Hydrogen Hybrid ICE Powertrains with Ultra-Low NO _x Emissions in Non-Road Mobile Machinery 2023-01-0471

In this paper, we will show the potentials of reducing NO_x emissions of an H₂-ICE to an ultra-low level by hybridizing the H₂-ICE in an NRMM powertrain. Real-world measurement data of NRMM together with a simulated hybrid powertrain and operating strategy form the input data for the H₂-ICE on the test bench. We have modified a turbocharged four-cylinder in-line gasoline engine for use with directly injected hydrogen. Within several iteration loops, we obtained measurement data that shows that, depending on the operating strategy, ultra-low NO_x emissions are reachable. The combination of hybridization, which implies the possibility of recuperation, and the CO₂ emission-free H₂-ICE leads to a highly efficient, robust, and economic drivetrain with the lowest emissions, perfectly suitable for Non-Road Machinery.

Additionally, we will discuss the overall coupled measurement and simulation setup and the reachable NO_x emission levels in our tested setup. We will give an outlook for additional NO_x emission reduction potentials with exhaust after-treatment systems and other methods of further reducing nitric oxides, which can take the H₂-ICE to near zero NO_x emissions.