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PRO- II beginners help 1

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GasProcess

Petroleum
Oct 14, 2003
33
I have started working on PRO - II recently. While making a simulation for water pumping system I came across an error as under:
"Liquid viscosity, vapor viscosity, and surface tension methods are required by the pipe unit. Ensure that methods are declared for them in the thermodynamic method set assigned to this pipe unit."

I have assigned "Braun K10" as thermodynamic method.

What does this error indicate and what other thermodynamic method is to be assigned if any

 
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In proII you have to explicitly call for calculating the socalled "transport properties". If you select the thermo model, press the "modify"-button after having chosen. There, click on "transport properties" and tick the checkbos "calculate transport properties". choose whatever method you'd prefer. then it should work fine.

As a side remark, for our purpose, the "pure component average" method is giving sufficiently accurate results.

hth,
chris
 
This is found in the Thermo section selection....

Stick with it -- Pro II has a steep learning curve -- almost a cliff, but after about 2 weeks you will come to appreciate how powerful a program it is.

AND DO NOT HESITATE TO CALL THE HELP DESK!!!! TYPICALLY THEY ARE EXCELLENT>>>>
 
Thanks Phex

It was realy helpful. Is there any rule / way to select a perticular property calculation method.There are so may of the methods available for selection. Or am I suppose to mug up names of all the methods that can be used for a perticular system
 
the different thermodynamic property methods have their "special fields". Typically, if you work in a vapor or vapor/liquid system, you should choose an equation of state type, if you are basically only in liquid phase, try the activity models (in this case, i consider a column to be a liquid system).
The pressure of the system is another very important factor. the srk-model in its unmodified version should for example be used only upo to 1 bar g pressure.
some other rules of thumb:
if you have hydrogen in your system, choose the "improved grayson streed" model. If you have alcohols (or other polar components), choose nrtl with unifac fill option (fill option can also be set by pressing the "modify"-button in the thermo dialog, then chose "enter data" behind the different main property categories).
Generally, i would recommend to try at least two different thermo systems on a problem and choose the worst case for design. Try to look via google, there are heaps of different opinions on which thermo to choose. you will get a feeling for this by evaluating the results and the amount of time needed to find the solution. keep on trying.
as for the "transport properties", i tend to stick to the "pure component average" method. it is the simplest, but has not yet mispredicted in a significant way.

hth,
chris

PS: remember, this is just my opinion. others will differ quite substantially from this point of view. you will need to do some "testing" for yourself at this point.
 
Once again thanks a lot Phex. You are very considerate and helpful. I will try as sugested. Thanks again
 
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