【答案】应助回帖

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1楼2013-07-01 21:08:48

twoflm

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【答案】应助回帖

感谢参与，应助指数 +1

看看程序里是那几个方程，然后对比一下那个除氧器的一般模型，看看少了什么，再补上试试呗

2楼2013-07-01 21:57:31

greatniu

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2楼: Originally posted by twoflm at 2013-07-01 21:57:31
看看程序里是那几个方程，然后对比一下那个除氧器的一般模型，看看少了什么，再补上试试呗

关键是我参考的文献里面写的全部方程，我都写上了，人家也没有写额外的方程。。。。

3楼2013-07-01 22:18:22

twoflm

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3楼: Originally posted by greatniu at 2013-07-01 22:18:22
关键是我参考的文献里面写的全部方程，我都写上了，人家也没有写额外的方程。。。。...

如果你确定方程足够了，那你查查是不是有多余的变量，是否有变量没有赋值或者跟其他某个变量有某种数量关系。
软件一般不会有问题。

4楼2013-07-01 22:36:53

qllq1661

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【答案】应助回帖

感谢参与，应助指数 +1

你的图片看不清楚。不知道具体有那些未知量可以消减。
除氧器作为一个混合式加热器，汇入的流量多，质量守恒和能量守恒方程联合，是能消去一些量的。
另外，一些变量与已知量符合一定的定量关系，也有助于减少未知量。

赞一下(1人)

5楼2013-07-02 04:28:56

greatniu

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5楼: Originally posted by qllq1661 at 2013-07-02 04:28:56
你的图片看不清楚。不知道具体有那些未知量可以消减。
除氧器作为一个混合式加热器，汇入的流量多，质量守恒和能量守恒方程联合，是能消去一些量的。
另外，一些变量与已知量符合一定的定量关系，也有助于减少未知 ...

model Deaerator
  replaceable package Medium=Modelica.Media.Water.StandardWater;
  import SI = Modelica.SIunits;
  Medium.SaturationProperties sat_p "saturation properties record";
  SI.Pressure p "pressure of the deaerator";
  SI.Pressure pvi "pressure of the bleed steam";
  parameter Real B=1
"quasi-linear admittance of the bleed steam,'zhun xianxing daona' in Chinese";
  parameter Real Kp=2e-3 "constant of pressure, this is a guess value!";
  parameter Real Kec=1.2e-5 "dynamic evaporating parameter";
  parameter Real Ka=9.5e-6 "water level constant";
  SI.MassFlowRate Wvo
"exhaust steam mass flow rate of the deaerator,'paiqi liuliang' in Chinese";
  SI.MassFlowRate Wcond
"condensate mass flow rate of the steam in the deaeratoring head";
  SI.MassFlowRate Wevcd
"dynamic evaporate mass flow rate of the water in the deaerator water tank";
  SI.MassFlowRate Wt
"steam mass flow rate in the deaeratoring head, i.e. steam mass flow rate inside the deaerator";
  SI.MassFlowRate Wvi "bleed steam mass flow rate";
  SI.SpecificEnthalpy hvi "bleed steam specific enthalpy";
  SI.SpecificEnthalpy ha
"average specific enthalpy of the steam in the deaeratoring head";
  SI.SpecificEnthalpy hs
"saturated steam specific enthalpy in the deaeratoring head";
  SI.SpecificEnthalpy hc
"saturated water specific enthalpy in the deaeratoring head";
  SI.Mass W "water mass in the deaerator water tank";
  SI.MassFlowRate Wcw "condensate water mass flow rate, coming from LP heaters";
  SI.SpecificEnthalpy hcw
"specific enthalpy of condensate water, coming from LP heaters";
  SI.MassFlowRate Wdw "dewater mass flow rate, coming from HP heaters";
  SI.SpecificEnthalpy hdw
"specific enthalpy of dewater, coming from HP heaters";
  SI.MassFlowRate Wfw "feedwater mass flow rate, flowing out of the deaerator";
  SI.SpecificEnthalpy hfw
"feedwate specific enthalpy, flowing out of the deaerator";
  SI.SpecificEnthalpy hf
"the specific enthalpy of water in the deaerator water tank, this is different from hc,CAUTION! this also equals the feedwater spcific enthalpy, i.e. hfw";
  SI.Length L "water level of the deaerator water tank";

