Droplet Distribution Research Articles

Mathematical Modeling to Predict the Formation of Micrometer-Scale Crystals Using Reverse Anti-Solvent Crystallization

The reverse addition process in anti-solvent crystallization is safer and more efficient than sieving when dealing with energetic compounds. A new mathematical model has been developed to understand the crystal size mechanism during the reverse addition of solvent in a binary system. This model incorporates droplet dynamics, distribution moments, and mass balance constraints. It can be used to predict the appropriate crystal size for designing explosive recipes with a desired particle size distribution to maximize energy output. The model was validated by conducting reverse-addition crystallization of sodium chloride in a deionized water/ethanol binary system at temperatures ranging from 10 to 50 degrees Celsius. The predicted results closely matched the experimental findings, which were confirmed using a Laser Particle Size Analyzer and Electron Microscope Scanning.

Water Droplet Templating Technique to Design Three-Dimensionally Ordered Porous Structures of Polymer Film.

We developed a unique water droplet templating method to fabricate polymer films with three-dimensionally ordered porous structures. This technique is based on a polymer/solvent/H2O ternary system, and the key is to choose a volatile and hydrophobic solvent that is slightly miscible with H2O. With the fast evaporation of the solvent, water droplets separate from the casting solution and condense from the air to act as pore templates inside the film and on the surface, respectively. According to this law, nitrocellulose (NC) films were produced from the NC/methyl acetate (MA)/H2O system in which the solubility of H2O in MA is 8.1 wt %. By modulating the solution concentration (density) from 3% to 9% NC, the distribution of separated water droplets (pores) in the solution can be flexibly controlled from sinking to floating. On the other hand, substantial ordered honeycomb pores, originated from condensed water droplets, distribute uniformly on the surface of NC films. This water droplet templating technique can be extensively applied in various polymer films, providing an effective pathway to designing polymer films with a desirable porous structure and diverse functionalities.

Camellia saponin modulates oleic acid/linoleic acid-induced lipogenesis in human sebocytes through lipophagy activation.

Oily skin not only threatens people with aesthetic and hygienic discomfort but also confronts them with annoying skin problems. To explore new skin care ingredients from herbal or plant extracts and understand their underlying mechanism for sebum control would assist in the discovery of desirable sebosuppressive agents, though it is still a deserving and challenging task. To explore the effect of Camellia saponin (CS) on modulating the lipogenesis of human sebocytes. Moreover, to explore the underlying mechanism of CS on oleic acid/linoleic acid (OL) mixture stimulated lipid accumulation. The lipid accumulation model of cells was constructed by OL-induction invitro. The lipid synthesis in SZ95 sebocytes was detected by Oil Red O, Nile Red and BODIPY staining and the distribution of lipid droplets and autophagosomes were evaluated by transmission electron microscopy (TEM). Fluorescence staining, immunofluorescence and western blot (WB) were used to characterize the spatial localization of lipid droplets (LDs)/autophagosome/lysosome, the levels of LC3 and P62 proteins related to intracellular autophagy, as well as the pH of lysosome. CS treatment significantly relieved OL-induced lipid accumulation in SZ95 sebocytes. Furthermore, CS maintained lysosomal acid environment to promote the fusion of autophagosome and lysosome, thus recovering the OL-induced blockage of autophagy flow. We also found that CS activated AMPK, and down-regulated mTOR in SZ95 sebocytes. CS was able to relieve OL-stimulated sebum accumulation in cultured human SZ95 sebocytes through lipophagy, in which process CS maintained lysosomal acid environment and activated the AMPK/mTOR pathway.

3D modelling and simulation of thermal effects and dispersion of particles carrying infectious respiratory agents in a railway transport coach

