Viscosity Increment Research Articles

Rheological study of low wax content hydrate slurries considering phase interactions

Regarded as two of the most challenging flow assurance issues during the production of oil and gas in offshore fields or ultra-deep seas, wax and hydrates may coexist in multiphase pipelines, greatly jeopardizing the safety of operation and transportation. Understanding the coupling rheological properties of the coexistence system is vital to guarantee the transportability of pipelines. In this work, the viscosity of the fluid with different wax contents during hydrate formation process were obtained, and rheological tests of waxy hydrate slurries were carried out. It was found that the relative viscosity of wax-containing flow systems was much higher than that of the wax-free flow system, and increased with the hydrate volume fraction monotonously. Aside from the independent contribution of hydrates and wax to the overall viscosity of waxy hydrate slurry, an “additional” viscosity increment was observed in wax-containing systems both in flow systems and rheometer systems, which was evidenced to be caused by the phase interactions among wax, hydrates and water droplets. Results of the rheological tests in the flow loop indicated that the thixotropy of waxy hydrate slurries in flow systems weakened as the wax content increased. A viscosity model for waxy hydrate slurries considering the phase interactions was developed, which was capable of calculating the cohesive force between hydrate particles in the presence of wax. The model could predict the viscosity of waxy hydrate slurries that formed under another formation and shearing condition with relative deviation smaller than 20%.

Thermal and rheological investigation of non-Newtonian fluids in an induced-charge electroosmotic micromixer

Microfluidic devices have drawn many researchers in the various fields of area such as biomedical diagnostics, biological and chemical analysis. Among these applications, micromixing has a prominent impact on the efficiency and sensitivity of microfluidic devices. In this study, an induced-charge electroosmotic solver with the presence of Joule heating effects has been developed in the open-source code package, OpenFOAM, to investigate the rheological effects of non-Newtonian fluids in a trapezoidal micromixer. The mathematical model and the developed solver are validated with existing data in the literature and the effects of micromixer geometry, various applied DC electric potential, rheological effects of fluid and the heat transfer are studied to attain an efficient micromixer. Results show that the proposed micromixer offers the advantages of high mixing efficiency with a high flow rate in comparison to other investigated geometries. Newtonian, Shear-thinning, and shear thickening fluids are studied in this article and it is shown that in Newtonian fluid and shear-thinning fluid, the mixing efficiency is enhanced by amplifying the applied electric field which can be concluded that the effects of vortices have more impact on mixing efficiency in comparison to the flow rate. On the other hand, in shear thickening fluid, the mixing efficiency is decreased by amplifying the electric field, because the flow rate is enhanced which leads to the increment of fluid viscosity and decrement of the strength of vortices. Finally, to analyze the fluid temperature rising because of the presence of Joule heating, the heat transfer is studied to assure the health of cells in the proposed micromixer.

Anomalously enhanced thermal conductivity of graphite-oxide nanofluids synthesized via liquid-phase pulsed laser ablation

Graphite-oxide (GO) nanofluids with enhanced thermal conductivity are successfully prepared using pulsed laser ablation in liquid (PLAL) of a graphite target in deionized water. The effects of laser frequencies are investigated on the variations of GO nanoparticles. The morphology, structure and composition of the nanoparticles are characterized using various spectroscopic techniques. During the PLAL process, graphite is oxidized to GO which is inherently hydrophilic, no surfactant is required in the preparation of nanofluid. The laser frequency significantly affects the size and morphology of the GO nanoparticles during laser ablation, leading to a profound variation in the thermophysical properties of the GO nanofluids. At the laser frequency of 10 Hz, the maximum thermal conductivity enhancement of 82% is achieved at a temperature of 50 °C while the maximum viscosity increment is recorded at a temperature of 30 °C. This study shows the great potential of the PLAL method in synthesizing GO nanofluid with anomalously enhanced thermal conductivity.

