Fluid displacement methods

The apparent particle density (or if the particles have no closed pores, also the true particle density) can be measured by fluid displacement methods, i.e. pyknometry, which are in common use in industry today. The displacement can be measured with either liquids or gases and there are, therefore, two groups of techniques and instruments available, as follows. 

Any of the three particle densities defined above should not be confused with bulk density of materials, which includes the voids between the particles in the volume measured. The different values of particle density can be also expressed in a dimensionless form, as relative density, or specific gravity, which is simply the ratio of the density of the particle to the density of water. It is easy to determine the mass of particles accurately but difficult to evaluate their volume because they have irregular shapes and voids between them. The apparent particle density, or if the particles have no closed pores also the true density, can be measured by fluid displacement methods, that is, pycnometry, which are in common use in industry. The displacement can be carried out using either a liquid or a gas, with the gas employed normally being air. Thus, the two known techniques to determine true or apparent density, when applicable, are liquid pycnometry and air pycnometry. 

The density of particles as determined by a given fluid displacement method The mass of the particles divided by the effective particle density... 

Electrode problems in the measurement of very thin plastic Aims can be overcome with the fluid-displacement methods described in ASTM D 1531. This method is speciflc for polyethylene, but can be used for other films. The immersion fluid should not attack the film and its dielectric constant should approximate that of the test specimen. Anhydrous benzene, silicone, and fluorocarbon liquids are often used the liquids must be completely free from moisture. 

When measuring membrane pore size using the fluid displacement method, the membrane pores are first filled by a fluid, which can be either air or a wetting liquid. The fluid inside the pores is then displaced by another immiscible fluid under applied pressure. The principle of the fluid displacement method is based on Young-Laplace equation [171] ... 

There is still another method by which the density of insoluble solids can be determined. It is based on an ancient principle known as Archimedes principle when an object is suspended in a fluid, it APPEARS to lose weight equal to the weight of the fluid displaced. We say that the object is "buoyed up," and that the "buoyancy" is equal to the apparent weight loss. In equation form, Archimedes principle could be stated as... 

ASTM D1531, 2001. Standard test methods for relative permittivity (dielectric constant) and dissipation factor by fluid displacement procedures. 

The two methods, most commonly used to measure gravimetric density, are pycnometric and flotation. In a pycnometric technique, the volume of the material is determined from the volume of a fluid displaced by the known mass of a material. In a flotation approach, a small particle, whieh can be a single crystal, is placed in a low-density fluid, where it... 

A limited number of studies have been carried out on more concentrated systems using variations of the traditional electrophoretic method, e.g., the tracer and mass-transport methods. Reed and Morrison (35) have shown that, for d.c. fields, even in highly concentrated systems, the hydrodynamic and electrostatic interactions cancel one another when the double layers are thin, and the only effect which must be taken into account is the reverse flow of fluid displaced by the moving particles. Zukoski and Sav-ille (3 6), using red blood cells mixed with ghosts, have verified that this is so and that the d.c. mobility, of a concentrated system of volume fiaction d> is given by the simple relation ... 

Colin [1] has reviewed some measurement methods in microscale flow, including the weighing method, thermal method, wave reflection method, acoustic vibration method, and so on. Here, two common methods, the weighing and displacement methods, are introduced. In the weighing method [2], the total mass M of fluids flowing out within a time At are measured, and the flow rate is calculated as... 

The displacement method [1, 3] is another kind of indirect method, which calculates flow rate by measuring the displacement L of a fluid in a capillary tube with a diameter D and interval At ... 

This imbibition method is dependent on both the chemical properties of the rock surface and the geometry of the pore network, particularly the pore throat size and shape. Since pore stmctnre can affect the measurement results, the reduction of the interfacial tension between pore fluids by surfactants can affect fluid movement through the pore structure. This method, therefore, is not strictly a measnre of surface wettability, but is a measure of the efficiency of fluid displacement that is normally most strongly affected by the wettability state of the pore surfaces. Within this framework of understanding, wettability alteration of the pore surfaces using snrfactants can be stndied with this measurement method. 

