5 replies to this topic

[Caggese]

Dear All,

 

I'm a beginner of hysys

 

I have a compressor and I need to insert a curve Power vs Flow rate (instead of a single value of power)..

 

I open the window of the compressor characteristics, I choose the tab ''rating'' and then curves, but if I add a new curve, the only variables I can complete are: head, volumerate and efficiency..

 

How can I add the variable ''POWER''?

 

thank you..

 

 

[Bobby Strain]

HYSYS will calculate the power.

 

Bobby

[Caggese]

In the tab "Design"-->"Parameter" I should insert the value of duty.  I'd like to insert not a single value but several values, namely a curve..

 

In order to do this I'd like to add a curve in the tab ''rating''-->curves, but in this way the variable ''duty'' doesn't appear..the only things appearing are head, volumerate and efficiency

 

o.

[PaoloPemi]

I am not an expert with Hysys (I use Prode Properties) but I suppose that compressors are solved in a similar way,

in design mode the simulator calculates output conditions starting from input conditions (p,t,composition), specifications (efficiency etc.).

The adiabatic or the polytropic stage model which you select is normally solved (in design mode) with a specified efficiency and the procedure calculates outlet conditions, inlet and outlet enthalpies and estimates the required power.

In rating mode the procedure estimates efficiency starting from inlet (p,t,composition) and outlet (p,t) conditions.

Usually if you know the (absorbed) power you have also inlet and outlet conditions and can calculate efficiency which is the usual approach,

if the program returns values (for absorbed power) very different from those you have measured (also considering mechanical efficiency) then it could be a problem with thermodynamics (calculated enthalpies).

[Erwin APRIANDI]

Hi Caggese,

 

What Bobby Strain & PaoloPemi has explain is correct,

Hysys will calculate the power based on the composition of the gas, flowrate, inlet conditions (P&T), outlet pressure, and efficiency

If you have curve that specify the power Vs flowrate I believe this is not valid for all compositions, since the power will be changing as the composition of gas is changing.

And based on my experience of comparing calculated power by HYSYS and in actual (for same Composition, Flowrate, Inlet and Outlet Pressure and Inlet Temperature) HYSYS calculated power is about max 3% lower, but this is in my case, different compressor may be different results.

[shan]

Compressor power is dependent variable of head, flow, and efficiency. If you want to enter a curve of power vs. flow at a constant head, you may obtain efficiency values by enter power values and flow values at the specified head in Design>Parameter. Then, you enter head, flow and efficiency values in Rating>Add Curve. The compressor will perform along power vs. flow curve you defined.