Experimental and numerical investigation on premixed H2/C3H8/air combustion and thermal performance in a burner with partially filled porous media

Abstract

• Combustion limits of premixed H 2 /C 3 H 8 /air in varied burners are tested. • Effects of porous media and C 3 H 8 blended on burner thermal performance are experimenatal studied. • Combustion characteristics of varied fuels are compared and analyzed. Micro combustion is challenged by small size, high area-volume ratio and heat loss ratio, affecting the flame stability and energy efficiency. Premixed H 2 /air combustion with C 3 H 8 blending and porous media (PM) setting are experimentally and numerically investigated in two size burners. Results indicate that partially inserted PM and enlarged combustor size both promote the combustion stability and broaden the burning limits, while C 3 H 8 blending inhibit it. These factors significantly affect the combustion characteristics and heat transmission, such as flame location and temperature distribution. The addition of small amount of C 3 H 8 is conducive to promote H 2 /air burning heat release and heat transfer in combustion chamber, while effects of C 3 H 8 blending on flame anchoring and burner wall temperature modification are weakened with increase of fuel input energy Q in and burner size. Furthermore, PM strongly improves the burner mean radiation temperature of 50 K for H 2 fueled combustion with Q in = 120.0 W in the burner with Od = 5 mm, while effects of PM is decreased with C 3 H 8 blended and burner size increased. The exhaust gas temperature of PM combustion is 274 K and 459 K lower than that of free flame in the burners with Od = 4 mm and Od = 5 mm, respectively. It also notes that the burner with Od = 5 mm and PM achieves the highest radiation efficiency 41.84% at Q in = 90.0 W, while the C 3 H 8 addition contributes to improve the efficiency of free flame in a small burner.