How to get critcal point values and accentric factor from the chemsep database

[Charan]

Hello all ,
I am using ironpython in the custom unit operation to desing a simple abosrption column . I know that one already exists in dwsim. I am just designing this for learning purposes.
I have serached everywhere and cannot find a way to acess these values from the chemsep database.I need these values to calculate the k-values using the Wilson correlation .
I usually acess all other basic properties using the GetProp function.
I apologise for asking such a basic doubt but im quite helpless here.

Thank you.

[Daniel Medeiros]

Hi Charan,

You can get compound information from a material stream added to the flowsheet, i.e.

air_stream = Flowsheet.GetFlowsheetSimulationObject('MSTR-000')

air_compound = air_stream.GetPhase('Mixture').Compounds['Air']

crit_temp = air_compound.ConstantProperties.Critical_Temperature

print crit_temp

For the other properties, see: http://dwsim.inforside.com.br/api_help5/html/T_DWSIM_Thermodynamics_BaseClasses_ConstantProperties.htm

Regards
Daniel

[Charan]

Daniel ,
Thank you.

[Charan]

I used the following code to get the Bubble temperature

feed_in = ims1
temp_out =  feed_in.GetPhase('Liquid').Properties.bubbleTemperature
Flowsheet.WriteMessage(str(temp_out))

I always get a None as the output. Can u please tell me where am i making a mistake ?

[Daniel Medeiros]

This variable is just a placeholder for the calculated value when you force calculation of bubble and dew points for all streams in the flowsheet. It is a flash algorithm setting, checked during the call to DW_CalcEquilibrium.

See here for more details: https://github.com/DanWBR/dwsim5/blob/master/DWSIM.Thermodynamics/Base%20Classes/PropertyPackage.vb#L1443

[Daniel Medeiros]

See this for a sample on how to calculate the value directly: https://github.com/DanWBR/dwsim5/blob/master/DWSIM.UnitOperations/Unit%20Operations/Pump.vb#L698