In this paper, laminar
combustion characteristics of methane/ammonia/air
flames are numerically investigated using the Chemkin/Premix code.
The initial temperature is set as 298 K; the initial pressures are
set as 1, 2, 5, 10, and 20 atm; and the equivalence ratios are set
as 0.8–1.6. Laminar burning velocity (LBV); adiabatic flame
temperature (AFT); net heat release rate (NHRR); and the mole fractions
of H, NH
2
, NO, NO
2
, and HCN at stoichiometric
ratio are studied with ammonia (NH
3
) addition. Meanwhile,
temperature sensitivity and rate of production (ROP) are analyzed.
The results show that with the increase of the initial pressures,
LBV decreases and AFT and NHRR increase. With the increase of ammonia
doping ratios, LBV, AFT, and NHRR decrease. From temperature sensitivity
analyses, the main reactions that promote temperature rise are R39
(H + O
2
< = > O + OH), R100 (OH + CH
3
< = > CH
2
(S) + H
2
O),
R102 (OH + CO < = > H + CO
2
), and R122 (HO
2
+ CH
3
< = > OH + CH
3
O). The main reactions
that inhibit temperature rise are R53 (H + CH
3
(+M) <
= > CH
4
(+M)), R36 (H + O
2
+ H
2
O <
= > HO
2
+ H
2
O), and R46 (H + HO
2
<
= > O
2
+ H
2
). For the rate of production
of
the free radical pool, the trends of H and NO are consuming first
and then producing, and the trends of NH
2
, NO
2
, and HCN are the opposite. The pathway from methane to carbon dioxide
is CH
4
→ CH
3
→ CH
3
O
→ CH
2
O → HCO → CO → CO
2
, and the pathway from ammonia to nitrogen is NH
3
→ NH
2
→ NH/HNO → NO/NO
2
→ N
2
.
