Teaching Modelica for Engineers at Technische Universität Braunschweig€¦ · Teaching Modelica...

1 University of Braunschweig – Institute of Technology

Teaching Modelica for Engineers at Technische Universität Braunschweig

W. Tegethoff, M. Gräber, R. Kossel, C. Richter

2

1. Classroom and Exam

2. Thinking in Objects

3. Course Example: Refrigeration Cycle

4. Course Example: Tire Service Garage

5. Course Example: Lumped Capacitors

6. Conclusion

Contents

Technische Universität Braunschweig

Classroom

3 Technische Universität Braunschweig

WilliWilli

ManuelManuel

24 Course Hours24 Course Hours

4

Final Exam

Learning targets:

•Modeling language Modelica

•Numeric for solving DAE-Systems (heuristic)

•Object-oriented analysis


Final Exam


What is What is Polymorphism?Polymorphism?

Exam Time:Exam Time:

30 Minutes30 Minutes

6






6. Conclusion

Contents


7

Thinking in Objects

Class: Construction Plan /Blueprint

Object: The house

What is a class? What is an object?

Instantiation: Building

More objects of the same class


Modifier

AnimalAnimal

Object-oriented Analysis


““is ais a””

““is part ofis part of””

AnimalAnimal



““is ais a””

66

111144

44

““is part ofis part of””

11

Overview of Course Examples

Refrigeration Cycle

Tire Service Garage

Lumped Capacitors


12






6. Conclusion

Contents


Refrigeration Cycle


14

Solving Non-linear Algebraic Equations

gascooler.idealOutletRefrigerant.p = 1E+007receiver.refrigerant.p = 0Residual:{ -0.0654391, 92922.9 }

gascooler.idealOutletRefrigerant.p = -1E+009receiver.refrigerant.p = -1.41559Residual:{ -0.101224, -9024.99 }

gascooler.idealOutletRefrigerant.p = -9.17831E+008receiver.refrigerant.p = -1.28344Residual:{ -0.0970766, -9024.99 }


15


NewtonNewton’’s Methods Method




Pitfalls:

17






6. Conclusion

Contents


Tire Service Garage


Tire Service GarageTire Service Garage

Tire Service Garage


Tire Service Garage

Car

<<partial>>

Tire

Firestone Michelin

Object DiagramObject Diagram

Tire Service Garage


IconIcon

CarCar


Tire Service Garage


CarCar

model Car

Firestone spareTire;

Michelin frontRightTire;

Michelin frontLeftTire;

Michelin backRightTire;

Michelin backLeftTire;

end Car;


Tire Service Garage


CarCar

model Car

replaceable Firestone spareTire extends Tireannotation (choicesAllMatching=true);

replaceable model TireModel = Michelin extends Tireannotation (choicesAllMatching=true);

TireModel frontRightTire;

TireModel frontLeftTire;

TireModel backRightTire;

TireModel backLeftTire;

end Car;

Tire Service Garage


Tire Service GarageTire Service Garage

redeclare model TireModel =

Michelin;

M M

24






6. Conclusion

Contents


25

Lumped Capacitors

TTss

RR11 RR22

22

2

211

1

Qdt

dTC

QQdt

dTC

=⋅

−=⋅

1Q 2Q

1C 2C

TT11 TT22

2

212

1

11

RTTQ

RTTQ s

−=

−=

22

212

21

21

11

11

RCTT

dtdT

RCTT

RCTT

dtdT s

−=

−−

−=


Euler’s Method


00 2020 3030 4040Time [s]Time [s]300300

380380

320320

340340

360360

Tem

pera

ture

[K

]Te

mpe

ratu

re [

K]

50501010

DasslDassl’’ss SolutionSolutionEulerEuler’’s Solutions Solution

Lumped Capacitors - Stiffness


00 400400 600600 800800

Time [s]Time [s]

10001000200200

6.0 e86.0 e8Te

mpe

ratu

reTe

mpe

ratu

re[K

][K

]

--6.0 e86.0 e8

00



TTss

RR11

1C 2C

TT11 TT22RR22

21 RR >>



00 44 66 88

Time [s]Time [s]

101022

Tem

pera

ture

Tem

pera

ture

[K]

[K]

400400

300300

350350

EulerEuler’’s Methods Method

ΔΔt = 1et = 1e--4 sec4 sec

Lumped Capacitors – Index Reduction


TTss

RR11

1C 2C

TT11 TT22

2

212

1

11

RTTQ

RTTQ s

−=

−=dt

d

dtd

Lumped Capacitors – State Selection


TTss

RR11

1C 2C

TT11 TT22

32






6. Conclusion

Contents


33

Conclusion

Students typically have to learn thinking in objects

Students learn modelling in Modelica by

• Carefully selected didactical concepts

• Well assisted assignments

• Final projects

In thermo-fluid systems, good knowledge about numerical solving of DAE-Systems is necessary


Teaching Modelica for Engineers at Technische Universität Braunschweig€¦ · Teaching Modelica...

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