Experimental and Numerical Study on the Combustion Characteristics of Premixed Methane/Air in Porous Media Burner

The porous media burner is considered as the promising alternative for residential water heaters. In this work, a two-layer porous media burner was designed and the maximum NOx emission was 48.7 mg/m3 under the firing rate of 666 kW/m2. A two-dimensional model was established; the effect of the pore parameters on the flame stability limit and NOx emission was investigated. The flashback, blow-off and flame instability were observed in the experimental and numerical investigations. Through the numerical optimization, the preferred pore parameters were 0.8 mm & 0.4 (preheating zone) and 1.6 mm & 0.7 (combustion zone); the predicted NOx emission was 32.9 mg/m3. The preferred porous media were produced and studied experimentally. Under the same condition, NOx emission was 28.7 mg/m3, which was less than 35 mg/m3 (the standard requirement, GB 18,111-2021) and reduced by 41% compared with that of the initial burner (48.7 mg/m3). The flash back limit was increased and the flame was stable at φ = 0.71.