Environmental Engineering Reference
In-Depth Information
Keywords In-cylinder
combustion
Surrogate
fuels
Low-dimensional
combustion
Fuel spray
Multiphase processes
1 Introduction
In 2013, almost 90 million barrels of liquid fuels were consumed in power and
propulsion devices worldwide. The United States was the largest consumer at 20 %
(USEIA 2014 ). The transportation sector accounted for approximately 70 % of this
consumption. The emissions produced, and the fact that much of the oil used is
imported, has motivated investments in alternative propulsion and energy tech-
nologies (e.g., electric, wind, solar, geothermal) that would also reduce reliance on
foreign supplies. However, these alternatives are not yet at the stage to signi
cantly
impact petroleum use or fully meet the transportation and energy needs of modern
societies (NSF 2011 ). And none of them currently matches the cost and energy
density of liquid fuels. Biofuels derived from nonfood feedstocks have generated
signi
cant interest to complement, and eventually replace, petroleum-based fuels.
There are, however, issues that need to be resolved for them to realize their full
potential as an alternative to petroleum fuels (Dirks et al. 2012 ). Nonetheless, the
need for liquid fuels is expected to remain even as the supply of petroleum-based
fuels is limited (NSF 2011 ).
Internal combustion and aircraft engines are the primary consumers of liquid
fuels. A further stimulus for improving engine ef
ciency comes from new regu-
lations (i.e., in the U.S.) for the ground transportation sector that mandate fuel
economy levels of 54.5 miles per gallon by 2025 for new model cars as shown in
Fig. 1 (FR 2012 ). As such, development of technologies that improve the ef
ciency
Fig. 1 New fuel economy
targets for 2025 (FR 2012 )
 
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