Engine exhaust emissions

This chapter provides a review of the testing implications of current emission legislation covering all sizes of internal combustion engine. Unlike previous editions it does not review the history of the legislative pathways from the 1980s to the present day, this may be extensively researched elsewhere. For automotive engineers generally, and exhaust emission specialists in particular, 2020 marks the start of a completely new international legislative framework. There is an industrial dichotomy in both the role of emission specialists and the instrumentation they use, with homologation work using legislatively defined facilities and R&D work requiring similar facilities but analytical instrumentation capable of the fastest possible response times; both are covered. The serious shortcomings in the existing test regimes and the existence of original equipment manufacturer sanctioned defeat strategies that emerged in 2011, through a series of “real-world” studies using portable emissions measuring system, have led to the introduction of the more realistic chassis dynamometer–based World Harmonized Transient Cycle and test procedure plus Real-Driving Emissions testing; details of these test procedures and the instrumentation required are discussed. Particulate emissions are now covered by legislation; their classification and measurement are discussed in some detail. Postcombustion treatment of exhaust emissions by catalytic conversion, absorption, and filtration is covered, along with the choice of site of emission testing laboratories and special safety considerations. Finally, the future trends of emission control are summarized.