Journal articles on the topic 'Water-soluble polymers Fluid dynamics'
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Zaim, Soumia, Omar Cherkaoui, Halima Rchid, Rachid Nmila, and Reddad El Moznine. "Rheological investigations of water-soluble polysaccharides extracted from Moroccan seaweed Cystoseira myriophylloides algae." Polymers from Renewable Resources 11, no. 3-4 (August 2020): 49–63. http://dx.doi.org/10.1177/2041247920960956.
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The rheological properties and spectrum infrared of polysaccharides extracted from Cystoseira myriophylloides algae were investigated in the concentrations range from 3 to 9% (w/v) and at different temperatures. Results of rheological characteristics in a steady shear rate showed pseudoplastic properties and the dynamic rheological properties showed a fluid-like viscoelastic behavior. The flow and viscoelastic characteristics of polysaccharides were described using the power-law (the Ostwald model). The values of flow behavior index of the sample were close to unity (0.91) for 3% and it decreased up to 0.71 for 9% revealing the shear-thinning (pseudoplastic) nature of these polysaccharides. Moreover, the consistency coefficient increased non-linearly with concentration and it was described by a power law. The flow behavior as a function of temperature was satisfactorily described using the Arrhenius law and the activation energy values were extracted. It decreased from 15.68 and 17.21 kJ/mol when the concentration increased from 5 to 9% (w/v). Additionally, in dynamic rheological measurements, tan δ > 1 and G″ > G′ reveling a shear-thinning behavior. Finally, the analysis of the FTIR spectra of these polysaccharides showed the presence of uronic acid groups. This behavior would suggest that polysaccharides extracted from Cystoseira myriophylloides could be an interesting additive as thickeners.
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Stella, Giovanna, Matteo Barcellona, Lorena Saitta, Claudio Tosto, Gianluca Cicala, Antonino Gulino, Maide Bucolo, and Maria Elena Fragalà. "3D Printing Manufacturing of Polydimethyl-Siloxane/Zinc Oxide Micro-Optofluidic Device for Two-Phase Flows Control." Polymers 14, no. 10 (May 22, 2022): 2113. http://dx.doi.org/10.3390/polym14102113.
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Tailored ZnO surface functionalization was performed inside a polydimethyl-siloxane (PDMS) microchannel of a micro-optofluidic device (mofd) to modulate its surface hydrophobicity to develop a method for fine tuning the fluid dynamics inside a microchannel. The wetting behavior of the surface is of particular importance if two different phases are used for system operations. Therefore, the fluid dynamic behavior of two immiscible fluids, (i) air–water and (ii) air–glycerol/water in PDMS mofds and ZnO-PDMS mofds was investigated by using different experimental conditions. The results showed that air–glycerol/water fluid was always faster than air–water flow, despite the microchannel treatment: however, in the presence of ZnO microstructures, the velocity of the air–glycerol/water fluid decreased compared with that observed for the air–water fluid. This behavior was associated with the strong ability of glycerol to create an H-bond network with the exposed surface of the zinc oxide microparticles. The results presented in this paper allow an understanding of the role of ZnO functionalization, which allows control of the microfluidic two-phase flow using different liquids that undergo different chemical interactions with the surface chemical terminations of the microchannel. This chemical approach is proposed as a control strategy that is easily adaptable for any embedded micro-device.
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Brattekås, Bergit, Martine Folgerø Sandnes, Marianne Steinsbø, and Jacquelin E. Cobos. "A Systematic Investigation of Polymer Influence on Core Scale Wettability Aided by Positron Emission Tomography Imaging." Polymers 14, no. 22 (November 21, 2022): 5050. http://dx.doi.org/10.3390/polym14225050.
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Polymers have been used as viscosifying agents in enhanced oil recovery applications for decades, but their influence on rock surface wettability is rarely discussed relative to its importance: wettability largely controls fluid flow in porous media and changes in wettability may significantly influence subsequent system performance. This paper presents a two-part systematic investigation of wettability alteration during polymer injection into oil-wet limestone. The first part of the paper determines wettability and wetting stability on the core scale. The well-established Amott–Harvey method is used, and five full cycles performed with repeated spontaneous imbibition and forced displacements. Wettability alterations are measured in a polymer/oil system, to determine polymer influence on wettability, and evaluated towards simpler brine/oil and glycerol/oil systems, to determine reproducibility and uncertainty related to the method and fluid/rock system. Polymer injection into oil-wet limestone core plugs is shown to repeatedly and reproducibly reverse the core wettability towards water-wet. Wettability changed both quicker and towards stronger water-wet conditions with polymer solution as the aqueous phase compared to brine and glycerol. The second part of the paper attempts to explain the observed behavior; by utilizing in situ imaging by Positron Emission Tomography, an emerging imaging technology within the geosciences. High resolution imaging provides insight into fluid flow dynamics during water and polymer injections, identifying uneven displacement fronts and significant polymer adsorption.
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Ortiz, Andrea C., Osvaldo Yañez, Edison Salas-Huenuleo, and Javier O. Morales. "Development of a Nanostructured Lipid Carrier (NLC) by a Low-Energy Method, Comparison of Release Kinetics and Molecular Dynamics Simulation." Pharmaceutics 13, no. 4 (April 10, 2021): 531. http://dx.doi.org/10.3390/pharmaceutics13040531.
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Lipid nanocarriers have a great potential for improving the physicochemical characteristics and behavior of poorly water-soluble drugs, such as aqueous dispersibility and oral bioavailability. This investigation presents a novel nanostructured lipid carrier (NLC) based on a mixture of solid lipid glycerides, fatty acid esters of PEG 1500 (Gelucire® 44/14), and an oil mix composed of capric and caprylic triglycerides (Miglyol® 812). These NLCs were developed by a simple low-energy method based on melt emulsification to yield highly encapsulating and narrowly distributed nanoparticles (~100 nm, PdI = 0.1, and zeta potential = ~−10 mV). Rhodamine 123 was selected as a poorly water-soluble drug model and owing to its spectroscopic properties. The novel NLCs were characterized by dynamic light scattering (DLS), zeta potential, nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and colloidal stability. The drug release was determined through a dialysis bag and vertical Franzs’ cells to provide insights about the methods’ suitability, revealing similar performance regardless of their different fluid dynamics. Rhodamine 123 followed a characteristic biphasic release profile owing to the swelling of the hydrophilic polymer coating and diffusion process from the lipid core as revealed by the Korsmeyers–Peppas kinetic modeling. Moreover, to elucidate the formation and incorporation of Rhodamine 123 into the NLC core, several molecular dynamics simulations were conducted. The temperature was shown to be an important condition to improve the formation of the nanoparticles. In addition, the liquid lipid incorporation to the formulation forms nanoparticles with imperfect centers, in contrast to nanoparticles without it. Moreover, Miglyol® 812 improves hydrophobic molecule solubility. These results suggest the potential of novel NLC as a drug delivery system for poorly water-soluble drugs.
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Chen, Zhang, Shomali, Coasne, Carmeliet, and Derome. "Wood–Moisture Relationships Studied with Molecular Simulations: Methodological Guidelines." Forests 10, no. 8 (July 26, 2019): 628. http://dx.doi.org/10.3390/f10080628.
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This paper aims at providing a methodological framework for investigating wood polymers using atomistic modeling, namely, molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations. Atomistic simulations are used to mimic water adsorption and desorption in amorphous polymers, make observations on swelling, mechanical softening, and on hysteresis. This hygromechanical behavior, as observed in particular from the breaking and reforming of hydrogen bonds, is related to the behavior of more complex polymeric composites. Wood is a hierarchical material, where the origin of wood-moisture relationships lies at the nanoporous material scale. As water molecules are adsorbed into the hydrophilic matrix in the cell walls, the induced fluid–solid interaction forces result in swelling of these cell walls. The interaction of the composite polymeric material, that is the layer S2 of the wood cell wall, with water is known to rearrange its internal material structure, which makes it moisture sensitive, influencing its physical properties. In-depth studies of the coupled effects of water sorption on hygric and mechanical properties of different polymeric components can be performed with atomistic modeling. The paper covers the main components of knowledge and good practice for such simulations.
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Correa, Andrea, Antonio De Nicola, Giuseppe Scherillo, Valerio Loianno, Domenico Mallamace, Francesco Mallamace, Hiroshi Ito, Pellegrino Musto, and Giuseppe Mensitieri. "A Molecular Interpretation of the Dynamics of Diffusive Mass Transport of Water within a Glassy Polyetherimide." International Journal of Molecular Sciences 22, no. 6 (March 12, 2021): 2908. http://dx.doi.org/10.3390/ijms22062908.
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The diffusion process of water molecules within a polyetherimide (PEI) glassy matrix has been analyzed by combining the experimental analysis of water sorption kinetics performed by FTIR spectroscopy with theoretical information gathered from Molecular Dynamics simulations and with the expression of water chemical potential provided by a non-equilibrium lattice fluid model able to describe the thermodynamics of glassy polymers. This approach allowed us to construct a convincing description of the diffusion mechanism of water in PEI providing molecular details of the process related to the effects of the cross- and self-hydrogen bonding established in the system on the dynamics of water mass transport.
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Zhang, Yongjian, Chenlong Liu, Xiuxing Tang, Xin Dong, Tan He, Heyi Wang, and Duyang Zang. "Dynamics of Rising Bubbles and Their Impact with Viscoelastic Fluid Interfaces." Polymers 14, no. 14 (July 21, 2022): 2948. http://dx.doi.org/10.3390/polym14142948.
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Bubble dynamics plays a significant role in a wide range of industrial fields, such as food, pharmacy and chemical engineering. The physicochemical properties of complex fluids can greatly affect the speed with which bubbles rise, and the lifetime of bubbles, which in turn can affect the efficiency of food and drug manufacturing and also sewage purification. Therefore, it is of great scientific and practical significance to study the influence mechanism of nanoparticles and surfactants on bubble rising and impact in a complex fluid interface. This paper selects a mixed dispersion liquid of nanoparticles (SiO2) and a surfactant (SDS) as the objects of the study, observes in real-time the entire processes of bubbles rising, impact at the gas-liquid interface, and rupture, and analyzes the dynamic mechanism of bubble impact in a complex fluid interface. By analyzing the morphological changes of the rising bubbles, the rising velocity and the lifetime of the bubbles, it is found that the surfactant molecules are distributed in the ultrapure water liquid pool and the liquid film surrounding the bubbles. Such distribution can reduce the viscoelasticity between bubbles and the liquid surface, and lower the surface tension of the liquid, which can reduce the rising velocity of bubbles, delay the drainage process of bubbles on a liquid surface, and enhance the lifetime of bubbles. If the liquid surface is covered with nanoparticles, a reticulate structure will be formed on the bubble liquid film, which can inhibit bubble discharge and prolong bubble lifetime. In addition, the influence of such a reticulate structure on liquid surface tension is limited and its function is far smaller than a surfactant.
