High Hydraulic Resistance Research Articles

Empirical formula of buckle propagation pressure for sandwich pipes with polymer core material

The sandwich pipe, with its high hydraulic pressure resistance and thermal insulation properties, presents itself as a potential choice for deepwater oil and gas exploration. This study developed a 3D finite element numerical model using ABAQUS software to simulate the collapse propagation of sandwich pipes under the high external hydraulic pressure. A parametric analysis was undertaken using a numerical model, which had been calibrated by experimental tests. The study aimed to assess the contributions of material properties, such as yield strength and Young's modulus, as well as geometric dimension, to the collapse propagation behavior of the sandwich pipe. Moreover, a simplified empirical formula was formulated to research the propagation pressure of polymer sandwich pipes. The research also investigated the contribution of the interaction property between the core layer and inner/outer steel layer on the propagation pressure. An interfacial factor was incorporated into the present simplified empirical formula. The empirical formula was validated using experimental results and data from various sources, including real interlayer interactions observed during tests. The results indicate that this formula offers an accurate prediction of the propagation pressure for polymer sandwich pipes.

HYDRAULIC CHARACTERISTICS AND CONSUMPTION PARAMETERS OF PIPELINE FOR MULTIPHASE FLOWS

Multiphase flows are found in almost all facilities and objects of the oil industry - oil and gas wells, oil transportation and storage facilities, oil refineries and petrochemical enterprises. Accurate modeling of the hydrodynamics of these processes is required to predict the productivity and operational efficiency of both hydrocarbon deposits and pipelines [2,7,8,10] . However, developing a reliable model for the correct modeling of processes is a very complex issue. Therefore, it is understandable that carrying out laboratory experiments are preferred. According to theoretical assessments and experimental data on the joint transportation of gas, oil, and water through the same pipeline the resistance to flow and the energy required for transportation will be significantly reduced if not oil, water is in contact with the pipe during flow, (although the pipeline's discharge capacity increases due to the addition of water) [8,10]. Experiments demonstrate that the high hydraulic resistance of the pipeline at ambient temperature makes it inefficient to transport high viscosity and paraffinic oils—which freeze at higher temperatures—as well as oil products using conventional methods. There are various multiphase flow structures that can be achieved when transporting oil and water together, regardless of whether the mixing is natural or artificial (for example, coaxial, emulsified, phase-separated, etc.), The coaxial structure forms because the water around the oil keeps it from coming into contact with the pipe wall. Since the contact of the water phase with the inner surface greatly reduces the friction, it significantly facilitates the transportation of the oil water mixture. Transport of multiphase mixtures is often accompanied by phase transformation, which leads to blockages caused by the gas liquid or solid phase is the collection or transport systems. Pipeline plugging results in a variety of technological complications and extra expenses incurred to eliminate their consequences. Most often phase imbalance at specific pressure values and a sudden shift in the carried product's viscosity lead to the formation of difficulties [2]. The article's primary goal is to investigate the hydraulic properties of pipes for multiphase flows. The primary techniques for the combined transportation of gas and oil, as well as an examination of the primary characteristics and structural configurations of multiphase flows. Keywords: multiphase flows, pipelines, consumption, pressure, temperature, volume, hydraulic characteristics, and pressure pulses.

Stiffness influence on particle separation in polydimethylsiloxane-based deterministic lateral displacement devices

Polydimethylsiloxane (PDMS) is a popular material to rapidly manufacture microfluidic deterministic lateral displacement (DLD) devices for particle separation. However, manufacturing and operation challenges are encountered with decreasing device dimensions required to separate submicron particles. The smaller dimensions, notably, cause high hydraulic resistance, resulting in significant pressure even at relatively low throughputs. This high pressure can lead to PDMS deformation, which, in turn, influences the device performance. These effects may often be overlooked in the design and operation of devices but provide a systematic source of error and inaccuracies. This study focuses in detail on these effects and investigates pillar deformation in detail. Subsequently, we discuss a potential solution to this deformation using thermal annealing to stiffen the PDMS. We evaluate the influence of stiffness on the separation performance at elevated sample flow rates with submicron particles (0.45 and 0.97 µm diameter). An excellent separation performance at high throughput is successfully maintained in stiffer PDMS-based DLD devices, while the conventional devices showed decreased separation performance. However, the increased propensity for delamination constrains the maximal applicable throughput in stiffer devices. PDMS deformation measurements and numerical simulations are combined to derive an iterative model for calculating pressure distribution and PDMS deformation. Finally, the observed separation characteristics and encountered throughput constraints are explained with the iterative model. The results in this study underline the importance of considering pressure-induced effects for PDMS-based DLD devices, provide a potential mitigation of this effect, and introduce an approach for estimating pressure-induced deformation.

