Hydrogen formation from methane rich combustion under high pressure and high temperature conditions

Experimental and computational studies on the hydrogen conversion from methane combustion were carried out in methane rich conditions. The experiments were conducted in a rapid compression machine (RCM) over conditions with varied pressures (18-24 bar), temperatures (962-1060 K) and equivalence ratios (2.0-2.6). Both major combustion products (H2 and CO) and intermediate species (H2, CH4, C2H2, C2H4, C2H6, C3H6, CO, and CO2) were sampled and analyzed by a fast sampling system equipped with gas chromatography (GC). Computational methods including chemical equilibrium and chemical kinetic modeling were used for comparison. The results showed that kinetic model was inadequate to predict hydrogen production at fuel rich conditions due to soot formation. The competition between chemical equilibrium and soot formation resulted in an optimal equivalence ratio at φ = 2.4, where hydrogen production is the highest. Besides, higher pressure and temperature within the test range also attributed to hydrogen formation.