我正在尝试在Modelica中构建一个非常简单的分布式热流体体积模型,并且正在努力使用流操作符正确实现它 . 本卷使用DryAirNasa作为媒介,我希望它没有大容量存储,没有压降,也没有能量存储(很像Modelica.Fluid.Pipes.StaticPipe模型) . 但是,我想明确地执行能量 balancer ,以便可以进行热传递 . 我也不希望在这个模型中定义质量流量,而是在连接到管道末端的一个边界中定义它(例如,Modelica.Fluid.Sources.MassFlowSource_h) .
我已经创建了这种模型的测试实现,但是根据Dymola,这个模型显然没有一个方程式 . 我很感激有关如何修复此模型的任何见解,以便它是正确的 . 如果我加上等式
port_a.h_outflow = Medium.specificEnthalpy(state_a)
对于方程部分,模型具有相同数量的方程和未知数,但我没有任何有理由添加这样的方程 .
model AirFlowTemp
// Objective: create a component that has no pressure drop, no mass storage,
and no energy storage, but that has a heat input.
import SI=Modelica.SIunits;
final replaceable package Medium=Modelica.Media.Air.DryAirNasa;
AirFlow.AirFlowPort port_a(redeclare package Medium
= Medium);
AirFlow.AirFlowPort port_b(redeclare package Medium
= Medium);
Interfaces.HeatPort heatPort;
Medium.EnthalpyFlowRate[2] H_flow "enthalpy flow";
SI.HeatFlowRate Q_flow "heat flow rate";
Medium.Temperature T_mean;
Medium.ThermodynamicState state_a;
Medium.ThermodynamicState state_b;
equation
// no pressure drop across the component.
port_a.p = port_b.p;
// Assume that there is no mass storage in the volume
0 = port_a.m_flow + port_b.m_flow;
// Energy balance
H_flow[1] = semiLinear(port_a.m_flow, inStream(port_a.h_outflow), inStream(port_b.h_outflow));
H_flow[2] = semiLinear(port_b.m_flow, inStream(port_b.h_outflow), inStream(port_a.h_outflow));
0 = Q_flow + H_flow[1] + H_flow[2];
state_a = Medium.setState_ph(port_a.p, inStream(port_a.h_outflow));
state_b = Medium.setState_ph(port_b.p, inStream(port_b.h_outflow));
T_mean = (Medium.temperature(state_a) +
Medium.temperature(state_b))/2;
heatPort.Q_flow = Q_flow;
heatPort.T = T_mean;
end AirFlowTemp;
connector AirFlowPort
replaceable package Medium = Modelica.Media.Interfaces.PartialMedium;
Medium.AbsolutePressure p;
flow Medium.MassFlowRate m_flow;
stream Medium.SpecificEnthalpy h_outflow;
stream Medium.MassFraction Xi_outflow[Medium.nXi];
end AirFlowPort;
connector HeatPort
extends Modelica.Thermal.HeatTransfer.Interfaces.HeatPort;
end HeatPort;
1 回答
大约4个星期前,我遇到了同样的问题 . 尝试将其作为接近正确使用inStream的步骤 .
heatPort.Q_flow = Q_flow; heatPort.T = T_mean; =>只测试管道,没有heatPort
而不是:H_flow [1] = semiLinear(port_a.m_flow,inStream(port_a.h_outflow),inStream(port_b.h_outflow)); H_flow [2] = semiLinear(port_b.m_flow,inStream(port_b.h_outflow),inStream(port_a.h_outflow)); 0 = Q_flow H_flow [1] H_flow [2];
=>这有用吗?
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