2- Stroke diesel Engine PDF

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2-ST 2-STROK ROK ROKE E DIE DIESEL SEL ENGIN ENGINE E A 2-stroke diesel engine is a type of IC engine which completes its power cycle in two strokes (up& down) of piston during only one crankshaft revolution. It was invented by Hugo Güldner in 1899. EXCEPTIONS of diesel engine;  HEAD VALVE All are exhaust valve.  FUEL INJECTOR  PORTS at BDC All ports are intake.  ROOD BLOWER For pre-compression of air. Working mechanism: In a 2-stroke engine the end of the combustion stroke happens simultaneously with INTAKE & EXHAUST (scavenging process) functions occurring at the same time. 1. COMPRESSION & IGNITION: When the piston is at the top of its cylinder it is on its compression stroke. The cylinder is filled with pressurized, super-heated air. Diesel fuel is injected and ignites. 2. POWER STROKE & EXHAUST: The piston moves down the cylinder for its power stroke. When the piston is near to the bottom of its power stroke, the exhaust valves open and most of the burned gases rush out of the cylinder. Now, as the piston continues to moves down the cylinder, it uncovers a series of ports, in the cylinder wall. Pressurized air is blown in through these ports, pushing the rest of the burned gases out of the cylinder and refilling it with fresh air charge.

3. BDC TO TDC: As the piston moves back up, it blocks the inlet ports, trapping the charge of fresh air in the cylinder. Although the piston as only covered a little over one stroke, it has already completed its power stroke, the exhaust process, and the inlet cycle. As the piston comes back up the cylinder on its second stroke, it compresses the fresh air. When it reaches the top of the cylinder, injection and combustion takes place, starting the cycle over again. SIGNIFICANCE over 4-stroke: 

A two stroke engine produces one power stroke in every complete cycle, while a four stroke produces one power stroke every for four strokes.

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Two-stroke engines often have a high power-to-weight ratio, power being available in a narrow range of rotational speeds called the "power band" . Compared to four-stroke engines, two-stroke engines have a greatly reduced number of moving parts, and so can be more compact and significantly lighter.

PV diagram:

Differences b/w 2-stroke diesel & petrol: 

The difference is fuel used, spark plug for gasoline combustion whereas diesel engine uses the heat of compression to self-ignite.  Gasoline engine run faster than diesel engine and gasoline burns easily and produce energy faster than diesel engine.  Efficiency is more in diesel engine due to high compression ratio and burns less amount of fuel for the same work done by gasoline engine.  Diesel engine has good lubrication, safer, reliable than petrol engine.

Difference b/w 4-stroke diesel & petrol engine:  A/F mixture is prepared inside cylinder in diesel engine while in petrol engine it is pre-mixed.  Diesel engine doesn’t have carburetor while petrol have.  Diesel have governor for speed stabilization while no stabilization in petrol engine.  Fuel control speed in diesel engine but A/F mixture control in petrol engine.  Differences between Diesel Engine and Petrol Engine On the basis of Structure Petrol Engine Diesel Engine Spark Plug is used Employs an injector. Occupies less space Occupies more space Light in weight Heavy in weight Smaller in size Bigger in size  Differences between Diesel Engine and Petrol Engine On the basis of Performance Petrol Engine Diesel Engine Thermal efficiency up to 25% Thermal efficiency up to 40% Has lower Compression Ratio Has Higher Compression Ratio Produce less Power Produce more Power Produce high RPM Produce low RPM Produce low Torque Produce high Torque Fast Acceleration Slow Acceleration Are less Durable Are more Durable.

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Differences between Diesel Engine and Petrol Engine On the basis of Environmental Effect Petrol Engine Diesel Engine Produce Low Vibrations Produce High Vibrations Produce low Noise Produce high Noise Produce more CO2 Emission Produce less CO2 Emission.  Differences between Diesel Engine and Petrol Engine On the basis of Economy Petrol Engine Diesel Engine Lower in Price Expensive in Price Lower Maintenance Cost Higher Maintenance Cost Less Fuel Efficient More Fuel Efficient.  Some Applications  High Speed Vehicles Petrol Engine  Diesel Engine  High Power Vehicles.

ADVANTAGES OF DIESEL ENGINE: 1. Diesel are Most gasoline engines convert about 30 more efficient. percent of their fuel energy into actual power. A traditional diesel converts about 45 percent. A nd advanced diesels can hit about 50 percent. 2. Diesels are more reliable. Because they don’t need highvoltage ignition systems, diesel engines never fail for lack of a spark. They also don’t emit radio frequency emissions that can interfere with a vehicle’s other electronic systems. 3. Diesels run cooler. Because they are more efficient, diesel engines release less waste heat while in operation. 4. Diesels last longer. Diesel engine parts are generally stronger than gas engine components, and diesel fuel has superior lubricating properties. As a result, diesel engines tend to last twice as long as gas- powered ones. 5. Diesel fuel is safer. Diesel fuel doesn’t release fumes like gasoline does. It’s more difficult to burn and won’t explode like its lighter counterpart. turbo-charged. Put under 6. Diesels are more easily sufficient pressure, gasoline engines will spontaneously detonate. By contrast, the amount of super or turbo charging pressures diesel engines can endure are limited only by the strength of , the engines themselves. 7. Diesels produce minimal carbon monoxide. This makes diesel. Generators useful in mines and submarines, environments in which gasoline engine exhaust , would prove deadly.

DISADVANTAGES: 1. Diesel engines, because they have much higher compression ratios (20:1 for a typical diesel vs. 8:1 for a typical gasoline engine), as compare to gasoline engine. 2. Diesel engines also more expensive.

3. Diesel engines, because of the weight and compression ratio, tend to have lower maximum RPM ranges than gasoline engines 4. This makes diesel engines high torque rather than high horsepower, and that tends to make diesel cars slow in terms of acceleration. 5. Diesel engines must be fuel injected, and in the past fuel injection was expensive and less reliable. 6. Diesel engines tend to produce more smoke and "smell funny". 7. Diesel engines are harder to start in cold weather, and if they contain glow plugs, diesel engines can require you to wait before starting the engine so the glow plugs can heat up. 8. Diesel engines are much noisier and tend to vibrate. 9. Diesel fuel is less readily available than gasoline 10. Diesel engine have air-lock problem while petrol doesn’t....