The document discusses four stroke engines, including the intake, compression, ignition/combustion, and exhaust strokes. It compares the processes and sequences of operation in diesel and gasoline engines. Ideal assumptions and real-world factors are outlined. The four main strokes are defined, and the Otto and Diesel thermodynamic cycles are examined through pressure-volume and temperature-pressure diagrams. Finally, gasoline and diesel engines are compared in terms of applications, costs, and efficiencies.

1. FOUR STROKE ENGINES
strokes(movements of piston from tdc to bdc
or either way)
corresponding rotation of crank how
many during 4 strokes?

2. EVENTS & SEQUENCE OF OPERATION
DIESEL ENGINE
• INTAKE OF AIR
• COMPRESSION OF AIR
• IGNITION OF FUEL
• IGNITION AND
COMBUSTION OF CHARGE
• EXPANSION OF GASES
• REMOVAL OF WASTE
GASOLINE ENGINE
• INTAKE OF FUEL AND AIR
• COMPRESSION OF FUEL AIR
MIXTURE
• IGNITION AND
COMBUSTION OF CHARGE
• EXPANSION OF GASES
• REMOVAL OF WASTE

3. ASSUMPTIONS
IDEAL
• FIXED AMOUNT OF MASS
• COMBUSTION PROCESS IS
REPLACED BY HT FROM AN
EXTERNAL SOURCE
• NO INTAKE OR EXHAUST
STROKES
• ALL PROCESSES ARE
INTERNALLY REVERSIBLE-NO
FRICTION OR HEAT LOSS
• SPECIFIC HEAT ARE ASSUMED
CONSTANT AT THEIR AMBIENT
TEMPERATURE VALUES
REAL/ACTUAL
• CHANGE IN COMPOSITION OF
THE GASEOUS CONTENTS INSIDE
THE CYLINDER DURING
COMBUSTION
• CALCULATION OF WORK
REQUIRED TO CHARGE THE
CYCLINDER & PURGE THE GASES
• HEAT TRANSFER CALCULATION
B/W GASES AND CYLINDER
WALLS
• FRICTION LOSSES,PRESSURE AND
TEMPERATURE GRADIENTS

4. FOUR STROKE ENGINES
. BLOW DOWN
OPENING OF EXHAUST VALVE
DURING EXPANSION
. OVERLAP
OPENING AND CLOSING OF VALVE
. RAM EFFECT
ADDITIONAL MASS OF FRESH
CHARGE.

5. FOUR STROKE ENGINES

6. FOUR STROKE ENGINES

7. FOUR STROKE ENGINES

8. STROKES DEFINED

9. SI ENGINES

10. THEORETICAL OTTO CYCLE

11. Otto cycle

12. PV OTTO CYCLE-COMPARISION

13. DIESEL ENGINES

14. THEORETICAL DIESEL CYCLE

15. IDEAL DIESEL CYCLE

16. IDEAL DIESEL CYCLE

17. PV DIESEL CYCLE-COMPARISION

18. PRESSURE /TEMPERATURE
RELATIONSHIP

19. 4 STROKE SI ENGINE

20. 4 STROKE CI ENGINE

21. CONCLUSIVE COMPARISION
SI ENGINES
• LIGHT WEIGHT
• LOW COST
• SUITABLE FOR SMALL &
MEDIUM SIZED
AUTOMOBILES
• DOMESTIC ELECTRIC
GENERATORS
• SAME COMPRESSION RATIO
THERMAL EFFICIENCY
MORE
CI ENGINES
• MEDIUM & LARGE SIZED
MOBILES-
LOCOMOTIVE/TRUCKS
• NOISY
• CAN USE LESS REFINED
FUELS-DUE HIGHER
COMPRESSION RATIO

22. SI &CI ENGINES -COMPARISION

23. SI &CI ENGINES -COMPARISION