Recent advances in understanding of flammability characteristics of hydrogen

Regimes of Spray Vaporization and Combustion in Counterflow Configurations

“…The local balance between the rate of heat loss from, and the rate of fuel diffusion into, the reaction sheet determines largely the peak temperature achieved at the flame. A decrease in Lep results in a reduction of the rate of heat loss relative to that of fuel diffusion, and therefore causes an increase of the flame temperature, a well-known differential-diffusion effect observed for instance in hydrogen combustion (Sanchez and Williams, 2014). This reasoning, based on the local molecular-transport balance at the flame, explains the results shown in Figure 4, where the peak temperature found for Lep = 1 is considerably larger than that corresponding to the heptane diffusivity.…”

The differential diffusion effect of the intermediate species on the stability of premixed flames propagating in microchannels

“…The earliest chain-branching kinetic model, proposed by Zel'dovich and explored later by Liñán in the frame of hydrogen-oxygen combustion [35,36], assumed that the chaintermination reaction was second order in Z, that is, 2Z + M → P + M. This former model suffered from the 'cold-boundary difficulty' [37] in the sense that branching is possible for all low concentrations of Z. Therefore, it is not possible to identify a temperature below which branching of intermediate species is cut off, as seen to occur in hydrogen chemistry [38]. Dold's model is more convenient.…”

Effects of Soret diffusion on spherical flame initiation and propagation

“…The readers are referred to Refs. [18,19] for a summary of previous studies on this subject. Recently, Liang et al [20,21] have examined the Soret diffusion effects on the ignition and propagation of H 2 /CO/air flames through numerical simulation with detailed chemistry and transport.…”