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Pooneeth, Vishwanath, Xu He, Hai Hang Wang, and Mlela Masoud Kamoleka. "Anti-Cavitation Approach in a Bio-Inspired Throttle Valve: A Study of Using Rubber-Like Materials." Materials Science Forum 976 (January 2020): 55–61. http://dx.doi.org/10.4028/www.scientific.net/msf.976.55.
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This multiscale molecular study emphasizes on reducing cavitation in a squid - inspired throttle valve. Molecular simulations on 10 different polymers bonded layer-wise to Iron (III) Oxide were done and the 5 ones having the strongest binding energies were further relaxed using xenon crystals (0.2ns). Changes in the radius of gyration were observed and post relaxation, the interaction energy, the cohesive energy density, and the Hildebrand solubility parameter of the polymer-water layer were determined. Consequently, Polytetrafluoroethylene (PTFE) chosen from the results was further equilibrated for 1.05 ns. To verify its wettability, a contact angle (water nanodroplet) of 115° was estimated. Next, the lined (3mm thick PTFE) valve seat of the chosen throttle valve was numerically analyzed. The computational fluid dynamics (CFD) code, ANSYS Fluent 17.0 was used to test the 3D model with assigned boundary conditions to determine the vapor fraction and the static pressure. Finally, thickness optimization of the lining was done to improve the valve’s performance within the fluid power system and minimize cost involvement.
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Nguyen, Thao X. D., Tuan V. Vu, Sepideh Razavi, and Dimitrios V. Papavassiliou. "Coarse Grained Modeling of Multiphase Flows with Surfactants." Polymers 14, no. 3 (January 28, 2022): 543. http://dx.doi.org/10.3390/polym14030543.
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Coarse-grained modeling methods allow simulations at larger scales than molecular dynamics, making it feasible to simulate multifluid systems. It is, however, critical to use model parameters that represent the fluid properties with fidelity under both equilibrium and dynamic conditions. In this work, dissipative particle dynamics (DPD) methods were used to simulate the flow of oil and water in a narrow slit under Poiseuille and Couette flow conditions. Large surfactant molecules were also included in the computations. A systematic methodology is presented to determine the DPD parameters necessary for ensuring that the boundary conditions were obeyed, that the oil and water viscosities were represented correctly, and that the velocity profile for the multifluid system agreed with the theoretical expectations. Surfactant molecules were introduced at the oil–water interface (sodium dodecylsulfate and octaethylene glycol monododecyl ether) to determine the effects of surface-active molecules on the two-phase flow. A critical shear rate was found for Poiseuille flow, beyond which the surfactants desorbed to form the interface forming micelles and destabilize the interface, and the surfactant-covered interface remained stable under Couette flow even at high shear rates.
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Ciaramitaro, Veronica, Alberto Spinella, Francesco Armetta, Roberto Scaffaro, Emmanuel Fortunato Gulino, George Kourousias, Alessandra Gianoncelli, Eugenio Caponetti, and Maria Luisa Saladino. "A New Methodological Approach to Correlate Protective and Microscopic Properties by Soft X-ray Microscopy and Solid State NMR Spectroscopy: The Case of Cusa’s Stone." Applied Sciences 11, no. 13 (June 22, 2021): 5767. http://dx.doi.org/10.3390/app11135767.
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Hydrophobic treatment is one of the most important interventions usually carried out for the conservation of stone artefacts and monuments. The study here reported aims to answer a general question about how two polymers confer different protective performance. Two fluorinated-based polymer formulates applied on samples of Cusa’s stone confer a different level of water repellence and water vapour permeability. The observed protection action is here explained on the basis of chemico-physical interactions. The distribution of the polymer in the pore network was investigated using scanning electron microscopy and X-ray microscopy. The interactions between the stone substrate and the protective agents were investigated by means of solid state NMR spectroscopy. The ss-NMR findings reveal no significant changes in the chemical neighbourhood of the observed nuclei of each protective agent when applied onto the stone surface and provide information on the changes in the organization and dynamics of the studied systems, as well as on the mobility of polymer chains. This allowed us to explain the different macroscopic behaviours provided by each protective agent to the stone substrate.
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Czarnecka, Elżbieta, Jacek Nowaczyk, Mirosława Prochoń, and Anna Masek. "Nanoarchitectonics for Biodegradable Superabsorbent Based on Carboxymethyl Starch and Chitosan Cross-Linked with Vanillin." International Journal of Molecular Sciences 23, no. 10 (May 11, 2022): 5386. http://dx.doi.org/10.3390/ijms23105386.
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Due to the growing demand for sustainable hygiene products (that will exhibit biodegradability and compostability properties), the challenge of developing a superabsorbent polymer that absorbs significant amounts of liquid has been raised so that it can be used in the hygiene sector in the future. The work covers the study of the swelling and dehydration kinetics of hydrogels formed by grafting polymerization of carboxymethyl starch (CMS) and chitosan (Ch). Vanillin (Van) was used as the crosslinking agent. The swelling and dehydration kinetics of the polymers were measured in various solutes including deionized water buffers with pH from 1 to 12 and in aqueous solutions of sodium chloride at 298 and 311 K. The surface morphology and texture properties of the analyzed hydrogels were observed by scanning electron microscopy (SEM). The influence of this structure on swelling and dehydration is discussed. Fourier transform infrared (FTIR) analyses confirmed the interaction between the carboxymethyl starch carbonyl groups and the chitosan amino groups in the resulting hydrogels. Additionally, spectroscopic analyses confirmed the formation of acetal crosslink bridges including vanillin molecules. The chemical dynamics studies revealed that new hydrogel dehydration kinetics strongly depend on the vanillin content. The main significance of the study concerns the positive results of the survey for the new superabsorbent polymer material, coupling high fluid absorbance with biodegradability. The studies on biodegradability indicated that resulting materials show good environmental degradability characteristics and can be considered true biodegradable superabsorbent polymers.
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Alade, O. S., D. A. Al-Ashehri, M. Mahmoud, K. Sasaki, and Y. Sugai. "Evaluation of laminar flow of surfactant-stabilized bitumen-in-water emulsion in pipe using computational fluid dynamics: Effects of water content and salinity." Journal of Dispersion Science and Technology 41, no. 8 (May 16, 2019): 1105–17. http://dx.doi.org/10.1080/01932691.2019.1614046.
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Ji, Jiayuan, Sheng-Feng Huang, Takuya Mabuchi, and Takashi Tokumasu. "Molecular Dynamics Study of Adsorption Phenomenon of Aromatic Hydrocarbon Ionomer in Catalytic Layer of Polymer Electrolyte Fuel Cell." ECS Meeting Abstracts MA2022-02, no. 41 (October 9, 2022): 1532. http://dx.doi.org/10.1149/ma2022-02411532mtgabs.
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In response to the current global energy crisis and environmental problems, fuel cells are an optional solution. Among them, polymer electrolyte fuel cell (PEFC) has high expectations because of its low operating temperature and suitability for applications in households and mobility devices. Since PEFC requires the use of proton exchange membranes, the transmission efficiency and durability of the exchange membrane is a major concern. To improve the proton transport efficiency, which is generally required, a catalytic layer is integrated into the PEFC. The catalyst layer of PEFC generally contains platinum catalyst covered with the ionomer membrane. Proton conductivity increases with ionomer thickness, while oxygen permeability decreases with ionomer thickness. Therefore, in order to improve the power generation efficiency of PEFC, it is important to design the catalyst layer. In addition, the fluorinated ionomer membrane material (such as Nafion) used for PEFC has good proton conductivity and chemical stability, but the synthesis cost is relatively high. As a consequence, new materials such as composite materials and non-fluorine-based materials have received a lot of attention in recent years. In this study, we focus on a new ionomer material of aromatic hydrocarbon (named SPP-BP) and elucidate the adsorption state of the ionomer on the platinum surface on a nanoscale using molecular dynamics (MD) simulations. Then, the structural properties and water diffusion characteristics of the ionomers of new material (SPP-BP) and conventional Nafion were analyzed based on the MD simulation results. The degree of polymerization (m, p, s) of the monomers were given as 20, 5, and 23 (molecular weight 7.38 kDa), respectively, based on the reported experimental values of SPP-BP. For the polymer composition, molecular models of a random type (r-type), which shows a randomness of monomers, were used. A molecular model of Nafion was also created as the conventional fluorinated membrane materials for comparison with the SPP-BP. The platinum surface was built with a three layers of platinum atoms in a face-centered cubic lattice structure. Regarding the calculation potentials, the DREIDING forcefield was used for the interactions with the molecules. While for the intermolecular potential, the Spohr potential was used for Pt-H2O and Pt-H3O+ interactions, and the others were applied with the Lennard Jones (LJ). The parameters of those potentials were based on the previous studies. In the ionomer membrane, water content is an important indicator that affects the transfer of protons and substances. Based on the water absorption results obtained in the experiment, the water content of SPP-BP was calculated to be between 1.8 and 7.2. Therefore, the water content during the MD simulation was used 3, 5, and 7. The computational size was 55.5 Å × 52.9 Å in the transverse direction of the ionomer membrane (X and Y directions), and the thickness of the membrane adsorbed on the platinum surface was about 50-60 Å. A vacuum region of about 40 Å was set at the top of the system. To calculate the diffusion coefficient and the cluster character of water, multiple simulations with different initial structure were considered. Furthermore, in order to compare to the Nafion, the number of polymers and the computational size was adjusted for containing the same water content. Based on the simulation results, the density distribution of water, hydrophilic sulfo groups, and main body of polymer was analyzed. By the analysis of density distribution, the structure of the ionomer at the interface-vacuum, near the Pt surface and inside was studied. In addition, the orientation of the sulfo group of SPP-BP and Nafion near the Pt surface was analyzed. Besides, the water cluster characteristics and water diffusion properties of the ionomers of SPP-BP and Nafion were also investigated. Acknowledgements: This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan through the fund for ECCEED'30 Projects (No. JPNP20003). Numerical simulations were performed on the Supercomputer system "AFI-NITY" at the Advanced Fluid Information Research Center, Institute of Fluid Science, Tohoku University.