Even though the COVID-19 pandemic now belongs to the long history of infectious diseases that have struck humanity, pathogenic biological agents continue to pose a recurring threat in private places, but also and mainly in places where the public congregates. In our recent research published in this journal in 2022 and 2023, we considered the illustrative example of a commuter train coach in which a symptomatic or asymptomatic passenger, assumed to be infected with a respiratory disease, sits among other travellers. The passenger emits liquid particles containing, for example, COVID-19 virions or any other pathogen. The size spectrum of particles varies depending on whether they are produced during breathing, speaking, coughing or sneezing. More specifically, droplets associated with breathing are in the range of 1–10 µm in aerodynamic diameter, while at the other end of the spectrum, drops associated with coughing can reach 100–1000 µm. In the first part of our research, we used Computational Fluid Dynamics (CFD) to model and simulate in 3D the transport and dispersion of particles from 1 µm to 1 mm in the turbulent flow generated by the ventilation of the railway coach. We used both the Eulerian approach and the Lagrangian approach and showed that the results were strictly similar and illustrated the very distinct aerodynamics, on one hand, of the aerosol of droplets suspended in the air and, on the other hand, of the drops falling or behaving like projectiles depending on their initial speed. In the second part of our research, we developed a model of filtration through a typical surgical mask and possible leaks around the mask if it is poorly adjusted. We resumed the twin experiment of the railway coach and compared the distribution of droplets depending on whether the passengers (including the infected one) wear masks or not and whether the masks are perfectly fitted or worn loosely. Our method made it possible to quantify the particles suspended in the air of the railway coach depending on whether the infected passenger wore their mask more or less well. In this third article, we specifically explore how thermal effects due to the presence of passengers influence the spatio-temporal distribution in the railway coach of aerosols produced by the breathing infected person. We demonstrate that the influence of thermal effects on aerodynamics is very significant and can be very favourable for air decontamination if the ventilation system is judiciously configured. Beyond its application to a commuter train, our work confirms the value of validated CFD tools for describing the airflow and dispersion of particles in complex spaces that do not always allow experimentation. The models that we have developed are applicable to any other semi-confined, ventilated public place, such as a classroom, a hospital room or a performance hall, and they enable the objective assessment of whether the occupation of these spaces could be critical with regard to infectious contamination and of how to limit this ubiquitous risk.

Tianxiangdan suppresses foam cell formation by enhancing lipophagy and reduces the progression of atherosclerosis.

The aim of this study is to assess the impact of Tianxiangdan (TXD) on lipophagy in foam cells and its underlying mechanism in treating atherosclerosis, particularly focusing on its efficacy in lowering blood lipids. In vivo, ApoE-/- atherosclerosis mouse models were established for group intervention. Blood lipid levels of the mice were measured, lipid deposition and autophagy levels in atherosclerotic plaques were assessed, and co-localization of lipid droplets and autophagosomes was examined. In vitro, human THP-1 cells were induced into macrophages and then transformed into foam cells using ox-LDL induction. Different intervention groups were established. Total cellular cholesterol (TC), free cholesterol (FC), and autophagy levels were assessed, while the morphology and distribution of lipid droplets and autophagosomes in cells were observed using transmission electron microscopy. Western blot analysis was performed to evaluate the expression levels of PI3K, Akt, mTOR, TFEB, LC3II/I, ULK1, ABCA1, and p62. TXD effectively lowers blood lipid levels in ApoE-/- atherosclerotic mice, enhances lipophagy, and reduces lipid accumulation in foam cells and arterial lipid plaques. It achieves this by suppressing the expression of p85, Akt, and mTOR, while activating downstream autophagy signals such as TFEB, LC3II/I, and ULK1. Additionally, TXD reduces the expression of p62 and enhances the expression of the cholesterol transport molecule ABCA1. Our findings indicate that TXD activates lipophagy via the PI3K/Akt/mTOR pathway, leading to a reduction in lipid deposition within foam cells and plaques, thereby mitigating atherosclerosis.

