Simulating the low-pressure direct injection system of a hydrogen-fueled engine

Abstract

To more effectively reduce carbon emissions from ships during op- eration, utilizing hydrogen as a fuel for ship engines has emerged as a promising direction. Given the unique physical properties of hydrogen, targeted modifications to existing engines are necessary for adaptation. In hydrogen-fueled engines, the injection system is a critical component. This study aims to adjust the design parameters of a novel injector to match large two-stroke ship engines and to theoretically demonstrate the feasibility of this novel injector for use in large two-stroke engines fueled by hydrogen.Currently, the ma- jority of hydrogen-fueled engines are four-stroke engines, typically employing high-pressure injection. However, high-pressure injection tends to shorten the lifespan of the injection system, consequently reducing the overall lifespan of the engine. Therefore, this study proposes a low-pressure injection scheme, combined with in-cylinder direct injection, to mitigate the risk of unintended ignition. Given the high autoignition temperature of hydrogen, spark ignition is employed to facilitate ignition. A critical step in evaluating feasibility is determining the appropriate injection timing.Initially, it was es- tablished that hydrogen should be injected after the commencement of the compression stroke to achieve optimal mixing. Subsequently, the study analyzed the in-cylinder pressure variations during the compression stroke to identify the feasible injection window. Finally, the design parameters of the injector were configured to align with these conditions. The findings theoretically demonstrate that this injector can achieve low-pressure direct injection in large two-stroke hydrogen engines.Due to time constraints, the study did not inves- tigate the effects of different injection angles and positions on the engine. Nonetheless, the theoretical analysis confirms the feasibil- ity of employing low-pressure direct injection in large two-stroke hydrogen engines.