Compressibilité des argiles gonflantes non saturées à partir des essais rhéologiques

1990 ◽  
Vol 27 (1) ◽  
pp. 90-104 ◽  
Author(s):  
T. K. Karalis
Keyword(s):  
Liquid Phase ◽  
Vapor Pressure ◽  
Key Words ◽  
Swelling Pressure ◽  
Swelling Clay ◽  
Soil Compressibility ◽  
Rheological Experiments

The expression for the modulus of compressibility has been established on the basis of rheological experiments in an oedometer that measured the swelling pressure and the vapor pressure of the adsorbed liquid phase of a swelling clay hydrated by water injections under different applied loads. Key words: swelling rheology, soil compressibility, unsaturated swelling clay, oncodynamics, swelling pressure. [Journal translation]

An Engineering Calculation Method for Multi-Component Stagnant Droplet Evaporation With Finite Diffusivity

1994 ◽  
Author(s):  
J. S. Chin
Keyword(s):  
Heat Transfer ◽  
Diffusion Coefficient ◽  
Liquid Phase ◽  
Vapor Pressure ◽  
Molecular Mass ◽  
Calculation Method ◽  
Engineering Calculation ◽  
Droplet Evaporation ◽  
Diffusion Resistance ◽  
Distillation Curve

A practical engineering calculation method has been formulated for commercial multicomponent fuel stagnant droplet evaporation with variable finite mass and thermal diffusivity. Instead of solving the transient liquid phase mass and heat transfer partial differential equation set, a totally different approach is used. With zero or infinite mass diffusion resistance in liquid phase, it is possible to obtain vapor pressure and vapor molecular mass based on the distillation curve of these turbine fuels. It is determined that Peclet number (Pef) is a suitable parameter to represent the mass diffusion resistance in liquid phase. The vapor pressure and vapor molecular mass at constant finite Pef is expressed as a function of finite Pef, vapor pressure, and molecular mass at zero Pef and infinite Pef. At any time step, with variable finite Pef, the above equation is still valid, and PFsPef=∞, PFsPef=0, MfvPef=∞, MfvPef=0 are calculated from PFsPef≡∞, PFsPef≡0, MfvPef≡∞, MfvPef≡0, thus PFs and Mfv can be determined in a global way which eventually is based on the distillation curve of fuel. The explicit solution of transient heat transfer equation is used to have droplet surface temperature and droplet average temperature as a function of surface Nusselt number and non-dimensional time. The effect of varying com position of multi-component fuel evaporation is taken into account by expressing the properties as a function of molecular mass, acentric factor, critical temperature, and critical pressure. A specific calculation method is developed for liquid fuel diffusion coefficient, also special care is taken to calculate the binary diffusion coefficient of fuel vapor-air in gaseous phase. The effect of Stefan flow and natural convection has been included. The predictions from the present evaporation model for different turbine fuels under very wide temperature ranges have been compared with experimental data with good agreement.

Surface Tension and Bubbles

2011 ◽  
Vol 354-355 ◽  
pp. 37-40
Author(s):  
Cai Xia Xu ◽  
Hai Rong Tang
Keyword(s):  
Phase Transition ◽  
Surface Tension ◽  
Liquid Phase ◽  
Vapor Pressure ◽  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Surfactant Solution ◽  
Liquid Phase Transition ◽  
Almost All

From a molecular perspective, we described the origin of surface tension. Surface tension is exceptionally good at rounding things out, such as bubbles can produce in surfactant solution , also in liquid or vapor-liquid phase transition. Through the experiment of determination of saturated vapor pressure of pure liquids, maybe we can conclude that almost all the bubbles were generated as result of the breakup of the gas-liquid interface.

An Experimental and Analytical Study of Steam/Water Capillary Pressure

2001 ◽  
Vol 4 (06) ◽  
pp. 477-482 ◽  
Author(s):  
Kewen Li ◽  
Roland N. Horne
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Liquid Phase ◽  
Vapor Pressure ◽  
Capillary Pressure ◽  
Water Flow ◽  
Capillary Tube ◽  
Relative Pressure ◽  
Kelvin Equation ◽  
Adsorption Data

