Confirm the residence-time and heating-history mechanism for larger-particle ignition failure

Determine whether the greater ignition failure observed for larger iron particles is caused by their slower heating and inadequate residence time in the hot coflow by analyzing the particle heating histories up to ignition.

Background

The particle-size analysis indicates that ignition failure is somewhat more prevalent among larger particles. The paper proposes that larger particles heat more slowly because of their greater thermal capacity and consequently require more time to undergo thermal runaway than is available during their residence in the hot coflow. This explanation remains unconfirmed, and the authors identify analysis of individual particle heating histories as necessary to test it.

References

This is hypothesized to be an effect of slower heating-up of larger particles, which have higher thermal capacity and hence require a longer time to ignite relative to the residence time in the hot coflow. Mi et al. showed that slower heating of the particle increases the critical temperature required for thermal runaway due to the buildup of the oxide layer. Further analysis into the heating history of the particles to ignition is required to confirm this hypothesis.

— LES of iron-powder combustion in a jet-in-hot-coflow burner - Insights on flame structure and ignition characteristics  (2608.28294 - Hemamalini et al., 28 Aug 2026) in Section 3.3, subsection “What causes partial oxidation?”