Viscosity Correlation Research Articles

Maximizing Blue Energy via Densely Grafted Soft Layers in Nanopores.

We investigate energy generation from salinity gradients inside a nanopore that is connected to reservoirs at both ends. We consider that the inner wall surfaces are grafted with a densely grafted polyelectrolyte layer (PEL). We developed the PEL grafting density-dependent correlation of dielectric permittivity, molecular diffusivity, and dynamic viscosity in this endeavor. Using these correlations, we employ the finite element framework to solve the equations describing the ionic and fluidic transport. We use a partially hydrolyzed polyacrylamide polymer solution, which exhibits a shear-thinning fluid, in combination with the KCl electrolyte for energy-harvesting analysis. To describe the shear-rate-dependent apparent viscosity of non-Newtonian liquid, we have employed the Carreau model. For a window of right-side reservoir concentration, we investigate the effects of ion-partitioning in conjugation with the change in PEL grafting density on the ionic field, ionic selectivity, pore current, osmotic power, energy conversion efficiency, and flow field. The findings of this endeavor demonstrate how the ion-partitioning effect lowers the screening effect and raises the electrical double layer (EDL) potential by reducing the counterions in PEL. We show that the unique distribution of the ionic field leads to a higher prediction of generated osmotic power and power density due to the ion-parting effect. Additionally, we establish that the augmentation in PEL space charge density leads to improvement in average flow velocity, osmotic power, and consequently energy conversion efficiency. We establish that the generated osmotic power density and the energy conversion efficiency become very high at the higher grafting density. In summary, inferences of this analysis are deemed pertinent in designing the nanoscale device intended for high and efficient osmotic energy generation.

Effect of Brinkman and Maiga's correlations of viscosity on forced convection turbulent flow

A numerical study on forced convection turbulent flow in a top-curved surface vented cavity is conducted to investigate the influence of uncertainties in the viscosity formulas using two different types of nanofluid i.e., water-Al2O3 and water-CuO. The Brinkman and Maiga et al. correlations for viscosity are employed to examine their effect on heat transfer and skin friction for a range of Reynolds number. A finite volume method using RNG k-ε turbulent model is considered for solving governing equations numerically. The outcomes of the present study exhibit significant difference in the average Nusselt number and average skin friction on the top-curved heated wall surface of the cavity for two viscosity models employed. For water-Al2O3 nanofluid, these differences are strongly dependent on volume fraction of nanoparticles as well as on the Reynolds number. In contrast, for water-CuO nanofluid, the difference in average Nusselt number is solely depended on Reynolds number while the average skin friction difference is vigorously reliant on volume fraction of the nanoparticles as well as on the Reynolds number.

Measurement of Acrylamido Tertiary Butyl Sulfonate Polymer Retention on Limestone by Three Methods Under Varying Temperature and Oil Presence

