Add a static pipe model for comparison

[marcusfuchs]

As discussed in the past, it is possible to model static pipe behavior within a model structure similar to the newly developed pipe model. This needs 2 changes

• change heat loss model to calculate heat losses based on current velocity instead of travel time of fluid parcels
• replace plug flow model with hydraulic resistance

I'll add such a model for comparison and reference.

@GersHub sorry for the long delay in getting to this.

[marcusfuchs]

@GersHub I added the static model to the branch pipe_issue76_static. Please raise any issues or questions you may encounter.

[marcusfuchs]

@bramvdh91 @GersHub I'm playing around with JModelica, and in the current implementation of HeatLossPipeStatic I get a type error on

Tin_a = Medium.temperature_phX(
    port_a.p,
    inStream(port_a.h_outflow),
    inStream(port_a.Xi_outflow));

Any objections to changing this to

  Tin_a = Medium.temperature_phX(
    port_a.p,
    inStream(port_a.h_outflow),
    Medium.X_default);

?

[k-sartor]

No if it works on both platform. Any idea for the origin of the error?

-----Message d'origine----- De : "marcusfuchs" notifications@github.com Envoyé : ‎04-‎07-‎17 21:55 À : "bramvdh91/modelica-ibpsa" modelica-ibpsa@noreply.github.com Cc : "Subscribed" subscribed@noreply.github.com Objet : Re: [bramvdh91/modelica-ibpsa] Add a static pipe model for comparison(#76)

@bramvdh91 @GersHub I'm playing around with JModelica, and in the current implementation of HeatLossPipeStatic I get a type error on Tin_a = Medium.temperature_phX( port_a.p, inStream(port_a.h_outflow), inStream(port_a.Xi_outflow));Any objections to changing this to Tin_a = Medium.temperature_phX( port_a.p, inStream(port_a.h_outflow), Medium.X_default);? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[marcusfuchs]

Haven't looked too deep into this, but I guess it has something to do with how JModelica and Dymola handle the mass fractions of a medium. Modelica.Media.UsersGuide.MediumUsage.BasicUsage gives a bit of information on this, including

If a fluid consists of a single substance, nXi = 0 and the vector of mass fractions Xi is not present.

Therefore, JModelica could be correct in returning an empty value of type Real[0] for inStream(port_a.Xi_outflow) with a single-substance water medium, raising an error as Medium.temperature_phX expects an input of type Real[1] for X. Dymola on the other hand seems to tolerate this.