[1] 22:16:26 Translation Error

Internal error Circular Equalities Detected for Variables:

condenser2.o.mdot

condenser2.i.mdot

----------------------------------

pump2.i.mdot

condenser2.o.mdot

----------------------------------

pump2.o.mdot

pump2.i.mdot

----------------------------------

[2] 22:16:26 Symbolic Error

[PTC: 995:5-995:122]: Model is structurally singular, error found sorting equations

model Pump_condenser

  PTC.Pump2 pump2 annotation();

  PTC.Condenser2 condenser2 annotation();

equation

  connect(condenser2.o, pump2.i) annotation();

  connect(pump2.o, condenser2.i) annotation();

end Pump_condenser;

model Pump2

extends PTC.PartialModels.PartialCSTComponentSISO;

  // Imports

  import Modelica.SIunits.*;

  import ThermoCycle.Media.*;

  import Modelica.Constants;

  // Outlet isentropic state

  Medium.ThermodynamicState state_isentropic;

  // Parameters

  parameter Length D = 2 "Diameter of pump";

  parameter Length w = 1 "Width of pump";

  parameter Real eta(unit = "1") = 0.7 "Isentropic efficiency of pump";

  constant Real pi = 2 * Modelica.Math.asin(1.0) "3.14159265358979";

  // Variables

  Power Wdot "Power input to pump";

  SpecificEntropy s_i "Specific entropy at inlet";

  SpecificEnthalpy hs "Specific enthalpy after isentropic compression";

initial equation

  medium_i.T = 363;

  medium_i.p = 80000;

  medium_o.T = 450;

  medium_o.p = 800000;

  i.h = Medium.specificEnthalpy(medium_i.state);

equation

  // Energy balance

  m * der(u) = (-Wdot) + i.mdot * actualStream(i.h) + o.mdot * actualStream(o.h);

  // Isentropic efficiency

  s_i = Medium.specificEntropy(medium_i.state) "Get inlet entropy";

  state_isentropic = Medium.setState_ps(medium_o.p, s_i) "Isentropic state";

  hs = Medium.specificEnthalpy(state_isentropic);

  eta = (hs - medium_i.h) / (medium_o.h - medium_i.h) "Isentropic efficiency";

  // Inlet pressure

  medium_i.p = 80000;

  // Mass

  m = pi * D ^ 2 * w * d / 4 "Mass of fluid in control volume";

  // Simulation parameters

  annotation();

  annotation();

end Pump2;

model Condenser2

extends PTC.PartialModels.PartialCSTComponentSISO;

  // Imports

  import Modelica.SIunits.*;

  // Parameters

  parameter Length L = 5 "Length of one tube";

  parameter Area A = 0.02 "Cross sectional area of tubes";

  parameter Integer N(unit = "1") = 10 "Number of tubes";

  parameter Temperature Tinf = 298 "Ambient temperature";

  parameter CoefficientOfHeatTransfer k = 3000 "Convection coefficient";

  // Variables

  HeatFlowRate Qdot "Heat flow rate from power block to condenser fluid";

  Temperature T "Average temp in CV";

initial equation

  medium_i.T = 450;

  medium_i.p = 8000000;

  medium_o.T = 363;

  medium_o.p = 80000;

  i.h = Medium.specificEnthalpy(medium_i.state);

equation

  // Energy balance

  m * der(u) = Qdot + i.mdot * actualStream(i.h) + o.mdot * actualStream(o.h);

  // Inlet pressure

  medium_i.p = 8000000;

  // Average temperature

  T = (medium_i.T + medium_o.T) / 2;

  // Heat flow rate

  Qdot = -k * (T - Tinf) "Newtons law of cooling";

  // Mass

  m = N * L * A * d "Mass of fluid in CV";

  // Simulation parameters

  annotation();

  annotation();

end Condenser2;

partial model PartialCSTComponentSISO

  // Imports

  import Modelica.SIunits.*;

  // Fluid imports

  replaceable package Medium = Modelica.Media.Water.StandardWater annotation(

    choicesAllMatching = true);

  // Set up inlet and outlet media

  Medium.BaseProperties medium_i;

  Medium.BaseProperties medium_o;

  // Connectors

  PTC.inlet i(redeclare package Medium = Medium) annotation();

  PTC.outlet o(redeclare package Medium = Medium) annotation();

  // Variables

  SpecificInternalEnergy u "Average specific internal energy in CV (control volume)";

  Mass m "Mass contained in CV";

  Density d "Average density of fluid in CV";

  // Parameters

  parameter MassFlowRate mdotCV = 3.0 "Mass flow rate through CV";

equation

  // Fluid equations

  medium_i.h = i.h;

  medium_i.p = i.p;

  medium_o.p = o.p;

  medium_o.h = o.h;

  // Mass flow rate 

  i.mdot = mdotCV;

  o.mdot + i.mdot = 0 "Mass balance";

  // Internal energy 

  u = (medium_i.u + medium_o.u) / 2 "Internal energy in CV is average of inlet and outlet u";

  // Miscellaneous 

  d = (medium_i.d + medium_o.d) / 2 "d in CV is average of inlet and outlet densities";

end PartialCSTComponentSISO;

connector inlet

  // Imports //

  import Modelica.SIunits.*;

  // Fluid imports //

  replaceable package Medium = Modelica.Media.Interfaces.PartialMedium "Medium model" annotation(

    choicesAllMatching = true);

  // Energy variables //

  Medium.AbsolutePressure p;

  stream Medium.SpecificEnthalpy h;

  // Flow variables //

  flow Medium.MassFlowRate mdot;

  annotation();

end inlet;