Unexpected significance of magnesium ion in the coupling effect of mixed divalent cations on polysaccharide membrane fouling

Divalent cations and organics are two main types of foulants in feed water to the membrane processes and cations often bind to organic foulants which significantly affects fouling. Extensive efforts have been devoted to exploring the influence of single cation on organic fouling while there are diverse cations in the feed. Thus, it is essential to understand the coupling influence of different divalent cations on fouling development. In this study, sodium alginate was chosen as a model foulant to investigate the effect of different Ca2+/Mg2+ ratios on its fouling behavior. Filtration performances, the quantity and morphology of transparent exopolymer particles (TEP) derived from alginate were analyzed along with the morphology and structure of corresponding fouling layers. TEP measurements reveal that the Ca2+/Mg2+ ratio is crucial in the characteristics of TEP, which further determines the structure of the fouling layer. At a low Ca2+/Mg2+ ratio, the TEP are amorphous-TEP (a-TEP) with small and unconsolidated structure which forms a fouling layer under pressure with high hydraulic resistance. In contrast, interactions between polysaccharides at high Ca2+/Mg2+ ratio are much stronger and result in large and tight particulate-TEP (p-TEP). Such p-TEP lead to a fouling layer with high porosity and low hydraulic resistance. The role of Mg2+ in polysaccharide fouling is more important than expected because it promotes the formation of a-TEP, which show a high fouling potential at high levels because more dense gel layer forms. This study suggests that the morphology and structure of TEP play crucial roles in polysaccharide fouling propensities. A-TEP at high levels needs more attention to ensure the successful operation of membrane systems in future work.

Do urban tree hydraulics limit their transpirational cooling? A comparison between temperate and hot arid climates

Evaporative cooling due to transpiration of urban trees in two contrasting climates is the subject of this study. Transpiration was studied experimentally on local tree species at ‘tree lab’ sites in Munich, Germany (temperate climate) and in Beer Sheva, Israel (hot arid climate), within various settings (park, street, square) with natural and sealed surface conditions. The comparison was based on linear relationship of midday canopy resistance to atmospheric vapor pressure deficit (VPD), where the slope is proportional to tree hydraulic conductance and midday stem water potential. Sap flux densities in all trees were similar but crown projected area (CPA) was larger in Beer Sheva, resulting in higher hydraulic resistance that limits transpirational cooling (regression slopes of 0.25–0.44 in Beer Sheva vs. 0.10–0.18 in Munich). The contribution of the transpirational cooling, studied as the proportion of latent heat to total available energy was about 40% less significant at noon hours in summer in Beer Sheva than in Munich. Results suggested that shading should be the main consideration in planting local trees in hot dry climates. The linear relationship of midday canopy resistance to VPD is proposed as an operative tool for comparing evaporative cooling between local trees in different climatic regions.

Evaluation of the Anti-Fouling Effects of Micro-Nano Bubbles on the Performance of Reverse Osmosis Membrane

Colloidal fouling on a brackish water reverse osmosis (BWRO) membrane was simulated by a lab-scale plate-and-frame module in the presence and absence of air micro-nano bubbles (AMNBs). Synthetic feed water samples with the same physical and chemical properties, but various concentrations of colloidal silica (50, 100, 200, and 300 mg/L), were used for experiments. The results illustrate that colloidal fouling caused a severe decrease in permeate flux (24%–56%) and salt rejection (1.25% to 4.18%) in the absence of AMNBs. This reduction in membrane performance was attributed to the high hydraulic resistance and the cake-enhanced osmotic pressure (CEOP) of a fouled gel layer that were intensified with increase in the colloidal concentration. On the other hand, presence of AMNBs decreased the deposition rate of colloidal particles significantly and increased the porosity of fouling layer. Thus, an improvement in the membrane permeate flux (21%–40%) and salt rejection (1.2%–2.6%) were seen in the different concentrations of colloidal particles. The SEM images also confirmed the formation of loose fouling layers which were easily removed from the membrane surface by a clean-in-place (CIP) process. This research introduces AMNBs technology as an effective in-line method to control the adverse effects of colloidal fouling in reverse osmosis (RO) systems.