Hydrodynamic cavitation: Process opportunities for ice-cream formulations

We report the viability of hydrodynamic cavitation (HC, 2400–3600 RPM/100–200 L h−1) to manufacture ice-cream with reduced stabilizer. The study was carried out at a pilot-scale level and consisted of determining the impact on particle size and rheological behavior of ice-cream mixes (ICM) and evaluating the resulting melting and meltdown behavior of ice-cream. Ice-cream manufactured with two-stage homogenization (2500/500 psi) was used as a control treatment. Overall, HC resulted in a larger mean particle size than the control mixes (3.52 ± 0.28 and 0.34 ± 0.02 μm, respectively). Additionally, HC (3600 RPM/100 L h−1) changed the flow behavior of ICM from viscoelastic solid to viscoelastic liquid. Cavitated mixes resulted in a 2.2-fold viscosity increment within the high spectrum of shear rate (30–50 s−1) compared with the control mixes. These modifications altered the melting and meltdown characteristics of the resulting ice-cream. The analysis of the particle size and gross microstructure of dripped melted ice-creams suggested a significant collapse of the ice-cream structure, allowing clumps of fat to migrate into the melted phase. This study showed that HC might have the potential to develop novel structures for frozen desserts.

Terpene polyacrylate TPA5 shows favorable molecular hydrodynamic properties as a potential bioinspired archaeological wood consolidant

There is currently a pressing need for the development of novel bioinspired consolidants for waterlogged, archaeological wood. Bioinspired materials possess many advantages, such as biocompatibility and sustainability, which makes them ideal to use in this capacity. Based on this, a polyhydroxylated monomer was synthesised from α-pinene, a sustainable terpene feedstock derived from pine trees, and used to prepare a low molar mass polymer TPA5 through free radical polymerisation. This polymer was extensively characterised by NMR spectroscopy (chemical composition) and molecular hydrodynamics, primarily using analytical ultracentrifugation reinforced by gel filtration chromatography and viscometry, in order to investigate whether it would be suitable for wood consolidation purposes. Sedimentation equilibrium indicated a weight average molar mass Mw of (4.3 ± 0.2) kDa, with minimal concentration dependence. Further analysis with MULTISIG revealed a broad distribution of molar masses and this heterogeneity was further confirmed by sedimentation velocity. Conformation analyses with the Perrin P and viscosity increment ν universal hydrodynamic parameters indicated that the polymer had an elongated shape, with both factors giving consistent results and a consensus axial ratio of ~ 4.5. These collective properties—hydrogen bonding potential enhanced by an elongated shape, together with a small injectable molar mass—suggest this polymer is worthy of further consideration as a potential consolidant.

Hybrid Layered Silicate/Calcium Carbonate Reinforced High-density Polyethylene Nanocomposites: Systematic Morphological Evaluation through Rheological Properties and Response Surface Method

High-density polyethylene (HDPE) based hybrid nanocomposites comprising varying concentrations of layered nanoclay (NC) and spherical nano calcium carbonate (nCaCO3) were prepared by a two-step melt compounding process in the presence of polyethylene grafted maleic anhydride (PE-g-MA) as the compatibilizer. Regarding multiple material variables (the NC, nCaCO3 and compatibilizer contents) participated in fabrication of the nanocomposites, response surface methodology (RSM) was utilized to find the correlation between the material variables, morphology and viscoelastic responses in the melt state. Intercalation of the layered silicates was investigated by X-ray diffraction (XRD) technique, and morphological characterization of the nanosized calcium carbonates was carried out by scanning electron microscope (SEM). The findings indicated that higher contents of the PE-g-MA facilitated the intercalation process and increased the interlayer distance. Interestingly, incorporation of the second nanoparticle, nano calcium carbonate, resulted in viscosity increment which is an influential factor on applied stresses during the melt mixing and subsequently, dispersion state of the nanoclay layers. The interplay between the designated material parameters was also discussed by means of interaction plots.

