Experimental Study on Thermal Management Strategy of the Exhaust Gas of a Heavy-Duty Diesel Engine Based on In-Cylinder Injection Parameters 2020-01-0621

The aftertreatment system is indispensable for the removal of the noxious pollutants emitted by diesel engines, whose efficiency depends largely on the exhaust gas temperature. Therefore, this study proposes a thermal management strategy including post injection, intake throttling and late post injection to improve the efficiency of the aftertreatment system for a heavy-duty diesel engine. In the experiments, the effects of main injection, post injection, injection pressure and throttle opening on the exhaust gas temperature at diesel oxidation catalyst (DOC) inlet were studied, with the influence of late post injection on the exhaust gas temperature at DOC outlet also investigated. The results showed that the reasonable control of throttle opening and post injection (such as the adjustment of injection timing and injection quantity) can significantly improve the average temperature at DOC inlet from 237.8°C to 333.6°C in the WHTC, with an increase of 40.3%. On the contrary, the influence of main injection timing on the temperature at DOC inlet was very limited, and reducing injection pressure can slightly raise the temperature at DOC inlet, which, however, can also lead to the remarkable increment of particulate matter (PM) emissions and the deterioration of the fuel economy. In addition, with the delayed late post injection timing, carbon monoxide (CO) emissions first increased and then decreased, while total hydrocarbons (THC) emissions kept rising. The temperature at DOC outlet increased with increasing injection quantity and delaying injection timing of late post injection, and the larger injection quantity was, the faster the temperature at DOC outlet increased. The active regeneration of the diesel particulate filter (DPF) can be realized by appropriate control of late post injection, while the lubricating oil dilution and fuel economy deterioration should be avoided by employing proper injection quantity.