Pressure drop due to friction

To calculate the heat duty it must be remembered that the pressure drop through the choke is instantaneous. That is, no heat is absorbed or lost, but there is a temperature change. This is an adiabatic expansion of the gas w ith no change in enthalpy. Flow through the coils is a constant pressure process, except for the small amount of pressure drop due to friction. Thus, the change in enthalpy of the gas is equal to the heat absorbed. 

The pressure drop due to friction is approximately (7.1/8.1) = 0.88 or 88 per cent of the total pressure drop, that is the drop due to friction plus the change in kinetic energy. 

The pressure drop due to friction and the velocity distribution resulting from the shear stresses within a fluid in streamline Newtonian flow are considered for three cases (a) the... 

Probably the most widely used method for estimating the drop in pressure due to friction is that proposed by LOCKHART and Martinelli(,5) and later modified by Chisholm(,8 . This is based on the physical model of separated flow in which each phase is considered separately and then a combined effect formulated. The two-phase pressure drop due to friction — APtpf is taken as the pressure drop — AP/, or — APG that would arise for either phase flowing alone in the pipe at the stated rate, multiplied by some factor 2L or . This factor is presented as a function of the ratio of the individual single-phase pressure drops and ... 

The properties of the fluid are viscosity 0.99 mNM 2 s, density 998 kg/m3. Calculate the total pressure drop due to friction when the flow rate is 3500 kg/h. 

The maximum distance the styrene must travel horizontally is around 300 ft. The total distance traveled inside pipes is 390 ft. If a pressure drop of 2 psi per 100 ft is assumed, the pressure drop due to friction will be about 8 psi (20.5 ft of styrene) and that due to elevation is 90 ft. The total pressure drop is 110.5 ft. Usually for normal flow rates the pressure drop due to the change of velocity is ignored. 

Equation (10-21) represents the net total (unrecovered) pressure drop due to friction in the orifice. This is expressed as a percentage of the maximum (orifice) pressure drop in Fig. 10-5. 

Plug flow reactors mostly operate at essentially constant pressure but sometimes pressure drop due to friction is appreciable. Thus problems P4.05.30 and P4.05.29 reveal a significant effect of friction on conversion and reactor size. For flow in pipelines, the pressure drop is given by... 

The pressure drop due to frictional losses lv is proportional to pipe length L for fully developed flow and may be denoted as the (positive) quantity AP = Pi - P2. 

From equation 3.18, the pressure drop due to friction is given by ... 

The pressure drop due to friction when a fluid is flowing parallel to and outside of tubes can be calculated in the normal manner described in Chap. 14 by using a mean diameter equal to four times the hydraulic radius of the system and by including all frictional effects due to contraction and expansion. In heat exchangers, however, the fluid flow on the shell side is usually across the tubes, and many types and arrangements of baffles may be used. As a result, no single... 

For the case of flow across tubes, the following equation can be used to approximate the pressure drop due to friction (subscript o refers to outside of tubes at bulk temperature) ... 

Determination of pressure drop due to friction. Assume Ud is constant over length of exchanger... 

The pressure drop due to friction through the tube side of the exchanger is... 

Boundaries in fast fluidization refer mainly to the column wall as well as the inlet and outlet. Effect of the wall on pressure drop due to friction between the fluidized solids and the wall surface is minimal (Li et al, 1978), although it is the very cause of radial distribution of parameters. The configuration of the inlet and the outlet often strongly affect gas-solids flow, especially with regard to axial voidage profile. 

As a close approximation for most design, pressure drop due to friction between particles and the pipe wall can be neglected, for which the following equation holds between solids height and pressure drop ... 

For small acid gas injection schemes, the reservoir pressure and static head terms are the only ones of significance. In particular, it is assumed that the pressure drop due to friction is not important, although the design engineer is advised to review these factors in each case. Thus equation (9.1) reduces to ... 

Calculate the total pressure drop due to friction when the flow rate is 3500 kg/h. 

---