Partial pressure gradient

When Che diameter of the Cube is small compared with molecular mean free path lengths in che gas mixture at Che pressure and temperature of interest, molecule-wall collisions are much more frequent Chan molecule-molecule collisions, and the partial pressure gradient of each species is entirely determined by momentum transfer to Che wall by mechanism (i). As shown by Knudsen [3] it is not difficult to estimate the rate of momentum transfer in this case, and hence deduce the flux relations. 

Ac Che limic of Knudsen screaming Che flux relacions (5.25) determine Che fluxes explicitly in terms of partial pressure gradients, but the general flux relacions (5.4) are implicic in Che fluxes and cheir solution does not have an algebraically simple explicit form for an arbitrary number of components. It is therefore important to identify the few cases in which reasonably compact explicit solutions can be obtained. For a binary mixture, simultaneous solution of the two flux equations (5.4) is straightforward, and the result is important because most experimental work on flow and diffusion in porous media has been confined to pure substances or binary mixtures. The flux vectors are found to be given by... 

By substituting from equations 10.7a and 10.76 into equation 10.4, the mass transfer rates NA and NB can be expressed in terms of partial pressure gradients rather than concentration gradients. Furthermore, NA and Ns can be expressed in terms of gradients of mole fraction. 

Maxwell,02) postulated that the partial pressure gradient in the direction of diffusion for a constituent of a two-component gaseous mixture was proportional to ... 

According to Maxwell s law, the partial pressure gradient in a gas which is diffusing in a two-component mixture is proportional to the product of the molar concentrations of the two components multiplied by its mass transfer velocity relative to that of the second component. Show how this relationship can be adapted to apply to the absorption of a soluble gas from a multicomponent mixture in which the other gases are insoluble and obtain an effective diffusivity for the multicomponent system in terms of the binary diffusion coefficients. 

The next step in developing an equation to describe moisture uptake in one dimension is to determine W p by applying Eq. (39). Note that the partial pressure gradient (dPJdx) must be calculated to solve for the moisture flux. We could take the derivative of either Eq. (42) or (43) for this purpose. If we take the derivative of Eq. (42), the resulting solution is given by... 

Diffusion is proportional to the surface area of the blood-gas interface (A) the diffusion constant (D) and the partial pressure gradient of the gas (AP). Diffusion is inversely proportional to the thickness of the blood-gas interface (T). 

The diffusion of oxygen and carbon dioxide also depends on their partial pressure gradients. Oxygen diffuses from an area of high partial pressure in the alveoli to an area of low partial pressure in the pulmonary capillary blood. Conversely, carbon dioxide diffuses down its partial pressure gradient from the pulmonary capillary blood into the alveoli. 

Gas diffusion in the nano-porous hydrophobic material under partial pressure gradient and at constant total pressure is theoretically and experimentally investigated. The dusty-gas model is used in which the porous media is presented as a system of hard spherical particles, uniformly distributed in the space. These particles are accepted as gas molecules with infinitely big mass. In the case of gas transport of two-component gas mixture (i = 1,2) the effective diffusion coefficient (Dj)eff of each of the... 

The concentration of an inhaled anesthetic in a mixture of gases is proportional to its partial pressure (or tension). These terms are often used interchangeably in discussing the various transfer processes involving anesthetic gases within the body. Achievement of a brain concentration of an inhaled anesthetic necessary to provide an adequate depth of anesthesia requires transfer of the anesthetic from the alveolar air to the blood and from the blood to the brain. The rate at which a therapeutic concentration of the anesthetic is achieved in the brain depends primarily on the solubility properties of the anesthetic, its concentration in the inspired air, the volume of pulmonary ventilation, the pulmonary blood flow, and the partial pressure gradient between arterial and mixed venous blood anesthetic concentrations. 

The driving force, that is, a partial pressure gradient, is obtained by a temperature gradient between the feed and the distillate side. In the osmotic distillation (OD), a partial pressure gradient is activated by a difference in concentration. As a consequence, OD can proceed at ambient temperature and flavor and fragrance compounds can be more conveniently preserved, than in thermally activated concentration processes. 

The greatest challenge in membrane extraction with a GC interface has been the slow permeation through the polymeric membrane and the aqueous boundary layer. The problem is much less in MIMS, where the vacuum in the mass spectrometer provides a high partial pressure gradient for mass transfer. The time required to complete permeation is referred to as lag time. In membrane extraction, the lag time can be significantly longer than the sample residence time in the membrane. An important reason is the bound-... 

The use of a baffle between the target and the substrate creates a reactive gas partial pressure gradient when the reactive gas is introduced near the substrate. In this way, the cathode can be operated in the metallic mode even with a high reactive gas partial pressure at the substrate. 

The processing techniques outlined earlier utilize either Zn desorption in the metallic mode or reactive gas partial pressure gradients for the deposition of transparent and conductive ZnO films. From a manufacturing viewpoint,... 

Acceleration force = converted momentum change partial pressure gradient + external forces - thermal diffusion force + shearing force + intermolecular friction force... 

In Eq. (13-88), 4 is termed the generalized driving force. For an ideal gas mixture the driving force is related to the partial pressure gradient and the mole fraction gradient as follows ... 

As the partial pressure gradient moves into the green body, the pores empty accordingly. For this reason, the green body will not be completely dry when the bulk gas used for drying has a nonzero partial pressure of the solvent. Some liquid will remain in the smallest capillaries where the radius of curvature is sufficiently small. These filled capillaries will contribute to a compressive capillary force which holds the green body together. 

Higher fluxes and lower effective pore diflusion coefficients wiU give a higher partial pressure gradient and result in a larger stress due to capillary pressure. 

Passive transport is the process of mass transfer across any separating barrier, diaphragm, membrane, or partition wall toward equihbrating any differences in chemical potential because of gradients of concentration, electrostatic potential, thermal, or (partial) pressure gradient. 

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