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Yang, Jiangen, Shengrui Yu, and Ming Yu. "Study of Residual Wall Thickness and Multiobjective Optimization for Process Parameters of Water-Assisted Injection Molding." Advances in Polymer Technology 2020 (December 10, 2020): 1–11. http://dx.doi.org/10.1155/2020/3481752.
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Residual wall thickness is an important indicator for water-assisted injection molding (WAIM) parts, especially the maximization of hollowed core ratio and minimization of wall thickness difference which are significant optimization objectives. Residual wall thickness was calculated by the computational fluid dynamics (CFD) method. The response surface methodology (RSM) model, radial basis function (RBF) neural network, and Kriging model were employed to map the relationship between process parameters and hollowed core ratio, and wall thickness difference. Based on the comparison assessments of the three surrogate models, multiobjective optimization of hollowed core ratio and wall thickness difference for cooling water pipe by integrating design of experiment (DOE) of optimized Latin hypercubes (Opt LHS), RBF neural network, and particle swarm optimization (PSO) algorithm was studied. The research results showed that short shot size, water pressure, and melt temperature were the most important process parameters affecting hollowed core ratio, while the effects of delay time and mold temperature were little. By the confirmation experiments for the best solution resulted from the Pareto frontier, the relative errors of hollowed core ratio and wall thickness are 2.2% and 3.0%, respectively. It demonstrated that the proposed hybrid optimization methodology could increase hollowed core ratio and decrease wall thickness difference during the WAIM process.
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Aneja, Madhu, Sapna Sharma, Sireetorn Kuharat, and O. Anwar Beg. "Computation of electroconductive gyrotactic bioconvection under nonuniform magnetic field: Simulation of smart bio-nanopolymer coatings for solar energy." International Journal of Modern Physics B 34, no. 05 (February 18, 2020): 2050028. http://dx.doi.org/10.1142/s0217979220500289.
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The water-based bioconvection of a nanofluid containing motile gyrotactic micro-organisms (moves under the effects of gravity) over a nonlinear inclined stretching sheet in the presence of a nonuniform magnetic field has been investigated. This regime is encountered in the bio-nanomaterial electroconductive polymeric processing systems currently being considered for third-generation organic solar coatings, anti-fouling marine coatings, etc. Oberbeck–Boussinesq approximation along with ohmic dissipation (Joule heating) is considered in the problem. The governing equations of the flow are nonlinear partial differential equations and are converted into ordinary differential equations via similarity transformations. These equations are then solved by the Finite Element Method. The effect of various important parameters on nondimensional velocity, temperature distribution, nanoparticle concentration, the density of motile micro-organisms is analyzed graphically in detail. It is observed from the obtained results that the flow velocity decreases with rising angle of inclination [Formula: see text] while temperature, nanoparticle’s concentration and density of motile micro-organisms increase. The local skin friction coefficient, Nusselt number, Sherwood number, motile micro-organism’s density number are calculated. It is noticed that increasing the Brownian motion and thermophoresis parameter leads to an increase in temperature of fluid which results in a reduction in Nusselt number. On the contrary, the Sherwood number rises with an increase in Brownian motion and thermophoresis parameter. Also, interesting features of the flow dynamics are elaborated and new future pathways for extension of the study identified in bio-magneto-nano polymers (BMNPs) for solar coatings.
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Whitlow, Harry J., Li Ping Wang, and Leona Gilbert. "Transport of Water and Particles in Microfluidics Devices Lithographically Fabricated Using Proton Beam Writing (PBW)." Advanced Materials Research 74 (June 2009): 129–32. http://dx.doi.org/10.4028/www.scientific.net/amr.74.129.
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Proton beam writing (PBW) is a MeV ion beam lithography technique that has gained interest in many biological applications such as fabricating microfluidic devices for Lab-On-a-Chip (LOC) applications where capillary forces are important for fluid flow. PBW has a unique capability of being able to direct-write patterns in thick (1-30µm) polymer resist layers with straight vertical sidewalls. It can be used to prepare master stamps and moulds for mass production in polymeric materials. A recent development, where the direct writing of an entire pattern element is carried out in parallel makes PBW especially well suited for Bio-MEMS LOC applications. In this study we have examined the flow dynamics using video microscopy of deionised water in fluidic channel patterns fluid reservoirs, capillary sections and a capillary pump written by PBW. The video microscopy data also demonstrated that the wetting behavior of the surface strongly influences the dynamics of fluid flow. This makes new approaches for LOC fabrication feasible and powerful.
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Chew, Y. M. J., W. R. Paterson, and D. I. Wilson. "Fluid dynamic gauging: a new technique for studying membrane fouling." Water Supply 7, no. 5-6 (December 1, 2007): 175–84. http://dx.doi.org/10.2166/ws.2007.140.
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The deposition of fouling layers on porous surfaces such as those experienced in membrane/filtration systems has been investigated using the technique of fluid dynamic gauging (FDG). In this work, dead end microfiltration was simulated using polymeric microfiltration membranes and Sphericel (hollow glass spheres) suspensions. FDG was used to track, in situ and in real time, the build-up of a Sphericel cake during the filtration process. The permeate flux through the membrane was also simultaneously monitored. Computational fluid dynamics (CFD) studies were also performed to illuminate the fluid dynamics of FDG, with particular focus on the flow patterns and on the stresses imposed on the porous surface. The governing Navier-Stokes, Darcy's and continuity equations were solved using the commercial partial differential equation solver, Fastflo™. Simulations of gauging flow with a permeable gauged surface were then conducted and comparison with filtration experiments showed excellent agreement.
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Bila, Alberto, and Ole Torsæter. "Enhancing Oil Recovery with Hydrophilic Polymer-Coated Silica Nanoparticles." Energies 13, no. 21 (November 2, 2020): 5720. http://dx.doi.org/10.3390/en13215720.
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Nanoparticles (NPs) have been proposed for enhanced oil recovery (EOR). The research has demonstrated marvelous effort to realize the mechanisms of nanoparticles EOR. Nevertheless, gaps still exist in terms of understanding the nanoparticles-driven interactions occurring at fluids and fluid–rock interfaces. Surface-active polymers or other surface additive materials (e.g., surfactants) have shown to be effective in aiding the dispersion stability of NPs, stabilizing emulsions, and reducing the trapping or retention of NPs in porous media. These pre-requisites, together with the interfacial chemistry between the NPs and the reservoir and its constituents, can result in an improved sweep efficiency. This paper investigates four types of polymer-coated silica NPs for the recovery of oil from water-wet Berea sandstones. A series of flooding experiments was carried out with NPs dispersed at 0.1 wt.% in seawater in secondary and tertiary oil recovery modes at ambient conditions. The dynamic interactions of fluids, fluid–rock, and the transport behavior of injected fluid in the presence of NPs were, respectively, studied by interfacial tension (IFT), spontaneous imbibition tests, and a differential pressure analysis. Core flooding results showed an increase in oil recovery up to 14.8% with secondary nanofluid injection compared to 39.7% of the original oil in place (OOIP) from the conventional waterflood. In tertiary mode, nanofluids increased oil recovery up to 9.2% of the OOIP. It was found that no single mechanism could account for the EOR effect with the application of nanoparticles. Instead, the mobilization of oil seemed to occur through a combination of reduced oil/water IFT, change in the rock surface roughness and wettability, and microscopic flow diversion due to clogging of the pores.
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Tiemeyer, Constantin, and Johann Plank. "Impact of Temperature on the Solution Conformation and Performance of AMPS®- and AHPS-based Fluid Loss Polymers in Oil Well Cement." Zeitschrift für Naturforschung B 69, no. 11-12 (December 1, 2014): 1131–40. http://dx.doi.org/10.5560/znb.2014-4096.
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Abstract A copolymer composed of 2-acrylamido-2-methyl propane sulfonic acid (AMPS®) and N,Ndimethylacrylamide (NNDMA) as well as a forpolymer based on AMPS®, NNDMA, 1-allyloxy- 2-hydroxy propane sulfonic acid (AHPS) and acrylic acid (AA) were synthesized and tested for their temperature stability. Both polymers were dissolved and aged in cement pore solution at temperatures between 100 and 220°C and 35 bar pressure, simulating conditions in actual well cementing. The influence of this high-temperature treatment on the fluid loss performance was assessed via highpressure filtration tests. Water retention capacity and adsorption of AMPS®-co-NNDMA was found to decrease as a result of temperature-induced shrinkage of the stiff, linear polymer chain, as evidenced by dynamic light scattering (DLS) measurement of its hydrodynamic radius. Oppositely, the AHPS-based fluid loss additive did not exhibit coiling under high-temperature conditions. Therefore, its adsorption remained unaffected, and a stable fluid loss performance was observed
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Tahir, Muhammad, Rafael E. Hincapie, Calvin L. Gaol, Stefanie Säfken, and Leonhard Ganzer. "Flow Dynamics of Sulfate-Modified Water/Polymer Flooding in Micromodels with Modified Wettability." Applied Sciences 10, no. 9 (May 7, 2020): 3239. http://dx.doi.org/10.3390/app10093239.
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This work describes the flow behavior of the oil recovery obtained by the injection of sulfate-modified/low-salinity water in micromodels with different wettabilities. It provides a detailed microscopic visualization of the displacement taking place during modified water flooding at a pore-scale level, while evaluating the effect of wettability on oil recovery. A comprehensive workflow for the evaluation is proposed that includes fluid–fluid and rock–fluid interactions. The methods studied comprise flooding experiments with micromodels. Artificial and real structure water-wet micromodels are used to understand flow behavior and oil recovery. Subsequently, water-wet, complex-wet, and oil-wet micromodels help understand wettability and rock–fluid interaction. The effect of the sulfate content present in the brine is a key variable in this work. The results of micromodel experiments conducted in this work indicate that sulfate-modified water flooding performs better in mixed-wet/oil-wet (artificial structure) than in water-wet systems. This slightly differs from observations of core flood experiments, where oil-wet conditions provided better process efficiency. As an overall result, sulfate-modified water flooding recovered more oil than SSW injection in oil-wet and complex-wet systems compared to water-wet systems.
