Annular mass

Note the typical apple-core appearance of the carcinoma on the volume-rendered image. Because annular masses may be indistinguishable from incompletely distended segments of the colon on 3D images, correlation with the axial 2D images is often required for differentiation... 

To this end, I traced, on three paper sheets, three shapes representing the bases of three formed systems, each of two portions of film spheres and a partition. I understand by the base of such a system the whole of the arcs of circles along which it is based on the surface of the liquid, neglecting the small annular masses. Here is one method by which I plotted the drawings in question ... 

Initially, the liquid of the vessel rises a little, by capillary action, on the outside and the inside face of the film shape, as it does at the base of any film which comes to be attached to its surface ( 189 and 192) it thus forms the small annular mass with concave meridian surfaces on the crest of which the cap rests. 

In the second place, one understands, accordingly, that if the imprisoned volume of air is rather small so that the space circumscribed by the edge of the film has little diameter, the surface of the liquid in this same space, will not have any plane part, but will present, even in its ntiddle, a more or less marked concave curvature, as inside a narrow mbe. This result agrees with experiment, and I assured myself, by a means that I will indicate soon, that the central portion of surface in question ceases appearing plane when the diameter of the film, at the crest of the small annular mass, is below approximately 2 centimetres. 

Imidazole, 4-methyl-annular tautomerism, 5, 363 association, 5, 362 boiling point, 5, 362 bromination, 5, 398 deuteration, 5, 417 diazo coupling, 5, 403 hydrogen bonding, S, 350 hydroxymethylation, 5, 404 iodination, 5, 400 kinetics, 5, 401 mass spectra, 5, 358 melting point, 5, 362 methylation, 5, 364 sulfonation, 5, 397 synthesis, 5, 479-480, 482, 484, 489 Imidazole, 5-methyl-annular tautomerism, 5, 363 Imidazole, l-methyl-4-chloro-ethylation, 5, 386 Imidazole, l-methyl-5-chloro-ethylation, 5, 386 nitration, 5, 395... 

Wetted-waU or falhng-film columns have found application in mass-transfer problems when high-heat-transfer-rate requirements are concomitant with the absorption process. Large areas of open surface are available for heat transfer for a given rate of mass transfer in this type of equipment because of the low mass-transfer rate inherent in wetted-waU equipment. In addition, this type of equipment lends itself to annular-type coohng devices. 

In heat transfer applications, this jacket is considered a helical coil if certain factors are used for calculating outside film coefficients. The equivalent heat transfer diameter, D, for a rectangular cross-section is equal to 4 w (w being the width of the annular space). Velocities are calculated from the actual cross-section of the flow area, pw (p being die pitch of die spiral baffle), and die effective mass flowrate W dirough die passage. The effective mass flowrate is approximately 60% of die total mass flowrate of die jacket. 

The above experimenters have used the technique described to obtain flow rate measurements of the liquid wall-film at various mass velocities, tube dimensions, etc., and some typical results from Staniforth and Stevens (S7) are shown in Fig. 7. Also shown are the values of burn-out heat flux obtained at the four different mass velocities indicated. It can be seen that the liquid-film flow rate decreases steadily with increasing heat flux until at burn-out the flow rate becomes zero or very close to zero. We thus have confirmation of a burn-out mechanism in the annular flow regime which postulates a liquid film on the heated wall diminishing under the combined effects of evaporation, entrainment, and deposition until at burn-out, the film has become so thin that it breaks up into rivulets which cause dry spots and consequent overheating. 

In an oil cooler 216 kg/h of hot oil enters a thin metal pipe of diameter 25 mm. An equal mass flow of cooling water passes through the annular space between the pipe and a larger concentric pipe with the oil and water moving in opposite directions. The oil enters at 420 K and is to be cooled to 320 K. If the water enters at 290 K, what length of pipe will be required Take coefficients of 1.6 kW/m2 K on the oil side and 3.6 kW/tn2 K on the water side and 2.0 kJ/kg K for the specific heat of the oil. 

Notably, the higher the mass flux, the earlier annular flow is reached. Bubbly flow is more or less non-existent for mass fluxes exceeding 1,000 kg/m s. The most important observation about the flow patterns is that their transitions are controlled primarily by the rate of coalescence, which is not recognized as a contributing factor by any of the micro-scale or macro-scale flow pattern maps. 

Zhao TS, Bi QC (2001b) Pressure drop characteristics of gas-liquid two-phase flow in vertical miniature triangular channels. Int J Heat Mass Transfer 44 2523-2534 Zimmerman R, Gurevich M, Mosyak A, Rozenblit R, Hetsroni G (2006) Heat transfer to air-water annular flow in a horizontal pipe. Int J Multiphase Flow 32 1-19... 

The heat transfer coefficient of boiling flow through a horizontal rectangular channel with low aspect ratio (0.02-0.1) was studied by Lee and Lee (2001b). The mass flux in these experiments ranged from 50 to 200 kg/m s, maximum heat flux was 15 kW/m, and the quality ranged from 0.15 to 0.75, which corresponds to annular flow. The experimental data showed that under conditions of the given experiment, forced convection plays a dominant role. 

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