Particulate Emissions from Hydrogen Diesel Fuelled CI Engines

Compression ignition engines are much-celebrated power plants for both heavy transport and stationary applications, owing to their high thermal efficiency and low-end torque. However, CI engines are infamous for emission of black smoke mostly composed of carbon soot particulates. These soot particulates are a complex agglomeration of carbonaceous materials, volatile organic compounds (VOC) and trace heavy metals. Moreover, the soot particulates are reported to be associated with numerous hazards like impaired human organ functionality, climate change and visibility. Attempts have been made to reduce the soot emissions using diesel particulate filters (DPF) and other catalyst-based after-treatment technologies. However, life and performance efficiency of these measures remain questionable. This chapter aims to report the influence of hydrogen addition in a diesel engine on the particulate formation. The researchers have concluded that the primary pathway for PM formation in diesel engines is through hydrogen abstraction acetylene addition (HACA) mechanism, where a polyaromatic hydrocarbon (PAH) acts as a precursor to soot formation. The literature reports that hydrogen presence in the combustion chamber can deteriorate the formation of PM by interfering with HACA mechanism. Considering PM size and number are essential emission control parameters in vehicular emission norms throughout the world, and it is highly imperative to critically evaluate the potential of hydrogen in the reduction of PM size and number. Therefore, the chapter discusses in detail the effect of hydrogen enhancement in a dual-fuel engine. Further, attempting to critically present the hydrogen's influence on particulate modes, distribution and morphology.