Fanning pressure drop equation

The relative pressure drop, AP, expression is based on the Fanning pressure-drop equation ... 

VALUE OF a, CONVERSION FACTOR IN THE FANNING PRESSURE DROP EQUATION... 

The pressure drop equation Eq. (c) not only accounts for friction losses in the straight portions and in the bends of the coil but also for changes in momentum. The first term in the brackets on the right-hand side arises from the Fanning equation, the second from Nekrasov s equation [20] for the additional pressure drop resulting from the curvature in the bends. Furthermore, since... 

The pressure drop equation (9.3.2-3) accounts for friction losses in the straight part of the coil according to the Fanning equation and to the additional loss in the bends, according to Nekrasov s equation [1969]. Furthermore,... 

The friction factor / now remains to be specified. The pressure drop equation, (11.5.1-3), requires special attention, it differs from the Fanning equation, in which the right-hand side is multiplied by 2. When a friction factor is substituted into (11.5.1-3), special care has to be taken to check from which type of pressure drop relation /was derived. Further, the units have to be handled with care. Equation (11.5.1-3) is written for S.i. units, with pt m Pa = N/m/ With other units, the right-hand side has to be multiplied by a conversion factor. When engineering units are used for pt (kg force/m = N x 9.81), the right-hand side has to be divided by g (mVs). 

Since heat exchangers cannot be designed or constructed without considering pressure drop, the number of velocity heads, NVH, is a useful concept in conjunction with the NTU. The pressure drop equation for fluids flowing inside of tubes, based on the Fanning friction factor, may be written as... 

This correlation is good for a Reynolds number range of between 2,100 and 10 . The Fanning equation for pressure drop is ... 

For a special fan situation, a straight air duct of uniform cross-sectional area is used on the leaving side. The outgoing velocity Cj is the same as the fan leaving velocity C2. The only minor loss is the outgoing loss = pcT Another part of the pressure drop is the frictional pressure drop Ap, . Equation (9.127) gives... 

Solution. Draw into the iv diagram the characteristic curve of the fan and the duct-pressure-drop volume flow dependency. The latter is a parabola passing through the origin with the following equation ... 

This equation shows that the operating pressure drop is proportional to the square of the filtering velocity. For a fixed set of operating conditions, increasing filtering velocity to reduce the size of the collector will result in increases in pressure drop, fan power costs, and penetration and probably reduction in bag life. 

It should be noted that Equations 13.9 and 13.10 apply to smooth pipes, whereas the pipes used for transmission of fluids usually have some surface roughness, which increases the friction factor. However, for short fluid transmission pipes, the overall pressure drop is usually dominated by the pressure drop in the pipe fittings (valves, bends, etc). Thus, for short transmission pipes, there is little point in calculating the straight pipe pressure drop accurately. If the transmission pipe is long (>100 m) and straight, then the Fanning friction factor can be correlated as7 ... 

For a fan the changes in pressure and temperature are small enough that the incompressible fluid flow equations given for pumps may be used. In fact, for most gas systems, if the pressure drop is less than 40% of absolute upstream pressure the fluids can be treated as incompressible.30... 

Bubbly flow. In bubbly flow, the holdup is generally known and/or near homogeneous flow condition exists, and the frictional pressure drop can be correlated through similarity analysis (Dukler et al., 1964). The development shows that the frictional loss is expressed by a Fanning-type equation,... 

A number of equations have been proposed for use in the calculation of pressure drop in coils of constant curvature [Srinivasan et al (1968)]. The latter are known as helices. For laminar flow, Kubair and Kuloor (1965) gave an equation for the Reynolds number range 170 to the critical value. In terms of the Fanning friction factor, their equation can be written as... 

Equation 2.73 is another way of writing equation 2.13 where, in this case, the pressure drop is expressed in height of fluid instead of in force per unit area. In equation 2.73, de is the equivalent diameter defined as four times the cross-sectional flow area divided by the appropriate flow perimeter,/is the Fanning friction factor for flow in an open channel and u is the mean velocity. Combining equations 2.72 and 2.73, and solving for u gives... 

An ideal gas in which the pressure P is related to the volume V by the equation PV = 75 m2/s2 flows in steady isothermal flow along a horizontal pipe of inside diameter d, = 0.02 m. The pressure drops from 20000 Pa to 10000 Pa in a 5 m length. Calculate the mass flux assuming that the Fanning function factor/= 9.0 x 10 3... 

By analogy to single-phase flow, the two-phase frictional pressure-drop can be expressed by the conventional Fanning equation, and thereby a friction factor is defined. These friction factors may be based on liquid properties, gas properties, or on a fictitious single fluid of mean properties obtained by some averaging procedure. Typical definitions, such as those shown in equation (32), have been given and discussed recently by Govier and Omer (G4) ... 

Equation (11) states that the conventional Fanning friction factor, which may be used through Eq. (10) to calculate pipe-line pressure drops, is a unique function of two dimensionless groups for Bingham-plastic fluids. Newtonian fluids represent that special case for which r , and hence the second dimensionless group, is equal to zero. 

The pressure drop AP (Pa) in turbulent flow of an incompressible fluid with density p (kg m ) through a tube of length L (m) and diameter d (m) at an average velocity of v (m s ) is given by Equation 2.10, namely, the Fanning equation ... 

It is convenient to express the pressure drop for heat exchangers in a form similar to the Fanning equation as presented in Chap. 14. Because the transfer of heat is involved, a factor must be included for the effect of temperature... 

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 pressure drop for flow through the gas passages resulting from momentum transfer from the flowing gas to the stationary screen-enclosed catalyst slabs follows from the general Fanning equation... 

The equipment used to compress a gas through a process piping system is different from that used for liquids. At low pressure drops, a simple fan may be adequate. At higher pressure drops, multistage compressors are commonly used. The different types of compressors and guidelines for their selection are discussed in Chapter 10, Section 10.12. Equations for the power consumed in gas compression are given in Section 3.13. 

The Fanning friction factor may be approximated as 0.003 since > 20,000. See Chapter 6 for additional details. Using Bernoulli s equation, the pressure drop in the duct is... 

---