Physical Properties Of Fluid Research Articles

New calculation method for tube cross-flow heat exchangers

A new method for thermal calculations of the cross-flow tube heat exchangers was proposed. The temperature of both fluids and the wall temperature are determined. The heat exchanger is divided into control volumes, in which outlet fluid temperatures are calculated by closed analytical formulas. Two examples of the application of the method for the calculation of two-pass cross-co-current and cross-countercurrent superheaters were presented. An exact analytical model was also developed for both superheaters to estimate the accuracy of the proposed method. The results of the superheater calculations using the developed method are in good agreement with the results obtained by the exact analytical models. The proposed method can be used to calculate heat exchangers with a complicated flow system in which the physical properties of fluids are temperature-dependent.

Eulerian–Eulerian Modeling of Multiphase Flow in Horizontal Annuli: Current Limitations and Challenges

Multiphase flows are present in many natural phenomena, processing technologies, and industries. In the petroleum industry, the multiphase flow is highly relevant, and special attention is paid to the development of predictive tools that determine flow conditions to guarantee safe and economic hydrocarbon extraction and transportation. Hydrodynamic aspects such as pressure drop and holdup are of primary relevance for the field engineer in daily operations like pumping power calculation and equipment selection and control. Multiphase flow associated with oil production is usually a mixture of liquids and gas. The hydrodynamic behavior has been studied in different pipeline configurations (i.e., vertical ascending/descending and horizontal/inclined pipelines). However, the available information about flow patterns as well as the general conditions present in horizontal annuli is incomplete, even if they are of fundamental relevance in today’s horizontal drilling, production, and well intervention in many oil wells around the world. This review aims to present an in-depth revision of the existing models developed to predict two-phase flow patterns and hydrodynamic conditions in annuli flow, focusing mainly on, but not limited to, horizontal configuration. Key flow parameters and effects caused by annuli geometry and the physical properties of fluids are extensively discussed in the present paper. Different empirical correlations and mechanistic and numerical models on two-phase flow through horizontal/inclined pipelines and in both concentric and eccentric annuli are analyzed. Some of these models partially agree with experimental results and show acceptable predictions of frictional pressure loss and flow patterns. Limitations in current models and challenges to be faced in the next generation of models are also discussed.

Experimental Insights Into the Interplay Between Buoyancy, Convection, and Dissolution Reaction

AbstractPredicting the instabilities that occur during the chemical reaction between a percolating fluid and a soluble rock leading to the development of macroscopic channels called wormholes is a key for understanding many geological processes. Their shape and their spatial distribution depend on two dimensionless numbers, namely Damköhler (Da) and Péclet (Pe) numbers. Although the dissolution phenomenon has been extensively studied both in the context of acid stimulation of oil wells in carbonate rocks and carbon capture and storage, few works have focused on the influence of the physical properties of fluids on wormhole patterns. Consequently, through interpretation of images acquired during the injection of pure water into a 2‐D reconstituted salt massif and considering different configurations of injection, we illustrate the buoyancy effects on wormhole formation. Contrarily to observation in fractures, experimental results suggest that dissolution regimes can still be described by the classical dimensionless numbers Da and Pe. As for the regime diagram, it remains practically unchanged for strong Péclet and weak Damköhler and undergoes a slowdown of the propagation of the dissolution front when the number of Richardson's increases. Analysis of morphological descriptors such as area, interface, and tortuosity shows that density contrast has an influence on intermediate‐ to high‐Richardson dissolution regimes that may be explained by the existence of buoyancy effects.