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Mann, K. A., S. Deutsch, J. M. Tarbell, D. B. Geselowitz, G. Rosenberg, and W. S. Pierce. "An Experimental Study of Newtonian and Non-Newtonian Flow Dynamics in a Ventricular Assist Device." Journal of Biomechanical Engineering 109, no. 2 (May 1, 1987): 139–47. http://dx.doi.org/10.1115/1.3138656.
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The fluid dynamic behavior of a Newtonian water/glycerol solution, a non-Newtonian polymer (separan) solution, and bovine blood were compared in the Penn State Electrical Ventricular Assist Device (EVAD). Pulsed doppler ultrasound velocimetry was used to measure velocities in the near wall region (0.95–2.7 mm) along the perimeter of the pump. Mean velocity, turbulence intensity, local and convective acceleration, and shear rate were calculated from the PDU velocity measurements. Flow visualization provided qualitative information about the general flow patterns in the EVAD. Results indicate that water/glycerol does not accurately model the flow characteristics of bovine blood in the EVAD. The non-Newtonian separan solution produced results closer to those of the bovine blood than did the water/glycerol solution. Near wall velocity magnitudes for the separan were similar to those of the bovine blood, but the profile shapes differed for portions of the pump cycle. All three fluids exhibited periods of stagnation. Bovine blood results indicated the presence of a desired rotational washout pattern at mid-systole, while results with the other fluids did not show this feature.
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Shu-guang, ZHANG, SHI Wen-yan, LEI Wu, XIA Ming-zhu, and WANG Feng-yun. "Molecular Dynamics Simulation of Interaction between Calcite Crystal and Water-soluble Polymers." Acta Physico-Chimica Sinica 21, no. 11 (2005): 1198–204. http://dx.doi.org/10.3866/pku.whxb20051102.
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ZHANG, SHU-GUANG, FENG-YUN WANG, and XIAO-YAO TAN. "MOLECULAR DYNAMICS SIMULATION THE HYDROXYAPATITE SCALE INHIBITION MECHANISM OF WATER-SOLUBLE POLYMERS." Journal of Theoretical and Computational Chemistry 09, no. 05 (October 2010): 889–902. http://dx.doi.org/10.1142/s0219633610006067.
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Molecular dynamics (MD) method was used to simulate the interaction between water-soluble polymers, such as polyacrylic acid (PAA), polymethylacrylic acid (PMAA), acrylic acid-methylacrylate copolymer (AA-MAE), acrylic acid-hydroxypropyl acrylate copolymer (AA-HPA), hydrolyzed polymaleic anhydride (HPMA), acrylic acid-maleic acid copolymer (AA-MA), and hydroxyapatite crystal. The sequence of binding energies of polymers binding with the (100) crystal surface of hydroxyapatite was as follows: AA-HPA > AA-MA > HPMA > PAA > AA-MAE > PMAA. After analyzing various energy components and pair correlation functions of all systems, it could be concluded that binding energies were mainly determined by Coulomb interaction. Polymers deformed during their combining with the hydroxyapatite crystal, but all the deformation energies were far less than respective nonbond energies. The dynamics behavior of carboxyls located at different positions of the polymer chains manifested different features during the processes of MD runs. Carboxyls at the ends of the polymer chains oscillated more acutely than those in the middle of the chains; therefore, the latter ones inhibited scale crystal growth more effectively than the former ones because they combined with hydroxyapatite crystal more firmly.
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Akdere, Musa, Sascha Schriever, Gunnar Seide, and Thomas Gries. "Increasing washing performance of wet-spun fibers." International Journal of Clothing Science and Technology 28, no. 3 (June 6, 2016): 293–99. http://dx.doi.org/10.1108/ijcst-03-2016-0034.
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Purpose – The wet-spinning process is very important for the development and production of new lightweight design materials. The washing process is determined as one of the most cost-expensive part of wet spinning. The purpose of this paper is to show the development of a new washing concept. It proposes to increase the washing performance by decreasing fiber-fiber-interfaces during the washing process. Design/methodology/approach – For this purpose, conventional washing concepts are investigated by means of simulations and experiments to obtain process knowledge. Computational fluid dynamics simulation and particle image velocimetry measurements are used to investigate the process. Findings – The overall deficit in conventional washing methods is the large number of fiber-fiber-interfaces, which inhibit the solvent transport out of the compact fiber bundle. Therefore, a new washing concept with included water nozzles is developed. Based on the simulations and observations it is found that the arrangement of the nozzles has direct influence on the fanning of the fiber bundle. Originality/value – With increased fanning of the fiber bundle a more efficient solvent transport is expected. The developed washing box is a prosperous concept to achieve a higher washing performance during the wet-spinning process. The variable design of the washing box makes it possible to test different nozzle configurations and designs. In this paper the two most promising nozzle arrangements are shown and compared to each other.
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Bou-Sai¨d, Benyebka, and Pascal Ehret. "Inertia and Shear-Thinning Effects on Bearing Behavior With Impulsive Loads." Journal of Tribology 116, no. 3 (July 1, 1994): 535–40. http://dx.doi.org/10.1115/1.2928877.
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The study of bearings subjected to impulsive loads have previously showed that inertia effects and surface accelerations play an important role in the bearing response. Although the lubricant was considered Newtonian, this assumption is no longer valid with modern lubricant. In industrial applications, mineral lubricants are added to several long soluble chains of polymer in order to conserve optimum properties under different operating conditions. The addition of these polymers results in the drop of viscosity under high shear-rate, in the range of 10−6–10−8s−1. This study presents a continuation of previous works. It examines the influence of both effects, the decrease in viscosity and the fluid inertia, in a journal bearing under impulsive loads. Using the power-law model, the results show important differences in shaft responses compared to the Newtonian cases. Furthermore, in high shear-thinning effects, a reduction of lubricant capacity to absorb sudden dynamic loads is observed.
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Ntente, C., A. Strekla, Z. Iatridi, M. Theodoropoulou, G. Bokias, and C. D. Tsakiroglou. "Polymer-functionalized nanoparticles as agents for the in situ remediation of oil-contaminated soils." IOP Conference Series: Earth and Environmental Science 1123, no. 1 (December 1, 2022): 012064. http://dx.doi.org/10.1088/1755-1315/1123/1/012064.
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Abstract In-situ flushing of chemicals, such as nanoparticle (NP) suspensions, and NP-based Pickering emulsions, is a well-promising method for the remediation of soils and aquifers contaminated with non-aqueous phase liquids (NAPLs) and the enhanced oil recovery from reservoir rocks. Linear and comb-type copolymers were synthesized by combining (i) hydrophilic, anionic monomers like 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and acrylic acid (AA) with (ii) hydrophobic monomers like dodecyl methacrylate (DMA). Moreover, polymer-coated nanoparticles (PNPs) was prepared by post-grafting and surface initiated free radical polymerization (FRP) on commercial silica nanoparticles. Dilute dispersions of polymers and PNPs were mixed with salts (NaCl, CaCl2), their dynamic surface and oil/water interfacial tensions were measured by the pendant drop method, and the wettability of all fluid systems to glass surface was quantified by measuring the contact angle. Oil-in-water Pickering emulsions were prepared by dispersing n-dodecane in polymers and n-decane in PNP-colloid with ultrasound probe, and their stability was evaluated by tracking the phase separation and changes of rheological properties, as functions of time. Furthermore, the most stable polymers and PNP-based dispersions and emulsions were chosen and tested as chemicals for the removal of residual oil from a transparent glass-etched pore network.
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Jha*, Dr Praveen Kumar, Dr Vinod Kumar Saxena, Prof Suresh Kumar Yatirajula, and Dr Ayanagounder Kumar. "Impact of Natural Polymer (Xanthan Gum) and Bentonite Clay on the Development of Oil-In-Water (O/W) Emulsion Drilling Fluids." International Journal of Innovative Technology and Exploring Engineering 10, no. 10 (August 30, 2021): 129–36. http://dx.doi.org/10.35940/ijitee.i9344.08101021.
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Drilling fluid plays the same role in oil and gas well drilling as the blood in human body. A new type of oil-in-water (o/w) emulsion drilling fluid has been developed using diesel oil as dispersed phase, brine water as continuous phase, xanthan gum as viscosity modifier and clay as emulsion stabilizer and filtration controlling agent. Initially, standard recommended techniques were opted to detect the rheological properties of the emulsions. The fluids have also shown stable properties upto 70°C after aging for 24 h. As drilling fluids encounter a lot of variation in temperature and pressure as drilling depth increases, hence the stability of such fluids becomes an imperative parameter. Furthermore, emulsion itself is a heterogeneous fragile system so the stability was investigated using shear stress-shear rate rheology measurements. Emulsions have shown strong shear-thinning (pseudoplastic) behaviour which is considered an advantageous property for the drilling fluids. Experiments conducted to determine the dynamic rheology of the emulsions have shown the elastic behaviour towards emulsion breakdown processes. The fluids have also shown physical stability after 30 days at ambient conditions. Inter-facial variables such as zaeta potential, inter-racial tension (IFT) and contact angle measurements were conducted to examine their role in stability characterization.
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Lolov, D. S., and Sv V. Lilkova-Markova. "Determination of the critical velocity of the fluid flowing in a single-walled carbon nanotubes embedded in a polymer matrix." PNRPU Mechanics Bulletin, no. 4 (December 15, 2019): 114–19. http://dx.doi.org/10.15593/perm.mech/2019.4.11.
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Since 90’s carbonic nanotubes are broadly used in nanophysics, nanobiology and nanomechanics in nanofluidic devices, nanocontainers for gas storage and nanopipes conveying fluid. They have a perfect hollow cylindrical geometry and superior mechanical strength. The flowing fluid can be water, oil, dynamic flow of methane, ethane and ethylene molecules. The problem of the fluid-structure interaction could be considered in the case of nanoscale. However, the experiments at the nanoscale are difficult and expensive. That is why the continuum elastic models have been used to study the fluid-structure interaction. The carbon nanotubes are considered with Euler- and Timoshenko-beam models. In this paper the dynamic stability of a single-walled carbon nanotube is investigated on the basis of the Euler-beam model and with the employment of the Generalized Differential Quadrature Method. The tube under investigation is assumed hinged at its both ends and is embedded in a polymer matrix. To study the influence of the surrounding elastic medium (for example, a polymer) on the stability of the pipe, an elastic base of Pasternak is introduced. A differential equation is presented that describes the transverse vibrations of a nanotube embedded in a polymer matrix. Dimensionless parameters are introduced. The scheme of Chebycheva-Gauss-Lobato is used for sampling. The coefficients are calculated using Lagrange interpolation functions. A system of homogeneous equations is written in the matrix form. The obtained numerical results are for flowing fluids with different densities. In order to study the effect of the surrounding elastic medium (such as polymer) on the stability of the pipe the Pasternak elastic foundation is introduced. The critical velocities of each type of fluid are determined for different stiffnesses of this matrix. A decrease in the critical speed with the increasing mass ratio has been established.
