CALCULATING STATIONARY GRAVITATIONAL FLOW IN PIPE USING EXCEL

CALCULATING STATIONARY GRAVITATIONAL FLOW IN PIPE USING EXCEL

The Bernoulli, Darcy, and Churchill equations (for calculating the friction factor) are implemented in Excel for calculating stationary gravitational flow. These equations are presented below:

Substituting equations (3) and (2) into (1), we get the equations (4a) and (4b):

The trancendental equations (4a and 4b) can be solved by Excel Solver tool.

If the Reynolds number > 4000 (turbulent flow), the spreadsheet considers the friction factor calculated by the equation 3, otherwise f = 64 / Re.

Example: Consider the figure, determine for the pipe section: v2 (m/s), Q (m3/h) and DP (kgf/cm2).

Solution:

Implement the equations in Excel and solve by: What-if Analysis - Goal Seek (see figure to Microsoft Excel).

The results are compared with the AFT Fathom 5.0 software:

Equations 1, 2, 3            AFT Fathom 5.0

 v2 = 3,13 m/s               v2 = 3,29 m/s      

Q = 92,7 m3/h               Q = 97,4 m3/h

DP = 0,56 kgf/cm2        DP = 0,61 kgf/cm2

Note: AFT Fathom 5.0 use Colebrook-White equation to obtain friction factors in the turbulent flow regime.


Download link to spreadsheet:

https://drive.google.com/open?id=0B0ClBxIeH9j2SWNYRUdUOW9KLVU

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