Fluid Flow Resistance Research Articles

Experimental Study on Improving the Recovery Rate of Low-Pressure Tight Oil Reservoirs Using Molecular Deposition Film Technology

The intricate geological characteristics of tight oil reservoirs, characterized by extremely low porosity and permeability as well as pronounced heterogeneity, have led to a decline in reservoir pressure, substantial gas expulsion, an accelerated decrease in oil production rates, and the inadequacy of traditional water injection methods for enhancing oil recovery. As a result, operators encounter heightened operational costs and prolonged timelines necessary to achieve optimal production levels. This situation underscores the increasing demand for advanced techniques specifically designed for tight oil reservoirs. An internal evaluation is presented, focusing on the application of molecular deposition film techniques for enhanced oil recovery from tight oil reservoirs, with the aim of elucidating the underlying mechanisms of this approach. The research addresses fluid flow resistance by employing aqueous solutions as transmission media and leverages electrostatic interactions to generate nanometer-thin films that enhance the surface properties of the reservoir while modifying the interaction dynamics between oil and rock. This facilitates the more efficient displacement of injected fluids to replace oil during pore flushing processes, thereby achieving enhanced oil recovery objectives. The experimental results indicate that an improvement in oil displacement efficiency is attained by increasing the concentration of the molecular deposition film agent, with 400 mg/L identified as the optimal concentration from an economic perspective. It is advisable to commence with a concentration of 500 mg/L before transitioning to 400 mg/L, considering the adsorption effects near the well zone and dilution phenomena within the reservoir. Molecular deposition films can effectively reduce injection pressure, enhance injection capacity, and lower initiation pressure. These improvements significantly optimize flow conditions within the reservoir and increase core permeability, resulting in a 7.82% enhancement in oil recovery. This molecular deposition film oil recovery technology presents a promising innovative approach for enhanced oil recovery, serving as a viable alternative to conventional water flooding methods.

Damage Factors and Protection of Low Permeability Reservoir

With the development of science and technology and the progress of society, people's production level has been significantly improved. In this context, people have also put forward higher requirements for the application and development of technology and processes in various production fields. The relevant construction technology of oilfield enterprises is no exception. Low permeability reservoir occupies a large proportion in China's reservoir resources. However, due to the small pore space and large fluid flow resistance of low permeability reservoir, it is more prone to reservoir damage in the development process, and even causes the reservoir to fail to produce in serious cases. Therefore, research on the potential damage factors and damage mechanism of low permeability reservoir and propose corresponding protection strategies are conducive to improving the development effect of low permeability reservoir. The potential damage factors of low permeability reservoir are systematically analyzed, which is of great significance to guide the efficient exploitation of low permeability reservoir.

Modeling and Evaluation of Fluid Flow Resistance Characteristics of the Cooling Channel in the Aircraft Oil-Cooled Electric Machine

Modeling and Evaluation of Fluid Flow Resistance Characteristics of the Cooling Channel in the Aircraft Oil-Cooled Electric Machine

Simulation of the effect of the structure and location of non-closed droplet microchannel on flow/ thermal performance

In order to investigate the effects of geometric parameters and flow modes on the fluid flow morphology, resistance and heat transfer effect in the non-closed droplet pin fin array, in this manuscript, a numerical simulation has been conducted under Re = 100–700 with different pin fin heights (Hp = 0.3 mm, 0.5 mm, 0.7 mm) and pin fin densities (β = 0.046, 0.059, 0.072), with different flow directions under heat flux (10 W/cm2 – 50 W/cm2) studied as well. It is discovered that increasing the height and density of the non-closed droplet pin fin increases the interference with the fluid, resulting in a greater flow resistance phenomenon. However, the enhancement of turbulence not only exacerbates the flow instability in microchannels, but also further promotes the mixing of hot and cold fluids, making the internal temperature distribution more uniform. In which way, the effect of optimizing heat transfer performance achieves. In addition, as q > 20 W/cm2, the overall heat transfer capacity of flow direction B (the tip of the pin fin as upstream fluid direction) is better than that of flow direction A (the cavity of the pin fin upstream as upstream fluid direction). When q = 30 W/cm2, there is a process transferring from single-phase flow to two-phase flow along with the direction of working fluid flow in the microchannel. Under this condition, the local maximum heat transfer coefficient is 15,502.4 W/(m2·K) in flow direction A and 16,094.8 W/(m2·K) in flow direction B. Furthermore, the comprehensive evaluation concludes that the channel flow/thermal performance is the best with Hp = 0.7 mm, β = 0.046.

