Experimental Study on the Performance of a Dual-Injection SDPF System Meeting Future Ultralow-Emission Requirements

In the future, strict diesel engine emission regulations will be implemented. To study the diesel engine aftertreatment technology route that meets the future emission regulations, a dual-injection selective catalytic reduction coated on diesel particulate filter (SDPF) system of diesel oxidation catalyst (DOC) + electrically heated catalyst (EHC) + SDPF + selective catalytic reduction (SCR) + ammonia slip catalyst (ASC) was designed. Through the diesel engine test bench, the emission performance of the SDPF outlet and the exhaust pipe under fresh, accumulated carbon, and accumulated ash conditions of the SDPF was tested. The results show that the characteristics of the SDPF outlet emissions vary under different conditions. Under different SDPF conditions, except for the accumulated carbon samples PN₁₀ (the quantity of particulate matter with a particle size of 10 nm or larger), which exceeded the standard under the WHSC cycle, all other conditions can meet the European Stage 7 heavy-duty vehicle emission regulations. The passive regeneration ability of SDPF is weaker than that of catalyzed diesel particulate filter (CDPF), but it can reach a carbon balance state at 600 s in the WHTC (urban-rural driving condition). The NO _x and NH₃ emissions of the dual-injection SDPF system are similar to those of the dual-injection SCR system. The N₂O emissions are slightly lower, while the PN₁₀ emissions are higher, but still there is a margin of over 50% compared with the Euro 7 emission regulations. The exhaust backpressure of the dual-injection SDPF system is higher than that of the dual-injection SCR system. Overall, the dual-injection SDPF system has the potential to meet the future emission regulations.