2 replies to this topic

[gmcgough600]

Hi,

 

I'm trying to set-up a spreadsheet to do compressible flow calculations based on Perry's (Adiabatic Flow with Friction in a Duct of Constant Cross Section) but I'm not sure which value I should use for the isentropic index k in equation 6-120 (easy to use k at inlet conditions but this will be different from the average). If I was dealing with air I would simply use 1.4 but I'm dealing with natural gas which seems to vary a lot more with conditions.

 

I have attached an extract outlining this approach, Example 8 is useful but this is for air. Any advice appreciated.

[Bobby Strain]

I always use isothermal flow to simplify calculations. Results are usually close enough. You might want to search this site and you may find lots of spreadsheets. Or online. Harvey Wilson (Katmar) has some reliable, inexpensive software. If you are looking at long pipelines, you should consider other correlations.

 

Bobby

[latexman]

Crane TP410 gives k = 1.27 for natural gas.

 

P.S. No extract attached.