Unsteady electroosmotic flow of Carreau–Newtonian fluids through a cylindrical tube

The present study aims to investigate the fully developed electroosmotic flow of Carreau–Newtonian fluids within a circular tube, considering two different boundary conditions of zeta potential. The unsteady behavior of Carreau–Newtonian fluids, is attributed to the pulsatile pressure-driven flow. Studying two distinct formulations, slip and no-slip zeta potentials, illustrates the relative movement of fluid particles and the charged surface. The proposed study’s framework is divided into two regions: a central region containing a non-Newtonian Carreau fluid exhibiting both shear-thinning and thickening behavior, and a peripheral region containing a Newtonian fluid with the effect of an electrical double layer at the solid wall of the cylindrical tube. The Poisson–Boltzmann equation under the assumption of Debye–Hückel approximation governs the potential distribution due to the electric double layer, facilitating the examination of electroosmotic flow through tube. Obtaining analytical solutions for the momentum equations in both regions becomes challenging due to the inclusion of pulsatile pressure-driven flow and a non-Newtonian Carreau fluid. Asymptotic series expansions are employed, utilizing small parameters such as the Weissenberg number (We≪1) and a pulsatile Reynolds number (α≪1), to derive velocity expressions for both regions. Wall shear stress fluctuations, as indicated by time-averaged wall shear stress and oscillatory shear index are assessed to gauge the temporal variation of wall shear stress from the dominant blood flow direction. By utilizing potential and hydrodynamic variables, an asymptotic formulation for the streaming potential is developed to ascertain the asymptotic expression of electrokinetic energy conversion efficiency and scrutinize the impacts of pertinent physical parameters on it. The proposed study prominently shows that the Debye–Hückel parameter, Weissenberg number, pulsatile Reynolds number, and time-dependent pressure gradient significantly influence the fluid velocity, flow rate, and flow resistance. The notable determination of the present study is that the velocity amplitude and electrokinetic energy conversion efficiency are enlarged in the slip-dependent case relative to the no-slip zeta potential. It is noteworthy that as inertial forces become more prominent compared to viscous forces, both time-average wall shear stress and oscillatory shear index experience a slight decrease, although the reduction in oscillatory shear index is minimal owing to the absence of obstruction within the tube wall. The NDSolve numerical scheme in Mathematica software is employed to calculate numerical solutions for the governing equations, which are subsequently verified against results obtained through asymptotic analysis. The findings of this study are expected to deepen our understanding of unsteady electroosmotic flows of Carreau fluid and contribute to the design and development of advanced microfluidic devices with enhanced performance for various applications.

Performance investigation of metal foam coupled to phase change material as coolant of photovoltaic concentrator systems: Optimization and electrical efficiency analysis

This research investigates the integration of graphitic metal foam with paraffin RT35HC to manage and reduce the temperature of PV cells, focusing on the rigorous examination of the synergistic effects of metal foam porosity and panel inclination on thermal management. A 2D numerical model was developed using ANSYS Fluent 14.0, where User-Defined Functions (UDFs) were employed to incorporate the Darcy-Brinkman-Forchheimer and Carman-Kozeny equations, accurately accounting for the effects of metal foam porosity on thermal conductivity and fluid flow resistance. Various foam porosities (ε = 0.80, 0.85, 0.90, 0.95, 1) were explored on both vertical and tilted panels across a spectrum of inclination angles (β= 0°, 30°, 45°, 75°, 90°). Results highlight critical parameters including PCM melting fraction, cell temperature evolution, and the resultant impact on solar cell electrical efficiency, both with and without metal foam. The integration of graphitic foam with RT35HC contributed to superior heat transfer and a marked reduction in cell temperature of the employed PV system by improving thermal conductivity and heat dissipation, particularly at slight inclination angles (β =0° to 30°), revealing a noteworthy enhancement in electrical efficiency ranging from 1.3 % to 3 %, respectively. Conversely, the absence of graphitic foam at steeper angles (β =45° to 90°) surprisingly strengthens the solar panel’s electrical performance. These findings provide valuable insights into the effects of metal foam integration at varying inclination angles, offering a pathway for the development of more efficient and reliable solar energy systems.