An electrostatically actuated microsensor for determination of micropolar fluid physical properties

Micropolar fluids as complex non-Newtonian fluids admittedly have numerous applications in various fields, especially in medicine. Blood as a micropolar fluid plays an important role in regulating the body’s system and maintaining homeostasis. Physical properties of micropolar fluids, especially their viscosity, affect their rheological behavior significantly. Therefore, measurement of viscosity of these complex fluids especially human blood seems very necessary as it is considered a key parameter in the diagnosis and treatment of several diseases. In this paper, a new comb-drive microsensor for estimation of physical properties of micropolar fluids is presented. Driving and sensing combs, a sensing plate attached to the shuttle of the resonator form the structure of the electrostatic sensor. The nonlinear dynamic behavior of the sensor due to the presence of the electrostatic force has been investigated to obtain the limitations of the linear behavior of the structure. It has been shown that calculating the resonance frequency and resonance amplitude variations of the lumped dynamic model of the sensor arising from damping and inertial effects of the fluid can lead to the determination of the physical properties of a micropolar fluid. The effects of the geometrical parameters of the sensor and the applied exciting voltage on the performance of the sensor have also been studied.

Simplified Calculation of Energy Efficiency Index for Plate Heat Exchanger

Based on GB/T 27698.3-2011 heat exchanger and heat transfer element performance test method Part 3: Plate heat exchanger, a simplified method for the calculation of energy efficiency index is proposed other than just experimental data required by NB/T 47004.1-2017 plate heat exchangers-part 1: plate-and-frame heat exchangers. The new equation of EEI in term of 12 parameters δρ , λρ , lh,l c, dh,d c, Ch,Cc,ah, bh,ac,bc incorporates both fitted correlations of experimental result and parameters for fluid physical properties and working conditions. Therefore, the method omits the intermediate processes such as total heat transfer coefficient k and pressure drops for both sides. It also solves the accuracy problem that deviates from the standard working conditions and is difficult to realize practically. The new test of high cost is unnecessary to obtain the energy efficiency index for old plate heat exchangers with part experimental data or correlations.

Effects of working temperature and fluid physical properties on heat transfer enhancement in conduction pumping: An experimental study

In the current study, heat transfer behavior in electrohydrodynamic conduction pumping of two different dielectric liquid films using flush electrodes has been experimentally studied, and effects of working temperature and fluid physical properties on heat transfer enhancement are investigated. The study is conducted for different liquid film thicknesses and working temperatures, while changing the magnitude of the applied electrical voltage. Results show that higher ion mobility difference and working temperature of the dielectric liquid, as well as lower density and viscosity increase flow rate and heat transfer of the pump. Also, it is seen that heat transfer coefficient is intensively enhanced for all different film thicknesses and working temperatures by using the conduction pump, which is due to the turbulent flow created in the vicinity of the electrodes. For 8 mm film thickness of n-hexane at35°C, the significant enhancement of heat transfer coefficient equal to 1040.9% was observed.

Characterization of starch, agar and maltodextrin blends for controlled dissolution of edible films

Biopolymer blend interactions influence the physical, mechanical and barrier properties of edible packaging. Starch (rice and hydroxypropyl cassava starch mixture), agar and maltodextrin were formulated to control the solubility of edible films. Blend materials were characterized for fluid rheology, solid microstructure, mechanical barrier and physical properties. Agar enhanced solid behavior and governed low temperature gelation of the blends, giving improved film forming ability and hydrophobicity. Flexibility of the films highly depended on integrity of polymer networks. Agar formed continuous networks entangled in starch matrices. Conversely, maltodextrin acted as a filler that reduced mechanical strength at high concentration (>40%) due to interruption of network integrity. Interaction between starch and agar led to poor water solubility that was insignificantly impacted by agar concentration (10% to 30%) due to identical molecular bonding. Maltodextrin produced highly miscible and plasticized starch-agar films and led to reduced mechanical relaxation temperature and shriveling of film structures after mold dipping. Solubility increased linearly with higher maltodextrin concentration. Molecular interaction between maltodextrin and starch/agar matrices insignificantly influenced solubility, while strong interaction between starch and agar highly controlled solubility. Findings clarified the interaction mechanisms and behavior of biological macromolecule materials in fluids and solid matrices for manufacture of edible packaging.

