Efficient lean combustion in a novel porous medium burner with the integrated of pellets and ceramic foam: Experimental study of flame propagation and stability

Porous medium combustion makes an important contribution to energy saving and emission reduction, and the porous structure significantly affects the combustion characteristics. To combine the advantages of typical ceramic foam and pellets, an integrated structure was designed in the porous medium burner. And the characteristics of flame propagation and stability were studied and compared with the traditional single structure. The experimental results indicated that with the decreasing of pellets diameter, the combustion wave velocity decreased but the combustion temperature increased. The combination of ceramic foam and pellets achieved uniform radial temperature, and the average temperature difference was reduced by nearly 50%. The annular ceramic foam also improved the upstream flame velocity of the pellets burner from -0.045 to -0.238 mm/s. In addition, increasing the equivalence ratio and decreasing the inlet velocity were both beneficial to the propagation of upstream flame. The 20 (8) burner obtained the maximum combustion temperature of 944 K with the preheating efficiency of 23% at ?=0.80 and v(in) = 20 cm/s. Moreover, as the combustion temperature increased, the NOx emission gradually increased and the maximum value reached 19.2 ppm. (C) 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.