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Gautam, Sidharth, and Chandan Guria. "Optimal Synthesis, Characterization, and Performance Evaluation of High-Pressure High-Temperature Polymer-Based Drilling Fluid: The Effect of Viscoelasticity on Cutting Transport, Filtration Loss, and Lubricity." SPE Journal 25, no. 03 (March 11, 2020): 1333–50. http://dx.doi.org/10.2118/200487-pa.
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Summary Viscoelasticity plays a significant role in improving the performance of the drilling fluid by manipulating its elastic properties. An appropriate value of the first normal stress difference (N1), extensional viscosity (ηe), and relaxation time (θ) enhance the cutting transportability, hole-cleaning ability, filtration loss, and lubrication behavior. However, the performance of the drilling fluid deteriorates during the drilling of high-pressure and high-temperature (HPHT) wells under acid gas and salt(s) contamination. Therefore, it is a challenging task to synthesize a thermally and rheologically stable drilling fluid, which is acid as well as salt(s) resistant, and maintain its desired properties. Although several water-soluble synthetic polymer-based drilling fluids have been used widely for the drilling of HPHT wells, most of these are limited at less than 200°C. Polyanionic cellulose (PAC) has an excellent heat-resistant stability, salt tolerance, calcium and magnesium resistant, and strong antibacterial activity, and it exhibits exceptional filtration and rheological behavior under HPHT conditions. However, using PAC beyond 200°C is limited because of the presence of the biodegradable cellulose units in it. To use the extraordinary properties of PAC, it is aimed to increase the thermal stability of PAC through appropriate modification. In this study, PAC-grafted copolymers involving acrylamide (a salt-tolerant viscosifying agent), 2-acrylamide-2-methyl-1-propane sulfonic acid (a thermally stable lubricating and fluid-loss control agent), and sodium 4-styrene sulfonate (a high-temperature deflocculant) is synthesized optimally through maximizing the thermal degradation stability of the grafted copolymer and minimizing the filtration loss as well as the coefficient of friction (CoF) of the drilling fluid simultaneously. Optimally synthesized PAC-grafted copolymers are then used to prepare water-based mud (WBM) involving American Petroleum Institute (API)-grade bentonite and alpha-glycol functionalized nano fly ash, and the tests for steady shear viscosity and viscoelasticity are performed to determine the rheological stability of mud beyond 200°C. The amplitude sweep tests for viscoelasticity are performed to determine the linear viscoelasticity range (LVR), structural stability, gel strength, and dynamic yield point (YP), whereas frequency, time, and temperature sweep tests are performed to obtain the elastic modulus (G′), viscous modulus (G″), and complex viscosity under HPHT conditions to check the stability of the drilling fluids under different holding times. Dynamic and static aging tests of the developed drilling fluids are performed at elevated temperature and pressure, and the aged muds are tested by evaluating the rheology, frictional, and filtration-loss behavior as per the API recommended procedure. The stability of the aged muds is also tested by evaluating the N1, ηe, and θ using a cone and plate rheometer. The performance of the proposed drilling fluids is also tested under acidic, sodium chloride (NaCl), and calcium chloride (CaCl2) environments at HPHT bottomhole conditions. The experimental results under HPHT conditions reveal that the performance of the mud (i.e., thermal stability, cutting transportability, hole-cleaning ability, filtration loss, and lubrication behavior) could be considerably improved by increasing the elastic properties of the drilling fluid by manipulating the molecular weight of the proposed PAC-grafted copolymer. Finally, the environmental effect of the developed muds is evaluated by finding the lethal concentration that kills 50% of the shrimp population (i.e., LC50) and the Hg and Cd contamination, and they are found to be environmentally safe.
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Huang, Yun-Ru, Melissa Lamson, Krzysztof Matyjaszewski, and Robert D. Tilton. "Enhanced interfacial activity of multi-arm poly(ethylene oxide) star polymers relative to linear poly(ethylene oxide) at fluid interfaces." Physical Chemistry Chemical Physics 19, no. 35 (2017): 23854–68. http://dx.doi.org/10.1039/c7cp02841e.
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Interfacial tension reduction, dynamic dilatational elasticity and extent of adsorption were investigated for linear poly(ethylene oxide) (PEO) chains of varying molecular weight and for PEO star polymers with an average of 64 arms per star at air/water, xylene/water, and cyclohexane/water interfaces.
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Muzzi, Chiara, Anastasios Gotzias, Enrica Fontananova, and Elena Tocci. "Stability of Graphene Oxide Composite Membranes in an Aqueous Environment from a Molecular Point of View." Applied Sciences 12, no. 7 (March 29, 2022): 3460. http://dx.doi.org/10.3390/app12073460.
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We used molecular dynamics to investigate the stability of graphene oxide (GO) layers supported on three polymeric materials, namely a polyvinylidene fluoride (PVDF), a pristine and a crosslinked polyamide–imide (PAI and PAI-cr). The membrane configurations consisted of a few layers of GO nanosheets stacked over the specified polymeric supports and submerged in water. We monitored the position, the tilt angle, and the radial distribution function of the individual GO nanosheets in respect to the plane of the supports. We showed that the outermost GO nanosheets were more distorted than those attached directly on the supports. The greatest distortion was observed for the GO nanosheets of the PVDF-supported system. Next, we recorded the density profiles of the water molecules across the distance from the layers to the polymer and discussed the hydrogen bonds between water hydrogens and the oxygen atoms of the GO functional groups.
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Wang, Yifan, Sai Vudata, Paul Brooker, and James M. Fenton. "Electrochemical Hydrogen Compression: Modeling, Internal States Estimation and System Control." ECS Meeting Abstracts MA2022-02, no. 40 (October 9, 2022): 1469. http://dx.doi.org/10.1149/ma2022-02401469mtgabs.
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Hydrogen is a clean and flexible energy carrier that can be produced from diverse renewable energy sources (e.g., wind, solar and biomass) and used in a broad range of applications (e.g., transportation and power generation). Due to its high efficiency and carbon-free emission, hydrogen will play a key role in transition to Net Zero Emissions by 2050. However, for a successful hydrogen economy to develop, the compression and storage costs of hydrogen must be lowered to overcome its low volumetric energy density (i.e., 0.01079 MJ/L at STP). Currently， conventional mechanical compression accounts for the largest percentage of operating costs in hydrogen refueling stations [1]. Electrochemical hydrogen compression (EHC) is an innovative non-mechanical technology that compresses hydrogen through application of voltage across membrane separators. Without the vulnerable moving parts of mechanical compressors, EHC is vibration-free, and the noise and possibility of compressor failure are reduced. Electrochemical compression is isothermal, in theory, and thus a higher efficiency is obtained than the adiabatic process of conventional mechanical compression. Consequently, EHC technology is attracting more and more attention as the hydrogen economy takes off. The proton conductivity of the proton exchange membrane (PEM) used in EHC is dependent on its water content and has a significant impact on the EHC performance. Unlike in PEM fuel cells, water is not a reaction product in EHC. Therefore, it is necessary to develop a control system to monitor the hydration degree of the membrane. Besides water management, thermal management is also important. Since high temperature can affect the stability of perfluoro-sulfonate polymers like Nafion®, their operating temperatures are typically below 353 K [2]. Reasonable optimization of operating conditions including current density, back pressure, gas flow, and inlet relative humidity, can effectively manage the temperature and moisture inside the EHC. However, the real-time internal states (e.g., temperature and water content) of EHC must be determined. Mathematical model of EHC with detailed geometries can be built to reveal the multiple coupling phenomena for mass/heat transfer, fluid flow and electrochemical reaction inside the EHC. Also, the EHC model can be used for system control and fault diagnosis. In this study, a high-fidelity dynamic model of EHC is developed with due consideration of two-dimensional distributed mass/heat transfer coupled with electrochemical kinetics. In the EHC model, the dynamics inside the anode and cathode gas channels are characterized by the discretized conservation equations of mass and energy balances, and a lumped parameter model is used to describe the transport and electrochemical reaction in the membrane electrode assembly (MEA). A numerical approach is implemented to solve the spatial derivatives of the gas channel model. Using appropriate boundary conditions, forward or backward differences are employed to realize finite-difference discretization. In the n-discretized finite elements model of EHC, the inlet and outlet flow of cathode and anode gas channels are considered as the boundary conditions. The reaction gas and water transport terms are considered as input disturbances for the discretized model, which can be determined based on the lumped MEA model. The EHC model can be used to detect local dehydration of PEM due to the unbalanced contribution of the electro-osmotic flow and the back diffusion of water across the membrane. The heterogeneities significantly affect the overall efficiency of an EHC. The physical parameters, such as the inlet relative humidity, discharge pressure, and PEM thickness, are optimized to enhance the overall efficiency of the system. [1] Parks, G., Boyd, R., Cornish, J., & Remick, R. (2014). Hydrogen station compression, storage, and dispensing technical status and costs: Systems integration (No. NREL/BK-6A10-58564). National Renewable Energy Lab. (NREL), Golden, CO (United States). [2] Sdanghi, G., Maranzana, G., Celzard, A., & Fierro, V. (2019). Review of the current technologies and performances of hydrogen compression for stationary and automotive applications. Renewable and Sustainable Energy Reviews, 102, 150-170.
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Mudedla, Sathish Kumar, Maisa Vuorte, Elias Veijola, Kaisa Marjamaa, Anu Koivula, Markus B. Linder, Suvi Arola, and Maria Sammalkorpi. "Effect of oxidation on cellulose and water structure: a molecular dynamics simulation study." Cellulose 28, no. 7 (March 3, 2021): 3917–33. http://dx.doi.org/10.1007/s10570-021-03751-8.
