Dymola 換熱器

Question

我正在為熱交換器開發 model。 我寫了能量平衡方程。 當我檢查 model 時，出現如圖所示的錯誤。 我無法弄清楚剩下的三個方程式

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;

誰能幫我這個？ 有免費的換熱器嗎？

Answer 1

您需要在所有情況下指定傳出的焓。 請查看如何使用stream變量——例如在Modelica.Fluid中或在這個簡單示例 package的 Wiki 中。

免費的Modelica Buildings Library有許多熱交換器模型。

代碼修改

如果您將能量平衡更改為：

  ...
  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;
  ...