Sand control mechanism of radial well filled with phase change material in hydrate reservoir

Radial well filled with phase change material has been proposed as a novel sand control method for hydrate exploitation. In order to reveal the sand control mechanism, CFD-DEM coupling method is applied to simulate the migration, settlement, and blockage processes of sand particles in the radial well. The obtained results indicate that three scenarios have been recognized for sand particles passing through sand control medium, based on the diameter ratio of sand control medium to sand particle (Dd): fully passing (Dd = 8.75–22.5), partially passing and partially blocked (Dd = 3.18–5.63), and completely blocked (Dd = 2.18–3.21). After being captured by the sand control medium, sand particles can block pores, which increases fluid flow resistance and causes a certain pressure difference in the radial well. The pressure in the radial well should be lower than the hydrate phase equilibrium pressure during sand control design, for the purpose of promoting hydrate decomposition, and sand capture. The length of the radial well should be optimized based on the reservoir pore pressure, production pressure difference, bottom hole pressure, and the pressure gradient in the radial well. It should be noticed that the sand control medium leads to a decrease in permeability after sand particles captured. Even the permeability is reduced to several hundred millidarcy, it is still sufficient to ensure the effective flow of gas and water after hydrate decomposition. Increasing fluid velocity reduces the blocking capacity of the sand control medium, mainly because of deterioration in bridging between sand particles.

Remarks on some unidirectional flows of Maxwell fluids through a rectangular channel filled with porous medium

AbstractExact solutions for the dynamics of incompressible fluids showing rate‐type behavior have mostly been found in circumstances where the boundary velocities are given in the body of existing research. This phenomenon results from the constitutive equation of the corresponding extra‐stress tensor, which specifies the natural relationship between velocity and shear stress. In this paper, we focus on a unique observation of the magnetohydrodynamic (MHD) movements of incompressible Maxwell fluids, and the governing equations regulating velocity and shear stress. We focus our analysis on the case of an infinite plate submerged in a porous substance. Within this framework, we do an analytical analysis of a motion issue with a boundary that has a predetermined shear stress. We can easily ascertain the shear stress associated with the motion brought on by a flat plate in order to be more exact. The fluid is subjected to a shear stress by this plate that changes over time. The velocity field from a boundary motion with a predetermined velocity is used to achieve this. We give two graphical representations of individual solutions for the sake of clarity and result verification. Last but not least, we use graphical depiction to highlight how a magnetic field and a porous media affect the fluid's flow resistance. The results show that the flow resistance of the fluid increases in the presence of a porous media and decreases when a magnetic field is present.

From Navier to Stokes: Commemorating the Bicentenary of Navier’s Equation on the Lay of Fluid Motion

The article presents a summarised history of the equations governing fluid motion, known as the Navier–Stokes equations. It starts with the work of Castelli, who established the continuity equation in 1628. The determination of fluid flow resistance was a topic that involved the brightest minds of the 17th and 18th centuries. Navier’s contribution consisted of the incorporation of molecular attraction effects into Euler’s equation, giving rise to an additional term associated with resistance. However, his analysis was not the only one. This continued until 1850, when Stokes firmly established the boundary conditions that must be applied to the differential equations of motion, specifically stating the non-slip condition of the fluid in contact with a solid surface. With this article, the author wants to commemorate the bicentennial of the publication of “Sur les Lois du Mouvement des Fluides” by Navier in the Mémoires de l’Académie Royale des Sciences de l’Institut de France.

