Dymola换热器

Question

我正在为换热器开发一个模型。我写了能量平衡方程。当我检查模型时，我得到了图中显示的错误。我想不出剩下的三个方程式

model HX1
  replaceable package Medium1 = Modelica.Media.Air.DryAirNasa annotation (
      choicesAllMatching=true);
  replaceable package Medium2 =
      Modelica.Media.Water.ConstantPropertyLiquidWater annotation (
      choicesAllMatching=true);
  Modelica.Fluid.Interfaces.FluidPort_a AirInlet
    annotation (Placement(transformation(extent={{-110,48},{-90,68}})));
  Modelica.Fluid.Interfaces.FluidPort_a WaterOutlet
    annotation (Placement(transformation(extent={{90,-48},{110,-28}})));
  Modelica.Fluid.Interfaces.FluidPort_b AirOutlet
    annotation (Placement(transformation(extent={{88,50},{108,70}})));
  Modelica.Fluid.Interfaces.FluidPort_b WaterInlet
    annotation (Placement(transformation(extent={{-110,-56},{-90,-36}})));
equation 
  WaterInlet.m_flow * (WaterOutlet.h_outflow - WaterInlet.h_outflow)
            = AirInlet.m_flow * ( AirInlet.h_outflow - AirOutlet.h_outflow);
  WaterInlet.m_flow = - WaterOutlet.m_flow;
  AirInlet.m_flow = -AirOutlet.m_flow;
  AirInlet.p  = AirOutlet.p;
  WaterInlet.p = WaterOutlet.p;
  annotation (Icon(coordinateSystem(preserveAspectRatio=false)), Diagram(
        coordinateSystem(preserveAspectRatio=false)));
end HX1;

有人能帮我吗？有免费的热交换器吗？

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Answer 1

您需要在所有情况下指定传出焓。请看一下如何使用stream变量--例如在Modelica.Fluid或这个简单的示例包的Wiki中。

自由Modelica建筑物图书馆有许多热交换器模型。

代码修改

如果将能量平衡改为：

  ...
  Modelica.Units.SI.HeatFlowRate Q_flow;
equation 
  WaterInlet.m_flow*(actualStream(WaterOutlet.h_outflow) - actualStream(
    WaterInlet.h_outflow)) = Q_flow;
  Q_flow = AirInlet.m_flow*(actualStream(AirInlet.h_outflow) - actualStream(
    AirOutlet.h_outflow));
  WaterOutlet.h_outflow = WaterInlet.h_outflow;
  AirInlet.h_outflow = AirOutlet.h_outflow;
  ...