Nonlinear Finite Element Analysis-Based Flow Distribution and Heat Transfer Model

A new strategy for fast, approximate analyses of fluid flow and heat transfer is presented. It is based on Finite Element Analysis (FEA) and is intended for large yet structurally fairly simple heat transfer equipment commonly used in process and power industries (e.g., cross-flow tube bundle heat exchangers), which can be described using sets of interconnected 1-D meshes. The underlying steady-state model couples an FEA-based (linear) predictor step with a nonlinear corrector step, which results in the ability to handle both laminar and turbulent flows. There are no limitations in terms of the allowed temperature range other than those potentially stemming from the usage of fluid physical property computer libraries. Since the fluid flow submodel has already been discussed in the referenced conference paper, the present article focuses on the prediction of the tube side and the shell side temperature fields. A simple cross-flow tube bundle heat exchanger from the literature and a heat recovery hot water boiler in an existing combined heat and power plant, for which stream data are available from its operator, are evaluated to assess the performance of the model. To gain further insight, the results obtained using the model for the heat recovery hot water boiler are also compared to the values yielded by an industry-standard heat transfer equipment design software package. Although the presented strategy is still a “work in progress” and requires thorough validation, the results obtained thus far suggest it may be a promising research direction.

The Effect of Physical Properties of Fluids on the Process of Purifying the Main Gas Pipeline from Liquid Pollutants

The article deals with modern technical methods of improving the efficiency of gas pipelines cleaning. The most effective method of improving the efficiency of a gas pipeline is its periodical cleaning with mechanical treating units. In practice, a large number of cleaning pistons of various technological designs are used. Regardless of the design, none of them can completely remove the fluid accumulations. The reason for the decrease in efficiency is the presence of fluid in the cavity of the pipeline. The fluid can be of two types – high-viscosity resinous deposits and low-viscosity liquid deposits. When moving, they perform the role of local resistance. The type of the main gas pipeline purification process is largely determined by the physical properties of the fluid which is being displaced. The authors specify the functional dependence of the velocity distribution in the pipe cross-section while displacing the Newtonian fluid, as well as the value of the initial pressure of the liquid phase on the cleaning piston. The interaction of a purifying device with fluid accumulations having different physical properties is investigated. The authors develop the algorithm of calculating the volume of the flows over a moving boundary into a back-piston space, in relation to their velocity. The dependence of the volume of fluid flows caused by hydraulic shock for Newtonian and non-Newtonian fluids is composed. Based on the calculations, the authors plot the graphical dependence of the correction coefficient on the ratio of dynamic viscosity to the degree of consistency, as well as the dependence of the total flow rate on the speed of movement of the cleaning unit. The formula for calculating the correction coefficient is obtained. The article presents the results of calculating the value of the correction coefficient which takes into account the rheological properties of the fluid. In relation to the properties and rheology of the non-Newtonian fluid, the authors determine the optimal velocity of a treating unit.

Experimental study on liquid oxygen chilldown in the horizontal pipe with an injector on the exit

Components downstream of the pump in the cryogenic liquid rocket engine were simplified to a horizontal pipe upstream of an injector. Cryogenic chilldown was investigated experimentally in this pipe by constant flow rate of LO2. The chilldown processes were discussed and the boiling curves were drawn to identify the boiling transition points, Leidenfrost point (LFP) and critical heat flux point (CHF). By fitting the present sets of data, correlation formats of the previous expressions were selected and revised linearly to give the suggested correlation expressions on TLeid, qLeid, TCHF and qCHF. Because these parameters could also be well correlated to the corresponding pressure, it could be supposed that the effects of pressure could be well represented by the physical properties of the fluid. The recommended correlations on TLeid, qLeid and TCHF include the physical properties of fluid only. The recommended correlation on qCHF include both the sensor position (Lse) and the physical properties of fluid. Furthermore, a couple of previous correlations based on cryogenic chilldown were validated, at least partially.

A Multiparameter Gas-Monitoring System Combining Functionalized and Non-Functionalized Microcantilevers.

