Long tube test

Continuous Settling Dilute Systems. When apphed to continuous sedimentation the long tube test is used to model the settling of particles in an elemental vertical volume of liquid moving throu the length of the clarifier. The corresponding overflow rate Vc, of a continuous ideal basin is given by H/ta, where H is the sanq)le point depth. 

The long tube test procedure assumes that a vertical element of suspension maintains its shape as it moves across... 

Figure 5.4 Schematic diagram of the long tube test (adapted from ref. 6)...

This model v/as used by Atwood et al (1989) to compare the performance of 12 m and 1.2 m long tubular reactors using the UCKRON test problem. Although it was obvious that axial conduction of matter and heat can be expected in the short tube and not in the long tube, the second derivative conduction terms were included in the model so that no difference can be blamed on differences in the models. The continuity equations for the compounds was presented as ... 

Table 5.9 Transient CHF tests in rod bundles and long tubes...

When wood confinement was employed, the sample was previously prepd in the form of short pellets 0.52-inch diam and these were inserted into a drilled hole of a wooden spool. When a metal confinement was required, the sample was loaded into a steel or Al tube 0.75-inch OD and 0.25-in ID, which was inserted into a wooden spool (See drawing beneath Fig 14). In both cases the sample was 1.03-inch long. For tests requiring... 

The UV dose data from bench-scale collimated beam tests for UV disinfection was first reported by Qualls and Johnson (23). Their original apparatus consisted of low-pressure UV lamps housed in a cardboard box with a 5.08 cm diameter, 72 cm long tube extending from a cut-out hole in the middle of the lamp arc length (20). 

Another simple form of apparatus, for fractionating low-boiling liquids, which is especially valuable when small quantities only are available, can be constructed from a Claissen flask and a test-tube in the way illustrated in Tig. 10. The cold water enters through the long tube in the test-tube and passes upward. By... 

The enrichment (or the pressure) needed to develop miscibility between the injectant and the oil is determined experimentally in one-dimensional slim-tube tests.As the enrichment (or pressure) increases, the slim-tube recovery reaches a plateau long before first contact miscibility is developed. This enrichment is called the minimum miscibility enrichment, or MME, which is a function of reservoir pressure, temperature, and contaminants in the solvent. Similarly, a pressure called the minimum miscibility pressure, or MMP, can be identified for any solvent. Other experimental methods (e.g., rising bubble method) are also available to determine MMP or MME. In vaporizing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the crude oil composition. In condensing three component systems, MMP (or MME) corresponds to the pressure (or enrichment) at which the critical tie line passes through the solvent composition. ... 

During a study of the applicability of "spray" or "fog" evaporation to sea water desalination, it was found that this technique was particularly useful for scale deposition studies. Thus, test conditions are reproducible and heat transfer coefficients are very high, so that the effect of scale formation is readily apparent. Three novel methods for the control of scale deposits on the evaporating surfaces of a spray evaporator were explored. One involves the addition of small quantities of low molecular weight polyacrylic acid to the feed water, which prevents the formation of adherent scale. The methods are applicable under certain conditions to scales formed from sea water containing substantial amounts of calcium sulfate in addition to alkaline scale-forming substances. While spray evaporation appears to be of limited application in water desalination, the scale-control methods developed are probably applicable to other types of evaporator, particularly of the long-tube type. 

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