Pumping pressure drop

Liquid viscosity data are needed for the design of fluid transport and mixing processes (e.g., pumps, pressure drops in pipes or pipelines, and stirred vessels) and have a significant influence on the effectiveness of heat exchangers and diffusion processes. The required accuracy for viscosity calculations is lower than for thermodynamic properties, but the correct order of magnitude must be met. 

While on the design page, click on Parameters to enter the pressure drop in the line before the pump (pressure drop = -19.3 kPa). The negative sign indicates the pressure rise due to the negative elevation of first pipe segment. 

The dispersed oil droplet size distribution may vary from point to point in a produced water system, and from one system to another. The size distribution is affected by interfacial tension, turbulence, temperature, system shearing (pumping, pressure drop across pipe fitting, etc.), and other factors. The droplet size distributions should be measured in the field when troubleshooting and/or upgrading systems, whenever possible. 

This property should also be within precise limits. In fact, a too-viscous fuel increases pressure drop in the pump and injectors which then tends to diminish the injection pressure and the degree of atomization as well as affecting the process of combustion. Inversely, insufficient viscosity can cause seizing of the Injection pump. 

The measurement of a crude oil s viscosity at different temperatures is particularly important for the calculation of pressure drop in pipelines and refinery piping systems, as well as for the specification of pumps and exchangers. 

Fig. 41(A) and (b), p. 65) into which the ethereal extract is allowed to run from a dropping-funnel at approximately the rate at which the solvent is distilling. When the ether has been removed, fit a capillary tube and thermometer, and continue the distillation at water-pump pressure. The diethyl ester of collidine-3,5-dicarboxylic acid (II) distils as a pale golden oil, b.p. i76 178°/i4 mm. Yield, 5 g. from 6 g. of the ester (I). 

The so-called hyperbar vacuum filtration is a combination of vacuum and pressure filtration in a pull—push arrangement, whereby a vacuum pump of a fan generates vacuum downstream of the filter medium, while a compressor maintains higher-than-atmospheric pressure upstream. If, for example, the vacuum produced is 80 kPa, ie, absolute pressure of 20 kPa, and the absolute pressure before the filter is 150 kPa, the total pressure drop of 130 kPa is created across the filter medium. This is a new idea in principle but in practice requires three primary movers a Hquid pump to pump in the suspension, a vacuum pump to produce the vacuum, and a compressor to supply the compressed air. The cost of having to provide, install, and maintain one additional primary mover has deterred the development of hyperbar vacuum filtration only Andrit2 in Austria offers a system commercially. 

Friction Coefficient. In the design of a heat exchanger, the pumping requirement is an important consideration. For a fully developed laminar flow, the pressure drop inside a tube is inversely proportional to the fourth power of the inside tube diameter. For a turbulent flow, the pressure drop is inversely proportional to D where n Hes between 4.8 and 5. In general, the internal tube diameter, plays the most important role in the deterrnination of the pumping requirement. It can be calculated using the Darcy friction coefficient,, defined as... 

Fluid Temperature, °C Minimum velocity, m/s Pumping rate factor Pressure drop factor Outside tubes Inside tubes... 

By changing the role of the piezoelecttic crystal from regulating drop formation to propelling drops, the need for high pressure ink-pumping systems, drop charging and deflection systems, and waste ink plumbing systems were eliminated. 

Optimum Pressure Drop. For most heat exchangers there is an optimum pressure drop. This results from the balance of capital costs against the pumping (or compression) costs. A common prejudice is that the power costs are trivial compared to the capital costs. The total cost curve is fairly flat within 50% of the optimum (see Fig. lb), but the incremental costs of power are roughly one third of those for capital on an aimualized basis. This simple relationship can be extremely useful in quick design checks. 

Cavitation. The subject of cavitation in pumps is of great importance. When the Hquid static pressure is reduced below its vapor pressure, vaporization takes place. This may happen because (/) the main stream fluid velocity is too high, so that static pressure becomes lower than vapor pressure (2) localized velocity increases and static pressure drops on account of vane curvature effect, especially near the inlets (J) pressure drops across the valve or is reduced by friction in front of the pump or (4) temperature increases, giving a corresponding vapor pressure increase. 

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. 

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