  ThermoPower.Water.FlangeA inlet_steam "inlet of the heating steam"
annotation (extent=[-10,62; 10,82]);
  ThermoPower.Water.FlangeA inlet_feedwater "inlet of condensate water"
annotation (extent=[64,-38; 84,-18]);
  ThermoPower.Water.FlangeA inlet_dewater "inlet of dewatering"
annotation (extent=[-6,-82; 14,-62]);
  ThermoPower.Water.FlangeB outlet "outlet of deaerator"
annotation (extent=[-80,-38; -60,-18]);
  annotation (Icon(Ellipse(extent=[-24,62; 26,-10],style(
      color=3,
      rgbcolor={0,0,255},
      gradient=2,
      fillColor=4,
      rgbfillColor={0,128,255},
      fillPattern=1)), Ellipse(extent=[-60,4; 64,-62],  style(
      color=3,
      rgbcolor={0,0,255},
      gradient=2,
      fillColor=4,
      rgbfillColor={0,128,255},
      fillPattern=1))), Diagram);

equation
  Wvi=inlet_steam.w;
  hvi=inlet_steam.hBA;
  Wcw=inlet_feedwater.w;
  hcw=inlet_feedwater.hBA;
  Wfw=outlet.w "need further consideration";
  Wdw=inlet_dewater.w;
  hdw=inlet_dewater.hBA;

  /*computation of saturated properties in the deaeratoring head*/
  sat_p=Medium.setSat_p(p);
  hs=Medium.dewEnthalpy(sat_p);
  hc=Medium.bubbleEnthalpy(sat_p);

  /*parameters needed further consideration*/
  Wvo=0;  //exhaust steam mass flow rate is very small, ignored here?

  der(p)=Kp*(B*(pvi-p)-Wvo-Wcond+Wevcd);  //equation of deaerator pressure

  /*steam side equations below*/
  Wt=Wvi+Wevcd-Wcond-Wvo;  //equation of steam mass balance; mass of steam in the deaeratoring head
  Wt*ha=Wvi*hvi+Wevcd*hs-Wcond*ha-Wvo*hs;  //equation of steam energy balance; average steam specific enthalpy ha is computed here
  Wcond=Wcw*(hc-hcw)/(ha-hc);  //equation of steam condensate mass flow rate

  /*water side equations below*/
  der(W)=Wcw+Wdw+Wcond-Wevcd-Wfw;  //equation of water mass balance
  Wevcd=Kec*(hf-hc);  //computation of evaporating water mass flow rate
  hfw=hf;  //means that hf and hfw refers to the same specific enthaply
  W*der(hf)=Wcond*(ha-hf)+Wcw*(hcw-hf)+Wdw*(hdw-hf)-Wevcd*(hs-hf);  //equation of water energy balance

  /*equations concerning water level*/
  L=Ka*W;  //very simple equation of the relation between water level and water mass
end Deaerator;

6楼2013-07-02 08:49:56

greatniu

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6楼: Originally posted by greatniu at 2013-07-02 08:49:56
model Deaerator
  replaceable package Medium=Modelica.Media.Water.StandardWater;
  import SI = Modelica.SIunits;
  Medium.SaturationProperties sat_p "saturation properties record";
...

问了问别人，现在好像是缺少一些边界条件，或者微分缺少初始值。

7楼2013-07-02 09:51:09

wjl6377

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请问有安装包可以分享吗

发自小木虫IOS客户端

8楼2017-10-25 00:07:11

liyunchao

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【答案】应助回帖

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7楼: Originally posted by greatniu at 2013-07-02 09:51:09
问了问别人，现在好像是缺少一些边界条件，或者微分缺少初始值。...

方法不对，只能一团雾水，要一步步列方程

9楼2020-09-25 13:14:10