Combustion enhancement and soot reduction of kerosene-based fuel under engine-relevant conditions enabled by fuel reactivity modulation

Abstract

Liquid fuels incorporating biomass components (e.g., bio-alcohols) offer a great potential for improving combustion performance and energy efficiency. However, the insufficient reactivity and Leidenfrost effect of these fuels are two long-standing challenges for its stable combustion under wide engine-relevant conditions. Herein, the effect of methoxydiethylborane (MDEB) on the spray combustion characteristics promotion of kerosene and binary kerosene/ethanol-based fuels is reported, where the suppression of Leidenfrost effect under air conditions is demonstrated. The synergistic effect of MDEB on oxidation heat release and active radical formation not only enable the resultant kerosene/ethanol-based suspended droplets to present high evaporation rate (∼44 % reduction in evaporation time), excellent ignition performance, e.g., elevating ignition reliability and ignition delay time dropping to 1051 ms (∼67 % reduction) at an ambient temperature of 820 °C, and soot reduction property (few residual black particles displayed in suspension unit) compared to neat fuel droplet, but also make single kerosene-based hybrid fuels exhibit improved atomization and jet combustion characteristics. Notably, the negative growth behavior of evaporation time associated with the Leidenfrost effect that is dominated by low thermal conductivity air and local fuel vapor layer can be eliminated by introducing MDEB. Further, the jet dynamic reflects the improvement of gas phase diffusion and fuel–air mixing in jet and radial directions, and the increased flame propagation rate and heat transfer efficiency, which highlights the applicability of fuel reactivity modulation strategy for the enhancement of combustion stability under wider engine-relevant conditions. The findings thus provide a promising way to engineering scalable liquid fuels for advanced aviation engines, and realizing pollutants control for efficient energy conversion and management.