Turbulent atomisation of impinging jets under rising backpressure

This study employs direct numerical simulations to examine the effects of varying backpressure conditions on the turbulent atomisation of impinging liquid jets. Using the incompressible Navier–Stokes equations, and a volume-of-fluid approach enhanced by adaptive mesh refinement and an isoface-based interface reconstruction algorithm, we analyse spray characteristics in the environments with ambient gas densities ranging from 1 to 40 times the atmospheric pressure under five different backpressure scenarios. We investigate the behaviour of turbulent jets, incorporate realistic orifice geometries and identify significant variations in the atomisation patterns depending on backpressure. Two distinct atomisation types emerge, namely jet-sheet-ligament-droplet at lower backpressures and jet-sheet-fragment-droplet at higher ones, alongside a transition from dilute to dense spray patterns. This variation affects the droplet size distribution and spray dynamics, with increased backpressure reducing the spray's spreading angle and breakup length, while increasing the droplet size variation. Furthermore, these conditions promote distributions that induce rapid, nonlinear wavy motion in liquid sheets. Topological analysis of the atomisation field using velocity-gradient tensor invariants reveals significant variations in topology volume fractions across different regions. Downstream, the droplet Sauter mean diameter increases and then stabilises, reflecting the continuous breakup and coalescence processes, notably under higher backpressures. This research underscores the substantial impact of backpressure on impinging-jet atomisation and provides essential insights for nozzle design to optimise droplet distributions.

Physiological accumulation of lipid droplets in newborn liver during breastfeeding is driven by TLR4 ligands.

The liver plays a central role in fat storage, but little is known about physiological fat accumulation during early development. Here we investigated a transient surge in hepatic lipid droplets observed in newborn mice immediately after birth. We developed a novel model to quantify liver fat content without tissue processing. Using high-resolution microscopy assessed spatial distribution of lipid droplets within hepatocytes. Lugol's iodine staining determined the timing weaning period, and milk deprivation experiments investigated the relationship between milk intake and fat accumulation. Lipidomic analysis revealed changes in the metabolic profile of the developing liver. Finally, we investigated the role of Toll-like receptor 4 (TLR4) signaling in fat storage using knockout mice and cell-specific deletion strategies. Newborn mice displayed a dramatic accumulation of hepatic lipid droplets within the first 12 hours after birth, persisting for the initial two weeks of life. This pattern coincided with exclusive milk feeding and completely abated by the 3rd week, aligning with weaning. Importantly, the observed fat accumulation shared characteristics with established models of pathological steatosis, suggesting potential biological relevance. Lipid droplets were primarily localized within the cytoplasm of hepatocytes. Milk deprivation experiments demonstrated that milk intake is the primary driver of this transient fat accumulation. Lipidomic analysis revealed significant changes in the metabolic profile of newborn livers compared to adults. Interestingly, several highly abundant lipids in newborns were identified as putative ligands for TLR4. Subsequent studies using TLR4-deficient mice and cell-specific deletion revealed that TLR4 signaling, particularly within hepatocytes, plays a critical role in driving fat storage within the newborn liver. Additionally, a potential collaboration between metabolic and immune systems was suggested by the observed effects of myeloid cell-specific TLR4 ablation. This study demonstrates a unique phenomenon of transient hepatic fat accumulation in newborn mice driven by milk intake and potentially regulated by TLR4 signaling, particularly within hepatocytes.

Prompting droplet breakup by imposing an electric field

Various means for manipulating droplets based on pressure, magnetic, optical, or other external fields have emerged. Despite the remarkable progress, the existing modalities of droplet formation control and manipulation still deserve further investigations, especially for the utilization of biodiesel. Here, we report a method for droplet manipulation using electric fields to achieve improved uniformity of droplet distribution, continuity, and stability of droplet generation. Leveraging on the weakening of surface tension by electric stress could manipulate the droplet size, generation period, and departure rate. When the applied voltage is 4 kV, the droplet size and formation time were reduced by 50% and 7.83 times, respectively. Furthermore, we utilized ethanol with lower surface tension and higher electrical conductivity to improve the response of biodiesel to the electric field, which reduced the droplet breakup time by 211.67 times. Among them, the electric field had the most significant effect on promoting the breakup of BE10. In addition, the effects of electrode structure and flow rate on droplet breakup in the electric field are also considered. These findings provide a satisfactory paradigm for droplet operation in various practical applications.

