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Since its implementation, exhaust gas recirculation has proven to be a reliable technique to control NOx emissions by lowering combustion temperature. Dilution with exhaust gas recirculation, whether in internal combustion engines or sequential-staged gas turbine combustors, affects flame reactivity and stability, which are related to the heat release rate and engine power. Another way to control emissions is to use hydrogen as a carbon-free alternative fuel, which is considered a milestone in the energy-decarbonization journey. However, the high reactivity of hydrogen is one of its hurdles and understanding this effect on laminar burning velocity is important. Flame propagation and burning velocity control the mixture reactivity and exothermicity and are related to abnormal combustion phenomena, such as flashback and knock. Therefore, understanding the effect of exhaust gas addition on the laminar burning velocity of hydrogen/air mixtures is imperative for engine design. In this work, a constant volume combustion chamber was used to observe the laminar burning velocity of stoichiometric hydrogen/air mixtures diluted with combustion products at 1 bar and 423K. Actual combustion products (35 % H2O + 65 % N2, by mole) were used for dilution at rates of 0-50%. The burned gas Markstein length was calculated for all mixtures. Experimental results of the laminar burning velocities for all mixtures were compared with kinetic modeling results. These measurements showed the monotonic reduction of reactivity and the laminar burning velocity with dilution. The reduced burning rates at higher dilution were reflected on the pressure gradient inside the vessel. Markstein length values decreased with dilution, meaning that flame instabilities increased with dilution.
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This content will become publicly available on May 21, 2026
On-board hydrogen-rich syngas production via waste heat recovery from compression-ignition engines: maximizing hydrogen content with novel multi-objective algorithms
A significant portion of fuel energy in internal combustion engines is lost as waste heat, yet limited efforts have been made to recover it effectively. This research explores the utilization of exhaust heat from a diesel engine to produce H2-rich syngas through the methanol-steam reforming (MSR) process. The engine operates at varying loads (15, 30, 45, and 60 Nm) while maintaining a constant speed of 2000 rpm. Exhaust heat is redirected to an MSR reactor, where the methanol-to-water (MtW) molar ratio is adjusted (0.5, 1, 1.5, and 2). Results reveal that the highest hydrogen content in syngas (70.3 %) is achieved at an engine load of 30 Nm and an MtW ratio of 1. To further optimize hydrogen production, three novel algorithms (DSC-MOPSO, MOSPO, and MOGWO) are applied to key operation parameters. Optimization increases hydrogen content to 72.5 % with DSC-MOPSO, 72.4 % with MOSPO, and 72.1 % with MOGWO, with error margins below 0.7 %.
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- Award ID(s):
- 2112554
- PAR ID:
- 10610213
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- International Journal of Hydrogen Energy
- Volume:
- 130
- Issue:
- C
- ISSN:
- 0360-3199
- Page Range / eLocation ID:
- 411 to 422
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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