Thursday, August 1, 2019

Piping : Pressure Drop Calculations Excel Calculator (Most Important Excel Sheet)


Description 
This Pressure Drop Calculator is designed for Newtonian Liquids and is for general use. The methods used are Hooper's 2K and Darby's 3K method as they give the better curve fits for pressure loss  vs k factor data for various fittings. The advantage with both the methods is that K values are compensated  for change in Reynolds Number and pipe internal diameter as well, unlike other famous methods.
This compensation brings more accuracy to the pressure drop calculation at any flow rate.  User can input the Pipe ID from the standard drop down list or use their own data Please check that proper option is chosen to input the pipe diameter .Though the spreadsheet takes input parameters in metric system, the corresponding calculated values in IP system give a clue to the user if they are not comfortable with metric system .

The friction factor is calculated using Poiseuille's equation for laminar flow and Colebrook's equation
for transitional and turbulent flows. However, Katmar's (fellow member at eng-tips.com) version of Churchill  be used as one single equation for all kinds of flow. I must appreciate Katmar (Harvey) for this.
I personally opine that, as both Hooper's and Darby's methods give better pressure loss values when compared  with conventional methods, collective data can be used for final pressure drop calculation, in the absence of  suitable correlations. For ex. as there are no correlations of K, incase of Darby, for miters other than 2 welds  and also for reducers, expanders and orifices, Hooper's values can be included to the final value of Darby's. I didn't include this in my calculation, at this juncture, and it is users discretion to use any other suitable method or logic.

This calculator is comfortable with single pipe size and I suggest, if there is a variation of pipe size, to  calculate the sections independantly. In a nut shell, my suggestion is not to calculate reducer and expander  pressure drops in a single step.

The friction factor worksheet calculates Darcy's friction factor by Colebrook's equation. However,
When dealing with Colebrook's equation, 5 steps of iteration are generally sufficient. I also included other explicit equations for the calculation of friction factor, based on the article Estimate friction factor accurately by TK Serghides appeared in March' 84 volume of Chemical Engineering Magazine.

Calculations we can do with this Excel Sheet :-
  • Pressure Drop Calculator 
  • Friction Factor Calculator
  • Comparison of Friction Factor
  • Hooper's 2-K Calculations
  • Darby's  3-K Calculations
  • Pipe Size Data
  • Pump Power Calculations
Download the Excel sheet πŸ‘‡πŸ‘‡πŸ‘‡ 
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