Investigation of a Lambda Leap Strategy for Hydrogen Internal Combustion Engines to Balance Efficiency with Performance and Vehicle Packaging King Abdullah University of Science and Technology

Format:

Book

Conference/Event

Author/Creator:

Fong Cisneros, Eric J., author.

Contributor:

Kodaboina, Raghu Vamsi

Turner, James W. G.

Vorraro, Giovanni

Conference Name:

17th International Conference on Engines and Vehicles (2025-09-14 : Capri, Italy)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2025

Summary:

The paper reports an investigation into employing a "lambda leap" (λ leap) strategy for hydrogen internal combustion engines (H₂ICEs), wherein inherently low emissions of oxides of nitrogen (NOx) are afforded at light load via operation at lambda 2.5, and at higher load by operation at stoichiometry utilizing a three-way catalyst (TWC) for NOx control.This approach means it is necessary under transient operation to "leap" between high values of lambda and stoichiometry from one cycle to the next, in order to avoid completely the λ 1.3 area where high combustion NOx is generated away from lambda equal to 1; this is because lean catalysis of NOx will be extremely challenging at the rate that it is generated there. To achieve this, a short cam profile was introduced to reduce air mass flow by 57.5%, enabling this leap without changing the fuel injection amount, while preserving favorable combustion characteristics via an early Miller cycle.The study models a 2.0 L inline four-cylinder turbocharged engine converted to hydrogen operation and equipped with the necessary valvetrain functionality. Engine maps show that the λLeap strategy increases peak brake efficiency to 38.6% and positions the high-efficiency region in a more usable part of the operating range of the engine. Vehicle-level simulations across three driving cycles (NEDC, WLTP, FTP75) and three vehicle classes (sedan, medium SUV, large SUV) show fuel consumption reductions of up to 9.9% and engine-out NOx reductions exceeding 50% compared to stoichiometric-only operation.The paper also explains why the strategy would be especially beneficial for light-duty H₂ICEs, given that they have different operating areas compared to heavy-duty ones, and why vehicle packaging, mass, and drag advantages would accrue as well. Finally, some discussion is made regarding how H₂ICEs might benefit from upsizing of their swept volumes if this strategy is successfully employed

Notes:

Vendor supplied data

Publisher Number:

2025-24-0070

Access Restriction:

Restricted for use by site license