Heavy-organic particle deposition from petroleum fluid flow in oil wells and pipelines

Suspended asphaltenic heavy organic particles in petroleum fluids may stick to the inner walls of oil wells and pipelines. This is the major reason for fouling and arterial blockage in the petroleum industry. This report is devoted the study of the mechanism of migration of suspended heavy organic particles towards the walls in oil-producing wells and pipelines. In this report we present a detailed analytical model for the heavy organics suspended particle deposition coefficient corresponding to petroleum fluids flow production conditions in oil wells. We predict the rate of particle deposition during various turbulent flow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of flowing conduits. The developed model accounts for the eddy diffusivity, and Brownian diffusivity as well as for inertial effects. The analysis presented in this paper shows that rates of particle deposition （during petroleum fluid production） on the walls of the flowing channel due solely to diffusion effects are small. It is also shown that deposition rates decrease with increasing particle size. However, when the process is momentum controlled （large particle sizes） higher deposition rates are expected.

Lie group analysis for the effect of temperature-dependent fluid viscosity and thermophoresis particle deposition on free convective heat and mass transfer under variable stream conditions

This paper examines a steady two-dimensional flow of incompressible fluid over a vertical stretching sheet. The fluid viscosity is assumed to vary as a linear function of temperature. A scaling group of transformations is applied to the governing equa- tions. The system remains invariant due to some relations among the transformation parameters. After finding three absolute invariants, a third-order ordinary differential equation corresponding to the momentum equation and two second-order ordinary differential equations corresponding to energy and diffusion equations are derived. The equations along with the boundary conditions are solved numerically. It is found that the decrease in the temperature-dependent fluid viscosity makes the velocity decrease with the increasing distance of the stretching sheet. At a particular point of the sheet, the fluid velocity decreases but the temperature increases with the decreasing viscosity. The impact of the thermophoresis particle deposition plays an important role in the concentration boundary layer. The obtained results are presented graphically and discussed.

Incense smoke(IS)inhalation exposure system:Physicochemical characterization,IS particle deposition and clearance in human airway using MPPD model

Incense smoke(IS)is source of indoor air pollution and key risk for diverse human diseases.Less in-formation is available regarding controlled IS rodent inhalation exposure system and IS particulate matter(PM)deposition in human airways.Study aimed to demonstrate stable ISPM physicochemical parameters of 10 incense products inside the customized whole body inhalation exposure chamber(without animal)connected to smoke generation unit via aerosol mixing device.IS analyzed for size segregated PM emission,ISPM in vitro aerodynamics(MMAD and GSD determination),fine and ultrafine particle's SEM,SEM-EDX and PAH analysis.Using real life exposure scenario by utilizing MMAD,GSD and PM concentration after Tier 1 exposure assessment as key input parameters,ISPM dosimetry in infant(3 months)and adult(21 years male and female)human airways was calculated using multiple-path particle dosimetry(MPPD 3.04)modeling.Mass median aerodynamic diameter(MMAD)and geo-metric standard deviation(GSD)ranged between 0.55 and 2.10μm and 1.22 to 1.77(polydisperse)respectively.PM1.0 and PM0.1 showed multiple morphology and presence of heavy and trace elements.PAH like acenaphthylene,anthracene,fluorene,naphthalene and phenanthrene were detected(0.84-143.17μg/g).MPPD results showed higher ISPM deposition in pulmonary region and lowest in trachea bronchial region.ISPM deposition in tissue was higher in lower,peripheral lung as compared to upper and central lung tissue.Whole body inhalation exposure system showed stable IS atmosphere(physi-cochemical parameters)indicating the device suitability in future inhalation studies.MPPD ISPM deposition fraction and clearance data showed deep lung penetrating and retention behavior with higher risk in infant followed by female and then male.These modeled particle deposition and clearance data may be useful in risk assessment analysis of IS.