Determining the optimal oxidation temperature of non-isothermal liquid fuels injections using modeling based on statistical droplet distribution

Single-hole injections of liquid hydrocarbon fuels (isooctane and dodecane) under high turbulence have been investigated using direct numerical simulation based on the statistical model considering the droplets’ atomization, distribution, and combustion. The study objects are the heat and mass transfer processes during atomization and combustion of liquid fuels injections within the combustion chambers of thermal engines. The temperature and carbon dioxide concentration distributions of the fuel-air mixture, the distributions of the droplets, their velocities, and the Sauter mean radius within the isooctane and dodecane oxidation in the engine’s combustion space were obtained. An investigation of the oxidizer’s initial temperature influence on the droplets’ atomization and combustion processes showed that the optimal temperature for both fuels is 900 K. The obtained modeling results were confirmed in good agreement with theoretical and experimental data. Thanks to the integrated use of approaches from statistical theory, numerical algorithms and 3D computer modeling techniques, the results obtained are distinguished by high accuracy, efficiency in reducing computational resources, scientific novelty in the type of droplet atomization and suitability for practical application for technological solutions not only for single-hole, but also for multi-hole injections of liquid fuels and studying the jet-to-jet interaction phenomena. The obtained research results can be applied in miscellaneous internal combustion engines development with different atomization types, which will allow us to contemporaneously settle the concerns of streamlining the combustion process, improving the completeness of fuel combustion and reducing emissions of harmful substances

An Improved Method for Measuring the Distribution of Water Droplets in Crude Oil Based on the Optical Microscopy Technique

The distribution of water droplets in crude oil is one of the key issues involved in the processes of oil extraction and transportation, and these water droplets might also be habitats for microorganisms in oil reservoirs. However, it is still a challenge to observe and measure the distribution of water droplets in crude oil quickly and directly. In this work, an improved method based on the optical microscopy technique is introduced, which is named the Plate Pressing (PP) method and can observe and determine the distribution of water droplets in crude oil directly. The reliability of this method was verified by comparing the results with those of a computed tomography (CT) scan, indicating that the PP method can measure the distribution of water droplets accurately. Meanwhile, the total number and size distribution of water droplets in three crude oil samples from different oilfields were obtained by the PP method, which consolidated the idea that the PP method is capable of determining the distribution of the water droplets in crude oil directly and is suitable for the statistical analysis of water droplets in multiple samples of crude oil.

Effects of Tank-Mix Adjuvants on Spray Performance Under Downwash Airflow Fields Using an Indoor Simulated UASS Spraying Platform

The unmanned aerial spraying system (UASS) has emerged as an advanced tool in precision agriculture for applying plant protection products (PPP). The addition of tank-mix adjuvants to PPP solutions is a common practice to enhance aerial spray performance. However, the effects of these adjuvants on spray performance under the downwash airflow fields generated by UASS rotors remain unclear. This study aimed to evaluate the impacts of adjuvant addition (AGE852B, AGE825, AGE809, and CCL846) on droplet size spectrum and spray deposition distribution with various rotor speeds and layouts, using an indoor simulated single-rotor/multi-rotor UASS spraying platform. The results showed that adding AGE809 and AGE825 made the droplet size and distribution much better in the flat fan nozzle LU110-015 under the downwash airflow field. The spray volume fractions made with droplets smaller than 100 µm (V100) went down by 48.15% and 21.04%, respectively. Furthermore, rotor speed was found to have a significant impact on volume median diameter, relative span, and V100 (p < 0.05). The downwash airflow field was observed to increase the vertical droplet velocity, achieving a more uniform spray distribution in the central airflow area. These results show that choosing the right adjuvants and making the most of the operational parameters can improve spray deposition, coverage uniformity, and drift reduction. This gives us useful information for making PPP applications more efficient and effective in precision agriculture.

Sericin stabilized emulgel for improving therapeutic efficacy of quercetin in treatment of diabetic wound healing

