Otto, Diesel, and Rotary Engine Cycles

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Otto, Diesel, and Rotary Engine Cycles

• Arenas Alejandro
• Julian Thompson
• Daniel Vertucci
• Matthew White

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Otto Engine
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Few things to remember

• Invented by Nikolas Augustus Otto in the 1870s.
• Also know as the four-stroke engine because of
  its four-stroke cycle.
• Internal combustion engine.
• Most commonly used for automotive industrial
  purposes.
• Used for cars, truck, generators, planes, and
  more.
• Requires a sparkplug in order to begin combustion
  

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Four-stroke Cycle

• Intake Stroke
• Compression Stroke
• Power Stroke
• Exhaust Stroke

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Intake Stroke
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Compression Stroke
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Power Stroke
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Exhaust Stroke
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Four-stroke cycle

1. Intake Cycle
2. Compression Cycle
3. Power Cycle
4. Exhaust Cycle

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(No Transcript)
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Otto Cycle Diagram
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The Diesel Engine
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There are a few differences between the diesel
engine and the gasoline engine.

• A gasoline engine intakes a mixture of gas and
  air, compresses it and ignites the mixture with a
  spark. A diesel engine takes in just air,
  compresses it and then injects fuel into the
  compressed air. So the diesel engine does not
  need a spark plug to operate. The heat of the
  compressed air lights the fuel spontaneously.

• A gasoline engine compresses at a ratio of 81 to
  121, while a diesel engine compresses at a ratio
  of 141 to as high as 251. The higher the
  compression ratio of the diesel engine leads to
  better efficiency and more power.

• Gasoline engines generally use either
  carburetion, in which the air and fuel is mixed
  long before the air enters the cylinder, or port
  fuel injection, in which the fuel is injected
  just prior to the intake stroke (outside the
  cylinder). Diesel engines use direct fuel
  injection -- the diesel fuel is injected directly
  into the cylinder.

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Diesel Fuel
Diesel fuel is heavier and oilier than regular
gasoline and it smells different. Diesel gas
evaporates much more slowly than gasoline
because it is heavier. Its chemical compound is
C14H30 as compared to gasoline which is C9H20.
It takes less refining to create diesel
fuel which is why it is usually cheaper than
gasoline. It has a higher energy density than
gasoline. One gallon of diesel fuel contains 155
million joules of energy compared to 132 million
with gasoline. The fact that diesel fuel has a
higher energy density and diesel engines run more
efficiently than gasoline engines creates better
mileage when traveling.
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How it works
The main difference between a gasoline engine and
a diesel engine is the spark plug. The injector
has to be able to withstand the temperature and
pressure inside the cylinder and still deliver
fuel in a fine mist. The injection process is
also different from gasoline engines. In
gasoline engines fuel is injected into the
cylinder during Intake stroke and then
compressed. The fuel and air mixture limits the
compression Ratio of the engine. If the air is
compressed to much then the fuel spontaneously
Ignites and creates knocking. A diesel
compresses air only, so the compression Ratio can
be much higher. The diesel cycle includes 4
stages which are the intake Of air, compression
of air, fuel injection, and then the exhaust
stage. The higher the compression ratio the
more horsepower from the engine. It is the heat
of the compressed air that ignites the fuel.
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The 4 stroke cycle
combustion
exhaust
Intake of air
Compression
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Rotary Engines
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Rotation and Orbit

• Each tip of the rotor follows a trochoidal path
  around the housing

Note The shaft rotates three times for
each Rotation of the orbit
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Four-Stroke Cycle (Revisited)

• Intake Stroke
• Compression Stroke
• Power Stroke
• Exhaust Stroke
• Same as Otto/Diesel Engine

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Rotary Cycle

• No cylinders or pistons
• Separate chambers of air

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Intake Stroke
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Compression Stroke
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Power Stroke
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Exhaust Stroke
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• 3 Cycles occur simultaneously (120 degrees out of
  phase)
• Drives rotor around shaft

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Mazda

• 1967 Cosmo Sport
• 2004 RX-8

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Alternative Fuels for Gas and Diesel Engines
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Biodiesel

• It can be made from many different types of plant
  oils
• Soy beans are the most commonly used.

• This makes biodiesel nontoxic and renewable when
  compared to fossil fuels

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Biodiesel vehicles are starting to increase in
popularity, especially among large fleets of
vehicles
Park rangers in Yellowstone National park use
biodiesel to decrease pollution from their pickups
Almost any type of diesel engine can be converted
to run on biodiesel, like this hummer
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Biodiesel doesn't hurt an engines performance,
but increases safety
Biodiesel can help an engine run better because
it acts as solvent
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Natural Gas Vehicles
Natural gas is a fossil fuel that is usually
found above and below oil deposits
The idea of using natural gas was first developed
in the 1930s, but until the invention of the
leak-proof pipe transporting gas was difficult
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1. NGVs burn natural gas that is compressed and
   stored in cylinders.
2. When the engine is started, natural gas flows
   into a fuel line.
3. The gas then enters a regulator where its
   pressure is reduced.
4. The natural gas feeds into the engine through a
   fuel injection system where its combined with
   air. The fuel/air mixture is adjusted to burn
   most efficiently and with the least possible
   emissions.
5. Natural gas burns in the engine just like
   gasoline.
6. NGVs can be refueled by attaching a hose at the
   fueling point.

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  Number of Natural Gas Vehicles Number of Fueling Stations
Argentina 1,200,000 1,105
Brazil 600,000 600
Pakistan 410,000 423
Italy 400,800 463
India 159,159 166
United States 130,000 1,300
China 69,300 270
Egypt 47,289 78
Venezuela 44,146 147
Ukraine 42,000 130
Source International Association for Natural Gas Vehicles. Statistics on IANGV website on December 17, 2003. Source International Association for Natural Gas Vehicles. Statistics on IANGV website on December 17, 2003. Source International Association for Natural Gas Vehicles. Statistics on IANGV website on December 17, 2003.
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http//www.biodiesel.org/ http//www.ngvc.org/ngv/
ngvc.nsf http//www.shermanlab.com/science/physics
/thermo/engines/OttoG.php http//www.geocities.co
m/henry_yu_84/illustratn/006e.jpg http//www.rotar
yengineillustrated.com/re101/mechanics1.php