Effect of symmetrical and asymmetrical structures of transverse tube on heat transfer performance of nanofluids in a solar collector system

AbstractIn an effort to enhance the heat transfer performance of solar collectors, this paper proposed to replace the smooth tube with symmetrical and asymmetrical transversely corrugated tubes, and to couple with SiO2‐H2O nanofluids for heat transfer of solar collectors. Effects of nanofluids mass fraction (w = .0%, .1%, .3%, and .5%), Reynolds number (3000, 4000, 5000, 6000, and 7000), and groove radius (1.5, 2, and 2.5 mm) on the flow and heat transfer properties of nanofluids in solar collectors were studied. The comprehensive evaluation index was used to consider the heat transfer property and flow resistance of fluid flow at the same time. Results showed that with the augment of nanofluids mass fraction, Reynolds number, and groove radius, the heat transfer enhancement performance of the collector becomes better. Among them, when the Reynolds number is 4000, the asymmetric transversely corrugated tube with a nanofluids mass fraction of .5% and a groove depth of 2.5 mm has the best comprehensive flow and heat transfer performance, and the comprehensive evaluation index can reach 1.62. The study results in this paper are beneficial to the coupling of nanofluids and transversely corrugated tubes and their application in the domain of enhanced heat transfer of solar collectors.

Interface Leakage Theory of Mechanical Seals Considering Microscopic Forces

The fluid flow in the small pore throat is a nonlinear flow, and the microscopic force between the fluid and the wall cannot be ignored. However, the previously established theories about the leakage between sealing interfaces have not considered the influence of microscopic forces. Based on contact mechanics and percolation theory, the void characteristics of the sealing interface were clarified, and the influence of microscopic force on fluid flow in porous medium was analyzed. Combined with the capillary force, the concept of a critical void radius between the mechanical seal interfaces is proposed. The fluid flow resistance model and leakage rate calculation equation of the sealing interface considering the van der Waals force are established, and the leakage judgment criterion of the sealing interface is provided. Through numerical calculation and experiments, the effect of microscopic force is verified in terms of the fluid flow law and macroscopic leakage rate. The results show that van der Waals forces have an important influence on the fluid flow between the sealing interfaces. As the microchannel size decreases, the van der Waals forces between solid and liquid increase, and the influence of these van der Waals forces on the fluid flow between the sealing interfaces cannot be ignored. The calculation model of the sealing interface leakage rate proposed in this paper shows little difference with the results of the Persson model, and is in good agreement with the experimental results; the maximum relative error is 8.7%, the minimum relative error is only 3.8%.

Microscopic Pore Structure Characteristics and Fluid Mobility in Tight Reservoirs: A Case Study of the Chang 7 Member in the Western Xin’anbian Area of the Ordos Basin, China

This research addresses the limited understanding of movable fluid occurrence characteristics in the Chang 7 reservoir by employing mercury injection capillary pressure, constant-rate mercury injections, and nuclear magnetic resonance methods. This study investigates the microscopic pore structure characteristics and movable fluids in the tight reservoir of the western Xin’an region, located in the Ordos Basin. The finding reveals that as permeability decreases, the distribution of the throat radius becomes more concentrated in the low-value area, resulting in a narrow distribution range with high curve peaks. Conversely, with an increasing permeability, the distribution range expands towards the high-value area while the curve peak decreases. This research underscores the significance of the throat radius, especially the main flow throat radius, in constraining the permeability of rock samples. Furthermore, this study highlights a stronger correlation between permeability and movable fluid saturation than porosity. This finding emphasizes the importance of considering movable fluid saturation when assessing reservoir characteristics. Notably, the throat radius plays a crucial role in influencing the occurrence characteristics of movable fluids, with a smaller throat radii posing hindrances to fluid flow in the reservoir. Additionally, the presence of clay minerals in the reservoir leads to pore segmentation and increased fluid flow resistance, ultimately reducing the saturation of movable fluids. I must be understood that these factors are essential for developing and producing reservoirs with similar characteristics. In conclusion, the insights gained from this study hold considerable theoretical value and provide essential references for developing and producing reservoirs with tight characteristics, particularly in the western Xin’an region of the Ordos Basin.

Thermal Performance Optimization of Integrated Microchannel Cooling Plate for IGBT Power Module.

