Diesel Exhaust Emissions and Mitigations

Abstract

This chapter presents a concise treatment of diesel engine exhaust emissions and its mitigations. The working principle of the diesel engine is first given to establish the background and further to describe the influence of various parameters that affect the formation of engine exhaust emissions. The factors that influence exhaust emissions are linked to the engine design and the operating factors that promote good fuel-air mixing and combustion. These factors are air induction, fuel injection equipment, fuel injection schemes, in-cylinder gas exchange process and heat transfer. Thermochemistry essentially gives insight to the global reaction kinetics and how this is applied in practical engine combustion determinations in terms of equivalence ratios. Based on these, the fuel spray structure, atomization, penetration and the spray combustion model are described. The formation of exhaust emissions such as carbon monoxide, unburnt hydrocarbon and its intermediates, oxides of nitrogen and soot in diesel engines has been discussed. The techniques of their mitigation from the view of internal factors that deals with the optimization of engine design and it performance, as well as various exhaust after-treatment techniques used for NO x and soot reduction have been briefly discussed.

Review of morphological and chemical characteristics of particulates from compression ignition engines

“…169,170 Soot formation begins with the combustion and pyrolysis of fuel in the combustion chamber. Studies 171,172 reported that the soot particles form by nucleation of heavy molecular weight PAHs. Precursors originate from acetylene, its higher analogs ( C n H n ), and PAHs.…”

“…The Sulfates can constitute up to 14% of the PM mass. 172 Tiszenkel et al 200 investigated the influence of thermal intensity on H 2 S O 4 nucleation and growth in a low-temperature environment.…”