SwRI reveals promising findings on lubricant durability in hydrogen engines

Lubricant Durability in Hydrogen Engines

Lubricant durability in hydrogen engines – The Southwest Research Institute (SwRI) has released new findings on lubricant durability in hydrogen-fueled internal combustion engines (H2-ICE). Presented at the 78th STLE Annual Meeting & Exposition in Minneapolis, Minnesota, USA, in May 2024, the study explores the impact of hydrogen combustion on lubricant performance and longevity.

SwRI has launched the Hydrogen Internal Combustion Engine (H2-ICE) Joint Industry Program (JIP) to develop and demonstrate the feasibility of hydrogen-fueled engines for heavy-duty applications. SwRI successfully converted a Cummins X15N engine to run on hydrogen and retrofitted it to a Class 8 heavy-duty vehicle, demonstrating its potential to achieve near-zero greenhouse gas (GHG) emissions and ultra-low emissions of nitrogen oxides (NOx) and particulate matter.

Study Findings

Lubricant Interaction: The research highlighted that hydrogen engines have a much shorter flame extinction distance and deeper flame penetration into the cylinder wall boundary layer. This can lead to increased lubricant oxidation and associated emissions.

Combustion Byproducts: Concerns about water ingress into lubricants and the potential formation of corrosive nitric acid were addressed. However, the study found minimal water accumulation in lubricants, debunking myths about excessive water production in hydrogen engines.

Durability Testing: Conducted on a modified Daimler DD15 engine, the study involved a 350-hour test cycle. Results showed that lubricant performance remained stable, with minimal changes in viscosity, Total Acid Number (TAN) and Total Base Number (TBN).

Technical Insights

Engine Modifications: Custom injectors, a split exhaust manifold design and a blow-by suction system were used to optimise performance and safety.

Detonation and Pre-Ignition: The engine was closely monitored for detonation and pre-ignition, with several instances of automated shutdowns due to pre-ignition.

Consistency of Results: Despite expectations, the lubricants did not show significant degradation.

Future Directions

While the study confirmed the durability of the lubricants in hydrogen engines under hot and steady-state conditions, more research is needed to understand the behavior of the lubricant in low-temperature and cold-start scenarios.

Conclusion

The SwRI research represents a significant step toward integrating hydrogen as a viable fuel for internal combustion engines. By addressing key challenges related to lubricant performance, this study supports the wider adoption of hydrogen technology in heavy-duty transportation, contributing to a cleaner and more sustainable energy future.