Pipe flow, pressure drop

FIGURE 10J1 Experimental pipe flow pressure drop measurements for purely viscous nonnewtonian fluids by Yoo [13] dashed lines extrapolated from Eq. 10.65. 

An innovation is a direct-contact condenser mounted on the vapor body. A short piece of vertical pipe connects the vapor body with the condenser to minimize piping and pressure drop. This design also eliminates structural steel for support of a separate condenser. For cooling tower applications, the hotwell is elevated to permit gravity flow of water from the hotwell to the top of the cooling tower, thus eliminating the need for a pump. 

The backpres.sure created by this drum is an additive to the pipe manifold pressure drops and the pressure loss through the separator. Therefore, it cannot be independently designed and not integrated into the backpressure system. The flow capacity of the relief valve(s) must... 

For liquids flowing in pipes the pressure drop is commonly taken proportional to a power of the flow rate, usually around 2. One of the simplest correlations used in water distribution network calculation is the Hazen-Williams formula,3... 

If one desires to design a pilot scale tubular reactor to operate isothermally at 500 °C, what length of 6-in. pipe will be required to convert 90% of the raw feedstock to methyl acrylate The feedstock enters at 5 atm at a flow rate of 500 lb/hr. Ideal gas behavior may be assumed. A 6-in. pipe has an area of 0.0388 ft2 available for flow. Pressure drop across the reactor may be neglected. 

The steady flow pressure drop in the pipe can be deduced from a momentum balance on a differential slice of the fluid-particle mixture in a... 

It is important to be able to predict at just what level of t in the inlet cone the slurry begins to consolidate into an ice bed with brine flowing through it. If the zone at which consolidation begins is well below the level of the screens, packed ice may back up and fill the inlet pipe. The pressure drop through the ice packed in the inlet cone is important for specification of the pumping head required. 

One means to obtain a desired uniform distribution is to make the average pressure drop across the holes Ap large compared to the pressure variation over the length of pipe Ap. Then, the relative variation in pressure drop across the various holes will be small, and so will be the variation in flow. When the area of an individual hole is small compared to the cross-sectional area of the pipe, hole pressure drop may be expressed in terms of the discharge coefficient C and the velocity across the hole VD as... 

Hydraulic Losses.—The hydraulic losses are the losses in pressure caused by the gas friction and by the sudden changes in the gas velocity or direction of flow. On the basis of D. W. Taylor s experiments on the flow of air in pipes, the pressure drop in the suction and in the discharge pipes (pounds per square inch) = L = lv s/4 00,-GOOD, where I is the length of pipe, feet, v the velocity of gas, feet per second, s the specific gravity of gas referred to free air (0.0764) as unity, and D the diameter of pipe, inches. For pipes of first-class workmanship and in very best condition, this loss may be reduced by about 20 per cent. The same care to have smooth pipe walls and to avoid too short bends should be taken with gases as with liquids. 

With cylindrical pipes also the pres sure drop with a laminar flow may be expressed by formula (2). The value which must here be ascribed to was found to be 0.51 independently of the radius r of the pipe, at any rate between r = 0.35 mm. and 0.92 mm. Thus with cylindrical pipes the pressure drop with a laminar flow is determined by... 

First, consider the flow of an incompressible fluid in a straight pipe. The pressure drop is a function of the density and viscosity of the fluid, the average velocity of the fluid, and the diameter and length of the pipe. The relationship is usually expressed by means of a friction factor defined as in Eq. (1) ... 

R. C. Xin, A. Awwad, Z. F. Dong, and M. A. Ebadian, An Experimental Study of Single-Phase and Two-phase Flow Pressure Drop in Annular Helicoidal Pipes, Int. J. of Heat and Fluid Flow, in press. 

An oil with a kinematic viscosity of 4.3 cSt and a specific gravity of 0.80 is flowing in a 3-in pipe. The pressure drop per 1000 ft is 30 psig. What is the flow rate in gallons per minute ... 

Friction in pipes. For straight horizontal pipes resistance to flow arises because of viscous shear or friction at the wall. Dimensional analysis leads to the conclusion that for smooth pipes the pressure drop (scaled to make it dimensionless) is a function only of the Reynolds number. The dimensionless group containing the pressure drop is known as the friction factor ... 

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