Summary. The Amott, USBM, Spontaneous Imbibition Index, imbibition rate, and capillary pressure are all displacement methods applicable to porous media and the possible evaluation of wettability alteration by surfactants. However, these methods must be complemented by more fundamental studies using contact angles or adhesion studies (Wilhelmy), etc. to meld the understanding of surface interactions with the macroscopic displacement of fluids. To comprehend how a surfactant alters the contact angle on a flat surface provides only part of the information to predict how the surfactant will interact in porous media. To measure only the fluid displacement in porous media provides little information on surface interactions. NMR and/or cryomicroscopy could help span this gap. Cryomicroscopy can directly look at pore surfaces, but for the moment, it is difficult and time consuming to use. Both techniques provide more of a qualitative measure of wettability than quantitative, but they are tools that can complement and help bridge between more fundamental measurements and quantitative displacement methods. 

Ejection of drops at high velocities in high-speed printers. To promote high speed, one typically resorts to very small structures. Such structures can be etched in silicon by standard techniques. However, the resulting systems must be active in the sense that they are capable of displacing fluids. Several methods exist ... 

Lopez-Avila et al. [86] have considered validation of analytical supercritical fluid extraction methods. When developing an SEE method, various critical factors need to be considered (i) solubility of the analyte in the supercritical fluid (SF) (ii) diffusion of the analyte from the solid matrix into the bulk fluid or displacement of the analyte by the SF that diffused into the matrix and (Hi) the matrix itself, which can be very adsorptive. Poor SEE recoveries may be attributed to matrix effects (e.g., not all of the analyte may be extractable), to inefficient retention of the analyte in the collection solvent or on the sorbent trap, or to inefficient desorption from the sorbent trap. Once an SEE procedure has been developed and tested with real matrices, the next step... 

A bstract Liquid flow as disturbed by the presence of a fluid interface of definite shape was studied during immiscible liquid/fluid displacement in a capillary tube. Microscopic cinematography with tracer method has been used to obtain flow patterns on both sides of the moving interface. The effect of the curvature of the interface on the distribution of velocity components was investigated. The experimental results obtained for flat liquid/fluid interfaces were compared with those calculated from an approximate solution of the flow equation by Kafka and Dussan V. 

This is a periodic treatment in which a large quantity of chemicals is used for an extended period of time. It is commonly used to treat flowing oil wells. Batch treatment is also called slug treatment For batch treating, the tube displacement method is employed. Several barrels of inhibitor are pumped into the tubing at the top. The inhibitor is displaced to the bottom of the tubing with the fluids in the oil well. The well is closed for a specific period before operation. The batch is used mciinly to treat water with biocides and not to supply inhibitors or scavengers. 

There are currently many methods to evaluate UHMWPE wear, including direct [7, 8], gravimetric [9, 10], radiographic [11-13], optical [14], fluid displacement [15], and more recently, microcomputed tomography (microCT) based [16, 17]. All of these techniques have their own... 

Nanocapsules act like a reservoir, which are called vesicular systems. They carry the active substance entrapped in the solid polymeric membrane or on their surfaces. The cavily inside contains either oil or water. A schematic diagram of Polymer Nanocapsules is shown in Fig. 9.2 [5], There are different methods that are used nowadays to prepare polymeric nanoparticles, such as nanoprecipitation (also termed as the solvent diffusion and solvent displacement method), solvent evaporation, dialysis, microemulsion, surfactant-free emulsion, salling-out, supercritical fluid technology, and interfacial polymerization [2]. Among these methods, nanoprecipitation is a fast and simple process, which does not require a pre-prepared polymer emulsion before the nanoparticle preparation. It produces a dispersion of nanoparticles by precipitation of preformed hydrophobic polymer solution. Under... 

The porosity of the samples was determined using QuantaChrome Stereopycnometer with Nitrogen gas medium using the gas pycnometer test method ASTM D6226-98. This method measures the accessible cellular volume of a material. The remaining volume is that occupied by closed cells, cell walls, and unfoamed sohd polymer. A gas pycnometer is designed to measure the volume of sohd objects. This is accomplished by employing the Archimedes principle of fluid displacement to determine the volume. The displaced fluid is a gas,... 

Miscible processes are aimed at recovering oil which would normally be left behind as residual oil, by using a displacing fluid which actually mixes with the oil. Because the miscible drive fluid is usually more mobile than oil, it tends to bypass the oil giving rise to a low macroscopic sweep efficiency. The method is therefore best suited to high dip reservoirs. Typical miscible drive fluids include hydrocarbon solvents, hydrocarbon gases, carbon dioxide and nitrogen. 

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