Abstract:

Diesel engines need co-optimization for in-cylinder purification and high efficiency exhaust aftertreatment technologies to meet the increasingly stringent emission regulations in the future. This paper compared different current emission regulations in Europe, the USA and China for heavy-duty diesel vehicles.
The analysis results show that for the diesel vehicles which meet the China VI, Euro VI, and US 2010 regulations, the influence of the harmful emissions on air can be neglected, so these regulations can be defined as near-zero emissions. To achieve the near-zero emission regulations, several in-cylinder clean combustion and aftertreatment technologies were described; based on these technologies, two technical routes of exhaust gas recirculation (EGR) and selective catalyst reduction (SCR)-only were summarized. To meet the ultra-low NO_x emission regulation in USA California, two technical routes of passive NOx absorber (PNA) and close-coupled SCR were compared. The results show that the EGR route has good control effect on low temperature NO_x emission; the SCR-only route has good fuel economy; the PNA route has low NO_x emissions and simple system structure; while the close-coupled SCR technology has low cost and good durability.

Key words: heavy-duty diesel truck, near-zero emission regulations, nitrogen oxides (NO_x), particle matter (PM), emission reduction,  in-cylinder purification, exhaust aftertreatment