Analysis of Boosting Architectures for Hydrogen Internal Combustion Engines

Restrictive future CO₂ emissions regulations are incentivizing evaluation of carbon-free fuels. This is particularly true in the difficult to electrify heavy commercial vehicle segment. The reemergence of hydrogen internal combustion (H₂ ICE) for large displacement engines can both expedite hydrogen adoption and reduce total cost of ownership. This paper covers how the application of various boosting architectures can address challenges unique to H₂ ICE. The research presented is derived from simulations conducted by AVL List GmbH and SuperTurbo Technologies on a 13L H₂ ICE. The GT Power model was calibrated from dyno testing at AVL of an operational engine and then modified with different boosting systems. The primary H₂ ICE challenge that is addressed is the requirement for the engine to maintain a lean-burn combustion strategy through transient operation in order to control NO_x formation and minimize aftertreatment requirements. This high lambda requirement can create challenges for turbochargers when available turbine power is insufficient for the desired compressor power. The simulation includes both conventional turbochargers – VGT and 2-stage - and driven turbochargers – SuperTurbo, E-boost, and E-turbo. Each system was evaluated through the WHTC drive cycle and load step transients to show instantaneous and cumulative NO_x, transient response capability and cycle efficiency. The goal of the research is to show the capability of different boosting systems related to the unique challenges for hydrogen combustion to maintain performance and drivability, while controlling engine out NO_x emissions to minimize aftertreatment NO_x conversion requirements.