Investigation of Recirculating Marangoni Flow in Three-Dimensional Geometry of Aqueous Micro-Foams

Experimental investigations of Marangoni flow in micro-foams have faced challenges due to the inherent difficulties in detecting and measuring this flow. The Marangoni flow manifests as small spots within the lamellae films, which makes it hard to accurately analyze. Hence, to elucidate Marangoni flow characteristics, this study introduces and investigates comprehensive three-dimensional models of flow in microscale foams. The geometric models contained Plateau Borders (PB), nodes, and films. The recirculating Marangoni flow was simulated and studied for different interfacial mobilities. Inside the foams, the Marangoni flow velocities were at the same scale with the PB flow velocity for mobile interfaces. However, for a more rigid interface, the magnitude of the Marangoni flow was considerably less than that of the PB owing to the combined effect of high surface hydraulic resistance on the Marangoni flows and nature of the Marangoni flow as a surface-only flow type. Furthermore, the effect of the film thickness on the Marangoni flow was analyzed. Thicker films have a stronger effect in reducing the Marangoni flow than PB flow. This is due to the higher ratio of gravity body force to the Marangoni-driven surface force for thicker films. Finally, the combined effect of the liquid–air interfacial mobility and film thickness on the Marangoni velocity was studied.

Monitoring Stem Water Potential with an Embedded Microtensiometer to Inform Irrigation Scheduling in Fruit Crops

The water status of fruit and nut crops is critical to the high productivity, quality and value of these crops. Water status is often estimated and managed with indirect measurements of soil moisture and models of evapotranspiration. However, cultivated trees and vines have characteristics and associated cultural practices that complicate such methods, particularly variable discontinuous canopies, and extensive but low-density, variable root systems with relatively high hydraulic resistance. Direct and continuous measurement of plant water status is desirable in these crops as the plant integrates its unique combination of weather, soil and cultural factors. To measure plant water potential with high temporal sampling rates, a stem-embedded microchip microtensiometer sensor has been developed and tested in several fruit crops for long-term continuous monitoring of stem water potential. Results on several fruit crops in orchards and vineyards have been good to excellent, with very good correlations to the pressure chamber standard method. The primary challenge has been establishing and maintaining the intimate contact with the xylem for long periods of time, with variable stem anatomies, stem growth and wound reactions. Sources of variability in the measurements and utilization of the continuous data stream, in relation to irrigation scheduling, are discussed. Direct continuous and long-term field measurements are possible and provide unique opportunities for both research and farming.

Biofilm Formation and Biofouling Development on Different Ultrafiltration Membranes by Natural Anaerobes from an Anaerobic Membrane Bioreactor.

Biofouling in anaerobic membrane bioreactors (AnMBRs) has not been studied widely. Moreover, the effect of membrane surface properties on biofilm formation beyond initial deposition is controversial. We investigated biofouling with polyvinyldifluoride, polyacrylonitrile, and zwitterion-modified polyethersulfone ultrafiltration membranes having different properties during 72 h filtration using natural anaerobes isolated from AnMBR and analyzed biofilm characteristics by physicochemical and molecular techniques. A decrease in membrane performance was positively correlated with biofilm formation on polyvinyldifluoride and polyacrylonitrile membranes, and as expected, physical cleaning effectively mitigated biofilm on hydrophilic and low-roughness membranes. Surprisingly, while the biofilm on the hydrophilic and low-surface roughness zwitterion-modified membrane was significantly impaired, the impact on transmembrane pressure was the highest. This was ascribed to the formation of a soft compressible thin biofilm with high hydraulic resistance, and internal clogging and pore blocking due to high pore-size distribution. Anaerobe community analysis demonstrated some selection between the bulk and biofilm anaerobes and differences in the relative abundance of the dominant anaerobes among the membranes. However, correlation analyses revealed that all membrane properties studied affected microbial communities' composition, highlighting the system's complexity. Overall, our findings indicate that the membrane properties can affect biofilm formation and the anaerobic microbial population but not necessarily alleviate biofouling.