Summary Polymer retention poses a significant challenge in polymer flooding applications, emphasizing the importance of accurately determining retention levels for successful project design. In carbonate reservoirs of the Middle East, where temperatures exceed 90°C, conducting adsorption tests under similar temperature conditions becomes crucial for the precise determination of adsorption values. The choice of analytical method potentially impacts the accuracy of retention measurements from effluent analysis. This study investigates the effect of temperature on the performance of a polymer, specifically its rheological behavior and retention. Rheological and polymer flooding experiments were carried out using an acrylamido tertiary butyl sulfonate (ATBS)-based polymer in formation water (167,114 ppm) at different temperatures (25°C, 60°C, and 90°C) with required oxygen control measures. Dynamic polymer retention was conducted in both the absence of oil (single-phase tests) and the presence of oil (two-phase tests). In addition, different analytical techniques were evaluated, including viscosity measurements, ultraviolet (UV)-visible spectroscopy, and total organic carbon-total nitrogen (TOC-TN) analysis, to determine the most accurate method for measuring the polymer concentration with the least associated uncertainty. Furthermore, the study investigates the effects of these uncertainties on the final dynamic polymer retention values by applying the propagation of error theory. The effluent polymer concentration was determined using viscosity correlation, UV spectrometry, and TOC-TN analysis, all of which were reliable methods with coefficient of determination (R2) values of ~0.99. The study analyzed the effects of flow through porous media and backpressure regulator on polymer degradation. The results showed that the degradation rates were around 2% for flow through porous media and 16% for mechanical degradation due to the backpressure regulator for all temperature conditions. For the effluent sample, the concentration of polymer was lower when using the viscosity method due to polymer degradation. However, the TOC-TN and UV methods were unaffected as they measured the TN and absorbance at a specific wavelength, respectively. Therefore, all viscosity results were corrected for polymer degradation effects in all tests. During the two-phase coreflooding experiment conducted at 25°C, the accuracy of the UV spectrometry and viscosity measurements was affected by the presence of oil, rendering these methods unsuitable. However, the TOC-TN measurements were able to determine effluent polymer concentration and, subsequently, the retention value. Moreover, the use of glycerin preflush to inhibit oil production during polymer injection in the two-phase studies showed that all three methods were appropriate. The error range was obtained using the propagation of error theory for all the methods. Accordingly, it was noted that the temperature did not affect the dynamic retention values in both single-phase and two-phase conditions. The findings of this study highlight that when adequate oxygen control measures are implemented, the temperature does not exhibit a statistically significant impact on the retention of the ATBS-based polymer under investigation. Furthermore, TOC-TN has been identified as the optimal analytical method due to its minimal uncertainties and ease of measuring polymer concentration under varying experimental conditions.

Abstract 420: The Correlation of Whole Blood Viscosity and Outcome in Mechanical Thrombectomy for Acute Ischemic Stroke

Introduction Whole blood viscosity (WBV), reflecting the intrinsic resistance of blood flow, is an established predictor of stroke events in individuals. This study aims to correlate the WBV at different shear rates with the outcome of endovascular thrombectomy, known to be an effective treatment for large vessel occlusion (LVO) stroke. Methods This is a single‐center retrospective study conducted at our comprehensive stroke center. The charts of 317 patients who underwent endovascular thrombectomy within 6 hours of LVO stroke were reviewed. The modified Rankin score (mRS) at discharge was used as the outcome measure, with individuals categorized as low (0‐2) or high (3‐6). WBV at different shear rates was calculated using De Simone's Formula, dependent on hematocrit and total protein levels. The T‐test and Chi‐square test were used to compare baseline quantitative and categorical data, respectively, amongst the mRS study groups. We elaborated multivariable logistic regression analyses to identify the independent risk factors associated with the outcome of interest following mechanical thrombectomy. Finally, Spearman rank order correlation was used to assess for r between mRS and WBV at different shear rates. Results Baseline group characteristics, constituted by variables pertaining to demographics and medical history, were similar across the two study groups. However, our study found no significant differences in clinical outcomes between the two groups with WBV at high shear rate (OR 0.969, 95% CI 0.77‐1.204, p = 0.780) and low shear rate (OR 0.998, 95% CI 0.988‐1.008, p = 0.779) following mechanical thrombectomy. Spearman rank order correlation between WBV at high shear rate (r=0.058, p=0.123) and low shear rate (r=0.048, p=0.128) was non‐significant. Conclusion This is one of the few studies to evaluate the effect of WBV at high and low shear rates on the clinical outcome of endovascular thrombectomy in patients with LVO. Our results revealed that WBV at high and low shear rates did not affect the outcome of endovascular thrombectomy, as measured by mRS at discharge. We propose that different components of blood viscosity may uniquely affect blood flow, and our study provides a path for future research to further study the correlation.

