Friction factor analysis for a nanofluid circulating in a microchannel filled with a homogeneous porous medium

This work presents the numerical solution for different velocity profiles and friction factors on a rectangular porous microchannel fully saturated by the flow of a nanofluid introducing different viscosity models, including one nanofluid density model. The Darcy-Brinkman-Forchheimer equation was used to solve the momentum equation in the porous medium. The results show that the relative density of the fluid, the nanoparticle diameters and their volumetric concentration have a direct influence on the velocity profiles only when the inertial effects caused by the presence of the porous matrix are important. Finally, it was found that only viscosity models that depend on temperature and nanoparticle diameter reduce the friction factor by seventy percent compared to a base fluid without nanoparticles; furthermore, these models show a velocity reduction of even ten percent along the symmetry axis of the microchannel.

An experimental study of the fire extinguishing ability of modular fire extinguishing installations if astralene-modified water mist is used

Introduction. The aim of the research project is to study the effect produced by one type of carbon nanostructures, or astralenes, on processes of extinguishing oil product flame using finely sprayed water. Materials and research methods. The research is focused on fire extinguishing suspensions used in modular water mist installations for the fire extinguishing of oil products. Astralene-modified distilled water, having the volumetric concentration of nanostructures equal to 0.05–1.0 percent, was used as a fire extinguishing substance under research. The experiment was focused on the study of thermophysical characteristics of fire extinguishing liquids, such as density, dynamic viscosity, surface tension, specific heat of vaporization. Also, studies were carried out to identify the rate of evaporation, the distribution of droplet sizes of sprayed fire extinguishing compositions, and the time needed to extinguish the model source of ignition of oil products.Research results. The dispersion of nanostructures of fire-extinguishing liquids allows to increase their density, surface tension by 20.6 %, increase the specific heat of vaporization if the volumetric concentration of astralenes is equal to 0.25 and 0.5 %, and boost the dynamic viscosity by 6.68–15.38 % at the temperature of 20 °С. The research was carried out to find the rate of evaporation of droplets of the modified fire-extinguishing liquid. It was found that an increase in the volumetric concentration of nanostructures from 0.05 to 0.5 % causes reduction in the evaporation rate.The droplet speed increases if the volumetric dispersion of astalenes goes up to 0 to 0.25 %. However, a further increase in the volumetric concentration of astralenes to 1.0 % causes a reduction in their speed. The extinguishing time was identified using a laboratory fire extinguishing installation. The distribution of droplet sizes of fire-extinguishing compositions is in the range of 20 to 160 microns. The fire extinguishing capacity of the installation was highest if a fire extinguishing composition had a 0.5 % volumetric concentration of astralenes.Conclusions. The modification of a fire extinguishing composition by carbon nanostructures leads to a change in its thermophysical characteristics. The addition of this composition to the installation, used at facilities involved in the processing of petroleum products, will increase its fire extinguishing ability. Further areas of research may include the development of astralene stabilization methods for suspensions and adaptation to low temperatures.

Laboratory studies of suspended particle volume concentration in atmosphere using a smartphone

The article presents the results of laboratory studies of the effect of volume concentration of suspended particles in contrast to the luminous slits image obtained by smartphone cameras of SAMSUNG Galaxy A3 and Honor 8 Lite. Experimentally it was found that a pattern of change in contrast to the luminous slits image from the volumetric concentration of suspended particles appears under ambient light. The pattern of contrast change can be expressed by an exponential function. The correlation coefficient is 0.97. Cigarette smoke was used as suspended particles.

Numerical Modeling of Multi-Frequency Complex Dielectric Permittivity Dispersion of Clay-Rich Rocks

Interpretation of complex dielectric permittivity measurements is challenging in clay-rich rocks, such as shaly sands and organic-rich mudrocks, due to complex rock fabric and mineralogical composition, which are overlooked by conventional interpretation models. For instance, the impact of fabric features (e.g., laminations, structural/dispersed shale) and diverse constitution (e.g., clay, kerogen, pyrite, brine) to the broadband complex permittivity is not well understood. Therefore, the main objective of this work is to develop a framework capable of reliably quantifying the impact of different minerals and their corresponding spatial distribution on the multi-frequency complex dielectric permittivity measurements in clay-rich rocks.To achieve the aforementioned objective, we introduce a numerical algorithm to compute the dielectric dispersion in 3D pore-scale images of clay-rich rocks. We numerically solve the quasi-electrostatic approximation to Maxwell's equations in the frequency domain through the finite volume method. The clay particles are often sub-resolution in most imaging methods. Therefore, we introduce a workflow to calculate the effective admittance of the clay network. Furthermore, we derive a new equation to incorporate the induced polarization effect into the effective admittance of pyrite particles. Finally, we perform a sensitivity analysis of the complex dielectric permittivity of clay-rich rocks in the frequency range from 100 Hz to 1 GHz to the volumetric concentration and spatial distribution of clays, cation exchange capacity (CEC), volumetric concentration of pyrite, and the orientation of the electric field. Results showed that clays can enhance or diminish electrical conductivity values at different frequencies depending on their intrinsic properties and spatial distribution. Laminations, for instance, significantly enhance dielectric permittivity in the sub-MHz frequency range, but their effect is imperceptible at 1 GHz. Furthermore, the impact of the variation of CEC on permittivity is approximately proportional at 100Hz but negligible at 1 GHz.

