Diesel Engines
Transportation
Mr. O’Rourke
History
Invented in the 1890’s in Germany by
Rudolf Diesel.
Invented because of the inefficiency of
steam power (10% efficient)
How it Works:
Internal Combustion engine
Similar to gasoline powered
Compression ignition vs.
spark ignition
Usually 4-stroke, sometimes 2-stroke
http://www.youtube.com/watch?v=x9yS2xdPJSU
How it Works (cont’d):
Intake- The intake valve opens up, letting in air only.
Compression-The piston moves back up and compresses the air.
Combustion -As the piston reaches the top, fuel is injected at just the right
moment and ignited by heat from compression, forcing the piston back
down.
Exhaust-The piston moves back to the top, pushing out the exhaust
created from the combustion out of the exhaust valve.
Gas vs. Diesel Engines
No Carburetor or port injection in Diesels
Uses direct injection into cylinder
No spark plugs
Glow plugs to heat engine
Much more compression than gasoline
engine (approx 2-3 times more)
Highest thermal efficiency of all engine
types
Important Notes:
Compression heats air to approx 1000
degrees F.
Air intake is constant unless a turbo is
used
Only fuel is added when throttle is applied
Fuel is added as a mist into cylinder
abrupt increase in pressure above the
piston causes knocking sound
Advantages:
Due to high compression and expansion
ratio, diesels are 45% efficient compared
to gasoline at 30%
No high voltage electrical system needed
Diesel engines usually last 2x longer than
gasoline due to stronger parts and better
lubrication
Advantages (cont’d):
Diesel fuel is safer than gasoline (not
explosive)
Fuel efficiency remains constant
Much more torque than gas due to longer
piston stroke (large diameter crankshaft
needed)
More potential for power due to adding of
turbo or sometimes supercharger
Disadvantages:
Louder engine due to large amount of
rapidly expanding gas
Diesel fuel is more expensive
Higher initial cost
Lower performance overall compared to
gas in regular driving
Problematic in cold weather
Low sulfur fuel now used but exhaust can
still smell and smoke
Uses:
90% of transportation industry
Power generators
Large boats/ships
Locomotives
Construction machinery
Cars and trucks
Largest diesel engine
109,000 hp @102rpm
Costs/Future:
Costs more per gallon due to demand
Higher initial costs, lower overall costs
Newer, cleaner fuels now being used
More cars using diesel
Quieter, more available cars
http://www.youtube.com/watch?v=vGhlgph
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