Pressure Drop Equations for Compresible Fluids
Pressure Drop Equations for Compresible Fluids
(OP)
Good Morning,
I have been reading about the expressions used to calculate the pressure drop in gas lines and mainly this thread:
thread 378-242585
Mr Montemayor uses for his calculations -in the spreadsheet- the expresion given in "Transport Processes and Unit Operations" by Geankoplis.
Mr Katmar said that Weymouth and Panhandle equations are old and they have a difficulty for beginners: the choose of the efficiency factor E. He recommends to use equation 2.7 from BigInch's document (the document appears in that thread).
Well my question is about the AGA equations. The GPSA Engineer Data Book (12th Edition) and the Exxon Company
recommends to use that equations calculations; however in the Journal of Petroleum Science and Engineering 14-1996 (page 137-158), the authors said that AGA Equations introduce erros with the elevations changes.
Now I am using AGA equations for my calculations but I would like to know if it is better to change the expressions?
(Usually I do not work with gas, so I do not have experience about the accuracy of these equations.)
Thank you,
Lij
I have been reading about the expressions used to calculate the pressure drop in gas lines and mainly this thread:
thread 378-242585
Mr Montemayor uses for his calculations -in the spreadsheet- the expresion given in "Transport Processes and Unit Operations" by Geankoplis.
Mr Katmar said that Weymouth and Panhandle equations are old and they have a difficulty for beginners: the choose of the efficiency factor E. He recommends to use equation 2.7 from BigInch's document (the document appears in that thread).
Well my question is about the AGA equations. The GPSA Engineer Data Book (12th Edition) and the Exxon Company
recommends to use that equations calculations; however in the Journal of Petroleum Science and Engineering 14-1996 (page 137-158), the authors said that AGA Equations introduce erros with the elevations changes.
Now I am using AGA equations for my calculations but I would like to know if it is better to change the expressions?
(Usually I do not work with gas, so I do not have experience about the accuracy of these equations.)
Thank you,
Lij





RE: Pressure Drop Equations for Compresible Fluids
Errors introduced with elevation changes on a single-phase gas line are absolutely not within the accuracy of the data gathered and are safely ignored. This is true of AGA and of the dominant "simplified" versions.
If I have significant liquid in a gas line then I use the Duckler correlation for two phase flow and the Flannigan correlation for positive elevation changes.
I've compared these three equations to a lot of actual field data and they consistently stand up very well. All of the pipeline models that have passed my "calibration test" start with these three equations. The "true" multi phase flow processes have not matched field data as well as the AGA equation with adjustments for friction and elevation in the high-liquid case.
David
RE: Pressure Drop Equations for Compresible Fluids
I will continue with AGA equation.
Regards,
Lij
RE: Pressure Drop Equations for Compresible Fluids
the AGA equations also uses an efficiency factor "E". Usually I take 0.90, but I am not sure about this (I think this is the point of Mr Katmar).
Do you have any reference about "E"?
Regards,
Lij
RE: Pressure Drop Equations for Compresible Fluids
David
RE: Pressure Drop Equations for Compresible Fluids
Regards,
Lij