Viscosity, tribological and physicochemical features of ZnO and MoS2 diesel oil-based nanofluids: An experimental study

In this research, two different diesel oil-based nanofluids were prepared and the influence of temperature and nanoparticle content were examined on viscosity, tribological, and physicochemical features of diesel oil. The kinematic viscosity of samples was experimentally evaluated based on standard ASTM D445. The greatest viscosity increment was diagnosed at 0.7 wt% and 100 °C for both of the prepared nanofluids. The anti-friction behavior of the nanofluids was studied utilizing a pin-on-disc tribometer. The acquired outcomes revealed that ZnO and MoS2 nanoparticles (NPs) could promote the tribological characteristics of pure diesel oil. By analyzing the friction coefficient values and line roughness of the wear surface (Ra), an optimal concentration of ZnO and MoS2 nanoparticles (NPs) were found to be around 0.4 wt% and 0.7 wt%, respectively. The friction factor and pumping power were also measured at diverse content of nanoparticles and flow rates showing that the pumping power was enhanced by the incorporation of nanoparticles.

Self – assembly of model surfactants as reverse micelles in nonpolar solvents and their role as interfacial tension modifiers

The self-assembly of linear surfactants into reverse micelles (RMs) in nonpolar solvents, and their efficiency in reducing the interfacial tension is studied using dissipative particle dynamic simulations. Given the importance of RMs as thickeners, among many other applications, their properties are studied here when formed in oil and in supercritical carbon dioxide (scCO2). Our simulations are found to be in agreement with experimental results of surfactant self-assembly in scCO2 that found viscosity increments of up to 90% with 10 wt % of surfactants. The role played by a small number of water molecules in RM formation is studied as well in both solvents, corroborating experiments reporting the enhancement of RM formation with the addition of a small quantity of water. The dynamics of water surfactant aggregation in nonpolar solvents is also discussed. Lastly, the performance of the model surfactant as an interfacial tension modifier is studied in detail. The results show that RMs are more easily formed in oil than in scCO2 and that the effectiveness of the surfactant in reducing the interfacial tension lies in its preference to adsorb at interfaces rather than self – association.

Experimental analysis of the efficacy of vegetable oil-based nanolubricants for improving journal-bearing performance

The present experimental study explores the performance of Hydrodynamic journal bearings operating with vegetable oil-based nanolubricants. For this study, titanium oxide nanoparticles have been added to canola oil by varying the volume fraction from 0% to 0.04%. An assessment of performance characteristics has been done by using a journal-bearing test rig under different operating conditions. The outcome of the experimental results aimed at the addition of nanoparticles to base lubricants to improve the performance was observed to be favorable. However, under high operating conditions, the influence of nanoparticles is observed to be less useful. The fluid film pressure of nanolubricants increased up to a specific volume concentration of titanium oxide nanoparticles (i.e. 0.02%) beyond which no further enhancement was observed. At a load of 3000 N, the fluid film pressure increased up to 10%, when a bearing is lubricated using canola oil with a 0.02% volume fraction of nanoparticles. The heat transfer rate was found to be higher for nanolubricants in comparison to a base oil and the fluid film temperature was reduced by up to 15% at a volume fraction of 0.04%. Furthermore, rheological studies reveal that the prepared nanolubricants exhibited Newtonian behavior under the given conditions. The percentage increment of viscosity varied from 2.1% to 15.4% and 2.43% to 13.89% for a volume fraction ranging from 0.01% to 0.04% at a temperature of 40 °C and 100 °C, respectively. The dynamic light scattering results confirmed that the particles were well distributed in a base lubricant without much aggregation.

Characterization and property investigation of microcrystalline cellulose (MCC) and carboxymethyl cellulose (CMC) filler on the carrageenan-based biocomposite film