Emulsion stability is vital for effectiveness, ensuring uniform distribution of droplets and preventing phase separation. Instability can lead to inconsistent performance and reduced therapeutic benefits. Thus, our research endeavors were directed toward the design and characterization of a sericin (SN) stabilized quercetin (QRN) emulgel (EG), specifically tailored for diabetic wound healing. Employing a two-factor, 3-level factorial design SN-stabilized QRN emulgel (QSEG) was prepared and the influence of varying percentages of olive oil and SN on zeta potential, globule size, and entrapment efficiency (%) was scrutinized. The optimized QRN emulgel (QSEG), composed of 10% oil and 5% SN (QSE-6), showcased a diminutive globule size of 809.2 ± 21.3 nm alongside an elevated zeta potential of −42.9 ± 3.79 mV. Submicron-sized spherical globules were observed without any signs of coalescence, confirmed by surface morphology analysis. FTIR showed compatibility, while DSC and XRD confirmed that QRN was amorphized and evenly dispersed within the emulgel. In-vitro scratch assays manifested reduced intercellular distances and wound closure, indicative of potent wound healing attributes of QSEG. QSEG demonstrated notable antibacterial efficacy against Escherichia coli (E. coli), with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of 3.125 ± 0.4 and 6.25 ± 1.2 μg/mL, respectively, surpassing that against Staphylococcus aureus (S. aureus). Cytotoxicity assays evidenced diminished toxicity toward fibroblast cells. Furthermore, in-vivo wound healing studies unveiled significant (p ˂ 0.001) enhancements with QSEG compared to QRN-treated and control groups. Our findings underscore SN’s role as a natural stabilizer, synergistically enhancing QSEG’s diabetic wound healing potential. Conclusively, QSEG emerges as a promising alternative to conventional diabetic wound healing treatments, offering inherent medicinal benefits.

A high-speed camera-based measurement system for monitoring and controlling the induced jet break-up fabrication of advanced ceramic breeder pebbles

The production of lithium-rich ceramic pebbles is crucial for future fusion reactors, as they are one of the most important components of the tritium-breeding blankets. In order to produce high-quality pebbles, a melt-based fabrication process KALOS (KArlsruhe Lithium OrthoSilicate) has been developed at the Karlsruhe Institute of Technology (KIT), which produces pebbles utilising the break-up of a molten laminar jet. Since the production of the pebbles is very precise (with diameters of hundreds of micrometres) and significantly influenced by process parameters, a system that monitors and regulates the fabrication in real-time is essential. This paper elaborates on a high-speed camera-based measurement system for automatically monitoring and controlling the production process. Experimental proof demonstrates that the presented measurement system can provide the real-time sizes, locations and distance distribution of the molten ceramic droplets accurately. In addition, the system is also designed to enable the control of the pebble production by adjusting a production parameter, i.e. the driving frequency, based on the real-time output of the proposed measurement system.

Emulsification Stability of An Amphiphilic Polymer for Chemical Flooding

Background: Emulsification plays a pivotal role in the process of enhanced oil recovery, especially in chemical flooding. Emulsification has emerged as one of the key mechanisms facilitating oil recovery in polymer flooding. Aim: This study aimed to solve the problem of emulsification and stability of amphiphilic polymers in the process of oil displacement. Materials and methods: The emulsion was prepared by stirring emulsification method in the lab, and the dynamic stability of the emulsion was determined by stabilizer, and the size and distribution of droplets were determined by laser particle sizing instrument. Results: The experimental results show that, with the increasing mass concentration of amphiphilic polymer, the apparent viscosity of the solution is significantly increased. The emulsification ability and the stability of the emulsion are also enhanced. In addition, the microstructure of the emulsion shows that the amphiphilic polymer with higher concentration helps to reduce the particle size of the emulsified oil droplets and impels the more uniform distribution. Furthermore, the amphiphilic polymer system was conductive to improving the oil-water emulsification ability and prolonging the stability of the emulsion, especially in high-salinity and high-temperature environments. Conclusion: The results of the study are of guiding significance for the emulsification of amphiphilic polymers for oil recovery.

Enhanced spray-wall interaction model for port fuel injection under medium load conditions