Numerical investigation of non-spherical particle deposition characteristics on filter media

In the building environment,PM2.5 seriously affects people’s health and quality of life,so it is necessary to study the particle deposition characteristics.In addition,it is essential for a thorough investigation of the dust removal mechanism to understand the non-spherical particles deposition characteristics.The stacking angle experiment was used to calibrate the discrete element simulation parameters.And four simulation methods(CFD-DPM,CFD-DEM,API interface loading drag model based on EDEM software and EDEM simulation)were used to numerically simulate the non-spherical particles deposition characteristics.The optimal simulation method EDEM was applied to study the non-spherical particles deposition characteristics in filter media,which saves the calculation time obviously.On this basis,the particle parameters on the particle deposition characteristics of filter media were investigated.The results show that the deposition rate of non-spherical(special shape)particles with the same volume is basically consistent on the filter media,hence it is more realistic that the dust actual shape is simplified into the triangular-shaped particles.As the particle size increases,the number of deposited particles on the filter media decreases.And the larger the particle size,the more dispersed the distribution.It has a significant impact on the number of particles deposited on the filter media when the particle velocity is 0.1 m/s.The particle deposits to the lower part of the filter media in the form of a parabola and deviates from the outlet seriously at 0.1 m/s.Moreover,it has little effect on the number of particle deposition at the other velocities,and most particles are deposited on the upper part of the filter media with the increase of particle velocity.

Bioconvective nanofluid flow over an exponential stretched sheet with thermophoretic particle deposition

The current work is being done to investigate the flow of nanofluids across a porous exponential stretching surface in the presence of a heat source/sink,thermophoretic particle deposition,and bioconvection.The collection of PDEs(partial differential equations)that represent the fluid moment is converted to a system of ODEs(ordinary differential equations)with the use of suitable similarity variables,and these equations are then numerically solved using Runge Kutta Fehlberg and the shooting approach.For different physical limitations,the numerical results are visually represented.The results show that increasing the porosity characteristics reduces velocity.The mass transfer decreases as the thermophoretic limitation increases.Increases in the porosity parameter reduce skin friction,increases in the solid volume fraction improve the rate of thermal distribution,and increases in the thermophoretic parameter increase the rate of mass transfer.

Modeling micro-particle deposition in human upper respiratory tract under steady inhalation

A representative human upper respiratory tract （URT） with idealized oral region and asymmetric tracheo- bronchial （TB） airway has been modeled, and laminar-to-turbulent airflow for typical inhalation modes as well as micro-particle transport and deposition has been simulated using CFX10.0 software from Ansys Inc. on a personal computer. The asymmetric TB airway could not be replaced by an extended straight tube as outlet of the oral region while investigating the tracheal airflow field and particle deposition. Compared to an idealized oral airway with an extended straight tube, several differences could be noted： （i） The laryngeal jet extends further down the trachea and inclines towards the anterior wall; （ii） the turbulence level in trachea is less and decays more quickly; （iii） three recirculation zones are visible with intense adverse current after the glottis; （iv） deposition of small particles in trachea is reduced due to lower turbulence. Refined unstructured mesh with densified boundary layer mesh could be a proper substitute for the structured mesh in the human URT model with asymmetric TB airway. Based on the refined unstructured mesh, the physiological structure of uvula in the soft palate is properly simulated in the present human URT model.

Particle deposition patterns on high-pressure turbine vanes with aggressive inlet swirl

Characteristics of particle migration and deposition were numerically investigated in presence of aggressive swirl at the turbine inlet.The isolated effects of the inlet swirl were considered in detail by shifting the circumferential position of the swirl and by implementing positive and negative swirling directions.Particles were released from the turbine inlet and the resulting deposition on the vanes was determined by using the critical velocity model in a range of particle diameters from 1 to 25 lm.Results show that the particles are more likely to move outwards to the boundary walls of the passage by the action of the swirling flow.However,this could be relieved by increasing the particle size.An imbalance problem of the deposition is found between the adjacent vanes,which could introduce additional inlet non-uniformities towards the downstream rotor and thus accelerate performance degradation of the turbine stage.Overall,the negative swirl case has higher overall capture efficiency within the entire turbine than the positive swirl case for larger particles,and when the inlet swirl is shifted to the mid-passage of the turbine,more deposits could be produced in comparison with the case in which the swirl aims at the vane leading edge.