Characteristics of Gas–Liquid Two-Phase flow in rectangular narrow slits with varying cross sections driven by large pressure drop

Pressure pipelines and vessels inevitably contain some defects. Under the most unfavorable load combinations, these defects may gradually develop into through-wall cracks. High-pressure subcooled fluid leaks through these cracks, and two-phase gas–liquid flow often occurs within the cracks. In this study, natural through-wall cracks were replaced with narrow rectangular slits with varying cross sections. Experiments were conducted to investigate the variation patterns of gas–liquid two-phase leakage flow rates and pressure drops. The study focused on four types of rectangular narrow slits with varying cross sections, a width of 28 mm, a length of 80 mm, and a gap gradually ranging from 0.134 to 0.334 mm. The liquid-phase mass flow rate ranged from 150 to 700 kg/h, whereas the gas-phase mass flow rate varied from 0 to 20 kg/h. A one-dimensional homogeneous flow model was established by coupling two-phase velocity of speed calculations. This calibrated model was then used to predict pressure drops and flow parameters for gas–liquid two-phase flow in narrow rectangular slits with varying cross sections. The experimental data were analyzed to determine the two-phase leakage characteristics of different test pieces. The results show that the inlet–outlet pressure drop and flow quality are key factors affecting the two-phase leakage flow rate. The frictional pressure drop constitutes a major part of the total pressure drop along the flow path in different test pieces. Compared with the acceleration pressure drop in the expanding slit, that in the constricting slit is higher, with an increase of approximately 32 %. Among several commonly used empirical formulas for calculating two-phase viscosity, the McAdams and Dukler empirical correlations were found to be less suitable for high-velocity two-phase flows. In contrast, the Cicchitti empirical correlation provides better predictions, with a mean absolute deviation (MAD) and mean relative deviation (MRD) of no more than 8 %. The viscosity of the gas-phase medium affects the two-phase flow characteristics in narrow slits, which should be considered in practical engineering applications.

Viscosity and structure correlation mechanism of Fe[sbnd]Cr[sbnd]C melt based on MD simulation

The viscosity of FeCCr melt affects the mass transfer behavior during steelmaking processes. Reasonable regulation of viscosity can improve production efficiency. There is a close relationship between melt viscosity and structure. Therefore, it is of great theoretical significance to analyze the correlation between viscosity and structure of chromium-containing iron melt for the optimization of the whole metallurgical process. This study experimentally investigated the viscosity of FeCCr melt and utilized molecular dynamics simulation to analyze the formation and growth behavior of atomic clusters, revealing the correlation mechanism between structure and viscosity. As the Cr content increased from 11 % to 13 %, the melt viscosity increased by 10.05 %. At a temperature range from 1773 K to 1473 K, the viscosity reached a maximum of 15.5 mPa·s, representing a 40.9 % increase. Simulation results indicated that CrC clusters within the melt act as intermediaries, connecting with CrFe and FeC clusters to form FeCrC clusters. The key influence of increased Cr content on viscosity lies in promoting the generation of FeCrC multicomponent clusters, while the key influence of temperature reduction lies in promoting cluster growth. With the increase in Cr content, the number of clusters at 1773 K increased from 154 to 175, and the average volume of clusters increased from 212 Å3 to 224 Å3. When the temperature decreased from 1773 K to 1473 K, the number of clusters increased by 51.2 %, and the average volume of clusters increased by 18.75 %. In comparison, the thermal state change had a greater impact on clusters, where temperature reduction led to rapid cluster growth, reduction of free volume within the melt, and ultimately resulted in increased viscosity due to the combined effects.

Advances in nanofluids for tubular heat exchangers: Thermal performance, environmental effects, economics and outlook

Heat transfer deterioration in thermal systems significantly limits the efficiency and practicality of these systems. This review explores state-of-the-art studies on the use of nanofluids (NFs) in various tubular heat exchangers (HEXs), addressing their influence on overcoming the limitations. It discusses the fundamentals of HEXs and NFs, including design criteria, heat transfer mechanisms and thermal transport properties. This work compiles effective thermal conductivity and viscosity correlations under diverse conditions and evaluates NF performance in reactor, flat and helical coiled tube, twisted tube, U-tube and finned tube-based HEXs. Results revealed substantial improvements in system efficiency, with SiC–MWCNT/water NFs achieving 99.9 % absorbance in solar collectors and Ag–rGO/water and Ag–ZnO/silicon oil NFs enhancing efficiency by 210 % and 240 %, respectively. Water–alumina NFs increased convective heat transfer rates and friction factors in flat tube HEXs by 123.6 % and 210 %, respectively. Helical coil exchangers exhibited a pressure drop of 47.35 % with MWCNT/water NFs and a 69.62 % rise in heat transfer coefficient with polyaniline–water NFs. This review suggests that optimising HEX efficiency depends on the strategic use of NFs and finned-tube designs. It also highlights the significance of selecting suitable source materials for NFs, the corresponding health risks, disposal and waste management. Economic viability depends on using optimal flow parameters, including temperature, concentration of nanoparticles, system compactness and installation and running costs. Finally, this review concludes with insights into existing challenges and prospects in thermohydraulic, environmental and economic aspects, pointing to future developments in engineered fluids and their commercial applications.

