As a hydrogen-rich carbon-free fuel, ammonia fuel has recently attracted considerable attention in the engine field. However, few studies on the tribological properties of ammonia-fueled engines have been reported, which limits the development of ammonia-fueled engines. In this study, the tribological behaviors of the cylinder liner‒piston ring (CLPR) were studied under dry friction, water, and ammonia solution media. The results indicated that both the water medium and the ammonia solution medium have a certain lubricating effect. The main wear mechanism of CLPR in dry friction is abrasive wear. In both the water medium and the ammonia solution medium, the surface damage to the CLPR was dominated by tribocorrosion, but their action mechanisms were completely different. The presence of ammonia causes the microelectrolytic reaction of the CLPR and changes the tribological behavior of the CLPR.

This study is an optimized extension based on the authors’ previous research on the tribo-chemical reaction under constant temperature field of two-stroke internal combustion engines (ICEs). It establishes a coupled analysis model that considers the tribo-chemical reactions, dynamic contact, and interface lubrication of the piston ring-cylinder liner (PRCL) system under transient temperature conditions. In this study, for the first time, the prediction of the tribofilm thickness and its influence on the surface micro-topography (the comprehensive roughness) are coupled in the working temperature field of the PRCL system, forming an effective model framework and providing a model basis and analytical basis for subsequent research. This study findings reveal that by incorporating temperature and tribofilm into the simulation model, the average friction deviation throughout the stroke decreases from 8.92% to 0.93% when compared to experimental results. Moreover, the deviation during the combustion regime reduces from 39.56% to 7.34%. The proposed coupled model provides a valuable tool for the evaluation of lubrication performance of the PRCL system and supports the analysis software forward design in two-stroke ICEs.