Evaluation of the internal combustion engine pre-heating methods and their influence on the cold engine start performance at an ambient temperature of –40°C

Introduction (statement of the problem and relevance). Starting an internal combustion engine (ICE) at negative ambient temperatures is difficult for a number of reasons. A decrease in the volatility of gasoline leads to the liquid fuel deposition on the cylinder walls, as a result of which the fuel-air mixture ignition is difficult or impossible. Another reason is the geometric dimensions reduction of the gaps in the plain bearings, which is a consequence of the use of materials with different thermal expansion coefficients in the engine design. The high kinematic viscosity of the oil creates a higher hydraulic resistance in the system. These factors complicate the engine oil flow to friction pairs, which can lead to an oil starvation and bearing shell life reduction.The purpose of the research was to determine the optimal pre-heating mode from the point of view of the process energy efficiency and the preservation of the engine resource.Methodology and research methods. To control the thermal state, the internal combustion engine and the cooling circuit were equipped with measuring equipment. The values of temperature, pressure and volume flow sensors were recorded. To implement the pre-heating modes proposed in the article, an engineering engine control unit was used, which allowed making changes in the basic software configuration.Scientific novelty and results. An alternative method of pre-heating has been proposed, including preheating of the engine oil-water heat exchanger to reduce the time for reaching the minimum oil pressure at the main gallery inlet during a cold start. The article provides descriptions of the regular and proposed pre-heating cycles, their assessment in accordance with the represented criteria. Experimental data on pre-heating cycles and cold starts at an ambient temperature of –40°C are presented. The necessity of warming up the engine standard water-oil heat exchanger before a cold start has been experimentally proved, the curves of pressure changes at the main gallery inlet, depending on the pre-heating mode, are given.Practical significance. Reducing the negative influence of cold start on the ICE resource.

High flux thin film composite (TFC) membrane with non-planar rigid twisted structures for organic solvent nanofiltration (OSN)

Organic solvent nanofiltration (OSN) has become an emerging green and efficient technique for the separation and purification of organic solvents. The key of the industrial application of this technique is OSN membrane. Till now, current OSN membranes still have relatively low solvent permeance due to the high hydraulic resistance of the dense structure of the OSN barrier layer. Herein, a thin-film composite (TFC) polyamide-polyarylate OSN membrane containing polymers of intrinsic microporosity (PIMs) structure was successfully prepared via interfacial polymerization (IP) using a kind of hydrophilic monomer with rigid twisted structure as aqueous co-monomer together with m-phenylenediamine (MPD). The added co-monomer remarkably enhanced the perm-selectivity of the prepared OSN membrane, with an increase of more than 1.5 times for ethanol permeance, while maintaining the rejection of rhodamine B (RDB, 479 Da) above 99% under the optimal conditions. Moreover, the prepared OSN membrane has a much high permeance to polar solvents, e.g., 110.5, 112.6 and 95.8 L m−2h−1 MPa−1, for ethyl acetate, methanol and DMF, respectively. The most exciting aspect of the prepared OSN membrane is its superior solvent resistance in strong polar organic solvent. It maintained an essentially unchanged solute rejection during 63 d immersion in DMF at 80 °C, and during 120 h continuous cross-flow filtration of the RB-DMF solution at room temperature, which is superior over most of the state-of-the-art literature works, indicating its broad application prospects for separation and purification of polar organic solvent systems.

MATHEMATICAL MODELLING OF THE VENTILATION SYSTEM OF A RESIDENTIAL BUILDING IN CONDITION THAT DIFFER FROM STANDARD

The natural ventilation systems of multi-story residential buildings are designed to meet the requirements for maximum air exchange. Their calculations under conditions significantly different from the standard, usually do not carry out and therefore do not provide measures to prevent their unstable operation. The article presents the results of the analysis of the ventilation system of a two-room section of a ten-story residential building using a mathematical model. To supply air to the apartment, ventilation valves are used. The air is removed from the apartments through two ventilation ducts. All apartments, except the last two floors, are connected to them via satellite channels. The system of equations of the model is based on the graph of the hydraulic network. It includes equations of the balance of air flow in the nodes of the graph and equations of pressure change in the links. In this case, the data presented in the catalogs of equipment manufacturers was used. The calculation results for conditions that differ from the design ones are presented, such as: significant differences in the supply air flow in individual apartments, the use of exhaust fans in some apartments, low outdoor temperature. The model under consideration allows us to explain the observed in practice air penetration through ventilation ducts from one apartment to another. It is shown that the main causes of this phenomenon are the low air transmission of modern window structures and the high hydraulic resistance of the supply valves, the use of ventilation ducts with various hydraulic resistances. The proposed approach allows already at the project stage to quantify the operation of the ventilation system in conditions that differ from standard and to optimize its design.

