2 replies to this topic

[stu]

Dear all,
Will you please explain me, In hysys while simulating pipeline, we specify the pipe dia, length etc.,.but there is another one called increments. Please explain what is increments, where it plays a role & then how we fix it.
Thanks
Stu

[Padmakar Katre]

Dear,
The increments on the Rating Tab-Sizing Button of the Pipe Segment property View is used to divide the segment in equal parts for calculation purpose. Its you could say in other words its an attempt to approach to know the conditions over the length of the pipe at different locations.

[JoeWong]

Padmakar,
Good explanation.

stu,
It is mean to increase the accuracy of your estimation. The more you cut, the more accurate you will get. All this relates to density change...

Some tips may consider...
For incompressible fluid i.e. water, the density change is insignificant. The results i.e. pressure drop may not significant for 1 segment or 1000 segment.

For compressible fluid i.e. air, HC vapor, etc, the density change is pretty significant with the in-situ pressure and temperature.

There are only two common conditions where one can treat a gas/vapor as an incompressible fluid.

(1) The total pressure drop in the system is less than 10% of the upsteam pressure. In this case, the density will be fairly constant and this is why you can treat the gas/vapor as an imcompressible fluid. You may consider 1 segment.

(2) The total pressure drop in the system is less than 40% of the upstream pressure. In this case you must use the average density between the upstream and downstream conditions.

If you would like to obtain more accurate results, then slice them more to obtain a better estimation.