Triangular channel pressure flow

Triangular channel pressure flow 1. Equilateral triangle3... 

The images of the representative flow patterns, together with the measured simultaneous pressure fluctuations, for the equilateral triangular channel having a side... 

Note that Eq. (5.14) is very close to a = 0.833/3 for large circular tubes given by Ar-mand (1946). Equation (5.14) is compared with the experimental data in Fig. 5.24. It is evident from Fig. 5.24 that the experimental data for the three tested channels can be best approximated by Eq. (5.14), 95% of the data falling within the deviation of 10% when j3 < 0.8. Equation (5.14) may be used to obtain the pressure drop of two-phase flow through the triangular channels. 

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... 

Before closing this chapter, we feel that it is useful to list in tabular form some isothermal pressure-flow relationships commonly used in die flow simulations. Tables 12.1 and 12.2 deal with flow relationships for the parallel-plate and circular tube channels using Newtonian (N), Power Law (P), and Ellis (E) model fluids. Table 12.3 covers concentric annular channels using Newtonian and Power Law model fluids. Table 12.4 contains volumetric flow rate-pressure drop (die characteristic) relationships only, which are arrived at by numerical solutions, for Newtonian fluid flow in eccentric annular, elliptical, equilateral, isosceles triangular, semicircular, and circular sector and conical channels. In addition, Q versus AP relationships for rectangular and square channels for Newtonian model fluids are given. Finally, Fig. 12.51 presents shape factors for Newtonian fluids flowing in various common shape channels. The shape factor Mq is based on parallel-plate pressure flow, namely,... 

We consider the problem of liquid and gas flow in micro-channels under the conditions of small Knudsen and Mach numbers that correspond to the continuum model. Data from the literature on pressure drop in micro-channels of circular, rectangular, triangular and trapezoidal cross-sections are analyzed, whereas the hydraulic diameter ranges from 1.01 to 4,010 pm. The Reynolds number at the transition from laminar to turbulent flow is considered. Attention is paid to a comparison between predictions of the conventional theory and experimental data, obtained during the last decade, as well as to a discussion of possible sources of unexpected effects which were revealed by a number of previous investigations. 

The development of an hydrodynamic model involves the prediction of pressure drop, hold-up, contact areas between phases, phases ratios and residence time distributions for a given column internal. Although various predictive models are available in the open domain (see e.g. Kooijman and Taylor (2000)), the model developed by The University of Texas Separations Research Program (SRP model) (Rocha et al., 2004, 1996 Fair et al., 2000) enjoys a widespread preference within packed columns internals. Lately, the Delft model has been introduced (Fair et al, 2000) and vahdated for the case of zig-zag triangular flow channels. Note that the following descriptions are referred to a VL system. 

In the analysis of flow in nuclear reactor cores, the geometry usually consists of plates with narrow rectangular channels, rods having square or triangular subchannels with rods located at the vertices. The plates and rods have wire or grid spacers to maintain separation between plates and rods. For these geometries various expressions for friction factors are available in the literature that enables one to calculate the pressure drop in the reactor core (Rust, 1979 Todreas and Kazimi, 1990). 

The velocity and pressure distribution experiment with Montz-pak (Fig. 69) has been repeated with 10 mm spacing between the packing and the wall. This open space creates wall cannels with a cross-section twice that of the triangular gas flow channels. Compartments 1 and 17, situated below tiie wall channels, are closed to avoid the direct feeding of the wall channels. The velocity profile measured at the top and the pressure profile measured at the bottom are shown in Fig. 70. From the velocity profile it is clear that only part of the gas that reaches the wall flows back into the packing. The low velocity measured for channel 6 indicates that this is more pronounced for the bottom... 

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