In high-integration electronic components, the insulated-gate bipolar transistor (IGBT) power module has a high working temperature, which requires reasonable thermal analysis and a cooling process to improve the reliability of the IGBT module. This paper presents an investigation into the heat dissipation of the integrated microchannel cooling plate in the silicon carbide IGBT power module and reports the impact of the BL series micropump on the efficiency of the cooling plate. The IGBT power module was first simplified as an equivalent-mass block with a mass of 62.64 g, a volume of 15.27 cm3, a density of 4.10 g/cm3, and a specific heat capacity of 512.53 J/(kg·K), through an equivalent method. Then, the thermal performance of the microchannel cooling plate with a main channel and a secondary channel was analyzed and the design of experiment (DOE) method was used to provide three factors and three levels of orthogonal simulation experiments. The three factors included microchannel width, number of secondary inlets, and inlet diameter. The results show that the microchannel cooling plate significantly reduces the temperature of IGBT chips and, as the microchannel width, number of secondary inlets, and inlet diameter increase, the junction temperature of chips gradually decreases. The optimal structure of the cooling plate is a microchannel width of 0.58 mm, 13 secondary inlets, and an inlet diameter of 3.8 mm, and the chip-junction temperature of this structure is decreased from 677 °C to 77.7 °C. In addition, the BL series micropump was connected to the inlet of the cooling plate and the thermal performance of the microchannel cooling plate with a micropump was analyzed. The micropump increases the frictional resistance of fluid flow, resulting in an increase in chip-junction temperature to 110 °C. This work demonstrates the impact of micropumps on the heat dissipation of cooling plates and provides a foundation for the design of cooling plates for IGBT power modules.

Thermal performance of MHD natural convection flow in a concentric semi-circle porous enclosure having corrugated radius

The amplitude and period of the corrugation can significantly affect heat transport in a concentric semi-circular enclosure with corrugated radius. By increasing the surface area of the walls and promoting convective heat transmission between the fluid and the walls, the corrugated walls can improve heat transfer. Such a type of system is utilized in energy storage systems, heat exchangers, chemical reactors, materials processing, and electronic cooling systems. The system's overall efficiency and dependability can be increased by using transverse MHD together with corrugated wall to control fluid flow and improve heat and mass transfer. Heat transfer enclosed in a semi-circular porous cavity with corrugated radius walls is addressed. Inner and out semi-circle are joint through heated corrugated walls and these walls are depending upon the amplitude and period of corrugation. The outer semi-circle is divided into three different portions with an angle of 60o each. The central portion is considered as adiabatic however the left and right part of outer semi-circle is cold. The governing equation are developed through law of conservation of mass, momentum, and energy. An inclined magnetic field is applied to the system that makes an angle αwith x−axis. The dimensionless system of nonlinear partial differential equations (PDE) is tackled through Finite Element Method (FEM) and parametric control analysis is developed. The impact of each parameter, for instance: inclination angle −60o≤α≤60o,Rayleigh number (104≤Ra≤108), the Permeability parameter (10−7≤Da≤10−2), Ha is the Hartmann number, amplitude (A) and period of corrugation (20≤f≤60) is reflected through isotherms and streamlines. The results depict that due to transverse angle of MHD, natural convection process within the cavity tilted either on right or left side based upon angle inclination angle. It is concluded that rate of heat transfer is increased by corrugation by increasing the radius's amplitude and higher Darcy numbers signify greater fluid flow resistance, and lower Darcy numbers signify less resistance. They acquire to the conclusion that the Raleigh number's impact on the isotherms profile can be further modified by the strength and direction of the magnetic field.

Operating flow rate prediction of H4 condition in NPP

In this study, we present a method to predict the working volume flow rate of H4 conditions in nuclear power plants. The working flow rate can be predicted using the intersection points of the two curves on a hydraulic characteristic diagram using the quantitative relationship between fluid flow and pipe resistance under the turbulence model and the hydraulic performance characteristics of the hydraulic equipment. The H4 condition volume flow rate of a power plant is predicted in this research using this method. The findings demonstrate that the method can substitute the actual H4 working condition test to lower operating costs while having high accuracy and little deviation. This approach can be usefully expanded to cover more comparable circumstances.