Abstract Hard capsule has received high demands not only in the pharmaceutical industry but also in food, cosmetics, and personal care applications. Current hard capsule made from gelatin has contributed to the rise of allergy and halal issues. Thus, many researches were looking for alternatives to produce hard capsule from natural and renewable sources such as carrageenan. In this study, carrageenan was incorporated with carboxymethyl cellulose (CMC) and microcrystalline cellulose (MCC) to toughen the carrageenan based biocomposite film and hard capsule. The cellulose filler used was expected to increase the tensile strength and viscosity properties of the carrageenan matrix due to the development of strong hydrogen bonding between the carrageenan and filler. The crystallinity and functional group properties of CMC and MCC were identified via X-ray diffraction (XRD) and Fourier transforms infrared (FTIR) analysis. Then, the hard capsule was prepared by incorporating carrageenan with isovanillin, PEG, alginic acid at different cellulose filler concentrations. The formulation solution was cast for biocomposite film development and dipped for hard capsule development. The tensile strength of the film was analyzed to study the effect of the cellulose filler on the film produced. Crystallinity result shows that CMC is an amorphous while MCC is a crystal, thus CMC has excellent solubility in water compared to MCC. Moreover, film and hard capsule mechanical properties demonstrated that Carra-CMC has the highest tensile strength in comparison to Carra-MCC. Incorporation of CMC in carrageenan biocomposite film shows a significant increment of viscosity up to 50% and the tensile strength up to 37%. The presence of main three functional groups in CMC structure increased the molecular interaction in the carrageenan biocomposite thus improve the film properties. It is predicted that a higher concentration of CMC is required to produce a more stable Carra-CMC biocomposite film and hard capsule.

Experimental investigation of rheological properties and thermal conductivity of SiO2\u2013P25 TiO2 hybrid nanofluids

Over many years, great efforts have been made to develop new fluids for heat transfer applications. In this paper, the thermal conductivity (TC) and viscosity of SiO2–P25 TiO2 (SiO2–P25) hybrid nanofluids were investigated for different nanoparticle volume concentrations (0.5, 1.0 and 1.5 vol%) at five various temperatures (20, 30, 40, 50 and 60 °C). The mixture ratio (SiO2:P25) in all prepared hybrid nanofluids was 1:1. Besides, pure SiO2, P25 nanofluids were prepared with the same concentrations for comparison with the hybrid nanofluids. The base fluid used for the preparation of nanofluids was a mixture of deionized water and ethylene glycol at a ratio of 5:1. Before preparing the nanofluids, the nanoparticles were analyzed with energy-dispersive X-ray analysis, scanning electron microscope, X-ray powder diffraction, and Fourier transform infrared spectroscopy. The zeta potentials of the prepared nanofluids except SiO2 nanofluids were above 30 mV. These nanofluids were visually observed for stability in many days. The TC enhancement of the hybrid nanofluid was higher than the pure nanofluid. In particular, with 1.0 vol% concentration, the maximum enhancement of SiO2, P25 and SiO2–P25 nanofluids were 7.5%, 9.9% and 10.5%, respectively. The rheology of the nanofluids was Newtonian. The viscosity increment of SiO2, P25 and hybrid nanofluids were 19%, 32% and 24% with 0.5 vol% concentration. A new correlation was developed for the TC and dynamic viscosity of SiO2–P25 hybrid nanofluid.

Effect of SiC nanoparticles concentration on novel feedstock Moringa Oleifera chemically treated with neopentylglycol and their trobological behavior

The increase in energy demand and deterioration of the petroleum products encouraged industrialists to search for environmentally friendly products. In this study, an attempt has been made to explore the potential of Moringa Oleifera oil for bio-based lubricant application. The Moringa Oleifera oil was modified through the chemical process with Neopentylglycol treatment. After chemical modification, the nanoparticles were added to the oil in different proportions. The physicochemical properties of the lubricants were tested according to the ASTM standards. The tribological application was examined using a pin on disc tribometer. For the examination of the worn surfaces, a scanning electron microscope was used. An improvement in the physicochemical properties of the lubricant was observed at 0.5% concentration. Increment in viscosity increment, relative viscosity becomes more at 1.0% nanoparticles concentration and 100 °C temperature. The proper dispersion at 0.5% nanoparticles addition was obtained and confirmed through the test. The reduction in the friction coefficient and wear of the parts was observed with chemically modified oil and optimum concentration of the 0.5% nanoparticles was found. The 1.0% concentration of nanoparticles showed higher wear of the parts due to their agglomeration on the surface. The worn surfaces during 0.5% nanoparticles addition to the lubricant also display minimum wear.