Design of drain tube with movable shutter in household refrigerators

• Infiltration of warm and humid air to the freezer results in frost accumulation. • For reduction of inflow, drain tube with a high hydraulic resistance is proposed. • Negative pressure is formed by air shrinkage after door opening and closing. • To release the negative pressure, the proposed drain tube has a movable shutter. • Movable shutter can control air vents depending on the pressure condition. The infiltration of warm and humid air from the outside into a freezer results in frost accumulation around the evaporator in household refrigerators. This can significantly reduce the cooling capacity of refrigerators. In this study, the pressure, temperature, and frost around a proposed drain tube were monitored through in-situ measurements until the first defrost process (about 54 h). The proposed drain tube has 220 times higher hydraulic resistance and shows 55 times lower inflow in computational fluid dynamics (CFD) analysis. Once the door of the freezer compartment is opened and closed, external warm air replaces the cold air in the freezer. Negative pressure is produced by the shrinkage of this external air under low-temperature conditions. The other role of the drain tube is to vent air between the outside and inside of the refrigerator under negative pressure. To release the negative pressure, the proposed drain tube has a movable shutter. In the CFD results, the secondary inlet increases the inflow by 3.2 times compared to the inflow in an I-type tube. To determine the design, the weight and inner diameter of the drain tube were changed. The performance of the proposed tube was validated by the lack of blockage of discharge until the first defrost process. The movable shutter did not allow the negative pressure to exceed -100 Pa by facilitating air venting after opening the door for 10 seconds and then closing it.

Adaptation of Abies fargesii var. faxoniana (Rehder et E.H. Wilson) Tang S Liu seedlings to high altitude in a subalpine forest in southwestern China with special reference to phloem and xylem traits

Key messageAbies fargesii var. faxoniana (Rehder et E.H. Wilson) Tang S Liu seedlings at high elevations compensate for the low efficiency of their water conducting system and high phloem hydraulic resistance by the enhancement in xylem:leaf area, phloem:leaf area, and phloem:xylem area.ContextMaintenance of xylem and phloem transport is particularly important for the survival and growth of trees at the treeline. How plants modify the allocation to leaf, xylem, and phloem structures to adapt to the treeline environment is an important issue.AimsThe purpose of this study was to estimate how xylem and phloem anatomy and volume as well as leaf functional traits of A. fargesii seedlings vary with elevation.MethodsWe examined elevation-related differences in a variety of phloem and xylem functional areas and hydraulic conduit diameters of A. fargesii seedlings growing at elevations between 2600 and 3200 m in the subalpine conifer forest of southwest China.ResultsXylem area, last xylem ring area, and leaf:sapwood area significantly decreased, while xylem:leaf area, phloem:leaf area, and non-collapsed phloem:xylem area significantly increased with elevation. Principal components analysis showed that xylem area, non-collapsed phloem area, and xylem:phloem area were positively correlated with growth rates.ConclusionOur results showed that A. fargesii tree seedlings at the treeline tend to facilitate growth and maintain functional water and sugar balance between stem and leaves by the enhancement in xylem:leaf area, phloem:leaf area, and phloem:xylem area, but not through differences in vessel lumen diameter.

Parameters of the plain weave meshfor the nozzle of a regenerative heat exchanger

Regenerative heat exchangers have disadvantages such as low heat transfer coefficient from the nozzle to the gas and high hydraulic resistance due to the design of the nozzles. Wire-mesh nozzles can eliminate these shortcomings of regenerators. Wire-mesh nozzles have low hydraulic resistance and large heat transfer surface. The process of heat and mass transfer in a regenerative heat exchanger is considered. A series of numerical simulation experiments was performed. Theoretically, the optimal configuration of the nozzle was calculated: a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm. The operational modes for the regenerator are considered, taking into account the period for drying the nozzle from moisture and the maximum mass of water that can hold the nozzle without the formation of drops. Given the condensation of moisture on the nozzle, the following assumptions are made: There is no temperature and concentration inhomogeneity in the cross section of the regenerator channel; The effect of thermal conductivity in the axial direction in contact between the nozzle elements on the temperature profile of the nozzle is insignificant; The time over which the regenerator is operated between the nozzle drying periods is quite short, and the thickness of the condensate layer does not affect the hydrodynamic mode of the heat regeneration process and the value of the heat transfer coefficient. The duration of the cooling and drying period depends on the humidity of the inlet air and the area of the nozzle. This is due to the need to prevent the accumulation of moisture in the device, which can lead to the reproduction of harmful bacteria and contamination of the nozzle. In the SolidWorks Flow Simulation application, simulation experiments were performed for a regenerator model accounting for the influence of compressed air motion resulting from grouped location of the nozzle elements, and the results are shown in the figures. Comparison of the results from analytical calculations and simulation experiments showed the efficiency of the mathematical model and the possibility of its use in the design calculation of regenerators. Correlation dependences have been established to determine the heat transfer coefficient and hydraulic resistance depending on the hydrodynamic conditions. The mathematical and physical model taking into account the condensation of moisture on the nozzle has been specified. Calculations have been performed for the optimal nozzle made in the form of a plain weave mesh with a wire diameter of 0.4 mm, a weaving step of 2 mm, and a step of placing nets of 1 mm.

