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

Micro combustion is challenged by small size, high area-volume ratio and heat loss ratio, affecting the flame stability and energy efficiency. Premixed H2/air combustion with C3H8 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 C3H8 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 C3H8 is conducive to promote H2/air burning heat release and heat transfer in combustion chamber, while effects of C3H8 blending on flame anchoring and burner wall temperature modification are weakened with increase of fuel input energy Qin and burner size. Furthermore, PM strongly improves the burner mean radiation temperature of 50 K for H2 fueled combustion with Qin = 120.0 W in the burner with Od = 5 mm, while effects of PM is decreased with C3H8 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 Qin = 90.0 W, while the C3H8 addition contributes to improve the efficiency of free flame in a small burner.

Automated summary

This study investigates the effects of premixed combustion and porous media setting on the flame stability and energy efficiency in micro combustion. Partially inserted porous media and larger combustor size promote combustion stability and broaden burning limits, while blending C3H8 inhibits these effects.