Hydrogen Hybrid ICE Powertrains with Ultra-Low NO x Emissions in Non-Road Mobile Machinery

In this paper, we will show the potentials of reducing NOx 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 NOx 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 NOx emission levels in our tested setup. We will give an outlook for additional NOx 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 NOx emissions.