The Diesel Cycle

Robert Amirault

Objective: To establish the function, pros and cons and uses of a diesel engine.

Gasoline Engine

• Burns unleaded refined gasoline• Lower compression ratio (8:1 to 12:1)• Subject to “knocking” at high compression• Mixes the fuel before injection• Uses spark plugs

Diesel Engine

• Burns less refined diesel fuel• High compression ratio (14:1 to 25:1)• Low risk of “knocking” easy to turbo

charge and supercharge• Relies only on pressure to ignite fuel• Uses glow plugs (larger engines do not)• Injects the fuel directly into the cylinder

Benefits

• More energy is contained in diesel fuel– One gallon of diesel contains 155 MJ– One gallon of gasoline contains 132 MJ

• More efficient• Cheaper fuel

Drawbacks

• More expensive to manufacture• Noisier• More pollutant• Low acceleration due to high torque• Required to run at lower RPM

The Diesel Cycle

• Definition– The diesel cycle is the combustion process of a type of internal

combustion engine in which the burning of the fuel is triggered not by a spark plug as in the Otto cycle, but rather by the heat generated in compressing the fuel-air mixture.

• Four parts– Intake– Compression– Injection/combustion– Exhaust

The Engine• The dissected engine

was a gasoline engine• The spark plug shows

that it is not diesel• Diesel engines are most

often found in large trucks, boats, trains and anything requiring a lot of power without much speed.

References• http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/diesel.html• http://www.google.ca/search?hl=en&lr=&safe=off&rls=GGGL,GGGL:2005-

09,GGGL:en&oi=defmore&defl=en&q=define:Diesel+cycle• http://auto.howstuffworks.com/diesel1.htm