Abstract:
Particulate matter (PM) emitted from compression ignition (CI) engines (diesel engines) has a detrimental effect on human health
and the environment. The physical and chemical characteristics of PM emitted from CI-engines are influenced by engine
operating conditions and fuel properties. The morphology, nanostructure, and chemical composition of PM affect its toxicity
and interaction with the environment. From automotive industry perspective, these parameters influence the design of diesel
particulate filters. This study presents a review of the physical and chemical characteristics of particulate emissions from the CIengine. The present study commences with a brief description about the composition of PM emitted from CI-engine and the
PM formation mechanism in CI-engine. Later on, the detailed review of PM’s physical and chemical characteristics and the effect
of engine operating parameters and alternative fuels on the particle number concentration, morphology, nano-structure, and
oxidative reactivity of PM is presented. Online and offline methods of diesel particulate characterization and emerging chemical
characterization techniques such as X-ray photoelectron spectroscopy and X-ray absorption fine structure (EXAFS) are also
discussed briefly. Correlation between physical and chemical properties, and oxidative reactivity of PM is also discussed. It was
found that engine operating parameters affect the physical and chemical properties of PM. Use of alternative fuels changes the
diesel particulate morphology, nanostructure, and chemical composition which enhances the oxidative reactivity of PM.
