4 replies to this topic

[SaintOlav]

Hi Everyone,

I'm building a dynamic simulation to simulate a blocked outlet scenario with PSVs using the HEM method. Using the built-in RV in hysys and specifying "HEM" as the calculation method would lead to having a very aggressive and sometimes wrong relief flowrate when the scenario is applied to the system (Error attached ) I was wondering if anyone has done/knows any example of HEM calculation as user variable in Hysys so that I can build my own method in the background of a valve and use it as PSV.

Any help would be appreciated!
Cheers,
 

 

Attached Files

•  Error.png   480.63KB   3 downloads

[Pilesar]

Consider whether this article might offer a useful path for your calculations: https://www.chemengo...ves-two-phases/

[PaoloPemi]

SaintOlav,

it may depend from the specific application of HEM method...

if you wish to use HEM to design / rate a nozzle (PSV)  there are many threads on cheresources which can help, see for example

 

https://www.cheresou...ng-temperature/   which contains a VBA code,

 

you can adopt HEM (Homogeneous Equilibrium Model, meaning vapor and liquid at equilibria traveling at same speed) for solving several problems, for example to evaluate critical two-phase flow in piping (you calculate the speed of sound in two phases flow) etc.

 

Note that there are several variants including slip, frozen flow etc. just to mention a few, my copy of Prode Properties includes HEM, HNE-DS, NHNE,.. and each model has specific fields of application (again, there are threads at cheresources discussing this)

Edited by PaoloPemi, 17 February 2023 - 10:23 AM.

[breizh]

Hi,

Consider reading these papers. 

[SaintOlav]

SaintOlav,

it may depend from the specific application of HEM method...

if you wish to use HEM to design / rate a nozzle (PSV)  there are many threads on cheresources which can help, see for example

 

https://www.cheresou...ng-temperature/   which contains a VBA code,

 

you can adopt HEM (Homogeneous Equilibrium Model, meaning vapor and liquid at equilibria traveling at same speed) for solving several problems, for example to evaluate critical two-phase flow in piping (you calculate the speed of sound in two phases flow) etc.

 

Note that there are several variants including slip, frozen flow etc. just to mention a few, my copy of Prode Properties includes HEM, HNE-DS, NHNE,.. and each model has specific fields of application (again, there are threads at cheresources discussing this)

Thanks a lot Paolo! I started writing my own HEM calculation to calculate the relief rate. I was wondering if you have any advice on how to get the parameters based on the integreator time in dynamic mode. For example pressure at sim. time = 1 min and at sim. time = 1.1 min. So that I can make the vdp integral in order to get the max flux.

Cheers,
Amir