Evaluating the emissions and performance of two dual-mode RCCI combustion strategies under the World Harmonized Vehicle Cycle (WHVC)

Abstract

This work compares the emissions and performance of two dual-mode reactivity controlled compression ignition (RCCI) combustion strategies under the World Harmonized Vehicle Cycle (WHVC), a chassis dynamometer version of the World Harmonized Transient Cycle (WHTC) test proposed by the EURO VI emission regulation for heavy-duty engines. The major difference between the two dual-mode combustion strategies investigated is that, while one of them relies on covering with conventional diesel combustion (CDC) the part of the map that cannot be covered by RCCI regime (RCCI/CDC dual-mode), the other does it relying on dual-fuel diffusion combustion (dualmode dual-fuel). The influence of the gear shifting strategy on the emissions and performance over the WHVC is discussed first. Later, both dual-mode concepts are compared considering the optimal gear shifting strategy. The results suggest that dual-mode dual-fuel concept allows reducing the specific fuel consumption by 7% in average versus RCCI/CDC concept. Moreover, NOx emissions are around 87% lower with dual-mode dual-fuel, meeting the EURO VI requirements without the need for an SCR aftertreatment system. In counterpart, HC and CO emissions are near 2 and 10 times greater, respectively, for dual-mode dual-fuel than for RCCI/CDC.

Sizing a conventional diesel oxidation catalyst to be used for RCCI combustion under real driving conditions

“…NOx and soot emissions with the dual-mode RCCI/CDC have been found substantially improved versus single CDC operation. However, the HC and CO emissions levels with this concept still are orders of magnitude greater than with CDC [35]. The major part of the HC and CO emissions are emitted during the operation in the RCCI portion of the map.…”

Influence of the number of injections on piston heat rejection under low temperature combustion conditions in an optical compression-ignition engine

“…Research in the automotive industry is exploring new technologies to comply with emissions regulations [1] [2]. Low temperature combustion [3] is a promising concept to reduce emissions of internal combustion engines while keeping a high indicated efficiency [4]. Among the technologies achieving this low temperature combustion, gasoline partially premixed combustion (PPC) is one of the most interesting [5].…”

Experimental investigation on the efficiency of a diesel oxidation catalyst in a medium-duty multi-cylinder RCCI engine

“…This allows extending the operating region of RCCI towards higher loads in the global map before the PRR problems start to appear. However, the UHC and CO emissions levels at low and medium loads with DMDF are higher than with dual-mode RCCI/CDC, and much higher than with CDC [34]. This occurs because the majority of engine operating conditions found during a real driving cycle fall in the low-medium load portion of the map, where RCCI operation is promoted.…”