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Mathcad Solve Block Example

Mathcad Solve Block Example. Ch E 111 David A. Rockstraw, Ph.D., P.E. New Mexico State University Chemical Engineering Department. Typical Problem Statement:

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Mathcad Solve Block Example

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  1. MathcadSolve Block Example Ch E 111 David A. Rockstraw, Ph.D., P.E. New Mexico State UniversityChemical Engineering Department

  2. Typical Problem Statement: What size pump (HP) is required to move water at an average velocity of Vavg = 3.0 ft/s through a 1" inner diameter (D) pipe 5,000 ft in length (L)? Assume the viscosity of water is  = 0.01 poise at room temperature and the pump has an efficiency of  = 0.70. Pump Sizing Problem

  3. Anytime you are designing a piping system, you will need to estimate the friction in the system, since friction can be responsible for much of the pressure drop (p) from one end of the pipe to another. Because of this friction, you need a pump to move the fluid, and you must calculate how big the pump must be. So you have to estimate the friction losses to estimate the pressure drop to calculate the size of the pump. There are many contributing factors to pipe friction: valves, bends in the pipe, rough pipe, a buildup of deposits in the pipes, etc. Pump Sizing Problem

  4. Consider the simplest situation of a clean, horizontal, smooth pipe with no valves or bends. For most flows in such a pipe, the Fanning friction factor fcan be calculated using the von Karman equation (valid for smooth pipe for NRe > 6000), for a pipe of diameter D, and a fluid of density  and viscosity , flowing at an average velocity of Vavg.: Pump Sizing Problem

  5. Once you know the friction factor, you can calculate the pressure drop in a horizontal pipe from Once you have the pressure drop, you can determine the energy per unit mass required to overcome friction: Then you can determine the pump power (PP) required (wherem is the mass flow rate of the fluid) Pump Sizing Problem

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