Transcript Chapter 1: Development of Off

Liquid Fuels
Crude Oil
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Found in rock formations that were
ocean floors.
Organic matter from seas became
trapped by sediments at ocean floor.
Cracking of the molecules and
elimination of oxygen turned organic
matter into petroleum.
Crude Oil
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Petroleum is made of 86% carbon
and 14% hydrogen.
Hydrocarbon molecules are
accompanied by dirt, water, sulfur
and other impurities.
Crude oil must be refined to
produce suitable engine fuels.
Fig. 5.1: Molecular Structures of Some
Hydrocarbon Fuel Families
Fuel Properties
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Standards Organizations
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SAE – Society of Automotive Engineers
ASTM – American Society for the
Testing of Materials
API – American Petroleum Institute
Specific Gravity
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A measure of the density of liquid fuels at
15.6 C as compared with water at the
same temperature.
API devised the following scale,
141 .5
API 
 131 .5
SG
o
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where SG is the specific gravity.
o
A hydrometer, calibrated in API , is used
to measure the specific gravity.
Fuel hydrometer.
Ideal Combustion
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All of the H in fuel is converted to
H20.
All of the C in fuel is converted to
CO2.
Air is 21% O and 79% N by volume.
Combustion of Gasoline
Stoichiometric Air/Fuel Mixture
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For gasoline…
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3.51  11.54 
A/ F 
 15.1 : 1
1
Table 5.2: Representative Fuel Molecules
Diesel Air/Fuel Ratios
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Stoichiometric air/fuel mixture for
CI engines 14.9:1.
However, most CI engines are
operated with a leaner air/fuel
ratios and therefore free oxygen is
often found in the exhaust.