Tube bundles friction factor

Figure 10-137. Heating and cooling in tube bundles—tube-side friction factor. (Used by permission Kern, D. Q. Process Heat Transfer, 1 Ed., p. 836, 1950. McGraw-Hill, Inc. All rights reserved. Using nomenclature of Standards of Tubular Exchanger Manufacturers Association.)...

The friction factor, f, is determined using Figure 10-140 for shell-side pressure drop with D, used in determining R,. For bundles with hare tubes (plain tubes), f, = f/1.2 (see Figure 10-140), calculate pressure drop ... 

Figure 10-140 is used for determining the friction factor (dimensional) for segmental type baffles. The loss across the tube bundle and through the baffle window is represented in the combined factor, f, which is to be used with the equation for pressure drop. ... 

Figure 9.30. Friction factor for flow over tube bundles...

For nonisothermal flow of liquids across tube bundles, the friction factor is increased if the liquid is being cooled and decreased if the liquid is being heated. The factors previously given for nonisothermal... 

Please observe that point B pressure has increased by approximately 2 psi above the starting point E pressure, 128 psia. Why The liquid static legLF, coupled with a low piping friction loss, has caused this pressure increase. Please note, also, that point B actually extends several feet below point C. This is a canceling static leg effect since the elevation distance of A to B is equal to the elevation distance of B to C. Point C is to be taken as the point at the tube bundle face entrance. Another factor that should be realized is that the tee-fitting pressure loss is included in the segment run from point A to point B. Thus, no tee pressure losses will be counted in the run from B to C. 

Based on the observation that the friction factors for turbulent flow in rod bundles differ only little from those of circular tubes, a very simple empirical correlation was proposed [12] ... 

Because of the relatively flat velocity profile in turbulent flow, the channel geometry has only a small influence on the friction factor (as discussed in the previous section) and the Sherwood and Nusselt numbers. The turbulent Sherwood and Nusselt numbers of rod bundles can therefore be related to those of circular tubes. The few experimental data, as compiled by Ref. 6, suggest that for relative pitches between 1.1 and 2.0 (which... 

FIGURE 14.13 Effect of two-phase flow on friction factor in a tube bundle [71]. 

FIGURE 17.55 Colburn factors and friction factors for ideal crossflow in tube bundles, 90° inline layout [106]. 

In this case, A is ratio between friction factor of a bundle (A) and that of round tube (Ao), subscripts "tr" and "sq" refer to triangular and square arrays respectively, and x=s/d is relative pitch of the pin bundle. 

To transform the friction factor to a shell side pressure drop, the number of the fluid crossing the tube bundle should be given. Because the fluid crosses between baffles, the number of crosses will be one more than the number of baffles, A b- If the number of baffles is unknown, it can be determined using the baffle spacing and tube length L ... 

The basic design data consisted of the Fanning friction factor and Colburn modulus versus Reynolds number characteristics (/versus Re and i versus Re) for gas flow both normal to the tube bundle and inside the turbulated tubes. The data for flow normal to the tubes were taken from a geometrically similar surface described by Kays and London [1] in their Fig. 45 and may be expressed by the equations / = 0.285 Re and j = 0.320 Re" , where 300 < Re < 15,000. Data for the turbulated tube were obtained partly from steam-air tests on a small shell and turbulated tube heat exchanger, and partly from transient tests with nitrogen on a hollow copper cylinder which contained a turbulator. The turbulated tube is described in Fig. 4, and the basic data are shown in Fig. 6. The data may also be expressed by the equations / 0.05 and j =0.05 Re" , where Re > 6000. 

The radiator pipe is the structure through which heat is rejected to space. Wall friction is turned off in favor of representing the desired friction factor with the Reynolds number dependent form loss coefficient option in RELAP5-3D. Idel chik (Reference 12-23) Section 8-2, paragraph 15, provides an empirical relation to determine the friction factor for flow past a bundle of vertically arranged tubes uniformly distributed over conduit cross sections. For a duct that is 3.8 cm wide with heat pipes in one row that have 12.5 cm between heat pipe centers and 2.2 cm outside diameters the equation for friction factor is ... 

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