Sodium hydrogen bicarbonate and water as blowing agent in palm kernel oil based polyol polyurethane foam

Palm kernel oil polyol based flexible polyurethane foams were synthesized by using two different types of natural blowing agentswater and sodium hydrogen bicarbonate (SHB), as alternatives to replace the climate change accelerating blowing agents (BA). The samples have been studied and analyzed by scanning electron microscopy (SEM), density measurements, Fourier transform infrared (FT-IR) spectroscopy and tear resistance test. SEM has revealed that adding water (2 php) has increased the cell size by 157% and pore size by 226%, while adding water (2 php) and SHB (25 php) have increased the cell size and pores by 276% and 920%, respectively. The addition of natural BAs has impacted struts differently. SHB has resulted in thicker struts compared to water due to increment of polyurethane mixture's viscosity. FT-IR spectroscopy has confirmed that both BAs did not affect the polyurethane’s functionalities, nor did react with any of the reactants. The absence of (–NCO) functionality peaks attributed to full exploitation of diisocyanate during the foaming reaction. It was found that additional of (2 php) water in the PU had reduced the density by 24%. On the other hand, additional of SHB (2 php) into PU, has increased the density of the foam, under water deficiency condition. It has been found that, adding 2 php SHB resulted high tear resistance strength (0.76 N/mm), which has shown an improvement of 26% of tear resistance strength as compared to the sample without blowing agents.

Systematic Experimental Study of the Viscosity of Nanofluids

The systematic experimental investigation of the viscosity of more than 30 different nanofluids was carried out. The investigated nanofluids were prepared based on distilled water, ethylene glycol and engine oil containing nanoparticles Al2O3, TiO2, ZrO2, CuO, Fe2O3, and Fe3O4, as well as nanodiamonds. The nanoparticle volume concentration ranged from 0.25 to 8%. The size of nanoparticles varied from 5 to 150 nm. The temperature changed from 25 to 60 °C. The effect of the nanoparticle concentration and size, as well as the base liquid properties, temperature, and additives of stabilizing surfactants on the viscosity of nanofluids were investigated. In particular, the factors affecting the rheology of nanofluids were studied. It was found that the viscosity of nanofluids depends on the material of the nanoparticles. It is shown that with decreasing nanoparticle size, the viscosity of nanofluids increases. In contrast to the classical microscopic suspensions, the relative viscosity of nanofluid depends on the viscosity of the base liquid. In general, the higher is the viscosity of the base fluid, the higher is the increment of the nanofluid viscosity. It was found, that the rheological behavior of the Newtonian nanofluid can become non-Newtonian with the growth of the volume fraction of nanoparticles and decrease of their size. At very high nanoparticle concentration the relative viscosity of nanofluid depends on temperature and characterized by hysteresis, i.e. the viscosity of nanofluid during heating and cooling differs significantly.

Rheological effects on peristaltic transport of Bingham fluid through an elastic tube with variable fluid properties and porous walls

AbstractThe peristaltic pumping of non‐Newtonian material configured by a tube is quite interesting phenomenon to examine the behavior of physiological fluids. The present paper investigates the role of variable viscosity and thermal conductivity on the peristaltic mechanism of Bingham fluid in an elastic tube with porous and convective boundary conditions. The long wavelength and small Reynolds number approximation is used to obtain the analytical solutions for velocity, plug flow velocity, streamlines, flow rate, and temperature. The theoretical determination of flux is calculated using the equilibrium condition, and an application to flow through an artery is highlighted by using the tension relation in an elastic tube. It is observed that the rate of flow within the elastic tube declined with variation of variable viscosity. An enhanced temperature distribution near the tube axis has been observed with increment of variable viscosity. An increasing influence of the porous parameter in the bolus size can also be seen from the streamlines plotted.

