Modelica 4.0.0简单流体建模：介质声明报错求助

报错Expected medium to be a component, but found package instead的核心原因是混淆了Modelica.Thermal.FluidHeatFlow库的介质使用逻辑——这个库的模型是通过继承介质包统一介质定义，而非将介质包作为参数传递给组件。

具体错误点 #

• 组件实例中写medium = medium，是把自定义的介质包当成组件对象传递，不符合库的参数要求。
• 同时继承Modelica.Thermal.FluidHeatFlow.Media.Medium会和自定义的medium包产生冲突，因为该基类已包含介质定义框架。

修正步骤 #

1. 删除所有组件实例里的medium = medium参数（比如PressureIncrease、Ambient中的该设置）。
2. 将extends Modelica.Thermal.FluidHeatFlow.Media.Medium替换为extends Modelica.Thermal.FluidHeatFlow.Media.Medium(medium = medium)，把自定义介质包注入到库的介质框架中。
3. 保留原有的replaceable package medium定义，LinearWater_pT_Ambient的选择是合理的。

修正后的完整代码 #

extends Modelica.Icons.Example;
  replaceable package medium =
      Modelica.Media.CompressibleLiquids.LinearWater_pT_Ambient
    constrainedby Modelica.Media.Interfaces.PartialMedium;
  extends Modelica.Thermal.FluidHeatFlow.Media.Medium(medium = medium);
  
  import Modelica.Units.Conversions.from_degC;
  import Modelica.Units;
 
  parameter Modelica.Units.SI.Temperature T_amb = from_degC(20);
  parameter Modelica.Units.SI.Pressure p_inc = 500000;

  Modelica.Thermal.FluidHeatFlow.Sources.PressureIncrease pressureIncrease(T(fixed = true, start = T_amb)) annotation(
    Placement(visible = true, transformation(origin = {-48, 2}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Blocks.Sources.Constant const(k = p_inc) annotation(
    Placement(visible = true, transformation(origin = {-72, 42}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Thermal.FluidHeatFlow.Sources.Ambient ambient(T(fixed = true, start = T_amb)) annotation(
    Placement(visible = true, transformation(origin = {-80, 2}, extent = {{10, -10}, {-10, 10}}, rotation = 0)));
  Modelica.Thermal.FluidHeatFlow.Sources.Ambient ambient1(T(fixed = true, start = T_amb)) annotation(
    Placement(visible = true, transformation(origin = {16, 2}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  Modelica.Thermal.FluidHeatFlow.Components.Pipe pipe annotation(
    Placement(visible = true, transformation(origin = {-16, 2}, extent = {{-10, 10}, {10, -10}}, rotation = 0)));
  Modelica.Thermal.HeatTransfer.Sources.FixedHeatFlow fixedHeatFlow(Q_flow = 10, alpha = 0.5) annotation(
    Placement(visible = true, transformation(origin = {-28, 44}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
equation
  connect(ambient.flowPort, pressureIncrease.flowPort_a) annotation(
    Line(points = {{-70, 2}, {-58, 2}}, color = {255, 0, 0}));
  connect(pressureIncrease.flowPort_b, pipe.flowPort_a) annotation(
    Line(points = {{-38, 2}, {-26, 2}}, color = {255, 0, 0}));
  connect(pipe.flowPort_b, ambient1.flowPort) annotation(
    Line(points = {{-6, 2}, {6, 2}}, color = {255, 0, 0}));
  connect(fixedHeatFlow.port, pipe.heatPort) annotation(
    Line(points = {{-18, 44}, {-16, 44}, {-16, 12}}, color = {191, 0, 0}));
annotation(
  Diagram(coordinateSystem(extent = {{-100, 60}, {40, -20}})));
end heatend_3d_printing;

内容的提问来源于stack exchange，提问作者Tobias R.