Thermal and flow characteristics in a square chamber with a nanoencapsulated phase-change material–water nanofluid under a linear temperature variation at all walls

In this study, the two-dimensional, steady-state, and incompressible flow and thermal behaviors of a water-based nanoencapsulated phase-change material (NE-PCM) nanofluid within a closed chamber were investigated, considering the impact of buoyancy. A novel approach was introduced by implementing linearly varying temperature conditions along all chamber walls. The effective dynamic viscosity and thermal conductivity correlations, derived experimentally, were used to model the governing equations. These equations were then rendered dimensionless through suitable transformations and solved using the Galerkin finite-element method. Results showed that the phase change region’s width increased with higher Rayleigh numbers, scaled phase change bonds, NE-PCM volume fractions, and fusion temperatures between 0.1 and 0.5, but decreased with fusion temperatures between 0.6 and 0.9. The highest Nusselt number occurred along the bottom wall for a fusion temperature range of 0.4–0.5. For optimal thermal performance, a square chamber with linearly varying temperature walls and a fusion temperature of 0.5 is recommended.

Existence of nano-sized aggregates in aniline and chloroform binary system

The liquid binary system of aniline (ANL) and chloroform (CHL) was discovered to form aggregates at a nano-size level responsible for the peculiar trends of some physico-chemical properties, reflected in morphology. The density and viscosity were recorded in the temperature range from 273.15 K to 313.15 K at ten different molar fractions. While the correlation of viscosity and density with molar fraction indicated a modest deviation from ideality, the excess molar volume values derived from density values exhibited a large discrepancy from the directly measured results, suggesting the potential aggregation leading to local inhomogeneity of mixtures’ concentration. On the other hand, FT-IR and Raman spectra showed no significant frequency shift both for N-H stretching on ANL and C-H stretching vibration on CHL upon mixing, in agreement with quantum mechanical calculations, which revealed the presence of a few complexes with stoichiometry ANL:CHL = 1:2 and 2:2, formed through CH···π interactions. The nano-scale morphology was characterised using the dynamic light scattering (DLS) method and SEM imaging. The calculated molecular electrostatic potential (MEP) of complexes indicated the capability for further association among complexes or between complexes and ANL or CHL molecules to form larger aggregates. For the first time, nano-sized aggregates were spotted for a liquid binary system made of small-sized organic molecules (solvents) using the combination of thermodynamic measurement, vibrational spectroscopy, quantum mechanical calculations and SEM imaging.

Relations Between Amylose Content and Physicochemical Properties of Starches from White and Red Sorghum Varieties

AbstractThis research aims to determine the relationship between amylose content and physicochemical properties in white and red sorghum starches. Five varieties of red sorghum and four varieties of white sorghum were evaluated. The chemical properties, the amylose content, the resistant starch content, scanning electron microscopy, the absorption and solubility index in water, the viscosity profile, the thermal properties, and the correlation between the amylose content were determined. Sorghum starches had an amylose content between 24.51% and 34.34%, but did not show any relationship with color. Regarding the microstructure, the starches that appear larger granules (20–30 µm) have lower amylose content. Sorghum red varieties shown higher values in gelatinization enthalpy, pasting temperature and water absortion index, this effect was attributed to the formation of complexes with phenolic compounds. Starches with a higher proportion of amylose shown lower viscosity profiles and a high thermal stability. Correlation matrix analysis reveals that amylose content had a negative correlation with water absorption index, water solubility index, maximum viscosity, minimum viscosity, and positive correlation with the resistant starch content. The amylose content can define the potential application of the sorghum starches.