Characterization of particle deposition during crossflow filtration as influenced by permeate flux and crossflow velocity using a microfluidic filtration system

Particle deposition during crossflow filtration is significantly influenced by the operating conditions,in particular the permeate flux and crossflow velocity.However,there is a lack of detailed knowledge about how deposit layer structures and distributions depend on operating parameters.This study uses a microfluidic visualisation filtration system to examine the influence of operating conditions on the deposition process during crossflow ultrafiltration from a microscopic perspective.Increasing the permeate flux caused an increasing amount of deposition and a thicker deposit layer.Higher crossflow velocities reduced the extent of deposition.The degree of deposition varied over a range of operating conditions due to the altered hydrodynamic forces exerted on the particles,which can be examined by the deposition probability according to an existing model.Building on this,an empirical correlation between the deposition probability and volume of deposition as a function of filtration time was developed,which gave good agreement with experimental results.The effect of solution conditions was also involved in this correlation as a interaction energies.This could be useful for predicting the dynamic deposition process during crossflow filtration over a range of operating and solution conditions.

Particle Deposition in Oral-tracheal Airway Models with Very Low Inhalation Profiles

Considerable progress has been made on modeling particle deposition in the oral-tracheal airway under some normal breathing conditions, i.e., resting, light activity and moderate exercise. None of these standard breathing patterns correspond to very low inhalation profiles. It is known that particle deposition in the oral-tracheal airway is greatly influenced by flow and particle inlet conditions. In this work, very low inhalation flow rates are considered. Particle deposition is numerically investigated in different oral-tracheal airway models, i.e., circular, elliptic and realistic oral-tracheal airway models. Both micro- and nano-particles that are normally present in cigarette smoke are considered. Results show that inhalation profiles greatly influence the particle deposition. Due to relatively low flow rate, for ultra-fine particles, the oral deposition is enhanced due to longer residence time in oral cavity and stronger Brownian motion. However, for larger particles, less particles deposit in the oral-tracheal airway due to the weaker impaction. The transition happens when particle size changes from 0.01 μm to 0.1 μm. The influence of the limited entrance area is shown and discussed. Under the low inhalation profiles, the highest deposition fraction could be in either circular or realistic models depending on the particle property and the geometric characteristic of oral cavity. The knowledge obtained in this study may be beneficial for the design of bionic inhaler and understanding of health effect from smoke particle on human being.

Deposition of duststorm particles during 2000–2012 in the South Yellow Sea,China based on satellite data

In this study,about 220 satellite images between 2000 and 2012 were obtained from FY-series,MODIS,CBERS,HJ-1A and HJ-1B to estimate the impact of duststorms on the South Yellow Sea（SYS）,which serve as an important source of particles there.The analyzing results from the images support a total occurrence of 88 duststorms（including the locally-generated dusty weather） that affected the SYS during 2000–2012.The annual occurrence was about 4–10 times（10 times in 2000 and 2004;four times in 2009 and 2012）,predominantly in March（29%）,April（33%） and May（22%）.By mapping the distribution of their frequency,the duststorms influencing the SYS were found primarily moving from the northwest（39 times,44.3%） and west（37 times,42%） to the study region with only 11 duststorms（12.5%） coming from the north and 1 duststorm（1%） from the southwest.We estimated that an annual amount of 0.5–3.5 million tons of sediment particles was brought to the SYS by the duststorms during 2000–2012.

Investigation of Movement and Deposition Behaviors of Solid Particles in Hydraulic Water Reservoir via the CFD‑DEM Coupling Method

Solid contamination existing as solid particles in power fluid transmission systems may lead to transmission performance reduction,system failures,and component damage.The hydraulic reservoir will deposit the contamination and store hydraulic fluid.To investigate its purification ability for solid contamination,experiments and simulations for the motion and deposition status of the typical hydraulic system particles are carried out to reveal the interaction of particles and fluid in hydraulic water reservoirs.The results show that the CFD-DEM coupling method could predict the accurate deposition position of iron particles and sand particles when ignoring the small-scale turbulence effect in the flow field.Besides,the particle motion traces and deposition patterns in the reservoir illustrate that the flow development on the bottom surface results in the particles turning,and particles tend to settle in the low flow energy position.The motion of particles is also linked to particles Stokes number,and the same-size sand particles are easily driven by the fluid.The contribution of this paper could provide a guide for predicting the particle motion and deposition pattern in the hydraulic reservoir.

Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

Deep bed filtration model for cake filtration and erosion

Many phenomena in nature and technology are associated with the filtration of suspensions and colloids in porous media. Two main types of particle deposition,namely, cake filtration at the inlet and deep bed filtration throughout the entire porous medium, are studied by different models. A unified approach for the transport and deposition of particles based on the deep bed filtration model is proposed. A variable suspension flow rate, proportional to the number of free pores at the inlet of the porous medium, is considered. To model cake filtration, this flow rate is introduced into the mass balance equation of deep bed filtration. For the cake filtration without deposit erosion,the suspension flow rate decreases to zero, and the suspension does not penetrate deep into the porous medium. In the case of the cake filtration with erosion, the suspension flow rate is nonzero, and the deposit is distributed throughout the entire porous medium. An exact solution is obtained for a constant filtration function. The method of characteristics is used to construct the asymptotics of the concentration front of suspended and retained particles for a filtration function in a general form. Explicit formulae are obtained for a linear filtration function. The properties of these solutions are studied in detail.

Effects of cartilaginous rings on airflow and particle transport through simplified and realistic models of human upper respiratory tracts

In the present study, computational fluid dynamics （CFD） is used to investigate inspiratory and expiratory airflow characteristics in the human upper respiratory tract for the purpose of identifying the probable locations of particle deposition and the wall injury. Computed tomography （CT） scan data was used to reconstruct a three dimensional respiratory tract from trachea to first generation bronchi. To compare, a simplified model of respiratory tract based on Weibel was also used in the study. The steady state results are obtained for an airflow rate of 45 L/min, corresponding to the heavy breathing condition. The velocity distribution, wall shear stress, static pressure and particle deposition are compared for inspiratory flows in simplified and realistic models and expiratory flows in realistic model only. The results show that the location of cartilaginous rings is susceptible to wall injury and local particle deposition.

Deposition of non-spherical microparticles in the human upper respiratory tract

We investigated the deposition pattern of microparticles with different particle diameters, shape factors, and initial flow conditions in a realistic human upper respiratory tract model. We identified a close relationship between the deposition fraction and the particle shape factor. The deposition fraction of the particles decreased sharply with increasing particle shape factor because of the decreasing drag force. We also found that the deposition varied at different positions in the upper respiratory tract. At low shape factors, the highest fraction of particles deposited at the mouth and pharynx. However, with increasing shape factor, the deposition fraction in the trachea and lungs increased. Moreover, for a given shape factor, larger particles deposited at the mouth and pharynx, which indicates that the deposition fraction of microparticles in the human upper respiratory tract is affected first and foremost by particle inertia as well as by the drag force.

A Study of the Velocity Field during Evaporation of Sessile Water and Water/Ethanol Drops

Many studies have investigated evaporation of sessile drops in an attempt to understand the effect of wetting on theevaporation process.Recently interest has also increased in the deposition of particles from such drops,with evaporative massflux being deemed to be responsible for ring-like deposits,and counteraction of the mass flux by Marangoni convection explainingmore uniform deposition patterns.Understanding of such deposition processes is important in biological applications,such as the Litos test-system endorsed by the Russian Ministry of Health for diagnosis of urolithiasis and the evaporation ofcolloidal drops for depositing and organizing proteins and DNA.In most cases where deposition from evaporating drops hasbeen studied,velocity information is inferred from the final deposition pattern or from mathematical modeling based on simplifiedmodels of the physics of the evaporation process.In this study we have directly measured the flow velocities in the baseof sessile drops,using micro particle image velocimetry,viewing the drop from below,through the cover slide.For water drops,a radial pattern of flow was observed with a maximum velocity close to but not at the pinned outer edge.For ‘azeotropic’ethanol/water mixtures,the velocity field is more chaotic to begin with,passing through a phase involving three or four recirculationcells and finally having the same radial pattern as for water drops.

