Friction factor Moody chart

Determination of friction factors for some fluid flow applications can involves a trial-and-error procedure because the friction factor is not a simple function of the Reynolds number. Process engineers, therefore, refer to a Moody chart that has been developed using the following relationships ... 

In practice the friction factors are calculated either by integration of Eq. (4.51) or by reference to a Moody chart. This is based on Eq. (4.51) by using equivalent roughness values representing the sand particle roughness (see Table 4.3). 

Figure 4.4 shows the Moody chart for tubes when k = 0.03 mm, which is the case for steel tubes. Friction factors for other values of k can be attained by using the following ratio ... 

Figure 2-3. Moody or regular Fanning friction factors for any kind and size of pipe. Note the friction factor read from this chart is four times the value of the f factor read from Perry s Handbook, 6th Ed. [5]. Reprinted by permission, Pipe Friction Manual, 1954 by The Hydraulic Institute. Also see Engineering DataBook, 1st Ed., The Hydraulic Institute, 1979 [2]. Data from L. F, Moody, Friction Factors for Pipe Flow by ASME [1].

Determine friction factor, f, from Moody Friction Factor Charts, Figure 2-3. 

Equations 2-60 and 2-61 are illustrated graphically in Figure 2-21. This chart is called a Moody diagram, and it may be used to find the friction factor, given the Reynolds number and the surface roughness. 

Charts and equations describing the variation of the friction factor, /, with the Reynolds number, Rep, and wall roughness ratio, elD, where e is a measure of the roughness of the walls, are available [18],[19], [20]. A Moody chart that gives the friction factor variation is shown in Fig. 7.4. 

Chemical engineers are familiar with the Fanning (or Darcy) friction factor,/, the Moody chart of/vs. Reynolds number, Rg, and how all of this fits together to calculate pressure drop for a given fluid flow in a given sized pipe. The friction factor is calculated from the Colebrook equation ... 

The Moody chart for the friction factor for fully developed flow in circular pipes 867... 

In turbulent flow, wall roughness increases the heat transfer coefficient h by a factor of 2 or more [Dipprey and Saber.sky (1963)]. The convection heat transfer coefficient for rough tubes can be calculated approximately from the Nusselt number relations such as Eq. 8-71 by using the friction factor determined from the Moody chart or the Colebrook equation. However, this approach is not very accurate since there is no further increase in h with/for /> 4/sn,ooih [Norris (1970)1 and correlations developed specifically for rough tubes should be used when more accuracy is desired. 

The friction factor corresponding to this relative roughness and the Reynolds number can simply be determined from the Moody chart. To avoid the reading error, we determine it from the Colebrook equation ... 

Table A-2 Boiling and freezing point properties 843 Table A-3 Properties of solid metals 844 846 Table A-4 Properties of solid nonmetals 847 Table A-5 Properties of building materials 848-849 Table A-6 Properties of insulating materials 850 Table A-] Properties of common foods 851-852 Table A-8 Properties of miscellaneous materials 853 TableA-9 Properties of saturated water 854 Table A 10 Properties of saturated refrigerant-134a 855 Table A-11 Properties of saturated ammonia 856 Table A-12 "Properties of saturated propane 857 Table A-13 Properties of liquids 858 Table A-14 Properties of liquid metals 859 Table A- 5 Properties of air at 1 atm pressure 860 TableA-16 Properties of gases at 1 atm pressure 861-862 Table A-17 Properties of the atmosphere at high altitude 863 Table A-18 Emissivities of surfaces 864-865 Table A-19 Solar radiative properties of materials 866 Figure A-20 The Moody chart for friction factor for fully developed flow in circular pipes 867...

The Moody chart for the friction factor for fully developed flow in circular pipes for use in the head loss relation -----. Friction factors in tlie turbulent flow... 

Figure 4.2 gives the Moody Friction Factor Chart. This chart allows Ito be read as a function of pipe roughness, e, divided by pipe diameter (e/D, the so called relative roughness) and the Reynolds number (Re= Dvp/p), where p is the viscosity of the fluid. One can also solve the Colebrook equation iteratively to find f ... 

For turbulent flows, the friction factor is a function of both the Reynolds number and the relative roughness, where s is the root-mean-square roughness of the pipe or channel walls. For turbulent flows, the friction factor is found experimentally. The experimentally measured values for friction factor as a function of Re and are compiled in the Moody chart [1]. Whether the macroscale correlations for friction factor compiled in the Moody chart apply to microchannel flows has also been a point of contention, as numerous researchers have suggested that the behavior of flows in microchannels may deviate from these well-established results. However, a close reexamination of previous experimental studies as well as the results of recent experimental investigations suggests that microchannel flows do, indeed, exhibit frictional behavior similar to that observed at the macroscale. This assertion will be addressed in greater detail later in this chapter. 

Method for calculation of major losses of liquids. First determine fluid properties such as the density, and dynamic viscosity at the operating temperature. Determine the inner diameter of the pipe, and evaluate its absolute roughness based on Table 20.3. Then calculate the Reynolds number for average velocity of the liquid. Afterwards, either use the Moody chart to evaluate the Fanning friction factor based on the Reynolds number and relative roughness, or compute the Colebrook equation by successive iterations. Finally, use the Darcy-Weisbach equation to determine the friction head loss. 

We now have to thank Stanton and PanneU, and also Moody for their studies of flow using numerous fluids in pipes of various diameters and surface roughness and for the evolution of a very useful chart (see Fig. 48.6). This chart enables us to calculate the frictional pressure loss in a variety of circular cross-section pipes. The chart plots Re)molds numbers (Re), in terms of two more dimensionless groups a friction factor < ), which represents the resistance to flow per unit area of pipe surface with respect to fluid density and velocity and a roughness factor e/ID, which represents the length or height of surface prelections relative to pipe diameter. 

For turbulent flow, numerous correlations exist for both smooth and rough-walled pipes. A number of charts have been prepared such as those by Moody, and by Stanton and Pannell, in which friction factor is correlated against Reynolds number for differing pipe surface roughness. Itisimportantto note thatthisFanningfrictionfactorhasavalueof one-quarter of the Darcy friction factor. 

Moody plot, chart, diagram A dimensionless representation of friction factor with Reynolds number tor a fluid flowing in a pipe. Presented on log-log scales, the diagram includes laminar, transition, and turbulent flow regimes. It also includes the effects of pipe relative roughness as a dimensionless ratio of absolute roughness with internal pipe diameter. The plot was developed in 1942 by American engineer and professor of hydraulics at Princeton, Louis Ferry Moody (1880-1953). 

The friction factor, f, can be determined from the Moody chart (Figure 2.2) or Swamee and Jain alternative equation. 

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