Viscosity impact investigation on erosion of carbon steel in sand-mixed-polivinyl alcohol

Erosion in oil and gas production sector is predominantly caused by fine particles’ migration into the processing facilities. Fine particles are mostly transported to the facilities via carrier fluid. Other than sand, the viscosity of the carrier fluid also contributes to the sand erosion phenomenon. However, the impact of viscosity on sand erosion is not fully discovered by previous researchers. Therefore, this paper investigated the impact of fluid viscosity on erosion of carbon steel surface. In the presented work, an experimental rig was fabricated and tested for the study of impact of fluid viscosity on erosion of the carbon steel by considering the water mixed-polyvinyl alcohol as a carrier fluid. The metal coupons were impacted with sand slurries of different viscosities. Scanning electron microscopy along with energy dispersive spectroscopy and Universal scanning probe microscopy were used to analyse the centred and adjunct areas of the coupons. These analyses revealed that the viscous slurry is least effective in removal of metal surface in comparison with the pitting erosion. The obtained results reflected a decrease in erosion rate as the fluid viscosity upsurges and the type of metal surface erosion changes from uniform erosion to pitting erosion by fluid viscosity increment.

Influence of NiO nano-flakes dispersion on the viscosity of lubricating oil

Protecting interacting surfaces of mechanical systems against friction and wear have a wide range of industrial applications. Viscosity is the supreme property of any lubricant which overpowers viscous drag in hydro-dynamically lubricated mechanical systems. The dispersion stability of NiO-nanolubricants is achieved by ultrasonication technique. The detailed study of the viscosity of NiO nano-flakes dispersed in SN500 lubricants with weight fraction of 0.25-1.5% was performed in the temperature between 40-90 °C. The results show that increasing the weight fraction of NiO nano-flakes resulted in consistence viscosity increment. Further, the measured viscosity is compared with different concentration and temperature dependent theoretical models. On the basis on experimental viscosity data a theoretical correlation is recommended to predict the viscosity of NiO-nanolubricants with less than 5% margin of deviation.
 
 Bull. Chem. Soc. Ethiop. 2020, 34(1), 203-214.
 DOI: https://dx.doi.org/10.4314/bcse.v34i1.19

Enhanced Shear Thickening of Silica Colloidal Suspension Using Polystyrene-Polyacrylamide Particles

Shear thickening (ST) refers to a non-Newtonian behavior of concentrated colloidal suspensions, which exhibits significant viscosity increments at high shear stress or high shear rate. A shear thickening fluid (STF) consists of well-dispersed solid particles in a liquid medium. Silica particles are often used as components of STFs due to the abundance of hydroxyl groups on their surfaces. Polystyrene core-polyacrylamide shell particles (PS-PAAm particles) were prepared to enhance the ST of silica particle-based colloidal suspensions. Addition of PS-PAAm particles to various particle weight fractions of silica particle-based STFs resulted in amplification of ST in all instances. These results suggest that PS-PAAm particles enhance inter-particle interactions due to the abundance of hydrogen-bonding donor groups in polyacrylamide.

Polyether-Based Thermoviscosifying Polymers for Enhanced Oil Recovery: Emulsion versus Powder

Thermoviscosifying polymers (TVPs) are a class of promising materials for chemically enhanced oil recovery (EOR) because of their unique viscosity increment with increasing temperature. However, pr...

Preparation and evaluation of aceclofenac dental pastes using dillenia fruit gum for periodontitis treatment

The present research deals with preparation and evaluation of aceclofenac dental pastes containing extracted dillenia fruit gum (DG) for periodontitis treatment. Dental pastes containing 1% w/w aceclofeanc were prepared with/without using extracted DG as a mucoadhesive polymer via conventional trituration method. The drug contents, viscosities and pHs of these dental pastes were observed within the permissible ranges. The tube extrudability and tube spreadability of these pastes containing extracted DG were found favorable. The in vitro aceclofenac release from all these dental pastes was found slower sustained over 6 h, which followed zero-order kinetic model (R2 = 0.9917–0.9988) with super case-II transport mechanism (n = 1.00–1.03). The in vitro aceclofenac release was found decreased with the viscosity increment of these dental pastes. These aceclofenac dental pastes containing extracted DG demonstrated excellent mucoadhesion onto excised porcine buccal mucosal membrane, which can be beneficial to get intimate contact with the action site during and after application to uphold the constant release of drugs over prolonged time. These dental pastes containing 1% w/w aceclofeanc can be applied for effective management of dental pain and inflammation with local delivery in the treatment of periodontitis.