Environmental Engineering Reference
In-Depth Information
Comparison of Primary and Secondary
Emissions from an Internal Combustion
Engine
Tarun Gupta, Avinash K. Agarwal and Pravesh Chandra Shukla
Abstract Diesel engines are among the most ef
cient power sources. Diesel
engine emit relatively lower amounts of CO and HC emissions as compared to the
gasoline engines but higher amounts of oxides of nitrogen (NO
X
) and particulate
matter (PM). NO
X
and PM are both associated with deleterious effects on human
health. Polycyclic aromatic hydrocarbons (PAHs) and trace metals are two most
toxic and harmful class of chemical species present in the engine exhaust. Diesel
emission is composed of a complex mixture of many organic compounds (OC) or
soluble organic fraction (SOF), nitrates, sulfate, metals, and irritants (such as
acrolein, ammonia, PAHs) which are typically adsorbed over elemental carbon
(EC) core.
Keywords Primary emissions
Secondary emissions
Particle bound PAHs
emissions
Elemental and organic carbon emissions
Particle number-size
distribution
Biodiesel
Toxicity
1 Introduction
Excessive utilization of diesel engines given their fuel economy, durability and
power advantage has resulted in exponentially high levels of diesel exhaust emis-
sions. This calls for a thorough understanding of the nature and fate of diesel
emissions in the ambient environment. Diesel emissions are mainly classi
ed as
regulated emissions (oxides of nitrogen, unburnt hydrocarbons, CO and particu-
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