00 internal combustion engine
- 1. Internal Combustion Engine Prepared by K KRISHNA MURTHY
- 2. Classification of IC Engines 1. Based on engine Design: a) Reciprocating engine b) Rotary engine 2. Based on number strokes a) Four stroke engine b) Two stroke engine 3. Based on type of cycle used a) Otto cycle engine b) Diesel cycle engine c) Duel cycle engine 4. Based on fuel used a) Petrol engine b) Diesel engine c) LPG and d) CNG
- 3. 5. Based on the fuel supply and mixture preparation a) Carbureted type b) Injection type 6. Based on the method of cooling a) Water cooling b) Air cooling 7. Based on valve or port position a) Overhead valve engine b) Side valve engine c) F- shaped engine d) Wedge shape engine e) Semi spherical shape engine 8. Based on cylinder arrangement a) Horizontal engine b) Vertical engine c) Inclined engine d) opposed engine
- 4. f) Inline engine g) V type engine 9. Based on type of application a) Stationary engine b) Automotive engine c) Locomotive engine d) Marine engine e) Air craft engine
- 6. Working principle of engines 1. Four stroke spark ignition engine 2. four stroke compression ignition engine 3. Two stroke engine
- 7. Four stroke spark ignition engine
- 8. Four Stroke Compression Ignition Engine
- 9. 1. Two stroke engine
- 10. Difference between SI Engine and CI engine: Description SI Engine CI Engine Basic cycle Working on Otto cycle or constant volume heat addition cycle. Working on diesel cycle or constant pressure heat addition cycle. Fuel Gasoline, a highly volatile fuel. Self ignition temperature is high Diesel oil, a non volatile fuel. Self ignition temperature is comparatively low Introduction of fuel A gaseous mixture of fuel air is introduced during the suction stroke a carburetor and an ignition system are necessary. Modern engines have gasoline injection. Fuel is injected directly into the combustion chamber at high pressure at the end of the compression stroke, a fuel pump and injector are necessary. Load control Throttle control the quantity of fuel air mixture introduced. The quantity of fuel is regulated. Air quantity is not controlled. Ignition Requires an ignition system with spark plug in the combustion chamber. Primary voltage is provided by either a battery or a magneto. Self ignition occurs due to high temperature of air because of the high compression. Ignition system and spark plug are not necessary.
- 11. Description SI Engine CI Engine Compression ratio 6 to 10. upper limit is fixed by antiknock quality of the fuel. 16 to 20 upper limit is limited by weight increase of the engine. Speed Due to light Wight and also due it homogeneous combustion, they are high speed engines. Due to heavy weight and also due to heterogeneous combustion they are low speed engines. Thermal efficiency Because of the lower CR the max valve of thermal efficiency that can be obtained is lower Because of the higher CR the max valve of thermal efficiency that can be obtained is higher. Weight Lighter due to lower peak pressure Heavier due to higher peak pressure.
- 12. Difference Between Four Engine and Two engine: Four stroke engine Two stroke engine The thermodynamic cycle is completed in four strokes of the piston or in two revolutions of the crank shaft. Thus one power stroke is obtained in every two revolutions of the crank shaft The thermodynamic cycle is completed in two strokes of the piston or in one revolution of the crankshaft. Thus the power stroke is obtained in each revolution of the crank shaft. Because of the above the turning moment is not so uniform and hence a heavier flywheel is needed Because of the above the turning moment is more uniform and hence a lighter flywheel is needed Again because of one power stroke for two revolutions power produced for same size of engine is less or for the same power the engine is heavier and bulkier Because of one power stroke for every revolution power reduced for same size of engine is twice, or for the same power the engine is lighter and more compact Because of one power stroke in two revolutions lesser cooling and lubrication requirements. Lower rate of wear and tear. Because of one power stroke in one revolutions greater cooling and lubrication requirements. Higher rate of wear and tear.
- 13. Four stroke engines have valves and valve actuating mechanisms for opening and closing of the intake and exhaust valves Two-stroke engines have no valves but only ports (some two stroke engines are fitted with conventional exhaust valves and reed valve). Because of comparatively higher weight and complicated valve mechanism, the initial cost of the engine is more. Because of comparatively light weight and simplicity due to absence of valve actuating mechanism, the initial cost of the engine is less. Volumetric efficiency is more due to more time for induction Volumetric efficiency is low due to lesser time for induction. Thermal efficiency is higher: part load efficiency better Thermal efficiency is lower: part load efficiency poor Used where efficiency is impotant, viz, in cars, buses, trucks, tractors, industrial engines, aeroplanes, etc Used where low cost, compactness and light weight are important , viz, in mopeds, scooters, motorbikes, hand sprayers etc.