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Operating Efficiency Improvement Considerations
Published in Heinz P. Bloch, Allan R. Budris, Pump User’s Handbook, 2021
Heinz P. Bloch, Allan R. Budris
Another way to look at the flow coefficient (CV) is that it is the flow rate that will cause a one psid pressure drop across the valve or system. According to equation 4–2, the lower the pressure drop the higher the CV valve. Therefore, to improved system efficiency, control valves and piping should be selected with the highest CV values when 100 percent open. Figure 4-7 shows the shape of typical “CV vs. % Open” curves for various valve types. Gate valves (Figure 4-8) are generally used for quick open applications, although they can and are used as control valves due to their relatively high 100% Open CV values. Ball valves have the highest 100% open CV values (Figure 4-9), but do come with higher price tags. Butterfly valves tend to have lower values of full open CV (Figure 4-10), but are often used for control valves due to their low cost. Globe valves are seldom used as control valves because of their higher cost and much lower CV valves (Figure 4-11). Control valves are often offered with different trims which can change the !00% open CV values and the shape of the CV characteristic (vs. percent valve opening). Actual valve CV values can be obtained from the valve manufacturer, or from field tests.
Two-Stage Impinging-Jet Injector Flow Dynamics and Mixing: Kerosene and Hydrogen Peroxide Propellants
Published in Combustion Science and Technology, 2023
Figure 2 shows the experimental setup. It consists of pressurized tanks, a flow control unit, injectors and their alignment platform, and a data acquisition system. The flow control unit is designed to supply test liquids, as well as to modulate the mass flow rates of the impinging jets. Feed lines for fuel and oxidizer, which are metered independently, consist of run tank, ball valve, forward pressure regulator, metering valve, backward pressure regulator, and solenoid valve. The pressure difference across the metering valve can be controlled by means of a forward and a backward pressure regulator. Different flow rates are obtained by adjusting the flow coefficient (Cv) of the metering valve. The relation of the flow rate, pressure drop, specific gravity of fluid, and flow coefficient is given below.
Simplifications for hydronic system models in modelica
Published in Journal of Building Performance Simulation, 2018
F. Jorissen, M. Wetter, L. Helsen
PressureDrop is a generic component for modelling pressure drops as follows: where is the pressure difference between the two fluid ports of the component, is the mass flow rate through each of the fluid ports of the component and k is a flow coefficient that is computed using a nominal value for the pressure drop and the mass flow rate. Note that a regularization around zero flow is implemented for , where is the mass flow rate around which turbulence occurs. See Wetter et al. (2015) for more details.
Method for combining valves with symmetric and asymmetric cylinders for hydraulic systems
Published in International Journal of Fluid Power, 2018
Mário C. Destro, Victor J. De Negri
As shown in this expression, the flow coefficient can be also correlated with the discharge coefficient (), fluid density () and orifice width () according to Bernoulli’s equation. Equations (4)–(7) below use flow coefficients determined for each valve working port ( and ), which means they were determined for pressure drops through P to A or A to T and P to B or B to T, respectively.