BRIEF INTRODUCTION• A diesel engine is an internal combustionengine.• It uses the heat of compression to initiateignition to burn the fuel that has beeninjected into the combustion chamber.• The engine was developed by Germaninventor Rudolf Diesel in 1893.• The engine works on the principle of dieselcycle
DIESEL CYCLEThe Diesel cycle is the thermodynamic cyclewhich approximates the pressure and volumeof the combustion chamber of the Dieselengine, invented by Rudolph Diesel in 1897. Itis assumed to have constant pressure duringthe first part of the "combustion" phase.RUDOLPH DIESEL
P-V AND T-S DIAGRAM FOR DIESELCYCLEP-V GRAPH T-S GRAPH
STROKES INVOLVED IN DIESEL ENGINE1. INTAKE stroke: Piston descends from the TDC to BDCincreasing the volume of the cylinder. Air is forcedinto the cylinder through the intake port.2. COMPRESSION stroke: with both valves closed, thepiston returns to TDC compressing the air intothe combustion chamber of the cylinder head.Temperature gets increased to hundred degrees.3. POWER stroke: While the piston is close to TDC, thecompressed fuel injected into a diesel engine ignitesdue to the heat generated in the air during thecompression stroke.4. EXHAUST stroke: Here, the piston once againreturns to top dead centre while the exhaust valve isopen. The spent fuel-air mixture is expelled.
BASIC COMPONENTS USED1. Crankshaft2. Cam shaft3. Cylinder head4. Piston5. And many more…
DETAILED VIEW OF THE COMPONENTS1. CRANKSHAFT– Singular costliest item in diesel engine.– Medium of transforming reciprocating motion torotary motion.– Balance weights can be either bolted up orwelded.
2. CAM SHAFT– Performs the vital role of opening & closing inlet &exhaust valves.– Allow timely injection of fuel inside the cylinder.– Usually 3 cams for each cylinder-2 outer cams for exhaust & inlet valves1 central cam for fuel injection.
3. CYLINDER HEAD– CH is held on the cylinder liners by 7 hold downstuds.– Subjected to high shock stress & combustiontemperature at the lower face.– Complicated casting where cooling passages arecored for holding water.– Space had been provided for passage of inlet air &exhaust gases.– Space for fuel injection nozzles, valve guides &valve seat.
4. PISTON–Compresses the air to required pressure &temperature–Receives the thrust of expanding gases &transmits the force through connecting rod.–With the help of piston rings, preventsleakage of gas from combustion chamber.
5. SOME OTHER PARTS– PISTON RINGS• Seal the combustion chamber• Prevent blow by of air & high temperature combustiongases.– CONNECTING ROD• Connects piston & crank shaft• Medium of converting reciprocating motion to rotarymotion.– LINERS• Forms the wall of the combustion chamber.• Guides the movement of piston.
A SHORT SUMMARY• Diesel Engine relies upon compression ignition.• Compression ratio lies b/w 16:1 and 25:1.• Temp. increases to 700 C to 900 C.• Piston approaches TDC, fuel is injected.• Ignition instantly occurs, causing a rapid increasein cylinder temperature & pressure.• Piston is driven downward with great force,pushing on the connecting rod & turning thecrankshaft.• Exhaust gases are expelled then.
ADVANTAGES• More efficient.• More reliable.• More durable.• Release less amount of harmful fumes.• Easily turbo-charged.• Produce minimal carbon monoxide.• Can easily accept synthetic fuels.CAN ACCEPT SYNTHETICFUELSNO HARMFUL EMISSIONS
DISADVANTAGES• More expensive.• Occasionally servicing can be more costly.• Parts tend to be more expensive.• The cost of diesel at the pump is higher.• Contribute to Greenhouse effect.• Generally more noisy.EXPENSIVEA BIT NOISY