Pressure drop in fluid

Figure 10-142. Pressure drop in fluid flowing across tube banks with segmental baffles. (Used by permission Buthod, A. P. Oil Gas Journal, V. 58, No. 3, 1960. PennWell Publishing Company. All rights reserved.)...

The last term is the rate of viscous energy dissipation to internal energy, Ev = jv <5 dV, also called the rate of viscous losses. These losses are the origin of frictional pressure drop in fluid flow. Whitaker and Bird, Stewart, and Lightfoot provide expressions for the dissipation function <5 for Newtonian fluids in terms of the local velocity gradients. However, when using macroscopic balance equations the local velocity field within the control volume is usually unknown. For such... 

Pressure Drop in Fluid-Fluid Microstructured Channels... 

A dimensionless ratio that relates to frictional pressure drop in fluid flow in pips, defined by D-V-p/yL for gasses and Newtonian liquids, where D is the inside pipe diameter, V is the average velocity of the fluid (= flow rate/cross-section), p is the fluid density, and p is the mass-based viscosity [Pa = kg/(m s) in SI units]. When Nile = 2,100—4,000, the character of the flow ranges from streamline (laminar) to turbulent. For Non-Newtonian liquids the criterion for flow transition by the Reynolds number is redefined. For a power-law liquid it becomes ) y-2-n / g j gn-i), g flow-behavior... 

Packing Maximum Operational C, (ft/s) Pressure Drop (in. fluid/ft)... 

The term pressure drop usually refers to the pressure loss that is not recoverable in the circuit, and it is lost energy that is dissipated into the fluid stream in the form of heat energy. The pressure drop in a flow circuit is associated with various forms of energy dissipation owing to friction, change in flow area, flow turning, and others ... 

The fluid dehvery in an air-spray system can be pressure or suction fed. In a pressure-fed system, the fluid is brought to the atomizer under positive pressure generated with an external pump, a gas pressure over the coating material in a tank, or an elevation head. In a suction system, the annular flow of air around the fluid tip generates sufficient vacuum to aspirate the coating material from a container through a fluid tube and into the air stream. In this case, the paint supply is normally located in a small cup attached to the spray device to keep the elevation differential and frictional pressure drop in the fluid-supply tube small. 

Gate valves are used to minimize pressure drop in the open position and to stop the flow of fluid rather than to regulate it. The problem, when the valve is closed, of pressure buildup in the bonnet from cold liquids expanding or chemical action between fluid and bonnet should be solved oy a relief valve or by notching the upstream seat ring. 

Common to all air cooled heat exchangers is the tube, through which the process fluid flows. To compensate for the poor heat transfer properties of air, which flows across the outside of the tube, and to reduce the overall dimensions of the heat exchanger, external fins are added to the outside of the tube. A wide variety of finned tube types are available for use in air cooled exchangers. These vary in geometry, materials, and methods of construction, which affect both air side thermal performance and air side pressure drop. In addition, particular... 

Because there are no moving parts in the Kenics mixer, only the processed materials are in motion. Therefore, the only energy required for the mixer is the energy required to overcome the pressure drop (AP). The general equation for calculating the pressure drop in an empty pipe for isothermal incompressible fluids is given by... 

For a fixed value of pressure drop, the fluid flow rate is approximately proportional to the size of the overflow diameter. A reduction in the overflow diameter leads to an increase in the pressure drop over the cyclone in order to keep the fluid flow rate unchanged. When the fluid flow rate is fixed, then, in general, the reduction in the size of the overflow diameter results in an increase in efficiency. This is simply because a small outlet opening makes it difficult for the particles to penetrate the cyclone. 

Again, an alternative approaeh to the predietion of bed pressure drop and fluid flow in porous media is to use frietion faetors (the analogue of the drag eoeffieient developed for partiele flow above). 

Tlie equation of momentum transfer - more commonly called die equation of motion - can be derived from niomentmii consideradons by applying a momentum balance on a rate basis. The total monientmn witliin a system is uiicluinged by an c.xchaiige of momentum between two or more masses of the system. This is known as die principle or law of conservation of monientmn. This differendal equation describes the velocity distribution and pressure drop in a moving fluid. 

Conversion between fluid head loss in feet and pressure drop in psi, any fluid ... 

Pressure Drop in Straight Pipe Incompressible Fluid... 

Sonic velocity will be established at a restricted point in the pipe, or at the outlet, if the pressure drop is great enough to establish the required velocity. Once the sonic velocity has been reached, the pressure drop in the system will not increase, as the velocity will remain at this value even though the fluid may be discharging into a vessel at a lower pressure than that existing at the point where sonic velocity is established. 

Scope, 52 Basis, 52 Compressible Flow Vapors and Gases, 54 Factors of Safety for Design Basis, 56 Pipe, Fittings, and Valves, 56 Pipe, 56 Usual Industry Pipe Sizes and Classes Practice, 59 Total Line Pressure Drop, 64 Background Information, 64 Reynolds Number, R,. (Sometimes used Nr ), 67 Friction Factor, f, 68 Pipe—Relative Roughness, 68 Pressure Drop in Fittings, Valves, Connections Incompressible Fluid, 71 Common Denominator for Use of K Factors in a System of Varying Sizes of Internal Dimensions, 72 Validity of K Values,... 

When a fluid flows over a stationary or moving surface, the pressure of the fluid decreases along the length of the surface due to friction. This is commonly called the pressure drop of the system. Of particular interest are the pressure drops in pipes (tubes) and in heat exchanger shells. 

---