FOUR STROKE ENGINES

strokes(movements of piston from tdc to bdc or either way)

corresponding rotation of crank how many during 4 strokes?

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

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

FOUR STROKE ENGINES

. BLOW DOWNOPENING OF EXHAUST VALVE

DURING EXPANSION. OVERLAP

OPENING AND CLOSING OF VALVE. RAM EFFECT

ADDITIONAL MASS OF FRESH CHARGE.

FOUR STROKE ENGINES

FOUR STROKE ENGINES

FOUR STROKE ENGINES

STROKES DEFINED

SI ENGINES

THEORETICAL OTTO CYCLE

Otto cycle

PV OTTO CYCLE-COMPARISION

DIESEL ENGINES

THEORETICAL DIESEL CYCLE

IDEAL DIESEL CYCLE

IDEAL DIESEL CYCLE

PV DIESEL CYCLE-COMPARISION

PRESSURE /TEMPERATURE RELATIONSHIP

4 STROKE SI ENGINE

4 STROKE CI ENGINE

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

SI &CI ENGINES -COMPARISION

SI &CI ENGINES -COMPARISION