A study on effect of a small amount of hydrogen content on ignition of flammable premixture

A study for the ignition of flammable premixture that contains CH4 and H2 at stagnation point of a hot rod was conducted, and a comparison between calculated and experimental results was reported in the paper. The catalytic reforming reaction of CH4 with steam in the furnace produced a small amount of H2, which was premixed with air. The mixture was then ignited by a hot rod located inside the test vessel. Experimental and calculated results both show that a small quantity of H2 can greatly reduce the ignition temperature, explained by the high reactivity and high diffusivity of H2. A new method for calculating the equivalent overall reaction rate is described in the paper, in which the gradient of local Damkohler number instead of the traditional temperature gradient on the surface of the hot rod is adopted as an ignition criterion.