and modeling studies were conducted to investigate the absorption performance and mass-transfer mechanism. Considering the properties of CSS, Ca(OH)2 slurry was used to simulate CSS for HCl and CO2 absorption in the RSR. The influences of solid content, rotational speed, gas flow rate, and liquid flow rate were investigated, resulting in HCl and CO2 absorption efficiencies of 87.3%–98.9% and 33.8%–65.7%, respectively. Two mechanistic mass-transfer models were established based on surface renewal theory and penetration theory, respectively, to depict the process. The predicted values aligned well with the experimental results, with deviations generally less than 25%. The study further explored the absorption of HCl and CO2 using an actual CSS operated in recycle in the RSR and investigated the characteristics of the solids in fresh and carbonated CSS using XRD, TGA, and SEM. The results indicated that the actual CSS had excellent absorption performance, generally consistent with Ca(OH)2 slurry, and that Ca(OH)2 in CSS was almost completely converted to CaCO3 (calcite).

An improved model for predicting hydrate formation and deposition in horizontal annular flow

The formation and deposition of hydrates in pipelines form flow barriers, which affect the safety of offshore oil and gas transportation. In this study, an improved model of hydrate formation and deposition is established by considering the non-uniform distribution of liquid film and droplets resulting from gravity, which is a non-negligible factor in the accurate prediction of hydrate deposition in horizontal annular flow. The uneven distributions of the hydrate deposit thickness along the radial and axial directions in a horizontal annular flow were calculated using the proposed model. Three different deposition characteristics of hydrates along the radial direction were found: concave W-type, convex W-type, and Ω-type. Meanwhile, the radial hydrate deposit thickness gradually increased as the gas flow rate increased. With an increase in the liquid flow rate, a greater axial distance between the pipe section and inlet results in a clearer increase in the radial hydrate deposit thickness. In addition, a peak value of the hydrate deposit thickness occurs at a certain position in the axial direction. This study provides a theoretical basis for the prediction and prevention of hydrate blockages during offshore gas transportation.