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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
Technische Universität Braunschweig
Final Exam
5 Technische Universität Braunschweig
What is What is Polymorphism?Polymorphism?
Exam Time:Exam Time:
30 Minutes30 Minutes
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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
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
Technische Universität Braunschweig
Modifier
AnimalAnimal
Object-oriented Analysis
8 Technische Universität Braunschweig
““is ais a””
““is part ofis part of””
AnimalAnimal
Object-oriented Analysis
9 Technische Universität Braunschweig
““is ais a””
66
111144
44
““is part ofis part of””
Object-oriented Analysis
10 Technische Universität Braunschweig
11
Overview of Course Examples
Refrigeration Cycle
Tire Service Garage
Lumped Capacitors
Technische Universität Braunschweig
12
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
Refrigeration Cycle
13 Technische Universität Braunschweig
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 }
Technische Universität Braunschweig
15
Solving Non-linear Algebraic Equations
NewtonNewton’’s Methods Method
Technische Universität Braunschweig
Solving Non-linear Algebraic Equations
16 Technische Universität Braunschweig
Pitfalls:
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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
Tire Service Garage
18 Technische Universität Braunschweig
Tire Service GarageTire Service Garage
Tire Service Garage
19 Technische Universität Braunschweig
Tire Service Garage
Car
<<partial>>
Tire
Firestone Michelin
Object DiagramObject Diagram
Tire Service Garage
20 Technische Universität Braunschweig
IconIcon
CarCar
Object DiagramObject Diagram
Tire Service Garage
21 Technische Universität Braunschweig
CarCar
model Car
Firestone spareTire;
Michelin frontRightTire;
Michelin frontLeftTire;
Michelin backRightTire;
Michelin backLeftTire;
end Car;
Object DiagramObject Diagram
Tire Service Garage
22 Technische Universität Braunschweig
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
23 Technische Universität Braunschweig
Tire Service GarageTire Service Garage
redeclare model TireModel =
Michelin;
M M
24
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
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
−=
−−
−=
Technische Universität Braunschweig
Euler’s Method
26 Technische Universität Braunschweig
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
27 Technische Universität Braunschweig
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
Lumped Capacitors - Stiffness
28 Technische Universität Braunschweig
TTss
RR11
1C 2C
TT11 TT22RR22
21 RR >>
Lumped Capacitors - Stiffness
29 Technische Universität Braunschweig
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
30 Technische Universität Braunschweig
TTss
RR11
1C 2C
TT11 TT22
2
212
1
11
RTTQ
RTTQ s
−=
−=dt
d
dtd
Lumped Capacitors – State Selection
31 Technische Universität Braunschweig
TTss
RR11
1C 2C
TT11 TT22
32
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
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
Technische Universität Braunschweig
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