Abstract This study presents an Eulerian-Lagrangian framework for the numerical analysis of spray dynamics, with a focus on droplet movement, spray-wall interactions, and the effects of varying injection parameters associated with port fuel injection (PFI) system. A grid-independent criterion is introduced to optimize mesh analysis for accurate predictions of fuel penetration length. The size distribution of secondary droplets is described using a probability density function, and statistical optimization is subsequently implemented to estimate their mean size. This probabilistic approach enhances the Lagrangian wall film (LWF) model, leading to accurate predictions of the Sauter mean diameter (SMD) at a given radial width ( $$R_\text{{w}}$$ R w ), with results closely matching experimental data. For $$8.0 ~\text {mm} \le R_\text{{w}} \le 24.0 ~\text {mm}$$ 8.0 mm ≤ R w ≤ 24.0 mm , the maximum SMD of 21.67 $$\mu$$ μ m corresponds to $$R_\text{{w}} = 14.0, \text {mm}$$ R w = 14.0 , mm , while the smallest SMD of 12.68 $$\mu$$ μ m is computed for a radial position of $$R_\text{{w}} = 24.0 ~\text {mm}$$ R w = 24.0 mm . The numerical investigation quantifies the role of spray-wall interactions in determining the trajectory of fuel distribution, particularly in the formation of wall films and the relative spatio-temporal diesel concentration (F/A) %. The study explores aspects such as droplet size variations, heat transfer during evaporation, and film behavior under different injection pressures, providing insights into the multiphysical characteristics of spray-wall systems. Near the impingement site ( $$2.0 ~\text {mm} \le R_\text{{w}} \le 4.0 ~\text {mm}$$ 2.0 mm ≤ R w ≤ 4.0 mm ), the plume height ( $$H_\text{{w}}$$ H w ) slightly decreases with an increase in injection pressure. While the CFD methodology in this current work has been primarily developed for automotive engineering sector (PFI engines), it also has potential applications in areas such as additive manufacturing, hydropower engineering, climate science, and environmental engineering.

Wind speed effects on rainfall-induced salinity and temperature anomalies at the sea surface microlayer at mid-latitudes

Sea surface salinity (SSS) and temperature (SST) can serve as proxies to detect freshwater fluxes at the sea surface during precipitation. Widely unknown, however, is the impact of precipitation (droplet sizes and velocities) and wind speed on the sea surface microlayer (SML), the <1 mm boundary layer between atmosphere and ocean. We used the autonomous surface vehicle HALOBATES in the German Bight, North Sea, to collect SSS and SST data with high vertical resolution at 7 depths in the top meter, spaced 10–30 cm apart, including the SML. During two rain events with similar maximum rainfall intensity, the magnitude and persistence of the resulting salinity anomaly (between SML and 100 cm depth) was dependent on wind speed. The maximum rate of change of salinity in the SML was 4 times faster with high wind speeds: 0.009 g kg min−1 at low wind speeds, 0.037 g kg min−1 at high wind speeds. A threshold of about 5 m s−1 determined whether stratification occurred in the near-surface layer or freshwater mixed with the underlying layers during precipitation. Strong winds still caused salinity changes in the near-surface layer and SML, but the water mixed rapidly with the underlying water masses. The SML salinity was affected by droplet distributions with smaller droplets, as small droplets stay at the surface. Salinity and temperature changes in the SML were >9 times higher than at 100 cm depth (−0.037 g kg min−1 vs. −0.004 g kg min−1) and still detectable during very high wind speeds. Overall, these results contribute to a better understanding of the vertical distribution of freshwater in the surface ocean and its dependence on rain intensity, wind speed, and droplet properties, helping to improve understanding of the fate of freshwater in a changing ocean due to climate warming.

Study on the total pressure and total temperature distortion of axial flow compressor based on different rain ingestion forms

Aero-engines are required to maintain stable operation under adverse weather conditions, such as heavy rain ingestion. Excessive water ingestion can significantly impact the aerodynamic performance of compressor, potentially leading to performance degradation and even stall. Current investigations reveal that rain ingestion causes losses in both total pressure and total temperature, contributing to the overall deterioration of the performance of compressor. However, these theoretical findings lack robust experimental validation, and the precise relationship between total pressure and temperature losses, alongside the heat and mass transfer mechanisms within the two-phase flow field inside the compressor, remains to be fully established. In this study, a comprehensive experimental and numerical investigation is conducted on a 1.5-stage compressor to assess the effects of water ingestion on compressor performance and internal flow characteristics with varying droplet size distributions and liquid water content (LWC). The results demonstrate that key performance indicators, such as total pressure ratio, efficiency, and the compressor’s stable operating range, are influenced by LWC, droplet size, and the spatial distribution of water ingestion at the inlet. Water ingestion induces non-uniformities in both total pressure and total temperature, with the extent of these distortions governed by factors such as droplet size, concentration, and ingestion patterns across different stages of the compressor. Specifically, increasing water ingestion rates and a concentrated droplet distribution exacerbate total pressure distortions, while simultaneously mitigating total temperature distortions due to the saturation of water vapor. Furthermore, the location and extent of the distorted regions are also influenced by these parameters.

