Basic principle liquid flow

This map has been checked by many researchers, indicating that it is applicable to a wide range of conditions. Also shown in Figure 3.4 are correlations derived by Mishima and Ishii (1984), which used similar basic principles except for the slug-to-churn transition. These authors pointed out that, in view of the practical applications of the separate-fluid model to transient analysis, flow regime criteria based on the superficial velocities of the liquid and gas may not be consistent with the separate-flow model formulation. A direct geometric parameter such as the... 

The basic structure and principle of all fuel cells is similar the cell consists of two electrodes which are separated by an electrolyte. The electrodes are connected through an external circuit. The electrodes are exposed to gas or liquid flows to supply fuel and oxidant (for instance hydrogen and oxygen). The electrodes have to be gas or liquid permeable and therefore possess a porous structure. The electrolyte should have a gas permeability as low as possible. For fuel cells with an acid electrolyte, hydrogen is oxidized at the negative electrode (the anode) according to the following equation. The protons formed enter the electrolyte and are transported to the cathode ... 

Generalizations of the Newton s flow law [7.2.3] for polymeric liquids are aimed to describe in more or less details the features of their rheological behavior. The most important among these features is the ability to accumulate elastic deformation during flow and thus to exhibit the memory effects. At first we restrict ourselves to the case of small deformation rates to discuss the basic principles of the general linear theory of viscoelasticity... 

The basic idea of on-chip DNA hybridization assays is to integrate assay operations such as sequential sample loading, transportation, mixing, incubation, and detection on a single microfluidic chip. Although the microfluidics-based DNA hybridization assays share the same basic principle, the formats of these assays vary. Generally, the present-day formats of the on-chip DNA hybridization assays remain the main types directed liquid flow-based on-chip DNA hybridization assays, surface-based on-chip DNA hybridization assays, bead-based on-chip DNA hybridization assays, and the on-chip DNA hybridization assays with membrane/film-based transducer. 

In order to design the appropriate liquid chromatography separation system, it is necessary to nnderstand on molecular level some basic principles and tendencies of the processes taking place in the chromatographic column. Above processes resnlt in differences in retention of sample constituents to allow their mutual separation. Extent of retention of macromolecules within colutim reflects the volume of mobile phase needed for their elution, their abovementioned retention volume, V. For the sake of simplicity, let us consider constant overall experimental conditions that is the elnent flow rate, temperature and pressure drop. The latter two parameters are dictated not only by the inherent hydrodynamic resistance of colunm that is inflnenced by the eluent viscosity, size and shape of packing particles but also by the sample viscosity, which may be rather high in polymer HPLC. Further, only one variable molecular characteristic of separated macromolecules will be... 

In recent times some companies now employ their own gas gener-atory plants instead of the liquid gas delivered by tanker load. The basic principle of these plants Involves the differential adsorption rates of nitrogen and oxygen from air pumped through carbon molecular sieves (coke) when oxygen is absorbed almost completely, leaving a flow of nitrogen up to 99-9 per cent pure. 

A better understanding of the basic principles of ultrafiltration has permitted the development of much more efficient equipment and corresponding commerical applications. A detailed consideration of the theory of ultrafiltration was published by Porter (134), who dealt specifically with the problem Of concentration polarization. As shown in Figure 4.4, the movement of particles toward the membrane results in the formation of a concentrated sol layer of high viscosity. This can reduce the flux or rate of filtration to a small fraction of that of the liquid medium in the absence of colloid. The resistance to flow is not due to plugging of pores, or even to an actual solid layer (gel) of close-packed colloidal particles. In has been observed... 

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