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AbstractEnzymatic cleavage of glycocidic bonds is an important, green and biocompatible means to refine lignocellulosic biomass. Here, the effect of the resulting oxidation point defects on the structural and water interactions of crystalline cellulose {100} surface are explored using classical molecular dynamics simulations. We show that even single oxidations reduce the connections within cellulose crystal significantly, mostly via local interactions between the chains along the surface plane but also via the oxidation defects changing the structure of the crystal in direction perpendicular to the surface. Hydrogen bonding on the surface plane of cellulose is analyzed to identify onset of desorption of glucose chains, and the desorption probed. To assess the actual soluble product profile and their fractions resulting from lytic polysaccharide monooxygenase (LPMO) enzyme oxidation on real cellulose crystal samples, we employ High-Performance Anion-Exchange Chromatography with Pulsed Amperometric-Detection (HPAEC-PAD) technique. The findings demonstrate the LPMO oxidation results in soluble glucose fragments ranging from 2 to 8 glucose units in length. Additionally, significantly more oxidized oligosaccharides were released in LPMO treatment of AaltoCell than Avicel, the two studied microcrystalline cellulose species. This is likely to result from the large reactive surface area preserved in AaltoCell due to manufacturing process. Furthermore, as can be expected, the oxidation defects at the surfaces lead to the surfaces binding a larger amount of water both via direct influence by the defect but also the defect induced protrusions and fluctuations of the glucose chain. We quantify the enhancement of water interactions of cellulose crystals due to the oxidation defects, even when no desorption takes place. The molecular simulations indicate that the effect is most pronounced for the C1-acid oxidation (carboxylic acid formation) but present also for the other defects resulting from oxidation. The findings bear significance in understanding the effects of enzymatic oxidation on cellulose nanocrystals, the difference between cellulose species, and cleavage of soluble products from the cellulosic material.
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Pogrebnyak, Volodymyr G., Igor I. Chudyk, Andriy V. Pogrebnyak, and Iryna V. Perkun. "Perforation of oil and gas wells by a high-velocity jet of polymer solution." Nafta-Gaz 78, no. 1 (January 2022): 3–12. http://dx.doi.org/10.18668/ng.2022.01.01.
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ABSTRACT: The work is devoted to the development of a technological process for perforating oil and gas well casing strings by a high-velocity jet of a polymer solution. The proposed method of well perforation refers to methods for the secondary opening of productive deposits in the well by hydrojet perforation of the casing strings, annulus cement ring (stone) and rock. The new knowledge about the dynamics of polymer solutions under the conditions of flow through the jet-forming nozzles of a hydroperfora-tor, which create a high-velocity jet, became the main scientific basis for this method of hydroperforation of oil and gas well casings. The study of the reaction of polymer solutions to the hydrodynamic effect with stretching led to the formulation of a structural con-cept, the “common denominator” of which is a strong deformation effect of the hydrodynamic field on macromolecular coils, which in terms of nonequilibrium thermodynamics generates a kind of rubber-like high elasticity. The peculiarities of the hydrodynamic behaviour of aqueous solutions of polyethylene oxide (PEO) during flow under the conditions of various nozzle jets were modelled, and the regularities of the influence of the resulting dynamic structures on the efficiency of hydrojet water–polymer perforation were established. The mechanism of hydrojet water–polymer perforation of casing columns in oil and gas wells was clarified. The mecha-nism of the large destructive capacity of a high-velocity polymer solution jet is not due to the reduction of turbulent friction by small polymer additives (the Toms effect), but consists in the destructive action of the dynamic pressure of the water–polymer jet “rein-forced” by highly developed macromolecular coils and the dynamic structures formed under the action of extended flow in the inlet section of the hydroperforator nozzles. The method of perforating oil and gas well casings comprises the exact determination of the perforation zone in lowering on production tubing a hydroperforator with 2–4 jet flow-forming nozzles for directing hydrojet to the zone of perforation, sealing the inside cavity of tubing pipes and the jet operators, actuating a ball valve at the bottom of the jet operators, sealing the annulus with a self-sealing gland and supplying the working cutting fluid to the tubing – which differs in that the aqueous solution of PEO used as a working cutting fluid has a molecular weight of 6 · 106 and a concentration 0.003–0.007% by weight and a working pressure of 100–300 MPa. The PEO additives are very environmentally friendly because this polymer is not harmful to humans or the environment. Experimental and industrial testing of this method of well perforation, which was carried out during the secondary opening of a reservoir at a well in the Carpathian oil- and gas-bearing region, confirmed the practical and eco-nomic feasibility of its use.
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Qu, Shuguo, Guanghui Chen, Jihai Duan, Weiwen Wang, and Jianlong Li. "Computational fluid dynamics study on the anode feed solid polymer electrolyte water electrolysis." Korean Journal of Chemical Engineering 34, no. 6 (May 19, 2017): 1630–37. http://dx.doi.org/10.1007/s11814-017-0094-1.
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Liu, Jinliang, Fengshan Zhou, Fengyi Deng, Hongxing Zhao, Zhongjin Wei, Wenjun Long, Amutenya Evelina, Cunfa Ma, Sinan Chen, and Liang Ma. "Improving the rheological properties of water-based calcium bentonite drilling fluids using water-soluble polymers in high temperature applications." Journal of Polymer Engineering 42, no. 2 (December 13, 2021): 129–39. http://dx.doi.org/10.1515/polyeng-2021-0205.
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Abstract Most of bentonite used in modern drilling engineering is physically and chemically modified calcium bentonite. However, with the increase of drilling depth, the bottom hole temperature may reach 180 °C, thus a large amount of calcium bentonite used in the drilling fluid will be unstable. This paper covers three kinds of calcium bentonite with poor rheological properties at high temperature, such as apparent viscosity is greater than 45 mPa·s or less than 10 mPa·s, API filtration loss is greater than 25 mL/30 min, which are diluted type, shear thickening type and low-shear type, these defects will make the rheological properties of drilling fluid worse. The difference is attributed to bentonite mineral composition, such as montmorillonite with good hydration expansion performance. By adding three kinds of heat-resistant water-soluble copolymers Na-HPAN (hydrolyzed polyacrylonitrile sodium), PAS (polycarboxylate salt) and SMP (sulfomethyl phenolic resin), the rheological properties of calcium bentonite drilling fluids can be significantly improved. For example, the addition of 0.1 wt% Na-HPAN and 0.1 wt% PAS increased the apparent viscosity of the XZJ calcium bentonite suspension from 4.5 to 19.5 mPa·s at 180 °C, and the filtration loss also decreased from 20.2 to 17.8 mL.
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Almubarak, Tariq, Mohammed AlKhaldi, Jun Hong Ng, and Hisham A. Nasr-El-Din. "Design and Application of High-Temperature Raw-Seawater-Based Fracturing Fluids." SPE Journal 24, no. 04 (April 25, 2019): 1929–46. http://dx.doi.org/10.2118/195597-pa.
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Summary Typically, water-based fracturing treatments consume a large volume of fresh water. Providing consistent freshwater sources is difficult and sometimes not feasible, especially in remote areas and offshore operations. Therefore, several seawater-based fracturing fluids have been developed in an effort to preserve freshwater resources. However, none of these fluids minimizes fracture-face skin and proppant-conductivity impairment, which can be critical for unconventional well treatments. Several experiments and design iterations were conducted to tailor raw-seawater-based fracturing fluids. These fluids were designed to have rheological properties that can transport proppant under dynamic and static conditions. The optimized seawater-based fracturing-fluid formulas were developed such that no scale forms when additives are mixed in or when the fracturing-fluid filtrate is mixed with different formation brines. The tests were conducted using a high-pressure/high-temperature (HP/HT) rheometer, coreflood, and by aging cells at 250 to 300°F. The developed seawater-based fracturing fluids were optimized with an apparent viscosity greater than 100 cp at a shear rate of 100 seconds–1 and a temperature of 300°F for more than 1 hour. The use of polymeric- and phosphonate-based scale inhibitors (SIs) prevented the formation of severe calcium sulfate (CaSO4) scale in mixtures of seawater and formation brines at 300°F. Controlling the pH of fracturing fluids prevented magnesium and calcium hydroxide precipitation that occurs at a pH value of greater than 9.5. Most importantly, SIs had a negative effect on the viscosity of seawater fracturing fluid during testing because of their negative interaction with metallic crosslinkers. The developed seawater-based fracturing fluids were applied for the first time in an unconventional and a conventional carbonate well and showed very promising results; details of field treatments are discussed in this paper.
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Rukmani, Shalini J., Grit Kupgan, Dylan M. Anstine, and Coray M. Colina. "A molecular dynamics study of water-soluble polymers: analysis of force fields from atomistic simulations." Molecular Simulation 45, no. 4-5 (October 12, 2018): 310–21. http://dx.doi.org/10.1080/08927022.2018.1531401.
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Qian, Xiaqing, Peng Zhang, Shengnian Wang, Shuangfeng Guo, and Xinyu Hou. "Grouting Additives and Information-Based Construction of Jet Grouting in the Water-Rich Sand Stratum." Applied Sciences 12, no. 24 (December 8, 2022): 12586. http://dx.doi.org/10.3390/app122412586.
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The dynamic action of groundwater in the water-rich sand stratum carries away injected cement slurry before it becomes solidified, which seriously affects the determination of the diameter and strength of the column. Grouting additives and information-based construction are two main actions to control the quality of jet grouting construction. This study introduced a solution of grouting additives and information-based construction of jet grouting in the water-rich sand stratum. First, high-polymer cement grout (HPCG), red mud and phosphogypsum cement grout (RPCG) and metakaolin cement grout (MKCG) additives were screened with a series of laboratory tests on solidification time and permeability; moreover, the mix proportion of grouting fluids was developed in order to adapt for water-rich sand strata. Secondly, information-based construction of jet grouting was conducted to control grouting quantity with real-time monitoring of drill rotational velocity, drill lifting speed and injection pressure equipped with the monitoring system on the double fluid jet grouting systems. Lastly, the validity of grouting additives and information-based construction in the water-rich sand stratum was verified via a test pile in situ, and a series of material tests on drilling core samples on permeability with SEM observation. The results indicate that the high polymer is the preferred additive of grouting fluids because the solidification time can be controlled in the range of 10 min to 20 min; the permeability of drilling core samples can reach the order of 10−7, with the mix proportion being A:B = 2:1, high-polymer additive:water > 1:3, with a water-cement ratio of 0.8. The specifications of information-based construction are a drill rotational velocity of 10 r/min, a drill lifting speed of 0.2 m/min, an injection pressure of 20 MPa and a grouting quantity of 40 L/min.
