I started with 1.16.2 found this problem. I then installed the nightly build  v1.18.0-dev-5 and it too has the same problem. Thinking it was a Windows installation issue I tried installing on Mac. Even on OSX the problem persisted.

I will try 1.16.1.

Thank you.

I am a new Modelica user and was trying to work out some examples. However, the diagram view of the examples do not match the documentation and they not run either. I do not see a connection for the DynamicPipe object either. This is even after turning on the use_HeatTransfer option.

Appreciate the help.

Thanks Rene. The polynomial fit makes total sense now. However, I do have initialization problems with the pump curves. I get the following warnings for all the pumps.

"The following assertion has been violated at time 0.000000"
pumps5149.delta_head_init >= 0.0
Variable violating min constraint: 0.0 <= pumps5149.delta_head_init, has value: -30.9507"

When I try to debug I see the following equation being violated
"
    final parameter SI.Height delta_head_init = flowCharacteristic(V_flow_single_init)-flowCharacteristic(0)
        "Used for simplified initialization model";
"
How do I resolve this.

crude-train-w-5pumps.mo

As the name suggests, a desuperheater is used to change the state of steam from superheated state to saturated state. All power plants that run on a Rankine cycle use high-pressure, superheated steam to turn a steam turbine. This is true immaterial of the heat source used to generate steam.

When a steam turbine trips, the superheated steam going to the turbine has to be somehow sent to the condenser. This is done using a desuperheating system. Some desuperheaters use a series of cages to rapidly reduce the pressure of steam and have a water spray system to reduce the temperature.

I have a model with multiple pumps in series. The pumps are defined to use a polynomial pump curve. When I run the model I get the following messages

"assert | warning | <p>Wrong pump curve -- head_nominal must be monotonically decreasing with increasing V_flow_nominal</p>"

and

"assert | warning | <p>The following assertion has been violated at time 0.000000<br>
pumps5150.delta_head_init &gt;= 0.0</p>
assert | warning | <p>Variable violating min constraint: 0.0 &lt;= pumps5150.delta_head_init, has value: -38.7444</p>"

I have checked the pump curves and they seem to be correct. Also, is there to verify the coefficients of the polynomial pump curve after running the model. Please see the attached model.

Thanks in advance and appreciate the help.


Pump-curves.mo

Rene,
I made some changes based on your suggestion. The model run now but is very slow. I am not sure if any other changes can be made to speed up the analysis. Also, can we get phase as an output instead of 1 phase, 2 phase or unknown.

Gopal
1510316965_SteamHammer-DynPipe.mo

I am trying to model a steam desuperheater and  measure the temperature and phase when water is sprayed into super-heated steam. The model with StaticPipes runs and gives me mixture temperature that corresponds with the saturation temperature of Water at that pressure. However, when I switch to DynamicPipes the model does not converge. I think the mixture is partially saturated and thus has trouble calculating enthalpy. How do I get around the problem of non-convergence with the dynamic pipes. Is there a way of determining the quality of steam and the phase of the medium as an output. I have attached both the models.

Thanks in advance.

SteamHammer-DynPipe.mo

SteamHammer.mo

Sri

Rene,
Thank you very much for the help.

I thought I had attached the model. But I see that I had not clicked on the "Add attachment to post". Another rookie mistake.



Thanks in advance.

I am a Modelica novice and I am trying build the simplest of fluid models. The model has a pressure boundary inlet, a controlled pump and a partially filled tank. The model fails to solve at time t=0. Can someone help me out with this please.