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.
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
