Teaching Modelica for Engineers at Technische Universität Braunschweig W. Tegethoff, M. Gräber, R. Kossel, C. Richter

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1 eaching Modelica for Engineers at echnische Universität Braunschweig W. egethoff, M. Gräber, R. Kossel, C. Richter University of Braunschweig Institute of echnology

2 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion echnische Universität Braunschweig

3 Classroom Willi 4 Course Hours Manuel 3 echnische Universität Braunschweig

4 Final Exam Learning targets: Modeling language Modelica Numeric for solving DAE-Systems (heuristic) Object-oriented analysis 4 echnische Universität Braunschweig

5 Final Exam Exam ime: 30 Minutes What is Polymorphism? 5 echnische Universität Braunschweig

6 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion 6 echnische Universität Braunschweig

7 hinking in Objects What is a class? What is an object? Class: Construction Plan / Blueprint Instantiation: Building Object: he house More objects of the same class Modifier 7 echnische Universität Braunschweig

8 Object-oriented Analysis Animal is a a is part of 8 echnische Universität Braunschweig

9 Object-oriented Analysis Animal is a a is part of 9 echnische Universität Braunschweig

10 Object-oriented Analysis 0 echnische Universität Braunschweig

11 Overview of Course Examples Refrigeration Cycle ire Service Garage Lumped Capacitors echnische Universität Braunschweig

12 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion echnische Universität Braunschweig

13 Refrigeration Cycle 3 echnische Universität Braunschweig

14 Solving Non-linear Algebraic Equations gascooler.idealoutletrefrigerant.p = E+007 receiver.refrigerant.p = 0 Residual: { , 99.9 } gascooler.idealoutletrefrigerant.p = -E+009 receiver.refrigerant.p = Residual: { -0.04, } gascooler.idealoutletrefrigerant.p = E+008 receiver.refrigerant.p = Residual: { , } 4 echnische Universität Braunschweig

15 Solving Non-linear Algebraic Equations Newton s s Method 5 echnische Universität Braunschweig

16 Solving Non-linear Algebraic Equations Pitfalls: 6 echnische Universität Braunschweig

17 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion 7 echnische Universität Braunschweig

18 ire Service Garage ire Service Garage 8 echnische Universität Braunschweig

19 ire Service Garage ire Service Garage Car <<partial>> ire Firestone Michelin 9 echnische Universität Braunschweig

20 ire Service Garage Car Icon Object Diagram 0 echnische Universität Braunschweig

21 ire Service Garage Car model Car Firestone spareire; Michelin frontrightire; Michelin frontleftire; Michelin backrightire; Michelin backleftire; end Car; Object Diagram echnische Universität Braunschweig

22 ire Service Garage Car model Car replaceable Firestone spareire extends ire annotation (choicesallmatching=true); replaceable model iremodel = Michelin extends ire annotation (choicesallmatching=true); iremodel frontrightire; iremodel frontleftire; iremodel backrightire; iremodel backleftire; end Car; Object Diagram echnische Universität Braunschweig

23 ire Service Garage ire Service Garage M M redeclare model iremodel = Michelin; 3 echnische Universität Braunschweig

24 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion 4 echnische Universität Braunschweig

25 5 Lumped Capacitors s R R Q dt d C Q Q dt d C = = Q Q C C R Q R Q s = = R C dt d R C R C dt d s = = echnische Universität Braunschweig

26 Euler s Method 380 emperature [K] Euler s s Solution Dassl s Solution 300 ime [s] echnische Universität Braunschweig

27 Lumped Capacitors - Stiffness 6.0 e8 emperature [K] 0 ime [s] -6.0 e echnische Universität Braunschweig

28 Lumped Capacitors - Stiffness R >> R s R R C C 8 echnische Universität Braunschweig

29 Lumped Capacitors - Stiffness 400 emperature [K] 350 Euler s s Method Δt t = e-4 4 sec 300 ime [s] echnische Universität Braunschweig

30 Lumped Capacitors Index Reduction s R C C d dt d dt Q Q = = s R R 30 echnische Universität Braunschweig

31 Lumped Capacitors State Selection s R C C 3 echnische Universität Braunschweig

32 Contents. Classroom and Exam. hinking in Objects 3. Course Example: Refrigeration Cycle 4. Course Example: ire Service Garage 5. Course Example: Lumped Capacitors 6. Conclusion 3 echnische 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 33 echnische Universität Braunschweig