Effect of hydrogen and helium addition to fuel on soot formation in an axisymmetric coflow laminar methane/air diffusion flame

Chemical effects of hydrogen addition on soot formation in counterflow diffusion flames: Dependence on fuel type and oxidizer composition

“…For instance, studies in ethylene/air coflow flames [11,16] indicated that hydrogen was more effective than He in inhibiting soot formation. The opposite was reported for methane coflow flames [13,29] in which the addition of H2 was less effective than the addition of He in reducing soot formation, suggesting that H2 may chemically enhance the production of soot. These results suggest the fuel-dependency of H2's chemical effects on soot formation.…”

“…The addition of non-or low-sooting tendency fuels in conventional hydrocarbons has long been regarded as a potential approach. Previous laboratory-scale studies demonstrated that the addition of hydrogen (H2) could inhibit soot formation in shock tubes [5][6][7][8], laminar premixed flames [9,10], coflow diffusion flames [11][12][13][14][15][16][17], as well as counterflow diffusion flames [18,19]. The suppression of soot emissions through the addition of H2 has also been reported under practical combustion conditions, such as in internal combustion engines [20][21][22] and turbulent non-premixed flames [23].…”

“…Due to the distinctive role that H2 plays in the growth of polycyclic aromatic hydrocarbon (PAH) [25,26] and soot surface mass [27], the chemical effect of H2 addition has been the focus of much research. The isolation of this chemical effect from other effects can be achieved by comparing the relative effectiveness of the addition of H2 and He on the inhibition of soot formation [11,13,14,16,28].…”

“…These results suggest the fuel-dependency of H2's chemical effects on soot formation. In this regard, Liu et al [13] performed numerical simulations of both methane and ethylene coflow flames and successfully predicted the chemical promotive (inhibitive) effects of hydrogen on soot formation in methane (ethylene) flames. By comparing the numerical results with H2 addition against that obtained with He addition, they further showed that the different chemical effects of H2 were caused by its opposite effects on PAH growth and soot inception processes in methane and ethylene coflow flames.…”

A numerical study on combustion behaviours of hydrogen-enriched low calorific value coal gases

“…Liu et al investigated effect of hydrogen and helium addition to fuel (methane) on soot formation. According to the results, helium addition was more effective than hydrogen addition to reduce soot formation [9]. Kutne et al conducted an experimental study relevant combustion behaviours of low calorific syngas mixtures.…”