Experimental study on the nonlinear flow characteristics of fractured granite after high-temperature cycling

To understand the influence of temperature on the flow characteristics of fractured granite, high-temperature cyclic thermal treatment and flow tests on the fractured rock sample with different joint roughness coefficients and intact rock samples were conducted. The larger confining pressure and larger joint roughness coefficient will increase the resistance of fluid flow and affect the flow characteristics of the fluid. With the temperature increasing, the aperture of the fractures, the number of micro-fractures, and micropores increase which forms a large number of new connected hydraulic channels in the matrix. Forchheimer's law and Izbash equation can well describe the nonlinear flow characteristics, and the fitting coefficients are greater than 0.99. As the increasing temperature, the slope of the curve between the volumetric flow rate and pressure gradient gradually decreases, and the coefficients in Forchheimer's law and the Izbash equation decrease. The transmissivity decrease with the increasing Reynolds number and the change range of that increase with the increasing temperature. When the temperature is at the lower level (T = 200 ~ 600 °C), the contribution of split fracture to the permeability is greater than that of the matrix. When the temperature continuously increases to 800 °C, the contribution of the matrix to the permeability gradually rises and then exceeds that of split fracture. The results indicate that 400 °C is the critical temperature, after which the flow characteristics of fractured granite after high-temperature cycling change more obviously.

Effects of surface nanotexturing on the wickability of microtextured metal surfaces

Hypothesis: Achieving spontaneous, rapid, and long-distance liquid transport is crucial for many practical applications such as phase change heat transfer and reactions at solid–liquid interfaces. Surface nanotexturing has been widely reported to improve the wickability of microtextured metal surfaces. Although surface nanotextures show high capillary pressure, the high fluid flow resistance through nanotextures prevents fluid transport. The underlying mechanisms responsible for the enhanced wickability of nanotextured surfaces are still unclear.Experiments: Herein, we prepared a variety of microtextures and nanotextures on copper surfaces by femtosecond laser micromachining and chemical oxidation, respectively. The wickability of these textured surfaces was quantitively compared by measuring wicking coefficient and capillary rise speed. We designed experiments to eliminate any possible effects of surface oxidation and metal composition on wickability. A theoretical model describing the vertical and horizontal capillary flow in V-shaped microgrooves was proposed and utilized to analyze the experimental results. The effects of time-dependent wettability on wickability were also examined.Findings: Surface nanotexturing can enhance surface wettability while altering the micrometer-scale structural characteristics. The greatly enhanced wickability of nanotextured surfaces can only be observed when the surface microtextures have a very small aspect ratio. Otherwise, for metal surfaces with fine microgrooves, the latter effect is more pronounced, and thus the surface wickability may deteriorate after preparing surface nanotextures; for surfaces with wide microgrooves, both effects are minimal, and the surface wickability enhances only marginally after surface nanotexturing. Furthermore, the wickability of microtextured surfaces will decay rapidly due to the adsorption of airborne organics, whereas adding surface nanotextures can significantly inhibit this degradation. The anti-contamination capability of surface nanotextures is considered likely to be a potential mechanism responsible for the greatly enhanced wickability of nanotextured surfaces noted in some studies.

Third mobile window syndrome (literature review and own series)

The report presents modern views on the “third mobile window syndrome”, starting with the anatomical and physiological features of the inner ear function, both in normal conditions and in the presence of an additional opening in the bony labyrinth, which changes the hydrodynamic resistance of fluid flow in the perilymphatic space. Characteristic symptoms and modern views (sometimes hypothesis) on the causes of its occurrence are described in detail. Attention focused on diagnostic methods at the outpatient and clinical conditions of a highly specialized department. The latest data on the modern classification of this syndrome and the conclusions of the consensus of the International Barani Society in 2021 are presented. Own series with a detailed description of the features of each case, illustration of the audiometric and tomographic images and successful results of surgical treatment are presented. In the conclusions, the attention of practicing doctors is focused on the signs of the “third mobile window syndrome” which can be detected at the outpatient service – pressure or sound-induced vertigo, bone conduction hyperacusis, and pulsatile tinnitus.