The effects of chain-length distributions on starch-related properties in waxy rices

Normal rice starch consists of amylopectin and amylose, whose relative amounts and chain-length distributions (CLDs) are major determinants of the digestibility and rheology of cooked rice, and are related to metabolic health and consumer preference. Here, the mechanism of how molecular structural features of pure amylopectin (waxy) starches affect starch properties was explored. Following debranching, chain-length distributions of seven waxy varieties were measured using size-exclusion chromatography, and parameterized using biosynthesis-based models, which involve breaking up the chain-length distribution into contributions from five enzyme sets covering overlapping ranges of chain length; structure-property correlations involving the fifth set were found to be statistically significant. Digestibility was measured in vitro, and parameters for the slower and longer digestion phase quantified using non-linear least-squares fitting. The coefficient for the significant correlation involving amylopectin fine structure for the fifth set was −0.903, while the amounts of amylopectin short and long chains were found to dominate breakdown viscosity (correlation coefficients 0.801 and − 0.911, respectively). This provides a methodology for finding or developing healthier starch in terms of lower digestion rate, while also having acceptable palatability. As rice breeders can to some extent control CLDs, this can help the development of waxy rices with improved properties.

A Review on Nano Fluid Production, Mathematical Modelling and Applications

Recently, nano fluids have taken on a significant role in many human endeavours. A fluid called a nanofluid includes nanoparticles, also called nanoparticles. Colloidal suspensions of nanoparticles in a base fluid are what these fluids are made of. The numerous production procedures and mathematical interpretation models for nanofluids are examined in this review study. Marangoni convection’s advantages, which enhance heat transfer and balance temperature distribution, are underlined. The effects of thermophoresis on surface tension as well as surface tension in laminar natural convection are also discussed in this work. The characteristics of carbon nanotubes and their prospective medical uses are covered in the article. The study covers electrochemical double layer capacitors, which offer greater safety, longer cycle stability, and better power densities. The study explores the impact of magnetic fields on entropy formation and natural convection in a hybrid nanofluid enclosure, revealing four distinct models based on thermal conductivity and viscosity correlations. The information review work is relevant. The review information work is relevant to flow tracers, prosthetic heart valves, oil pipelines, chemical industry separation methods, and oil recovery.

Measurements of the Viscosity of Hydrogen and a (Hydrogen + Methane) Mixture with a Two-Capillary Viscometer

AbstractMeasurements of the viscosity of pure hydrogen and a binary (hydrogen + methane) mixture with a nominal composition 90 mol % hydrogen are presented. The measurements were conducted with a two-capillary viscometer relative to helium along three isotherms of (298.15, 323.15, and 348.15) K and at pressures of up to 18 MPa. Expanded relative combined uncertainties in viscosity range from (0.65 to 2.7) % (k = 2) for the hydrogen data, and from (0.91 to 3.2) % (k = 2) for the (hydrogen + methane) data. The viscosity data are compared to experimental literature data and viscosity correlations implemented in the NIST REFPROP v10.0 database. Good agreement between this work’s data, literature data, and the viscosity correlation was achieved for pure hydrogen. The (hydrogen + methane) mixture was compared to the Extended Corresponding States (ECS) model implemented in REFPROP v10.0. Relative deviations between the experimental data and the ECS model exceed the experimental uncertainty and were found to exhibit a positive trend with increasing density and a weakly pronounced negative trend with increasing temperature. No experimental literature data are available at overlapping state regions. Nonetheless, deviations to the ECS model imply reasonable consistency of this work’s data and literature data. In addition to experimental viscosities, experimental zero-density viscosity ratios of the fluids under investigation and helium are reported. Fairly good agreement within the experimental uncertainty of this work with a highly accurate literature value and a value obtained from accurate ab initio calculated data was achieved for hydrogen.

