Flow characterisation

Leak paths and natural Through faults and May origin leak high flows Characterisation... 

Gascoyne, M. and Wuschke, D.M., 1990. Fracture detection and groundwater flow characterisation in poorly-exposed ground using helium and radon on soil gases. United Kingdom Dept. Energy, Report no. DOE/RW/90/079. 

Thus, Equations 4.1-4.3, in the case of the homogeneous mixing of liquid flows, characterised by density and viscosity, provide an efficient commercial application of tubular turbulent reactors at almost any stage limited by mass exchange. The optimal operation conditions of the tubular turbulent reactors in the quasi-plug flow mode can be calculated due to the changes of the physical characteristics of the liquid flow, the kinetic parameters of the fast chemical reactions and the reaction construction parameters. 

Tsukiji, T. Utashiro, T. Flow Characterisation of E. R. Fluids Between Two Parallel Plate Electrodes. Proc. ASME Int. Congress and Expo., San Francisco, Developments in Electrorheological flows FED Vol. 235, MD Vol. 71 (Nov. 1996), pp. 37-42... 

A constitutive equation is a relation between the extra stress (t) and the rate of deformation that a fluid experiences as it flows. Therefore, theoretically, the constitutive equation of a fluid characterises its macroscopic deformation behaviour under different flow conditions. It is reasonable to assume that the macroscopic behaviour of a fluid mainly depends on its microscopic structure. However, it is extremely difficult, if not impossible, to establish exact quantitative... 

The standard melt flow index machine is often used for characterising the flow properties of polypropylene and to provide a rough measure of molecular weight. Under the conditions normally employed for polyethylene (2.16 kg load at 190°C) the flow rate is too low for accurate measurement and in practice higher loads, e.g. 10 kg, and/or higher temperatures are used. It has been found that a considerable pressure drop exists in the barrel so that the flow towards the end of a test run is higher than at the beginning. 

The Melt Flow Rate Test is a method used to characterise polymer melts. It is, in effect, a single point ram extruder test using standard testing conditions (BS... 

Hydrodynamic Characterisation of Flow in Fluidised/Expanded Beds and Bed Yoidage... 

The group udp/p, known as the Reynolds number, is one which frequently arises in the study of fluid flow and affords a criterion by which the type of flow in a given geometry may be characterised. Equation 1.8 involves the reciprocal of the Reynolds number, although this may be rewritten as ... 

Mtllf.r and Gidaspow 82 have studied transport of 75 pm catalyst particles in a 75 mm diameter vertical pipe. The flow was characterised by a dilute rising core and a dense annular region at the walls which tended to move downwards. The fractional volumetric concentration of the solids was from 0.007 to 0.04 in the core and up to 0.25 in the annular region. 

At low values of the Reynolds number, less than about 10, a laminar or viscous zone exists and the slope of the power curve on logarithmic coordinates is — 1, which is typical of most viscous flows. This region, which is characterised by slow mixing at both macro-arid micro-levels, is where the majority of the highly viscous (Newtonian as well as non-Newtonian) liquids are processed. 

From these results it seems to be obvious that experimental investigations in viscosimeters could not characterise the relationships in the turbulent flow of stirred tanks. 

The variation in wall thickness and the development of cell wall rigidity (stiffness) with time have significant consequences when considering the flow sensitivity of biomaterials in suspension. For an elastic material, stiffness can be characterised by an elastic constant, for example, by Young s modulus of elasticity (E) or shear modulus of elasticity (G). For a material that obeys Hooke s law,for example, a simple linear relationship exists between stress, , and strain, a, and the ratio of the two uniquely determines the value of the Young s modulus of the material. Furthermore, the (strain) energy associated with elastic de-... 

One method of characterising the residence time distribution is by means of the E-curve or external-age distribution function. This defines the fraction of material in the reactor exit which has spent time between t and t -i- dt in the reactor. The response to a pulse input of tracer in the inlet flow to the reactor gives rise to an outlet response in the form of an E-curve. This is shown below in Fig. 3.20. 

Axial and radial dispersion or non-ideal flow in tubular reactors is usually characterised by analogy to molecular diffusion, in which the molecular diffusivity is replaced by eddy dispersion coefficients, characterising both radial and longitudinal dispersion effects. In this text, however, the discussion will be limited to that of tubular reactors with axial dispersion only. Otherwise the model equations become too complicated and beyond the capability of a simple digital simulation language. 

The range of semi-dilute network solutions is characterised by (1) polymer-polymer interactions which lead to a coil shrinkage (2) each blob acts as individual unit with both hydrodynamic and excluded volume effects and (3) for blobs in the same chain all interactions are screened out (the word blob denotes the portion of chain between two entanglements points). In this concentration range the flow characteristics and therefore also the relaxation time behaviour are not solely governed by the molar mass of the sample and its concentration, but also by the thermodynamic quality of the solvent. This leads to a shift factor, hm°d, is a function of the molar mass, concentration and solvent power. 

Principles and Characteristics Less well-characterised extraction methods include solvent leaching at high temperature with forced-solvent flow. In the... 

Bulk property detectors function by measuring some bulk physical property of the mobile phase, e.g., thermal conductivity or refractive index. As a bulk property is being measured, the detector responses are very susceptible to changes in the mobile phase composition or temperature these devices cannot be used for gradient elution in LC. They are also very sensitive to the operating conditions of the chromatograph (pressure, flow-rate) [31]. Detectors such as TCD, while approaching universality in detection, suffer from limited sensitivity and inability to characterise eluate species. 

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