Port Injected Hydrogen Split Cycle Engine for Decarbonization and Emissions Control

To meet the future EU emissions targets, this work presents the first of its kind experimental results from an engine representing the expansion cylinder of a recuperated split cycle engine (RSCE), operating with direct injection diesel and port injected hydrogen. The separate valve and cylinder geometry optimization of the compression and expansion cylinders, with quasi-isothermal compression and internal waste heat recovery in the RSCE, offers greater opportunities to optimize efficiency. The partial hydrogen substitution increases the calorific value and reduces overall carbon content. Results are examined at new test conditions, using the validated Ansys Chemkin-Pro numerical simulation. The results suggest that selected hydrogen content substantially reduces C02 to the 2030 targets. While this may come with NOx penalties, when liquid nitrogen is used in the process of quasi-isothermal compression, the dilution of the charge air with this species was found to reduce these emissions to approaching Euro 7 limits when coupled with the current NOx after-treatment system.