System Level Simulation of H2 ICE after Treatment System 2024-01-2625
Hydrogen Internal Combustion Engines (H2 ICE) are gaining recognition as a nearly emission-free alternative to traditional ICE engines. However, H2 ICE systems face challenges related to thermal management, N2O emissions, and reduced SCR efficiency in high humidity conditions (15% H2O). This study assesses how hydrogen in the exhaust affects after-treatment system components for H2 ICE engines, such as Selective Catalytic Reduction (SCR), Hydrogen Oxidation Catalyst (HOC), and Ammonia Slip Catalyst (ASC). Steady-state experiments with inlet H2 inlet concentrations of 0.25% to 1% and gas stream moisture levels of up to 15% H2O were conducted to characterize the catalyst response to H2 ICE exhaust. The data was used to calibrate and validate system component models, forming the basis for a system simulation. System model validation involved comparing the model against real-world data from production diesel engine after-treatment systems for transient cycles, including Federal Test Procedure (FTP) and Ramp model cycle (RMC) data. Subsequent simulations replicated H2 ICE exhaust conditions for steady-state and transient scenarios, yielding insights for optimizing H2 ICE applications. The paper’s final section presents results from an improved system comprising of HOC, SCR, ASC, and Hydrogen Particulate Filter (HPF), offering a potential pathway to achieving ultra-low NOx emissions in H2 ICE engines while addressing challenges like thermal management, N2O formation, and reduced SCR activity in high humidity conditions (15% H2O).