Theoretical and Experimental Antiscaling Performance Study of Several Inhibitors to Prevent Barium Sulfate Formation during Water Injection in Oil Reservoirs

One of the hazards from mineral precipitation during oilfield production is scaling, which mainly manifests in the following three aspects: it leads to reduction in permeability, in deliverability, and in water intake capacity of reservoir; the flowing area of pipeline shrinks, which could elevate the fluid flow resistance and even lead to well shut; and scaling could also contribute to pressure loss and may cause tube blasting when it is serious. Therefore, scaling not only improves production costs but also poses a serious threat to production safety. The injection of scale inhibitors in the process of water flooding is the main method to combat scale build-up. Efficiency of inhibitor or adsorption between inhibitor and scale is the key factor that determines success or failure of the scale inhibitor squeeze treatments. Previous studies have confirmed that interaction between the inhibitor and the scale surface plays an important role in scale prevention and control. Although many studies have been carried out on inhibitor efficiency and inhibition mechanism, a comprehensive understanding of inhibitor-scale interaction is yet available and the adsorption behavior between inhibitor and scale surface requires further research. Thereupon, this study presents performance evaluation and computational study of three inhibitors, including EDTMPS, DTPMP, and DTPA-5Na based on the scaling prediction result of the Huaqing oilfield. It was found that BaSO4 was the main type of scaling and the antiscaling performance of the three inhibitors was experimentally displayed as DTPA-5Na > DTMP > EDTMPS at the concentration from 40 mg/L to 120 mg/L. SEM micrographs of BaSO4 surfaces in the absence and presence of inhibitors at the concentration of 80 mg/L showed that the inhibitors obviously influenced the process of crystal growth of BaSO4 by lattice distortion and chelate effect. In addition, density functional theory (DFT) calculations unraveled that adsorption capacity of inhibitors interacting with three surfaces of BaSO4 increased in the order of DTPA-5Na > EDTMPS > DTPMP. DPTA-5Na was likely to be chemisorbed on the surfaces of BaSO4 while DTPMP and EDTMPS tended to be adsorbed on (210) and (001) surfaces of BaSO4 by chemical and physical effect, respectively. Calculation of difference charges and DOS analysis indicated that DTPA-5Na interacted with BaSO4 by combining atoms of oxygen and sodium to form new chemical bonds while EDTMPS and DTPMP interacted with BaSO4 by combining hydrogen and oxygen atoms to form physical bonds. The research results can provide a better understanding of the interaction between inhibitors and scale surfaces and can also lay scientific foundation for barite scale prevention and further development of inhibitors.

Characteristics of heat transfer and flow resistance of magnetic fluid flow through porous media combined with magnetic field effect

The heat transfer and flow resistance of magnetic fluid flow under a magnetic field in the absence and presence of porous media were investigated experimentally in a rectangular duct. A ceramic foam, with a pore density of 13PPI (pores per inch), was used as a porous media. The mainstream flow rate varied between 0.1 and 3.7 l/min, while the magnetic intensity was adjusted to 0, 100, 300, and 500 mT. The results showed heat transfer was enhanced in both the non-porous and porous ceramic by applying the magnetic field to the magnetic fluid flow. Under a magnetic intensity of 500 mT, the heat transfer increments in the absence and presence of the foam were approximately 16.8% and 15.3%, respectively. By applying a magnetic fluid flow through the foam, the maximum heat transfer increment reached 171.7% compared to the absence of foam at the same flow rate. Notably, combining the use of a magnetic field and the ceramic foam resulted in a synergetic enhancement in heat transfer at low flow rates. The magnetic fluid flowing through the foam had a substantially higher flow resistance than the non-foam magnetic fluid flow. The pressure drop increased by applying a magnetic field to the magnetic fluid in the absence and presence of foam. The performance of the combined heat transfer techniques was evaluated in this research based on a performance evaluation criterion value. The results revealed that by applying the magnetic field, the performance evaluation criterion value of the magnetic fluid flow in the presence of foam was higher than in the absence of foam. Finally, the predictive formulas for Nusselt number and performance evaluation criterion as a function of Magnetic fluid heat transfer number were proposed.