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Amri, Nedjla, Djamila Ghemati, Nadia Bouguettaya, and Djamel Aliouche. "Swelling Kinetics and Rheological Behavior of Chitosan-PVA / Montmorillonite Hybrid Polymers." Periodica Polytechnica Chemical Engineering 63, no. 1 (August 2, 2018): 179–89. http://dx.doi.org/10.3311/ppch.12227.
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This study involved preparation of hybrid polymer systems based on chitosan-poly(vinyl alcohol) (PVA) blends and modified Montmorillonite. These structures were characterized through microscopy and infrared spectroscopy; swelling measurements were performed to explore polymer absorbency. The behavior of polymer systems was studied through steady and oscillatory shear rheology. Results showed that more stable blend membranes were formed due to the strong interaction between chitosan and PVA. The membranes exhibited appreciable water uptake and were sensitive to saline solution with a slight shrinking.Shear viscosity was described by Cross model to characterize non-Newtonian behavior of all polymer solutions, the shear thinning increases with PVA content, while viscosity increases with chitosan extent. In oscillatory experiments, it was observed that all measured viscoelastic properties were influenced by blends composition and clay content. For all samples, results show a typical behavior of an entangled system in the case of semi-dilute macromolecular viscoelastic fluids. The dynamic moduli exhibited higher values for blends, compared with values of neat polymers, which are an indication of a good stability and a tendency of gel formation. Therefore, the prepared chitosan-PVA systems, which exhibited high swelling degrees and suitable viscoelastic properties, have promising applications in tissue engineering and membrane processes.
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Lohne, Arild, Liqun Han, Claas van Zwaag, Hans van Velzen, Anne-Mette Mathisen, Allan Twynam, Wim Hendriks, Roman Bulgachev, and Dimitrios G. Hatzignatiou. "Formation-Damage and Well-Productivity Simulation." SPE Journal 15, no. 03 (May 20, 2010): 751–69. http://dx.doi.org/10.2118/122241-pa.
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Summary In this paper, we describe a simulation model for computing the damage imposed on the formation during overbalanced drilling. The main parts modeled are filter-cake buildup under both static and dynamic conditions; fluid loss to the formation; transport of solids and polymers inside the formation, including effects of porelining retention and pore-throat plugging; and salinity effects on fines stability and clay swelling. The developed model can handle multicomponent water-based-mud systems at both the core scale (linear model) and the field scale (2D radial model). Among the computed results are fluid loss vs. time, internal damage distribution, and productivity calculations for both the entire well and individual sections. The simulation model works, in part, independently of fluid-loss experiments (e.g., the model does not use fluid-leakoff coefficients but instead computes the filter-cake buildup and its flow resistance from properties ascribed to the individual components in the mud). Some of these properties can be measured directly, such as particle-size distribution of solids, effect of polymers on fluid viscosity, and formation permeability and porosity. Other properties, which must be determined by tuning the results of the numerical model against fluid-loss experiments, are still assumed to be rather case independent, and, once determined, they can be used in simulations at altered conditions as well as with different mud formulations. A detailed description of the filter-cake model is given in this paper. We present simulations of several static and dynamic fluid-loss experiments. The particle-transport model is used to simulate a dilute particle-injection experiment taken from the literature. Finally, we demonstrate the model's applicability at the field scale and present computational results from an actual well drilled in the North Sea. These results are analyzed, and it is concluded that the potential effects of the mechanistic modeling approach used are (a) increased understanding of damage mechanisms, (b) improved design of experiments used in the selection process, and (c) better predictions at the well scale. This allows for a more-efficient and more-realistic prescreening of drilling fluids than traditional core-plug testing.
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Pinheiro, José Aurélio, Nívia do Nascimento Marques, Marcos Antônio Villetti, and Rosangela de Carvalho Balaban. "Polymer-Decorated Cellulose Nanocrystals as Environmentally Friendly Additives for Olefin-Based Drilling Fluids." International Journal of Molecular Sciences 22, no. 1 (December 31, 2020): 352. http://dx.doi.org/10.3390/ijms22010352.
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In this study, we intended to evaluate the performance of olefin-based drilling fluids after addition of cellulose nanocrystal (CNC) derivatives. For this purpose, firstly, cellulose nanocrystals, produced from sulfuric acid hydrolysis of cotton fibers, were functionalized with poly(N-isopropylacrylamide) (PNIPAM) chains via free radicals. The samples were then characterized via Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), confocal microscopy, dynamic light scattering (DLS), and zeta potential measurements in water. The FTIR and NMR spectra exhibited the characteristic signals of CNC and PNIPAM groups, indicating successful grafting. As expected, X-ray diffractograms showed that the crystallinity of CNCs reduces after chemical modification. TGA revealed that the surface-functionalized CNCs present higher thermal stability than pure CNCs. The confocal microscopy, zeta potential, and DLS results were consistent with the behavior of cellulose nanocrystals decorated by a shell of PNIPAM chains. The fluids with a small amount of modified CNCs presented a much lower volume of filtrate after high-temperature and high-pressure (HTHP) filtration tests than the corresponding standard fluid, indicating the applicability of the environmentally friendly particles for olefin-based drilling fluids.
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Suzuki, Hiroto, Takuya Mabuchi, and Takashi Tokumasu. "Molecular Dynamics Simulations of Cerium Ion Transport Phenomena in Polymer Electrolyte Membranes of Polymer Electrolyte Fuel Cells." ECS Meeting Abstracts MA2022-02, no. 41 (October 9, 2022): 1503. http://dx.doi.org/10.1149/ma2022-02411503mtgabs.
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As energy demand increases, global warming progresses, and energy resources are scarce in the future, expectations for fuel cells, which generate electricity through a chemical reaction between hydrogen and oxygen, are rising. There are various types of fuel cells, which are classified according to the electrolyte. This study deals with polymer electrolyte fuel cells (PEFCs), which are used in automobiles and household fuel cells. Currently, there are two main challenges for the practical application of PEFCs: durability and cost reduction. The target value for durability is required to be 40,000 h or more. However, the current durability is about 10,000 h, so an investigation into the causes of deterioration and countermeasures are urgently needed. One of the causes of degradation is the chemical deterioration of polymeric membranes. When the by-product hydrogen peroxide comes into contact with impurities such as iron ions, hydroxyl radicals (・OH) are generated, which attack and decompose the polymer membrane. In order to suppress this degradation, research have been conducted to add a substance that renders hydroxyl radicals inactive (radical scavenger) to polymer membranes, and this has been put to practical use. One of the most useful radical scavengers is cerium ions. However, it has been reported that cerium ions migrate in the electrolyte membrane, resulting in non-uniform distribution in the proton exchange membranes (PEMs), and in places where the concentration is low, and degradation progresses. The addition of too much radical scavenger hinders proton transport in the electrolyte membrane, reducing the output capacity of the PEFC. Therefore, understanding the cerium ions transport mechanism in the PEM is important to control cerium ions migration and improve the durability of the electrolyte membrane to maintain its performance as a fuel cell. However, the cost of operating experiments over 40,000 h is enormous, and it is difficult to analyze the phenomena occurring inside nanostructured electrolyte membranes by experiment, so simulation analysis is required. In this study, molecular dynamics simulations have been performed for analysis of structure and cerium ions transport properties in PEM, consisting of polymer chains, cerium ions, water molecules, and hydronium ions. In all simulations, Nafion chain, which has the chemical structure with EW=1114, has been employed. Water content λ, which indicates the ratio of solvent molecules to sulfonic groups in Nafion, was changed to 4, 9, 14. Fig. 1 shows the self-diffusion coefficient of cerium ions at a cerium ions content of 1.1 wt% (20 pcs added) as a function of temperature for each water content, indicating that the coefficient increases with increasing temperature for all water contents. In addition, the increase in the self-diffusion coefficient of cerium ions with temperature is small at low water content (λ = 4), and the rate of increase in the self-diffusion coefficient of cerium ions with temperature becomes larger as the water content increases. From the radial distribution functions (RDFs) of cerium ions around the sulfone group, cerium ions are distributed at about 4.15 Å around the sulfone group at low water content, while at high water content they are distributed at about 6.0 Å. From the RDF of water molecules around the sulfone group, water molecules are located at about 4 Å around the sulfone group. The results indicate that cerium ions coordinate directly to the sulfone groups at low water content because fewer water molecules collect around the sulfone groups. Conversely, at high water content, water molecules cover the sulfone groups, and cerium ions coordinate outside the sulfone groups, which lead to the increase of the diffusion coefficient. Acknowledgments This work was supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan, Grant number JPNP20003. It was performed on the Supercomputer system “AFI-NITY” at the Advanced Fluid Information Research Center, Institute of Fluid Science, Tohoku University. Figure 1
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Xu, Chaohang, Hetang Wang, Deming Wang, Xiaolong Zhu, Yunfei Zhu, Xing Bai, and Quanlin Yang. "Improvement of Foaming Ability of Surfactant Solutions by Water-Soluble Polymers: Experiment and Molecular Dynamics Simulation." Polymers 12, no. 3 (March 4, 2020): 571. http://dx.doi.org/10.3390/polym12030571.
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Aqueous foam is widely used in fire extinguishing and dust suppression technologies. Improving the foaming ability is the key to reducing the added concentration of foaming agents as well as the economic cost. In this work, the effect of a water-soluble polymer (polyvinyl alcohol, PVA) on the foaming ability of anionic surfactant (sodium dodecyl ether sulfate, SDES) was studied by an experiment and molecular dynamics simulation. The experimental results showed that PVA greatly improves the foaming ability of SDES solutions when the surfactant concentration is less than 0.1%, which is attributed to the fact that the polymer can enhance the stability of bubble films and reduce the bubble rupture rate during the foam generation process. The simulation results indicate that PVA can enhance the hydration of surfactant head groups and contribute to the formation of a three-dimensional hydrogen bond network between surfactants, polymers, and water molecules, thus greatly improving the stability of bubble liquid films. The above results suggest that water-soluble polymers can be used to improve the foaming ability of surfactant solutions by enhancing the bubble film stability, which is beneficial as it reduces the added concentration of foaming agents in aqueous foam applications.
