Thermal Dynamics and Heat Management in Hydrogen Internal Combustion Engines

The road transportation sector faces unprecedented pressure to achieve carbon neutrality. While internal combustion engines (ICEs) remain indispensable for heavy-duty and commercial applications due to their durability and power density, upgrading traditional ICEs to operate on zero-carbon fuels is an urgent global priority.Hydrogen presents a highly promising pathway to eliminate tailpipe CO2 emissions. However, hydrogen's unique physicochemical properties—such as its extremely high flame speed and high combustion temperatures—introduce severe thermal challenges. These extreme thermal environments significantly alter in-cylinder heat transfer dynamics and thermal boundary conditions compared to conventional fuels.To address these challenges, ammonia-hydrogen fusion combustion has emerged as a particularly promising pathway for zero-carbon ICEs. Ammonia (NH₃) serves as a high-energy-density hydrogen carrier with mature storage and transportation infrastructure, while hydrogen acts as a combustion enhancer due to its low ignition energy and high flame speed. This thermal advantage makes ammonia-hydrogen fusion engines a compelling subject for thermal engineering research. However, the thermal management of such engines introduces unique complexity: hydrogen's high reactivity must be carefully balanced against ammonia's low laminar burning speed and high auto-ignition temperature, and the fuel-bound nitrogen characteristics of ammonia give rise to high NOx, unburned NH₃, and N₂O emissions. Notably, higher hydrogen fractions improve efficiency but increase NOx emissions, and raising intake temperature increases thermal NOx —underscoring the critical need for precise thermal management strategies in these engines.Consequently, a deep understanding of thermal engineering within hydrogen engines—and increasingly within ammonia-hydrogen fusion engines—is critical to managing the intense thermal stress and heat losses that currently limit their full potential.Thermal engineering provides the key tools to understand and address these challenges. In-cylinder heat transfer modelling, thermal boundary characterization, and combustion heat release analysis can reveal how hydrogen's distinct combustion properties—and the synergistic thermal effects of ammonia-hydrogen blends—drive abnormal events such as pre-ignition, backfire, and knocking. In ammonia-hydrogen engines, thermal management strategies must additionally address the trade-off between reducing unburned ammonia and N₂O emissions through elevated intake temperatures and the associated increase in near-TDC heat transfer losses. Advanced thermal management solutions for ammonia-hydrogen engines include liquid ammonia phase-change cooling systems that leverage ammonia's favorable thermodynamic properties, on-board ammonia decomposition units (ADUs) that utilize engine exhaust waste heat for hydrogen production, and cathode-exhaust-assisted intake humidification strategies that reshape high-temperature zones and NOx formation pathways. Advanced thermal management strategies—including injection timing, charge dilution, and cooling system design—offer pathways to suppress these phenomena under high-load conditions and control thermal-NOx formation. At the same time, developing effective thermal solutions for H2-ICEs and ammonia-hydrogen fusion ICEs requires careful attention to the trade-off between maximizing thermal efficiency and managing the high-temperature environments that drive emissions.This Research Topic explores the thermal engineering of hydrogen internal combustion engines (H2-ICEs) and ammonia-hydrogen fusion internal combustion engines. The aim is to advance the scientific understanding of in-cylinder thermal dynamics and thermal management strategies, particularly where thermal complexity limits engine performance and broader commercialization.Submissions should contribute to improvements in thermal efficiency, in-cylinder heat transfer understanding, and thermal boundary control in H2-ICEs and ammonia-hydrogen fusion ICEs. Studies that address abnormal combustion phenomena, NOx mitigation, ammonia slip and N₂O control, or high-load thermal management from a rigorous thermal perspective are particularly encouraged.This Research Topic welcomes Original Research, Review, and Mini Review articles whose primary focus lies within thermal engineering and thermodynamic disciplines. Specific themes of interest include, but are not limited to:• In-cylinder heat transfer mechanisms and thermal boundary layer modeling in H2-ICEs and ammonia-hydrogen fusion ICEs.• Strategies for maximizing gross thermal efficiency and managing combustion heat release in hydrogen and ammonia-hydrogen engines.• Advanced high-load thermal management solutions to prevent engine thermal degradation.• Thermal perspectives on abnormal combustion: heat-induced pre-ignition, backfire, and knocking.• Thermal mechanisms of NOx formation and advanced thermal-based mitigation strategies, including fuel-NOx and thermal-NOx pathways in ammonia-hydrogen combustion.• The impact of hydrogen injections and advanced ignition technologies on spatial thermal distribution.• Thermal management strategies for ammonia-hydrogen synergy systems, including liquid ammonia thermal management supply systems, ammonia decomposition units (ADUs) utilizing exhaust waste heat, and intake humidification approaches.• Thermal analysis of ammonia-hydrogen combustion modes (spark ignition, jet ignition, and compression ignition) and their effects on heat release characteristics, thermal stratification, and emission formation. Topic editors: Ping SUN, Jun Deng, Yaodong Du Source: https://www.frontiersin.org/research-topics/85233/thermal-dynamics-and-heat-management-in-hydrogen-internal-combustion-engines