The aim of the study is to develop a compact, robust and maintenance free gas concentration and humidity monitoring system for industrial use in the field of inert process gases. Our multiparameter gas-monitoring system prototype allows the simultaneous measurement of the fluid physical properties (density, viscosity) and water vapor content (at ppm level) under varying process conditions. This approach is enabled by the combination of functionalized and non-functionalized resonating microcantilevers in a single sensing platform. Density and viscosity measuring performance is evaluated over a wide range of gases, temperatures and pressures with non-functionalized microcantilevers. For the humidity measurement, microporous Y-type zeolite and mesoporous silica MCM48 are evaluated as sensing materials. An easily scalable functionalization method to high-throughput production is herein adopted. Experimental results with functionalized microcantilevers exposed to water vapor (at ppm level) indicate that frequency changes cannot be attributed to a mass effect alone, but also stiffness effects dependent on adsorption of water and working temperature must be considered. To support this hypothesis, the mechanical response of such microcantilevers has been modelled considering both effects and the simulated results validated by comparison against experimental data.

Characterization of the solvent specific evaporation from a fluoropolymer surface roughened by layered double oxide (LDO) particles

Abstract Solid/ liquid interaction strongly depends, among other things, on the chemical and physical properties of fluids, therefore, there are unexploited analytical possibilities in investigating the surface wetting and evaporation behavior. Strongly hydrophobic rough surface thin films were prepared by spray-coating a fluoropolymer film with incorporated layered double oxide (LDO) microparticles. We studied the evaporation of ethanol–water mixtures from the low energy (8.4 ± 2.6 mJ/m2) composite surfaces by simultaneous high-speed visible imaging, infrared imaging and weight loss monitoring. The wetting behavior changed from Cassie's wetting mode (pure water) to Wenzel's (pure ethanol) as a function of solvent composition. The vaporization process could be divided into three stages described by constant evaporate rates and the heat transfer coefficient between the studied layer and water is KT = 1768 W/(m2K). We have found strong correlations between parameters of the measured evaporation profiles and certain physical properties of the solvents. It is possible to estimate the viscosity, the boiling point, or the surface tension of a studied liquid merely from the total evaporation time. This novel solvent identification method can serve as a new application field for such low energy hybrid surfaces.

Investigation of thermal model effects on geothermal and oil reservoir well testing behavior during water and steam injection

Global warming and reducing fossil fuel resources have increased the interest in using renewable resources such as geothermal energy. In this paper, in the first step, heat transfer equations have been presented for reservoir during water (steam) injection by considering heat loss to adjacent formations. According to radius of thermal front, the reservoir is partitioned into two regions with different fluid physical properties. The heat transfer model is coupled with a fluid flow model which is used to calculate the reservoir pressure or fluid flow rates. Then by calculating outer radius of heated region and using radial composite reservoir model, the fluid flow equations in porous media are solved. Using pressure derivative plot in regions with different thermal conductivity coefficients, a type curve plot is presented. The reservoir and adjacent formation thermal conductivity coefficients can be calculated by matching the observed pressure data on the thermal composite type curve. Additionally, the interference test in composite geothermal reservoir is discussed. In the composite reservoir model, parameters such as diffusivity coefficient, conductivity ratio and the distance to the radial discontinuity are considered. New type curves are provided to introduce the effect of diffusivity/conductivity contrast ratios on temperature behavior. Improving interpretations, and performing fast computations and fast sensitivity analysis are the benefits of the presented solutions.

Analysis of the influence of ultrahigh pressure on wellbore Fluid properties——Take Well ST1 in north Sichuan as an example

According to the research on wellbore pressure temperature prediction of ultra-high pressure gas Wells, the influence of ultra-high pressure on wellbore fluid physical property parameters cannot be ignored, the component model is adopted to calculate wellbore fluid PVT physical property, and the multi-phase flow model is modified to accurately predict wellbore pressure temperature distribution. For the prediction of gas deviation factor of well flow and gas viscosity of well flow, the component model has a high precision. By comparing with the prediction results of 8 black oil model methods, the pressure has a great influence on the black oil model. When the pressure is equal to 100MPa, the deviation value between the predicted results of Gopal method and Dranchuk-Abu-Kassem method and the component model is greater than 0.1, which can no longer guarantee the accuracy of gas deviation factor and gas viscosity prediction. Therefore, it is recommended to use the component model to predict the deviation factor and gas viscosity of gas well flow.