Laboratory Analysis of Debris Flow Characteristics and Berm Performance

In this study, laboratory tests were used to determine the deposition characteristics (runout distance, lateral width, and deposition area) of debris flow and their relationships with the flow characteristics (flow velocity and flow depth) according to the presence of a berm. An experimental flume 1.3 to 1.9 m long, 0.15 m wide, and 0.3 m high was employed to investigate the effects of channel slope and volumetric concentration of sediment with and without the berm. The runout distance (0.201–1.423 m), lateral width (0.045–0.519 m), and deposition area (0.008–0.519 m2) increased as the channel slope increased and as the volumetric concentration of sediment decreased. These quantities also increased with the flow velocity and flow depth. In addition, the maximum reductions in the runout distance, lateral width, and deposition area were 69.1%, 65.9%, and 93%, respectively, upon berm installation. The results of this study illustrate general debris flow characteristics according to berm installation; the reported relationship magnitudes are specific to the experimental conditions described herein. However, the results of this study contribute to the design of site-specific berms in the future by providing data describing the utility and function of berms in mitigating debris flow.

Features of ultrafiltration of milk obtained from cows with CSN3 polymorphism

Мембранные процессы широко внедрены на современных предприятиях молочной промышленности, поскольку они способствуют обеспечению максимальной степени использования сырья и повышению качества готовой продукции. При этом они без затруднений интегрируются в классическую технологическую цепочку. Научные изыскания, направленные на дальнейшее совершенствование технологий баромембранного концентрирования молочного сырья, а также использование генетического подхода к формированию его технологических свойств весьма актуальны. Целью данной работы являлось исследование закономерностей процесса ультрафильтрации обезжиренного молока, полученного из молока коров с генотипами АА и ВВ по гену CSN3. Объектом исследований служило обезжиренное молоко, полученное из молока от КРС черно-пестрой породы с гомозиготными генотипами по гену CSN3 (АА и ВВ). Концентрирование молока осуществляли на пилотной установке с полиэфирсульфоновыми мембранами с порогом задержки по молекулярной массе 50 кДа при температуре 15…20 °С и объемном факторе концентрирования 3,5. В результате исследований выявлена закономерность снижения скорости процесса ультрафильтрации вследствие большей эффективности концентрирования массовых долей белка и сухих веществ обезжиренного молока, полученного из молока коров с генотипом АА по гену CSN3, по отношению к молоку от коров с генотипом ВВ. Membrane processes are widely used in modern dairy production, as they help to maximize the use of raw materials and improve the quality of end product. At the same time, they are easily integrated into the classical technological chain. Further improvement of the baromembrane concentration of dairy raw products technologies and the use of the genetic approach to the formation of its technological properties is an urgent scientific study today. The aim of this work was to study the regularities of the ultrafiltration process of skim milk obtained from the milk of cows with genotypes AA and BB according to the CSN3 gene. The object of research was skim milk obtained from milk from black-and-white cattle with homozygous genotypes for the CSN3 gene (AA and BB). Milk concentration was carried out on a pilot plant with polyethersulfone membranes with a retention threshold in molecular weight of 50 kDa at a temperature of 15…20 °C and a volumetric concentration factor of 3.5. As a result of the research, a regularity of the decrease in the rate of the ultrafiltration process was revealed due to the greater efficiency of concentration of mass fractions of protein and dry matter of skim milk obtained from milk of cows with the AA genotype according to the CSN3 gene in relation to milk from cows with the BB genotype.

Three-Dimensional Radiative Flow of Hybrid Nanofluid Past a Shrinking Plate with Suction

Hybrid nanofluid has been widely used in various heat transfer applications especially as the heat exchanger due to the great thermal conductivity compared to the conventional fluid. However, numerous investigations should still be carried out to properly understand its properties. Hence, in this study, a three-dimensional radiative flow of hybrid Cu-Al2O3/water nanofluid past a permeable shrinking plate is numerically analyzed. The boundary layer including the energy equations are reduced to a system of ordinary differential equations using the similarity transformations and are then solved numerically by using the bvp4c solver in MATLAB. The application of suction through the permeable plate is necessary in aiding the fluid motion past the shrinking surface. Dual solutions are also observable, hence the stability analysis is conducted to mathematically validate the real solution. The enhancement of copper volumetric concentration in the hybrid nanofluid is capable in decelerating the boundary layer separation.