Jet dispersion and deposition of charged particles in confined chambers

Dispersion and surface deposition of charged particles by gas-solids jets in confined chambers are constantly encountered in many industrial applications such as in electrostatic precipitation and dry powder coating processes. Understanding and control of flow patterns and trajectories of charged particles are important to the optimal design and operation of such devices. In this study, modeling of flow fields and particle trajectories of dilute gas-solid two-phase flows with charged particles in confined chambers is performed. The dilute gas-solid two-phase flows are simulated by use of a hybrid Eulerian-Lagrangian approach with the one-way coupling between the gaseous phase and particle phase. The space charge distribution is included as a source term in equations of motion or Lagrangian equation of charged particles, which in turn depends on the particle trajectories that determine the space charge distribution. Our modeling predictions suggested that the electrostatic charge plays a significant role in particle radial dispersion. Effect of voltage has limited influence on particle trajectories however it can have a big impact on the residence time. Cone angle has a significant effect on the structure of flow field. For cone with a larger cone angle （typically over 15°）, there will be a flow separation along the side wall near the flow entrance region. By comparing with the conical chamber, the cylindrical chamber has a big vortex and three smaller vortexes in the lower part of the chamber, which would complicate the particle dispersion with or without the coupling of charging.

Numerical study of particle fouling deposition on heat transfer surface

An integrated Eulerian model for fouling in turbulent flow was developed to simulate the particle fouling charac-teristics.The model comprises a deposition process and removal process.The deposition process considers four various factors affecting the particle deposition which are Brownian and eddy diffusion,gravity,thermophoretic,and turbophoretic forces.This study compares the Lagrangian and Eulerian approaches under the same operat-ing conditions with an emphasis on their performance in predicting particle deposition.The deposition height calculated by using the Eulerian approach is in good agreement with the experimental data and the deposition morphology is similar to that observed in experiments.Furthermore,this paper explores the deposition charac-teristics and predicts the deposition morphology under different particle sizes.

Conduction-radiation effect on transient natural convection with thermophoresis

This paper discusses the effect of thermophoretic particle deposition on the transient natural convection laminar flow along a vertical fiat surface, which is immersed in an optically dense gray fluid in the presence of thermal radiation. In the analysis, the radiative heat flux term is expressed by adopting the Rosseland diffusion approximation. The governing equations are reduced to a set of parabolic partial differential equations. Then, these equations are solved numerically with a finite-difference scheme in the entire time regime. The asymptotic solutions are also obtained for sufficiently small and large time. The obtained asymptotic solutions are then compared with the numerical solutions, and they are found in excellent agreement. Moreover, the effects of different physical pa- rameters, i.e., the thermal radiation parameter, the surface temperature parameter, and the thermophoretic parameter, on the transient surface shear stress, the rate of surface heat transfer, and the rate of species concentration, as well as the transient velocity, temperature, and concentration profiles are shown graphically for a fluid （i.e., air） with the Prandtl number of 0.7 at 20℃ and 1.013 × 10^5 Pa.

Lattice Boltzmann method and RANS approach for simulation of turbulent flows and particle transport and deposition

Using the lattice-Boltzmann computational approach in conjunction with the Reynolds averaged Navier-Stokes （RANS） model, several turbulent flows and the transport and deposition of particles in different passages were studied. The new lattice Boltzmann method （LBM） solved the RANS equations coupled with the standard and renormalization group k-E turbulence models. In particular, the LBM formulation was augmented by the addition of two transport equations for the probability distribution function of populations of k and 8. The discrete random walk model was used to generate the instanta- neous turbulence fluctuations. For turbulent channel flows, the analytical fits to the root mean-square velocity fluctuations obtained by the direct numerical simulation of the turbulent flow were used in the analysis. Attention was given to the proper evaluation of the wall normal turbulent velocity fluctuations particularly near the wall. The simulation results were compared with the available numerical simulation and experimental data. The new LBM-RANS model is shown to provide a reasonably accurate description of turbulent flows and particle transport and deposition at modest computational cost.