L.D.COLLAGE OF ENGINEERING, AHMEDABAD SUBJECT : ELEMENTS OF MECHANICAL TOPIC: TWO- STROKE DIESEL ENGINE
A two-stroke , or two-cycle , engine is a type of internal combustion engine which completes a power cycle with two strokes (up and down movements) of the piston during only one crankshaft revolution. This is in contrast to a " four-stroke engine ", which requires four strokes of the piston to complete a power cycle. In a two-stroke engine, the end of the combustion stroke and the beginning of the compression stroke happen simultaneously, with the intake and exhaust (or scavenging ) functions occurring at the same time. INTRODUCTION
TWO STROKE DIESEL ENGINE
The Diesel cycle is a combustion process of a reciprocating internal combustion engine . In it, fuel is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. This is in contrast to igniting the fuel-air mixture with a spark plug as in the Otto cycle (four-stroke/petrol) engine. Diesel engines are used in aircraft , automobiles , power generation , diesel-electric locomotives , and both surface ships and submarines DIESEL CYCLE
Diesel engines have the lowest specific fuel consumption of any large internal combustion engine employing a single cycle, 0.26 lb/ hp·h (0.16 kg/kWh) for very large marine engines (combined cycle power plants are more efficient, but employ two engines rather than one). Two-stroke diesels with high pressure forced induction, particularly turbocharging , make up a large percentage of the very largest diesel engines.
Process 1 to 2 is isentropic compression of the fluid (blue) Process 2 to 3 is reversible constant pressure heating (red) Process 3 to 4 is isentropic expansion (yellow) Process 4 to 1 is reversible constant volume cooling (green
The 2-stroke diesel engine is an internal combustion engine with the five events common to all such engines. First is intake, when a blower forces air alone into the cylinder. Compression, squeezing the air into a small volume. This is when fuel is sprayed into the chamber. Ignition. Just as with a 4-stroke diesel engine, the heat of the compressed air ignites the mixture of air and fuel. There is no spark plug. Power, forcing the piston down. Exhaust, removing burned gases. All in just two strokes. The whole process is a cycle. Everything is back where it began, ready to run again. DISEL ENGINE WORKING
The 2-stroke diesel engine is an internal combustion engine with the five events common to all such engines. First is intake, when a blower forces air alone into the cylinder. Compression, squeezing the air into a small volume. This is when fuel is sprayed into the chamber.
Ignition. Just as with a 4-stroke diesel engine, the heat of the compressed air ignites the mixture of air and fuel. There is no spark plug. Power, forcing the piston down. Exhaust, removing burned gases. All in just two strokes. The whole process is a cycle. Everything is back where it began, ready to run again.
INJECTER PISTON CONNECTING ROD CRANK SHAFT INLET PORT EXHUST PORT TRANSPHER PORT PARTS
High engine speeds of about 3000 rpm. Lighter in a weight because maximum pressure and temperature is less. Less initial cost. Less maintenance cost. ADVANTAGES
HIGH compression ratio ranging from 15 to 17. The thermal efficiency is HIGHER due to HIGHER compression ratio. Running cost higher because petrol is costlier. DISADVANTAGISE