Advanced

Design and Implementation of Object-Oriented Model Libraries using Modelica

Tummescheit, Hubertus LU (2002) In PhD Theses TFRT-1063.
Abstract (Swedish)
Popular Abstract in Swedish

Matematiska modeller och simulering är viktiga verktyg för att hantera tekniska system. Trenden idag är att öka komplexiteten i system genom integrerad produktion och processoptimering. Att hantera dessa komplexa system kräver kunskaper inom många områden samtidigt. Modellbibliotek är ett bra sätt att paketera kunskap. Kommersiella simuleringsprogram tillandahåller bra modellbibliotek, men de är ofta ämnes-specifika och tillåter ingen insyn. Komplexa, multi-displinära system kräver öppna modellbibliotek skrivna i ett generellt modelleringsspråk. Modelica är ett sådant modelleringsspråk som stödjer objekt-orienterad modellering av dynamiska system. Modelica har specificerats genom ett europeiskt... (More)
Popular Abstract in Swedish

Matematiska modeller och simulering är viktiga verktyg för att hantera tekniska system. Trenden idag är att öka komplexiteten i system genom integrerad produktion och processoptimering. Att hantera dessa komplexa system kräver kunskaper inom många områden samtidigt. Modellbibliotek är ett bra sätt att paketera kunskap. Kommersiella simuleringsprogram tillandahåller bra modellbibliotek, men de är ofta ämnes-specifika och tillåter ingen insyn. Komplexa, multi-displinära system kräver öppna modellbibliotek skrivna i ett generellt modelleringsspråk. Modelica är ett sådant modelleringsspråk som stödjer objekt-orienterad modellering av dynamiska system. Modelica har specificerats genom ett europeiskt samarbete och är en öppen standard.



Avhandlingen beskriver principer för objekt-orienterade och ekvations-baserade modellbibliotek. Tillämpningen är modellering av termo-hydrauliska system, dvs processer som innefattar flöden av värme och vätska eller gas. ThermoFluid är ett av flera basbibliotek i det nya modelleringsspråket Modelica, och är mer generellt tillämpbart för termo-hydrauliska system. Modellerna bygger på fysikaliska principer med kontrollvolymer som innehåller dynamiska balansekvationer för massa, energi och rörelsemängd. Basbiblioteket är byggt på ett flexibelt sätt. Den grundläggande kontrollvolymen kan innehålla olika vätskor/gaser, med en eller flera komponenter, och den kan diskretiseras i flödesriktningen för en noggrannare beskrivning. Flera specifika tillämpningar beskrivs i avhandlingen: en microgasturbinsystem, ett ångnät i en pappersmassafabrik, speciella modeller för evaporatorer och ett koldioxid-baserad kylsystem. (Less)
Abstract
This thesis describes basic models for thermo-fluid systems and the implementation of the models using a flexible object-oriented structure in the ThermoFluid library. Model libraries provide an excellent way to package engineering knowledge of systems to be reused by non-experts. Many commercial simulation packages provide good model libraries, but they are usually domain specific and closed. Modelica(TM) is an open standard of an object-oriented modeling language for heterogeneous, multi-domain dynamic systems. Modelica combines the expressive power of equation based modeling with advanced object-oriented structuring features. A unique feature of Modelica are class parameters which allow a high-level parameterization of physical... (More)
This thesis describes basic models for thermo-fluid systems and the implementation of the models using a flexible object-oriented structure in the ThermoFluid library. Model libraries provide an excellent way to package engineering knowledge of systems to be reused by non-experts. Many commercial simulation packages provide good model libraries, but they are usually domain specific and closed. Modelica(TM) is an open standard of an object-oriented modeling language for heterogeneous, multi-domain dynamic systems. Modelica combines the expressive power of equation based modeling with advanced object-oriented structuring features. A unique feature of Modelica are class parameters which allow a high-level parameterization of physical phenomena.