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Rodd, Lucy E., Timothy P. Scott, Justin J. Cooper-White, and Gareth H. McKinley. "Capillary Break-up Rheometry of Low-Viscosity Elastic Fluids." Applied Rheology 15, no. 1 (February 1, 2005): 12–27. http://dx.doi.org/10.1515/arh-2005-0001.
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Abstract We investigate the dynamics of the capillary thinning and break-up process for low viscosity elastic fluids such as dilute polymer solutions. Standard measurements of the evolution of the midpoint diameter of the necking fluid filament are augmented by high speed digital video images of the break up dynamics. We show that the successful operation of a capillary thinning device is governed by three important time scales (which characterize the relative importance of inertial, viscous and elastic processes), and also by two important length scales (which specify the initial sample size and the total stretch imposed on the sample). By optimizing the ranges of these geometric parameters, we are able to measure characteristic time scales for tensile stress growth as small as 1 millisecond for a number of model dilute and semi-dilute solutions of polyethylene oxide (PEO) in water and glycerol. If the final aspect ratio of the sample is too small, or the total axial stretch is too great, measurements are limited, respectively, by inertial oscillations of the liquid bridge or by the development of the well-known beads-on-a-string morphology which disrupt the formation of a uniform necking filament. By considering the magnitudes of the natural time scales associated with viscous flow, elastic stress growth and inertial oscillations it is possible to construct an “operability diagram” characterizing successful operation of a capillary breakup extensional rheometer. For Newtonian fluids, viscosities greater than approximately 70 mPas are required; however for dilute solutions of high molecular weight polymer, the minimum viscosity is substantially lower due to the additional elastic stresses arising from molecular extension. For PEO of molecular weight 2 · 106 g/mol, it is possible to measure relaxation times of order 1 ms in dilute polymer solutions with zero-shear-rate viscosities on the order of 2 – 10 mPas.
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Sun, Liang, Baozhu Li, Hanqiao Jiang, Yong Li, and Yuwei Jiao. "An Injectivity Evaluation Model of Polymer Flooding in Offshore Multilayer Reservoir." Energies 12, no. 8 (April 15, 2019): 1444. http://dx.doi.org/10.3390/en12081444.
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Good polymer flood performance evaluation requires an understanding of polymer injectivity. Offshore reservoirs are characterized by unfavorable water–oil mobility ratios, strong heterogeneity, and multilayer production, which collectively contribute to unique challenges. Accordingly, this article presents a semi-analytical model for the evaluation of commingled and zonal injectivity in the entire development phase, which consists of primary water flooding, secondary polymer flooding, and subsequent water flooding. First, we define four flow regions with unique saturation profiles in order to accurately describe the fluid dynamic characteristics between the injector and the producer. Second, the frontal advance equation of polymer flooding is built up based on the theory of polymer–oil fractional flow. The fluid saturation distribution and the injection–production pressure difference are determined with the method of equivalent seepage resistance. Then, the zonal flow rate is obtained by considering the interlayer heterogeneity, and the semi-analytical model for calculating polymer injectivity in a multilayer reservoir is established. The laboratory experiment data verify the reliability of the proposed model. The results indicate the following. (1) The commingled injectivity decreases significantly before polymer breakthrough and increases steadily after polymer breakthrough. The change law of zonal injectivity is consistent with that of commingled injectivity. Due to the influence of interlayer heterogeneity, the quantitative indexes of the zonal flow rate and injection performance are different. The injectivity of the high-permeability layer is better than that of the low-permeability layer. (2) The higher the injection rate and the lower the polymer concentration, the better the injectivity is before polymer breakthrough. An earlier injection time, lower injection rate, larger polymer injection volume, and lower polymer concentration will improve the injectivity after polymer breakthrough. The polymer breakthrough time is a significant indicator in polymer flooding optimization. This study has provided a quick and reasonable model of injectivity evaluation for offshore multilayer reservoirs.
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Quezada, Gonzalo R., Norman Toro, Jorge Saavedra, Pedro Robles, Iván Salazar, Alessandro Navarra, and Ricardo I. Jeldres. "Molecular Dynamics Study of the Conformation, Ion Adsorption, Diffusion, and Water Structure of Soluble Polymers in Saline Solutions." Polymers 13, no. 20 (October 14, 2021): 3550. http://dx.doi.org/10.3390/polym13203550.
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Polymers have interesting physicochemical characteristics such as charge density, functionalities, and molecular weight. Such attributes are of great importance for use in industrial purposes. Understanding how these characteristics are affected is still complex, but with the help of molecular dynamics (MD) and quantum calculations (QM), it is possible to understand the behavior of polymers at the molecular level with great consistency. This study was applied to polymers derived from polyacrylamide (PAM) due to its great use in various industries. The polymers studied include hydrolyzed polyacrylamide (HPAM), poly (2-acrylamido-2-methylpropanesulfonate) (PAMPS), polyacrylic acid (PAA), polyethylene oxide polymer (PEO), and guar gum polysaccharide (GUAR). Each one has different attributes, which help in understanding the effects on the polymer and the medium in which it is applied along a broad spectrum. The results include the conformation, diffusion, ion condensation, the structure of the water around the polymer, and interatomic polymer interactions. Such characteristics are important to selecting a polymer depending on the environment in which it is found and its purpose. The effect caused by salinity is particular to each polymer, where polymers with an explicit charge or polyelectrolytes are more susceptible to changes due to salinity, increasing their coiling and reducing their mobility in solution. This naturally reduces its ability to form polymeric bridges due to having a polymer with a smaller gyration radius. In contrast, neutral polymers are less affected in their structure, making them favorable in media with high ionic charges.
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HAYASHI, HIDEMITSU, SATORU YAMAMOTO, and SHI-AKI HYODO. "LATTICE-BOLTZMANN SIMULATIONS OF FLOW THROUGH NAFION POLYMER MEMBRANES." International Journal of Modern Physics B 17, no. 01n02 (January 20, 2003): 135–38. http://dx.doi.org/10.1142/s0217979203017217.
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Simulations of flow through three-dimensional porous structures of NAFION polymer membranes are performed with a Lattice-Boltzmann method (LBM) for incompressible fluid. Geometry data of NAFION are constructed from a result of a dissipative particle dynamics simulation for three values of the water content, 10%, 20%, and 30%, and are used as the geometry input for the LBM. Permeability of the porous structure is extracted from results of the LBM simulation using Darcy's low. The permeability K is shown to be expressed as K = L2 × Ktpl with a characteristic length L and the dimensionless permeability Ktpl depending only on the topological structure of the porous media. Dependence of Ktpl is examined on the pressure gradient, the fluid viscosity, and the resolution of the computational grid.
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Herrera, Julia, Luis Prada, Gustavo Maya, Jose Luis Gomez, Ruben Castro, Henderson Quintero, Robinson Diaz, and Eduar Perez. "CFD simulation of HPAM EOR solutions mechanical degradation by restrictions in turbulent flow." CT&F - Ciencia, Tecnología y Futuro 10, no. 2 (December 17, 2020): 115–29. http://dx.doi.org/10.29047/01225383.255.
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Polymer flooding is a widely used enhanced oil recovery (EOR) technology. The purpose of the polymer is to increase water viscosity to improve reservoir sweep efficiency. However, mechanical elements of the polymer injection facilities may impact the viscosity of the polymer negatively, decreasing it drastically. Mechanical degradation of the polymer occurs in case of flow restrictions with abrupt diameter changes in valves and control systems. Such flow restrictions may induce mechanical stresses along the polymer chain, which can result in its rupture. In this research, physical experiments and numerical simulations using CFD (Computational Fluid Dynamics) were used to propose a model for estimating the mechanical degradation for the flow of polymer solutions. This technique involves the calculation of velocity gradients, pressure drawdown, and polymer degradation of the fluid through geometry restriction. The simulations were validated through polymer injection experiments. The results show that with the greater volumetric flow and lower effective diameters, there is more mechanical degradation due to polymer shearing; nonetheless, this depends on the rheology properties inherent in each polymer in an aqueous solution.
This method is suitable to estimate the mechanical degradation of the polymer solution in flooding facilities and accessories. Further, the results obtained could enhance the use of the polymer, calculating its actual mechanical degradation, minimizing it, or using it to support the development of new accessories.
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Zhao, Zhenhua, Sinan Chen, Fengshan Zhou, and Zhongjin Wei. "Gel Stability of a Calcium Bentonite Suspension in Brine and Its Application in Water-Based Drilling Fluids." Gels 8, no. 10 (October 10, 2022): 643. http://dx.doi.org/10.3390/gels8100643.
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With the development of the oil industry and the increasingly complex drilling environment, the performance of drilling fluids has to be constantly improved. In order to solve the problem of bentonite dispersion and hydration in a saline medium, a drilling fluid additive with good performance and acceptable cost was sought. The effects of several water-soluble polymers, such as cellulose polymers, synthetic polymers and natural polymers, on the rheology and gel suspension stability of calcium-based bentonite were compared in this study. Among the examined polymers, the xanthan gum biopolymer (XC) was the least negatively affected in the saline medium used. However, its high price limits its industrial application in oil and gas drilling fluids. In this study, a salt-tolerant polymer, modified plant gum (MVG), was prepared by a cross-linking modification of a natural plant gum, which is abundant and cheap. Then, a salt-tolerant polymer mixture called SNV was prepared, composed of the salt-resistant natural polymer MVG and the biopolymer XC. The salt tolerance and pulping ability of SNV and common water-soluble polymers were evaluated and compared. We then selected the most suitable Herschel–Bulkley model to fit the rheological curve of the SNV–bentonite aqueous suspension system. SNV improved the rheological properties of the calcium-based bentonite slurry and the dispersion stability of bentonite. In an SNV concentration of 0.35%, the apparent viscosity (AV) of the base slurry increased from 2 mPa·s to 32 mPa·s., and the low shear reading value at 3 rpm increased from 0 dia to 5 dia. This could greatly improve the viscosity and cutting carrying capacity of the bentonite drilling fluid. The bentonite drilling fluid prepared with SNV could be directly slurried with brine and even seawater; this means that when drilling in ocean, coastal saline water and high-salinity-surface saline water areas, the slurry preparation cost and preparation time can be conveniently reduced.