Viscosity measurement and correlation for dense fluid mixture of carbon dioxide and ethanol at 313–343 K and 15–30 MPa

The viscosity ηm of dense fluid mixtures of carbon dioxide and ethanol was determined from the pressure drop between the inlet and outlet of a packed bed using the Ergun equation at temperatures from 313.2 K to 343.2 K and pressures from 15 MPa to 30 MPa over the entire range of ethanol composition. The ηm values for the fluid mixtures decreased with increasing temperature and increased with increasing pressure under isocratic conditions. In addition, the values measured ηm with Ergun eq. were correlated with the equation combining the Eyring theory and the perturbed chain statistical associating fluid theory equation of state (PC-SAFT EoS) and with that based on the rough hard-sphere (RHS) model proposed by Dymond and Assael. The accuracies of the Eyring + PC-SAFT EoS and the RHS model were 8.7% and 12%, respectively, in terms of average relative deviation for 80 conditions over the entire range of ethanol composition.

Significance of Inclined MHD on Hybrid Nanoliquid Flow in an Annulus Using Modified Buongiorno Model in the Presence of Two Different Heat Sources: Response Surface Methodology

In this modern fluid field technology, hybrid nanoliquid are of great interest to researchers because of their thermal properties which provide superior heat transfer improvements compared to nanoliquid. Thus, in this study, the heat and mass transport characteristics in a horizontal annular duct filled with the water-based Cu–Al2O3 hybrid nanoliquid is analyzed using the modified Buongiorno model (two-phase model). The two different heat sources namely, temperature-related heat source (THS) and exponential space-related heat source (ESHS) are analyzed in thermal analysis. An inclined magnetism and viscous dissipation aspects are also taken into account. The correlation for effective thermal conductivity and viscosity are modeled by utilizing the experimental work of Corcione. The coupled nonlinear equations were solved numerically using the finite difference method. Further, the heat transport rate is optimized using the response surface methodology (RSM). The significance of effective parameters on the flow structure, thermal pattern, concentration field, heat and mass transport rate are visualized through two-dimensional (2D) and three-dimensional (3D) surface plots. It is noticed that the chaotic motion of nanoparticles advances the thickness of the thermal and solutal boundaries. The velocity field has an inverse association with the applied magnetic field and its angle of inclination. The consequence of the Reynolds number is favorable for the velocity and temperature fields. The heat transport is more dominated by the Reynolds number compared to the chaotic motion of nanoparticles and thermophoretic aspect. Furthermore, the sensitivity of the Nusselt number to the Reynolds number, chaotic motion of nanoparticles and thermophoretic aspect are always negative.

Numerical Simulation of Graphene-Nanoplatelet Nanofluid Convection in Millimeter-Sized Automotive Radiator

The depletion of fossil fuels and environmental considerations in transportation sector motivate the researchers to enhance the efficiency and performance of the automotive systems. However, the poor thermal performance of conventional coolant poses a limitation in the development of energy-efficient vehicle due to the cooling constraint. In the present study, a comprehensive numerical study is conducted to scrutinize the convective performance of graphene nanoplatelets (GnP) nanofluid in millimeter-sized automotive radiator, aiming to enhance the understandings on the underlying physical significance of the suspension of graphene-based nanoparticle in water for the performance enhancement of automotive radiator. The temperature-dependent thermophysical properties of GnP-water nanofluid is predicted via existing correlations, while a modified viscosity correlation is developed. ANSYS Fluent is employed in the present numerical simulation to investigate the effects of various pertinent parameters such as Reynolds number, nanoparticles aspect ratio, tube aspect ratio and tube hydraulic diameter on the heat transfer performance of the radiator. Double precision and second-order upwind scheme with inclusion of viscous heating, and convergent criteria of 10˗6 are adopted for the present simulation. It is observed that the convective performance of the radiator is significantly enhanced by increasing Reynolds number and nanoparticle volume fraction while decreasing the aspect ratios of nanoparticle and radiator tube, with an enhancement rate as much as 1816%. Therefore, it is evident that the suspension of GnP intensifies the heat transfer performance of millimeter-sized automotive radiator, which could possibly lead to a more efficient radiator that is smaller and lighter.