Summary Significant mass transfer between the steam and water phases makes it difficult to measure steam/water capillary pressure using routine methods. Because of the difficulties, few experimental data are available. A formula was derived on the basis of the Kelvin equation to calculate steam/water capillary pressure. The water-phase temperatures and pressures measured with a steady-state flow method were used to perform the calculations. The preliminary results of both drainage and imbibition steam/water capillary pressure were obtained. It was confirmed that the lowering of vapor pressure was small, but the capillary pressure was significant for the system studied. This experimental observation is consistent with thermodynamic analysis. Introduction It has often been assumed in steam numerical simulators that steam/water flow in porous media can be represented as gas (air or nitrogen)/water flow. In recent years, attention has been paid to the measurements of steam/water relative permeability.1–6 Horne et al.2 found that there were significant differences between nitrogen/water and steam/water relative permeabilities. Accordingly, there may also be significant differences between nitrogen/water and steam/water capillary pressures. To compare the two, reliable experimental data for steam/water capillary pressure are required. However, there have been few direct measurements of steam/water capillary pressure from steam/water flow experiments. Less attention has been paid to the measurements of steam/water capillary pressure, even though capillary pressure is of equal significance to relative permeability and plays an important role in controlling fluid distributions and recoveries in petroleum and geothermal reservoirs. Tsypkin and Calore7 developed a mathematical model of steam/water phase transition. They found that steam/water capillary pressure could play a stabilizing role for the vaporization front, causing a sharp zone to develop. Urmeneta et al.8 also studied the role of capillary forces in fractured reservoirs and found that capillary pressure tended to keep the vapor phase in the fracture and the liquid phase in the matrix. Using the adsorption data of Horne et al.9 for rock samples from The Geysers geothermal field, Sta. Maria and Pingol10 inferred the values of steam/water capillary pressure. They found that the steam/water capillary pressure ranged from 0 to 86,000 psi. Persoff and Hulen11 also inferred the capillary pressure from adsorption data of The Geysers rock samples and found that the steam/water capillary pressure ranged from 0 to approximately 28,000 psi. The graywacke core samples used by Persoff and Hulen11 were similar to those used by Sta. Maria and Pingol.10 The porosity was approximately 2%, and the permeability was in the nanodarcy (nd) range. The adsorption/desorption tests that have been used to infer steam/water capillary pressure are static processes in which there is no steam/water flow. In actual petroleum and geothermal reservoirs, however, capillary pressure plays an important role while steam and water flow simultaneously through the rocks. Hence, the process governing an adsorption test may not represent the mechanisms under actual fluid-flow conditions in those reservoirs. The steam/water capillary pressures from adsorption data may or may not be the same as those measured with a dynamic method in which steam and water are flowing. Very strict sealing requirements must be achieved for long periods of time during the adsorption tests, which is very difficult, especially at high temperatures. These disadvantages may be overcome by using a steady-state flow method. The main purpose of this paper was to develop a method to calculate steam/water capillary pressure using data from the experiments of steady-state steam/water flow. An X-ray computerized tomography (CT) technique was used to measure the water saturation and its distribution in the core sample. The effect of temperature on CT values used to calculate the water saturations was studied experimentally. Method Capillary Pressure. Using the Kelvin equation, steam/water capillary pressure can be calculated from the experimental data of liquid-phase pressure, temperature, and related parameters. The procedure is described in this section. The relative pressure (pv/p0) is used to characterize the capillary condensation on curved surfaces. Kelvin established the relationship between the relative pressure and the curvature of the interface, along with other properties of the fluid and the substrate. In a circular capillary tube with a radius of r, the relative pressure can be calculated using the Kelvin equation as follows:Equation 1 where p0=the vapor pressure when the vapor/liquid interface is flat; pv=the vapor pressure in a capillary tube of radius r when the vapor/liquid interface is curved; s=the interfacial tension and ?=the contact angle measured through the liquid phase; R=the gas constant; T=the absolute temperature; Mw=the molecular weight of liquid; and ?w=the density of liquid. The Kelvin equation assumes that (1) all adsorption is caused only by capillary condensation, (2) adsorbate density is equal to bulk liquid density, and (3) the validity is unimpaired at low values of r. The capillary pressure, Pc, in a circular capillary tube is also determined by the interface curvature and fluid and substrate properties and can be calculated asEquation 2 Combining Eqs. 1 and 2,Equation 3 Capillary pressure is defined as the pressure difference between the nonwetting and the wetting phases and is expressed as follows:Equation 4

The Solvation of High Molecular Substances, Especially Rubber

1930 ◽  
Vol 3 (3) ◽  
pp. 409-417
Author(s):  
P. Stamberger ◽  
C. M. Blow
Keyword(s):  
Experimental Data ◽  
Molecular Weight ◽  
Vapor Pressure ◽  
Swelling Pressure ◽  
Viscosity Measurements ◽  
Molecular Substances ◽  
Dissolved Phase

Abstract 1. On the basis of new experimental data on rubber, the theories of the solvation of high molecular substances are discussed. 2. In this discussion the measurements of the swelling pressure of rubber in toluene are described. The values obtained, and also the measurements of the depression of the vapor pressure lead to the conclusion that rubber cannot be considered a mixture of homologous polymers. 3. The consistency or viscosity of gels is without effect on the decrease in the activity of the solvent (measured by the depression of the vapor pressure and the swelling pressure). 4. The conclusion is drawn that mastication cannot be considered a depolymerization. 5. On the basis of measurements of the viscosity of solutions of rubber-gas black compounds it follows that conclusions as to the molecular weight of the dissolved phase cannot be drawn from viscosity measurements without further ado. 6. The theories of the distribution of high molecular substances in solution are briefly discussed.

POLYSACCHARIDE DEGRADING ENZYMES IN MICROBIAL POPULATIONS FROM THE LIQUID AND SOLID FRACTIONS OF BOVINE RUMEN DIGESTA

1984 ◽  
Vol 64 (5) ◽  
pp. 58-59 ◽  
Author(s):  
A. G. WILLIAMS ◽  
N. H. STRACHAN
Keyword(s):  
Liquid Phase ◽  
Key Words ◽  
Glycoside Hydrolase ◽  
Microbial Populations ◽  
Bovine Rumen ◽  
Degrading Enzymes ◽  
The Stability

Polysaccharide depolymerase and glycoside hydrolase enzymes involved in the degradation of plant structural polysaccharides were most active in the adherent particle-associated microorganisms, whereas soluble saccharides were metabolized by the liquid phase and nonadherent populations. The activities were constant confirming the stability of the populations. Key words: Polysaccharidase, glycosidase, particle-associated microorganisms

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