Economic Velocity
Pipe flow velocity that results in the minimum total cost of building and operating a particular piping system.
FluidFlow uses the Generaux equation to calculate economic velocity. This calculation requires not only process conditions, fluid properties, and pipe system details, but also considers installation costs, maintenance expenses, depreciation, energy costs, booster efficiency, and tax implications.
V = \frac{4}{\pi D^2} \cdot K^{1/(2.84)}
K = \frac{D^{(4.84+n)} \cdot nXE(1+F)[Z+(a+b)(1-\phi)]}{(1+\frac{0.794L_e’}{D})(0.000189YK\rho^{0.84}\mu^{0.16})[(1+M)(1-\phi)+\frac{ZM}{(a’+b’)}]}
M= (a^′+b^′)(E∙P)/((17.9 K∙Y) )
n= (Log C-Log X)/(Log D)
Where:
| a | Fractional annual depreciation on pipeline, dimensionless |
| b | Fractional annual maintenance on pipeline, dimensionless |
| a’ | Fractional annual depreciation on pumping installation, dimensionless |
| b’ | Fractional annual maintenance on installation, dimensionless |
| C | Installed cost of pipeline including fittings, $ / feet |
| D | Inside pipe diameter, feet |
| E | Combined fraction efficiency of pump and motor, dimensionless |
| F | Factor for installation and fitting, dimensionless |
| K | Energy cost delivered to the motor, $ / kWhr |
| Le’ | Factor for friction in fitting, equivalent length in pipe diameter per length of pipe, 1 / feet |
| M | Factor to express cost of piping installation in terms of yearly cost of power delivered to the fluid, dimensionless |
| n | Exponent in pipe-cost equation, dimensionless |
| P | Installation cost of pump and motor, $ /hp |
| Q | FluidFlow, ft3/s |
| S | Cross sectional area, ft2 |
| V | Velocity, feet / sec |
| X | Cost of 1 ft of 1 ft diameter pipe, $ |
| Y | Operating days |
| Z | Fractional rate of return of incremental investment, dimensionless |
| Φ | Factor for taxes and other expenses, dimensionless |
| ρ | Flow density, pounds/ ft3 |
| µ | Fluid Viscosity, cP |
Related definitions
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