1. INTERNAL COMBUSTION ENGINES LECTURER PROF.Dr. DEMIR BAYKA

2. OTTO CYCLE compression Q in expansion Q out

3. COMPRESSION : 1 to 2 PV n = C

4. ENERGY BALANCE FOR POLYTROPIC COMPRESSION

8. Curve fitting to experimental data indicates that n c < k this means that Q 1-2 < 0

9. HEAT INPUT OR COMBUSTION BOTH HEAT INPUT OR COMBUSTION WILL BE AT CONSTANT VOLUME

10. HEAT INPUT Q 2-3 is totally fictitious and represents the overall effect of combustion

11. COMBUSTION Q 2-3 : HEAT LOSS U 2 = U R : INTERNAL ENERGY OF REACTANTS U 3 = U P : INTERNAL ENERGY OF PRODUCTS

12. EXPANSION isentropic

13. polytropic

14. Experimental data indicates that n e < k this means that Q 3-4 > 0 this is due to afterburning

15. HEAT REJECTION

16. EXAMPLE OTTO CYCLE isentropic comp. P 1 =100 kPa T 1 =300 K C p =1.05 kJ/kg-K R =0.28 kJ/kg-K r =8 REQUIRED W 1-2 = ? GIVEN SOLUTION

17. P 1 =100 kPa T 1 =300 K C p =1.05 kJ/kg-K

18. P 1 =100 kPa T 1 =300 K C p =1.05 kJ/kg-K and

21. EXAMPLE OTTO CYCLE P 1 =100 kPa T 1 =300 K C p =1.05 kJ/kg-K R =0.28 kJ/kg-K P 2 =1500 kPa T 2 =600 K REQUIRED W 1-2 = ? GIVEN SOLUTION

22. n c = ? r = ?

23. divide the equations

24. DUAL CYCLE 1) ONLY AIR IS COMPRESSED 2) CONSTANT PRESSURE WORK DURING COMBUSTION

25. ENERGY BALANCE FOR HEAT INPUT PROCESS

28. ENERGY BALANCE FOR COMBUSTION PROCESS Q 2-4 is the heat transfer from hot gases to the cylinder walls

29. OTTO CYCLE MODES OF OPERATION UNTHROTTLED 1-2 : COMPRESSION 2-3 : COMBUSTION 3-4 : EXPANSION 4-5 : BLOWDOWN 5-6 : EXHAUST 6-7 : VALVE OVERLAP 7-1 : INLET

30. OTTO CYCLE MODES OF OPERATION THROTTLED 1-2 : COMPRESSION 2-3 : COMBUSTION 3-4 : EXPANSION 4-5 : BLOWDOWN 5-6 : EXHAUST 6-7 : VALVE OVERLAP 7-1 : INLET

31. OTTO CYCLE MODES OF OPERATION SUPERCHARGED 1-2 : COMPRESSION 2-3 : COMBUSTION 3-4 : EXPANSION 4-5 : BLOWDOWN 5-6 : EXHAUST 6-7 : VALVE OVERLAP 7-1 : INLET

32. DUAL CYCLE MODES OF OPERATION LOW SPEED NATURALLY ASPIRATED 1-2 : COMPRESSION 2-4 : COMBUSTION 4-5 : EXPANSION 5-6 : BLOWDOWN 6-7 : EXHAUST 7-8 : VALVE OVERLAP 8-1 : INLET

33. DUAL CYCLE MODES OF OPERATION HIGH SPEED NATURALLY ASPIRATED 1-2 : COMPRESSION 2-4 : COMBUSTION 4-5 : EXPANSION 5-6 : BLOWDOWN 6-7 : EXHAUST 7-8 : VALVE OVERLAP 8-1 : INLET

34. DUAL CYCLE MODES OF OPERATION SUPERCHARGED 1-2 : COMPRESSION 2-4 : COMBUSTION 4-5 : EXPANSION 5-6 : BLOWDOWN 6-7 : EXHAUST 7-8 : VALVE OVERLAP 8-1 : INLET

35. RESIDUAL GAS FRACTION DEFINITION : DURING BLOWDOWN IT CAN BE ASSUMED WITH ACCEPTABLE ERROR THAT DUE TO THE ESAPING GAS THE REMAINING GAS EXPANDS ISENTROPICALLY UNTIL THE PRESSURE AND TEMPERATURE FALLS DOWN TO P RES AND T RES

36. ISENTROPIC EXPANSION OF GAS IN THE CYLINDER TO 5 (MASS DECRESES AND THEREFORE SPECIFIC VOLUME INCREASES)

41. QUIZ No: 4 (300) DRAW THE IDEAL P-V DIAGRAM OF A FULL THROTTLE (UNTHROTTLED) SPARK IGNITION ENGINE AND SHOW THE COMPRESSION AND EXPANSION PROCESSES.