Heat transfer time determination based on DNA melting curve analysis

The determination of the physical properties of fluids—such as the thermal characteristics, which include heat transfer time (Δt)—is becoming more challenging as system sizes shrink to micro- and nanometer scales. Hence, knowledge of these properties is crucial for the operation of devices requiring precise temperature (T) control, such as polymerase chain reactions, melting curve analysis (MCA), and differential scanning fluorimetry. In this paper, we introduced a flow-through microfluidic system to analyze thermal properties such as Δt among samples and the sidewall of a silicon chip using microscopic image analysis. We performed a spatial MCA with double-stranded deoxyribonucleic acid (dsDNA) and EvaGreen intercalator, using a flow-through microfluidic chip, and achieved a T gradient of ≈ 2.23 K mm−1. We calculated the mean value of Δt as ≈ 33.9 ms from a melting temperature (TM) location shift along the microchannel for a variable flow rate. Our system had a T resolution of ≈ 1.2 mK pixel−1 to distinguish different dsDNA molecules—based on the TM location within the chip—providing an option to use it as a high-throughput device for rapid DNA or protein analysis.

Fluid–Structure Interaction and Flow Redistribution in Membrane-Bounded Channels

The hydrodynamics of electrodialysis and reverse electrodialysis is commonly studied by neglecting membrane deformation caused by transmembrane pressure (TMP). However, large frictional pressure drops and differences in fluid velocity or physical properties in adjacent channels may lead to significant TMP values. In previous works, we conducted one-way coupled structural-CFD simulations at the scale of one periodic unit of a profiled membrane/channel assembly and computed its deformation and frictional characteristics as functions of TMP. In this work, a novel fluid–structure interaction model is presented, which predicts, at the channel pair scale, the changes in flow distribution associated with membrane deformations. The continuity and Darcy equations are solved in two adjacent channels by treating them as porous media and using the previous CFD results to express their hydraulic permeability as a function of the local TMP. Results are presented for square stacks of 0.6-m sides in cross and counter flow at superficial velocities of 1 to 10 cm/s. At low velocities, the corresponding low TMP does not significantly affect the flow distribution. As the velocity increases, the larger membrane deformation causes significant fluid redistribution. In the cross flow, the departure of the local superficial velocity from a mean value of 10 cm/s ranges between −27% and +39%.

Fracture Unclogging: A Numerical Study of Seismically Induced Viscous Shear Stresses in Fluid‐Saturated Fractured Rocks

AbstractDynamic shaking imposed by passing seismic waves is able to promote various hydrological processes in fractured reservoirs. This is often associated with seismically induced fracture unclogging due to mobilization of deposited colloids in the fracture network which, in turn, affects permeability at the reservoir scale. Numerous laboratory and field studies pointed out that fracture unclogging can be initiated when viscous shear stresses in the fracture fluid are in the range of 0.1–1 Pa. In this numerical study, we compute viscous shear stress in a fluid‐saturated fractured medium due to the action of passing P and S waves. We perform a sensitivity analysis in terms of fluid, fracture, and host rock physical properties as well as seismic wave characteristics. Our results show that seismically induced viscous shearing increases with frequency and seismic strain and can be in the order of those initiating fracture unclogging for typical seismic strains and frequencies. S waves tend to produce viscous shearing approximately 2 times larger than P waves, and, for anisotropic distribution of fractures, it is extremely dependent on the direction of wave propagation. Moreover, larger viscous shearing is expected for more viscous fluids and stiffer host rocks. Regarding the fracture network distribution, for the same fracture density, the presence of longer fractures drastically increases the potential of fracture unclogging at seismic frequencies. The fracture aperture distribution, on the other hand, can also affect the development of viscous shearing. Fractures with correlated distributions of contact areas exhibit an order of magnitude larger viscous shearing than uncorrelated ones.