The models are based on first principles. Control volumes contain the thermodynamic balance equations in lumped or one-dimensional discretized form. The library is built to be flexible: fluid property models in the control volume can be exchanged, single- or multi-component fluids are supported and the momentum balance submodel can be static or dynamic. Chemical reactions can be added to the model separately from other phenomena. Thermodynamic Jacobians are used to transform the dynamic equations into an efficient form. Low order moving boundary models for two phase flows are another result of the thesis. They make use of a novel approach for approximating the mean void fraction in the two phase region.



The experiences from designing an object-oriented, reusable model library are summarized using design patterns. Design patterns are an attempt to describe "good practice" in modeling in a semi-formal way.



The library has been used successfully for a broad range of industrial applications, among others modeling of micro gas turbine systems, carbon-dioxide based refrigeration systems, fuel cells, power plants and steam networks. The applications are briefly described in the thesis. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Murray, Richard, California Institute of Technology
organization
publishing date
type
Thesis
publication status
published
subject
keywords
modeling languages, thermo-fluid systems, process modeling, process control, control systems, thermo-hydraulic systems, non-linear models, model library design, object-oriented, modeling, simulation, Automation, robotics, control engineering, Automatiska system, robotteknik, reglerteknik
in
PhD Theses
volume
TFRT-1063
pages
257 pages
publisher
Department of Automatic Control, Lund Institute of Technology (LTH)
defense location
Maskinhuset, room M:B
defense date
2002-08-30 13:15
ISSN
0280-5316
language
English
LU publication?
yes
id
4abd7220-8f4b-48df-bb2d-77a2dda579f9 (old id 20836)
date added to LUP
2007-05-28 13:41:43
date last changed
2016-09-19 08:44:57
@phdthesis{4abd7220-8f4b-48df-bb2d-77a2dda579f9,
  abstract     = {This thesis describes basic models for thermo-fluid systems and the implementation of the models using a flexible object-oriented structure in the ThermoFluid library. Model libraries provide an excellent way to package engineering knowledge of systems to be reused by non-experts. Many commercial simulation packages provide good model libraries, but they are usually domain specific and closed. Modelica(TM) is an open standard of an object-oriented modeling language for heterogeneous, multi-domain dynamic systems. Modelica combines the expressive power of equation based modeling with advanced object-oriented structuring features. A unique feature of Modelica are class parameters which allow a high-level parameterization of physical phenomena.<br/><br>
<br/><br>
The models are based on first principles. Control volumes contain the thermodynamic balance equations in lumped or one-dimensional discretized form. The library is built to be flexible: fluid property models in the control volume can be exchanged, single- or multi-component fluids are supported and the momentum balance submodel can be static or dynamic. Chemical reactions can be added to the model separately from other phenomena. Thermodynamic Jacobians are used to transform the dynamic equations into an efficient form. Low order moving boundary models for two phase flows are another result of the thesis. They make use of a novel approach for approximating the mean void fraction in the two phase region.<br/><br>
<br/><br>
The experiences from designing an object-oriented, reusable model library are summarized using design patterns. Design patterns are an attempt to describe "good practice" in modeling in a semi-formal way.<br/><br>
<br/><br>
The library has been used successfully for a broad range of industrial applications, among others modeling of micro gas turbine systems, carbon-dioxide based refrigeration systems, fuel cells, power plants and steam networks. The applications are briefly described in the thesis.},
  author       = {Tummescheit, Hubertus},
  issn         = {0280-5316},
  keyword      = {modeling languages,thermo-fluid systems,process modeling,process control,control systems,thermo-hydraulic systems,non-linear models,model library design,object-oriented,modeling,simulation,Automation,robotics,control engineering,Automatiska system,robotteknik,reglerteknik},
  language     = {eng},
  pages        = {257},
  publisher    = {Department of Automatic Control, Lund Institute of Technology (LTH)},
  school       = {Lund University},
  series       = {PhD Theses},
  title        = {Design and Implementation of Object-Oriented Model Libraries using Modelica},
  volume       = {TFRT-1063},
  year         = {2002},
}