Synergetic carbon and NOx reduction in ammonia-diesel ICCI hybrid powertrain: comparison of offline and online energy management strategies

The development of hybrid electric vehicle technology integrated with ammonia-fueled internal combustion engine (ICE) is expected to effectively promote the mitigation of greenhouse gas (GHG) emissions in the transportation sector. The intelligent charge compression ignition (ICCI) mode based on direct-injection ammonia-diesel dual-fuel engine has been proven to achieve high thermal efficiency and low carbon emissions at medium and high loads. However, its thermal efficiency and GHG emissions are significantly constrained at low-load conditions. To fully exploit the energy-saving advantages of hybrid powertrains and the emission reduction characteristics of ICCI engines, this paper designs and integrates a hybrid powertrain for the ammonia-diesel ICCI (AD-ICCI) engine. Furthermore, dynamic programming (DP) and adaptive equivalent consumption minimization strategy (AECMS) energy management strategies are formulated, and powertrain parameter sizing is conducted. On the basis of the sized powertrain, charge-sustaining simulations are performed. The results demonstrate that, compared with the conventional diesel combustion (CDC) engine hybrid powertrain, the AD-ICCI engine hybrid powertrain achieves substantial GHG emission reductions under comparable power performance, with a 36.5% tank-to-wheels GHG reduction under the DP strategy and a 45.6% NOx reduction under the AECMS strategy. Furthermore, the robustness analysis of the energy management strategies verifies that such emission reduction capabilities are maintained under both charge-depleting and battery-replenishing operations.