Simulation of dual firing of hydrogen-rich reformate and JP-8 surrogate in a swirling combustor

Flame control, particularly at very lean conditions, is a critical requirement for external combustion power sources such as thermoelectric and thermophotovoltaic generators. The availability of in-situ produced hydrogen from JP-8 fuel reforming presents a potential supply of hydrogen at the application site, such as the battlefield, without adding a second fuel to the logistics system. This research investigates the use of small amounts of hydrogen co-fired with JP-8 for improved energy efficiency, operational flexibility and environmental protection. Numerical simulations were conducted in a 6 kW (thermal) swirling flow combustor under different conditions. The simulations use hydrogen and a single hydrocarbon surrogate for JP-8 with a 4-step reaction mechanism. It also examined the effect of using hydrogen-rich reformate containing hydrogen, carbon monoxide and other gases dual-fired with JP-8. Results showed that at lean conditions, dual firing of hydrogen or reformate with JP-8 provided improved fuel conversion, better flame stability and higher fuel burnout. Dual firing hydrogen-rich reformate and JP-8 led to increased burner capacity, reduced system size and weight requirements. However, dual firing with hydrogen provided little benefit to JP-8 combustion under stoichiometric or fuel rich conditions because they were limited by mixing rather than chemical kinetics. These results indicate that dual firing of hydrogen with JP-8 is a promising method for improving lean flame stability and burner control. This has the potential to enable small scale power applications with specific temperature requirements such as thermoelectric and thermophotovoltaic generators.

► Co-firing JP-8 and hydrogen combines advantages of both fuels.
► Hydrogen co-firing increases JP-8 lean flame stability.
► Lean flame stability offers opportunities to reduce pollutant formation.
► Hydrogen-rich reformate reduces flame quenching near combustor walls.
► Hydrogen-rich reformate increases JP-8 combustor capacity.