Development of Polysulfone Membrane via Vapor-Induced Phase Separation for Oil/Water Emulsion Filtration.

The discharge of improperly treated oil/water emulsion by industries imposes detrimental effects on human health and the environment. The membrane process is a promising technology for oil/water emulsion treatment. However, it faces the challenge of being maintaining due to membrane fouling. It occurs as a result of the strong interaction between the hydrophobic oil droplets and the hydrophobic membrane surface. This issue has attracted research interest in developing the membrane material that possesses high hydraulic and fouling resistance performances. This research explores the vapor-induced phase separation (VIPS) method for the fabrication of a hydrophilic polysulfone (PSF) membrane with the presence of polyethylene glycol (PEG) as the additive for the treatment of oil/water emulsion. Results show that the slow nonsolvent intake in VIPS greatly influences the resulting membrane structure that allows the higher retention of the additive within the membrane matrix. By extending the exposure time of the cast film under humid air, both surface chemistry and morphology of the resulting membrane can be enhanced. By extending the exposure time from 0 to 60 s, the water contact angle decreases from 70.28 ± 0.61° to 57.72 ± 0.61°, and the clean water permeability increases from 328.70 ± 8.27 to 501.89 ± 8.92 (L·m−2·h−1·bar−1). Moreover, the oil rejection also improves from 85.06 ± 1.6 to 98.48 ± 1.2%. The membrane structure was transformed from a porous top layer with a finger-like macrovoid sub-structure to a relatively thick top layer with a sponge-like macrovoid-free sub-structure. Overall results demonstrate the potential of the VIPS process to enhance both surface chemistry and morphology of the PSF membrane.

COMPOSITE PIPELINES EFFICIENCY FOR OIL TRANSPORTATION SYSTEM

Background About 1.3 % of the country's total electricity consumption, which is more than 14 billion kWh, is consumed annually to drive the pumping equipment of the Russian oil trunk transportation system. To achieve the aims and objectives of the energy policy of Transneft, a program was developed and implemented to save energy and improve energy efficiency in the Company. In accordance with the program, only in 2018 the company achieved savings of 18,595 tons of standard fuel in the amount of 438.7 million rubles, including electricity - 111 764 thousand kWh for the amount of 376 524 million rubles. Thanks to the implemented energy-saving measures, electricity consumption decreased by 0.8 %, and energy resources in general - by 0.9 % compared to 2017. But a further reduction in energy costs is problematic for objective factors and reasons. The specific energy consumption for oil transportation is a power-law dependence on cargo turnover, and an increase in the latter will lead to an increase in energy consumption. Pumping high-viscosity, heavy and asphalt-tar oils, whose share is growing annually in the total volume of pumping, is carried out using complex, expensive, special methods that require additional costs. The complex of energy saving measures of Transneft PJSC, planning for by the strategic program until 2024, provides for the optimization of oil pumping modes, the use of frequency regulation of main and booster pumps, and the use of special methods for pumping oil and oil products. The economic effect of implementing a set of measures to reduce the consumption of all types of energy resources for the system of Transneft Urals, JSC alone amounted to 32,8 million rubles in 2018. Currently, the dynamics of decreasing specific electricity consumption in the oil trunk transportation system is reaching an asymptotic level. In such a situation, the energy effect can bring the introduction of only radically new effective solutions. One of such directions for the further development of the main oil pipeline system authors see in the composite pipes with high corrosion and minimal hydraulic resistance. Aims and Objectives Estimate the effectiveness of composite pipelines for oil transportation systems. Results The energy effect for substantiating the decision in favor of the composite system is determined by the example of a conditional oil pipeline 100 km long. A model of the dependence of the energy effect on the diameter of the pipeline and the pumping speed with an average dispersion of adequacy of 0.974 was developed.