Prediction of Hydrate Formation in Long-Distance Transportation Pipeline for Supercritical-Dense Phase CO2 Containing Impurities.

Supercritical-dense phase CO2 pipeline transportation has been proven to have excellent economic and safety benefits for long-distance CO2 transportation in large-scale. Hydrates are easily generated in the high-pressure and low-temperature sections, resulting in blockage, so it is necessary to build the prediction model for hydrate formation in the long-distance CO2 pipeline transportation. In the prediction model of hydrate formation of our work, the phase equilibrium was determined by the Chen-Guo model, and the lateral growth of hydrate was calculated by the comprehensive growth model, and the hydrate growth was estimated by analogy with the condensation process. Subsequently, the prediction model for hydrate volume in the CO2 pipeline was established considering the process of hydrate growth and water droplet distribution. The effects of thermodynamic conditions, impurities, and operating conditions on the hydrate formation were analyzed. The impurities can expand the temperature and pressure ranges for hydrate generation. The increase in the moisture content, the increase in the pressure, the decrease in the temperature, or the increase in the fluid velocity could increase the volume of hydrates in the pipeline. After running for 10 h, the hydrates volume in the pipeline with the moisture molar fraction of 0.05% is over 10 times that with the moisture molar fraction of 0.005%. In addition, by using the proposed hydrate formation prediction model, the hydrate formation in a supercritical-dense phase CO2 long-distance pipeline was predicted, and a suggested cleaning cycle was achieved. This study can guide the operation of CO2 long-distance transportation pipelines.

Dynamic mechanism of biodiesel-ethanol-graphene droplets during micro-explosion and puffing: droplet evaporation, distribution and velocity characteristics

Adding graphene to biodiesel and ethanol blends can significantly improve the combustion efficiency, which can significantly reduce pollutant emissions when applied to alternative engine fuels. The study of the droplet dynamic properties of biodiesel-ethanol-graphene blends can help to aid in a deeper understanding of the properties of the fuel, which in turn can provide a theoretical basis for the application of the fuel. In this paper, a modified tube furnace experimental platform was used to investigate the evaporation, micro-explosion, and dynamic properties of parent and child droplets of biodiesel-ethanol-graphene. The micro-explosion and dynamics mechanisms of the parent droplets and child droplets of the blended fuel were further investigated in terms of graphene content, ambient temperature and biodiesel/ethanol blend proportion. During the research, three modes of bubble growth in droplet were proposed, the number and velocity of child droplets and the intensity of micro-explosion were found to have a positive correlation trend. It is found that BD50E50(1%G) droplets show high micro-explosion effect and evaporation rate, and can be considered as a sustainable alternative fuel for airlines or oil companies. The movement law of mixed droplets is analyzed, and the internal conditions and external characterization parameters of micro-explosion are summarized.

Synergistic effect and mechanism of stabilization of Pickering emulsion by carboxymethyl starch and xanthan gum

Pickering emulsions were prepared using different proportions of carboxymethyl starch (CMS) and xanthan gum (XG) combined systems as emulsifying stabilizers (The mass ratios of CMS and XG were 10:0, 9:1, 7:1, 5:1, 3:1 and 1:1, respectively). The synergistic mechanism between CMS and XG was also explored. The results demonstrated that CMS particles were uniformly and densely embedded in the gel-like structure formed by XG, and the electrostatic repulsion between CMS and XG led to a reduction in droplet size (from 3370 nm to 482 nm), resulting in a more compact and orderly droplet distribution. Combined systems of CMS and XG at different proportions enhanced the hardness (3.05–8.36 g), adhesiveness (3.26–8.41 g), and chewiness (4.05–8.20 g) of the emulsion. AFM observed that the emulsion particles were finer and more evenly dispersed. After heat treatment at 25 °C, 60 °C and 80 °C, the emulsion showed no significant stratification phenomenon, and CMS/XG enhanced the heat stability of the emulsion. LF-NMR confirmed that the oil and water could be evenly distributed and the emulsification of the system was complete. Especially when the ratio of CMS and XG was 3:1 and 1:1, the emulsion with a stable and long storage period could be obtained.