The carotid sinus acts as a mechanotransducer of shear oscillation rather than a baroreceptor

The carotid sinus is a dilated area at the base of the internal carotid artery of humans and is located immediately superior to the bifurcation of the internal and external carotid arteries. It is widely accepted, in the fields of medicine and physiology, to function as a baroreceptor in its central control role. This paper presents a hypothesis challenging this paradigm - that the carotid sinus functions by detecting oscillations at the vessel wall which result from shear stress due to vortical flow. This is contrary to conventional thinking which presumes that the carotid sinus responds to blood pressure or wall pressure. Our hypothesis is based on anatomy, physiology and physical properties of fluid which make the sinus the area of highest vorticity. Utilizing magnetic resonance angiograms of undiseased carotid vessels, we computed the oscillatory shear index (OSI) via a computational fluid dynamics simulation of flow. This region of highest OSI coincides with the area where the nerve to the carotid sinus lies within the vessel wall. Accordingly, the hypothesis is that the carotid sinus acts as a mechanotransducer of wall shear stress oscillation and not as a baroreceptor.

Electrocoalescence of water droplets in sunflower oil using a novel electrode geometry

Electrocoalescence is an energy-efficient and environmentally-friendly process for breaking water-in-oil emulsions. It has been used extensively in the oil and petroleum industries. However, the current technology requires long residence times, giving rise to bulky vessels for industrial scale operations and making it less attractive for offshore application. It is also highly desirable to develop compact devices for down-the-well use. In this study, the performance of a novel electrode geometry, a ladder-shaped set of electrodes through which the emulsion flows, is assessed for enhancing the electrocoalescence, hence providing the potential for a compact design. The electrodes are formed into a V shape, with the apex pointing towards the direction of flow. This configuration enables nesting a series of electrodes in a compact form. Furthermore, the water-in-oil emulsion flows through the electrodes rather than passing by them, thus maximizing the effect of the electric field for coalescence. The system under study uses dispersed water droplets in sunflower oil, flowing in a narrow rectangular duct through the electrodes, providing essentially a two-dimensional flowing stream. The performance of this design is investigated for different electrical parameters (i.e. electric field intensity, frequency and waveform), fluid physical properties (i.e. conductivity and water content) and residence time. Of the three types of electric field waveform (i.e. half-sinusoidal, square and sawtooth), sawtooth performs best at high conductivities. Experiments reveal the existence of optimal values of electric field intensity, electric field frequency, salt concentration and water concentration, where the coalescence efficiency is maximum for the current design. Numerical simulation of the electrocoalescence process is conducted to assess the influence of various geometric and process parameters on the coalescence mechanisms of the V-shape electrodes. The outcome of this work is potentially useful for optimizing the design of compact and efficient oil–water separators.

Influence of Gas Migration on the Sustained Casing Pressure (SCP) of Subsea Wellhead in Deepwater Wells

SCP is one of the significant factors affecting the integrity of subsea wellhead in deepwater wells. In this paper, a new model has been established for predicting the SCP in multilayer casings based on the Darcy percolation flow model and the pressure–volume–temperature equation of state, in which the effect of inter-coupling compression of multilayer casing and volume change of annulus and casing has been considered. An iterative calculation computer program is coded for solving the model. On this basis, the influence of the gas migration parameters, the casing program, the physical properties of fluid in the annulus, and the cement permeability on the SCP is discussed, respectively. Analysis results show that the gas migration has a significant influence on the SCP, which indicates that the importance of the cement sealing performance to the integrity of subsea wellhead. In particular, the gas migration would cause the SCP increase at the beginning and then tend to be stable finally. The increase in the cement permeability, fluid density, or cement top can decrease the time when SCP reaches to stability. On the contrary, the high fluid bulk modulus can increase the time. Casing deformation provided additional annular space for gas migration, the calculation results agree well with field data, and the study provides guidance for the casing program design, the cement job, and the prediction and control of the wellbore integrity in deepwater wells.