Simultaneous improvement of microgeometry and surface quality of spur and straight bevel gears by abrasive flow finishing process

This article reports on influence of extrusion pressure, abrasive particle size and volumetric concentration on simultaneous reduction of surface roughness and microgeometry errors of spur and straight bevel gear by abrasive flow finishing (AFF) process. A vertical configured experimental apparatus was developed for two-way AFF and developed fixtures for finishing gears. Experimental investigations were conducted to identify optimum parametric combination, using response surface methodology, based on Box–Behnken design approach. Results revealed that higher values of abrasive particle size and volumetric concentration yield more percentage decrease in surface roughness and microgeometry error. Roughness profile, bearing area curve, microhardness, surface morphology, and wear resistance of the gear having best quality finishing were studied. Surface morphology analysis of the flank regions of the best finished spur and straight bevel gears found them to be smooth and free from cracks and burrs. Reciprocating wear test results revealed higher wear resistance of the AFF finished gears as compared to the unfinished gears. AFF also enhanced microhardness of the finished gears, which would enhance their operating performance and service life. This study shows that AFF is a flexible, economical, productive, easy to operate, and sustainable nontraditional process for precision finishing of gear that can simultaneously improve microgeometry, surface finish, microhardness, surface morphology, wear resistance, and residual stresses of the finished gears. Gear manufacturers and users will be benefited by the outcome of this study. JEL codes: C00, C20

APPLICATION OF IMAGE LOGS FOR ENHANCED RESISTIVITY-BASED WATER SATURATION ASSESSMENT IN ORGANIC-RICH MUDROCKS

Organic-rich mudrocks are complex in terms of rock fabric (i.e., the spatial distribution of rock components), which impacts electrical resistivity measurements and, therefore, estimates of hydrocarbon reserves. Conventional resistivity-saturation-porosity methods for assessment of water/hydrocarbon saturation do not reliably incorporate the spatial distribution of rock components and pores in the assessment of fluid saturation. Extensive calibration efforts are required for indirectly projecting the impact of rock fabric on resistivity models. For instance, none of the existing shaly-sand models incorporate a realistic distribution of clay network. This might be acceptable in conventional reservoirs. However, oversimplifying assumptions can cause significant uncertainty in reserves evaluation in organic-rich mudrocks. It should be noted that even the methods which incorporate the realistic distribution of rock components are difficult to calibrate. To address the aforementioned challenge, we introduce a joint interpretation of conventional resistivity and resistivity image logs to improve water saturation assessment by honoring the type of rock component, the spatial distribution of the conductive and non-conductive rock components, and the volumetric concentration of fluids and minerals in the rock. Borehole image logs are a source of high-resolution continuous rock sequence records and can provide detailed rock-fabric-related features. In this paper, we propose a method for the estimation of lamination density and mean resistivity value from image logs within each rock type. These fabric-related features are used to quantify the geometric model parameters for each conductive component of the rock. We use these geometric model parameters as inputs to a new resistivity model that considers volumetric concentration and spatial distribution of rock components for a depth-by-depth assessment of water saturation. The other inputs to the workflow are the volumetric concentration of conductive and non-conductive rock components, electrical conductivity of rock components, and porosity estimates from the joint interpretation of well logs. We successfully applied the proposed workflow to a dataset from the Wolfcamp formation in the Permian Basin in which resistivity image logs were available. We observed a measurable variation in estimated image-log-based geometric model parameters, which were in agreement with the visual content of the images. Incorporation of the estimated rock-class-based geometric model parameters in the resistivity model improved water saturation assessment. Results demonstrated a relative improvement in water saturation estimates of 44.2% and 59.1% against Waxman-Smits and Archie's models, respectively. We then used the estimated geometric model parameters for each rock type for a depth-by-depth assessment of water saturation in one additional well without image logs. This led to a faster and more reliable assessment of water saturation within a certain distance from the well with image logs, where the rock types remain comparable. This distance can be evaluated using variogram analysis. We demonstrated that using the estimated geometric model parameters could improve estimates of hydrocarbon reserves in the Permian Basin by approximately 34%. It should be noted that the proposed method for assessment of geometric model parameters is completely based on the actual spatial distribution of rock components and does not require core-based calibration efforts.