Empirical correlations for density, viscosity, and thermal conductivity of pure gaseous hydrogen

Empirical correlations for density, viscosity, and thermal conductivity of pure gaseous hydrogen

Viscosity Correlation of CO2, HFCs, HFOs, and Their Mixtures: Review of Experimental Data and Modeling Techniques

Viscosity Correlation of CO2, HFCs, HFOs, and Their Mixtures: Review of Experimental Data and Modeling Techniques

Computing of temperature-dependent thermal conductivity and viscosity correlation for solar energy and turbulence appliances via artificial neuro network algorithm

The growing popularity of artificial intelligence approaches has led to their application in a wide range of engineering fields. The most widely used artificial intelligence tool, artificial neural networks, can be used to predict data with high accuracy. An artificial neural network approach is being used to predict effective and accurate thermal conductivity and viscosity models for hybrid nanofluid systems. Here, new types of correlations relating to the thermophysical properties of Fly Ash–Cu nanoparticles with diameter sized 15.2[Formula: see text]nm and which are temperature-dependent are developed. The highest thermal conductivity and viscosity values were obtained for hybrid nanofluids with a mixture ratio of 20:80, with maximum amplification exceeding 83.2% and 65%, respectively, over the base fluid. The Fly Ash–Cu/water hybrid nanofluid’s viscosity and thermal conductivity are evaluated for a concentration range of 0–4%. The evaluation of the Fly Ash–Cu/water hybrid nanofluids system at concentrations ranging from 0 to 4% most likely entails a scientific or engineering study aimed at understanding the behavior and properties of this nanofluid mixture. Nanoparticles can agglomerate or settle in the base fluid over time, compromising the stability of the nanofluids. Researchers may be interested in determining how varied quantities of Fly Ash and Cu nanoparticles affect the nanofluid’s stability and sedimentation behavior. The heat transfer potential is examined within the optimistic range of temperatures of 30–80∘C. Many fruitful results for turbulence and solar energy have been drawn. The Mouromtseff number achieved an optimal value for all concentration levels. The heat transfers of turbulent flow and thermal conductivity of hybrid nanofluids increase with the augmented values of concentrations and temperature. Researchers found an increase in thermal conductivity of hybrid nanofluids at 0–4% concentrations, potentially impacting heat transfer applications. The conclusion explores the potential integration of the developed correlations and neural network model into practical engineering or industrial applications involving solar energy and turbulence appliances. In this work, we extend the work of Kanti et al. [Sol. Energy Mater. Sol. Cells 234 (2022) 111423] which is on the properties of water-based fly ash-copper hybrid nanofluid for solar energy applications.

ANALYSIS OF VISCOSITY CORRELATIONS APPLICABILITY FOR OILS OF THE REPUBLIC OF BASHKORTOSTAN

Decisions quality of infrastructure development also depends on the reliability of multiphase flow modeling results in oil and gas production systems. Different specialized bundled software and Informational System RN-KIN are used for the modeling of multiphase systems to solve the assigned tasks for Republic Bashkortostan’s oil fields.
 The modeling practice assumes the handling of large amount of initial data: geometrical properties of pipe systems, terrain elevation, technological modes of pumping, conditions of heat exchange with the environment, transport properties of oil fluid. Information about network construction and terrain elevation can be obtained from the projects and the acts of implementation of these projects, the conditions of pumping are available from operation-dispatch information, but verification of viscosity properties of oil fluids causes difficulties and requires additional laboratory tests. At the same time on
 oil fields of Republic Bashkortostan a lot of experimental physicochemical properties data of oils belonging to different oil reservoirs has been accumulated, which requires systematization and generalization of available experimental data.
 The article describes the difficulties in modeling of viscosity of oil fluids taking into account the characteristics of physicochemical properties of oils of Republic Bashkortostan’s oil fields. The necessity of systematization of existing retrospective laboratory tests and selection of viscosity correlations is indicated. 
 The authors of the article for the first time analyzed and selected correlations of viscosity of oil and water-oil emulsions for Republic Bashkortostan’s oil fields, which will allow to increase accuracy and efficiency of hydraulic calculations on which basis the decisions about development of infrastructure of fields are made.