Development and Investigation of a New Rotary Valve for Power Steam Turbines

Control valves are actuating elements of a steam turbine control system; the quality of their performance directly affects the reliability of the overall steam turbine unit. Accordingly, these valves must meet very stringent requirements. Among the factors and characteristics responsible for the quality of control valves, an important place is occupied by the design simplicity, manufacturability, serviceability, ease of installation, high operating reliability, low hydraulic resistance, low dynamic loads acting on the valve stem, and moderate noise level. At the same time, it should be noted that there is quite a large fleet of old, obsolete steam turbine power units at present in Russia with valves featuring both high hydraulic resistance and poor reliability. In new, linear control valves developed in the last decade, almost all design possibilities for their improvement have been exhausted. Hence, rotary control valves may be of great interest for practice. It is this type of valve that is considered below. This information includes a description of valve design, results from the investigation of flow parameters in the valve flow path, and the flow characteristic obtained by a mathematical simulation technique. This valve meets the above-mentioned requirements to the maximum extent, is fully balanced of axial thrust, has almost zero steam leakage along the drive stem, and is operated with low-power actuators with any bores and any initial steam pressures.

Morphology of Dune-Like Relief in Rivers

Linearized equations of two-dimensional hydraulics have been analyzed by the method of small perturbations within a wide range of alluvial features sizes at large values of Froude numbers and hydraulic resistance. The preservation of three-dimensional effects in depth-averaged equations of motion, continuity, and deformation enabled the authors to identify domains with combinations of flow hydraulic characteristics that correspond to alluvial features of different size and morphology. The study confirmed the results of the earlier analysis for subcritical flows with small hydraulic resistance and showed new types of relationships between alluvial features morphology and the hydraulic characteristics of flow for flows with large Froude numbers and high hydraulic resistance. In addition, a relationship between the length of two-dimensional ultramicroforms and hydraulic resistance has been established. A new class of macroforms—two-dimensional macroforms—have been identified. The verification of the results of theoretical analysis by measurements data on the morphology of channel formations and hydraulic characteristics of the flow has shown that the analysis of linearized equations of two-dimensional hydrodynamics by small-perturbation method can be used to determine the morphology and dimensions of channel forms in both subcritical and supercritical streams. The step–pool systems in torrential streams in mountain rivers are analogues of antidunes (in supercritical flows) and ripples (in subcritical flows), obtained in large flumes with sand alluvium. Three-dimensional macroforms are most common in rivers. If such macroforms are well developed in wide channels (at flow width greater than the half-width of the macroform), their length is determined by channel depth. Macroforms in narrower channels cannot develop completely, and their lengths are limited by channel width and can be calculated only through this width.

Low-cost electrochemical filtration carbon membrane prepared from coal via self-bonding

Electrochemical filtration membranes are highly effective for wastewater treatment. However, their relatively high production cost may limit their large-scale production and industrial application. In this work, a low-cost and efficient electrochemical filtration carbon membrane (ECM) was developed via a simple method using coal as the precursor and relying on its self-bonding property. The effects of raw coal blending ratio, carbonization temperature and the addition of pore former on the performance of ECMs were systematically studied. The electrochemical filtration efficiency of the ECM was evaluated using four typical organic pollutants (phenol, bisphenol A (BPA), tetracycline (TC) and rhodamine B (RhB)). Finally, the oxidation mechanism of the ECM was also explored. The high caking property of the raw coal resulted in high mechanical strength ECMs but also led to low porosity and small pore size, which may cause high hydraulic resistance. The overall performance of the ECMs was improved by using blended coal samples as raw materials. The ECM obtained by the optimal preparation conditions exhibited a porosity value of 51.83%, mean pore width of 0.88 μm, mechanical strength of 78.8 N, electrical resistivity of 33.91 mΩ cm and high permeability (393.17 L·m−2·h−1·bar−1). Under a cell potential of 2.0 V, the removal rates of the ECM for all four pollutants were greatly enhanced by electrochemical oxidation, and the electrochemical oxidation activity of the ECM involve both direct and indirect oxidation. Overall, these results demonstrated the potential applicability of ECMs for large-scale production and organic wastewater treatment.