Thermal management and catalytic combustion stability characteristics of premixed methane/air in heat recirculation meso-combustors

Abstract

Summary In order to illuminate heat recirculation effect on catalytic combustion stability and further improve energy conversion efficiency in meso‐combustor, the catalytic combustion characteristics of the combustor with/without preheating channels are numerically studied at steady conditions. It is found that methane conversion rate and combustion efficiency increases by 2% to 3% and approximately 9% in the heat recirculation meso‐combustor, indicating that heat recirculation effect facilitates more complete combustion of methane and medium components. Preheating channels show positive effects on improving combustion stability in the heat recirculation meso‐combustor. On one hand, preheating channels facilitate heat recirculation effect, and heat recirculation rate exceeds 10% for all cases and reaches 31.8% with an inlet velocity of 0.5 m/s, leading to significant increment of methane‐specific enthalpy at the preheating channel outlet. On the other hand, Rh(s)/O(s) ratios of catalytic surface and catalytic surface temperature in main reaction zone are enlarged by the preheating channels, facilitating methane adsorption at catalytic surface. Specially, most of fuels are consumed in a shorter distance with higher methane conversion speed, which brings benefits to promote combustion efficiency and may be helpful to inhibit the combustion instability in heat recirculation meso‐combustors.

A numerical study on the flame characteristics and pollutant emissions in a premixed burner: Comparison between porous and solid bluff bodies

“…The methane conversion rate is a parameter that can be used to evaluate the length of the combustion chamber required for complete combustion. In this study, the methane conversion rate is defined as the ratio between the mass fraction of methane converted at the middle of the combustion chamber ( x = 0.477 m) and the mass fraction of the inlet methane, which is expressed by equation (27) 46 …”

Numerical investigations on the emitter power and energy conversion efficiency improvement of micro‐cylindrical combustor by an internal spiral fin for micro‐thermophotovoltaic systems

“…3,4 Based on high energy density of hydrocarbon or hydrogen fuel, micro-and mesoscale combustion has a wide range of potential applications. [5][6][7] However, due to tiny size and large surface-to-volume, the micro-combustor faces the challenges of large heat loss and flame instability. In MTPV system, micro-combustor as the important component plays a key role in maintaining flame stability and energy conversion efficiency.…”

Experimental study of volatile organic compounds catalytic combustion on Cu‐Mn catalysts with different carriers

“…3 In fact, an enormous amount of unorganized VOCs emissions directly jeopardize the normal growth of fauna and flora, 4,5 as well as form the important precursors 6,7 of ozone and secondary aerosols, which could contribute secondary pollution and even lead to more serious destruction to environment and organism. Nowadays, adsorption, 8,9 combustion oxidation, [10][11][12][13][14] and biodegradation 15 all have been widely used in the treatment of VOCs treatment, and catalytic combustion is one of the most vital methods in reducing VOCs. 16 Aiming at the catalytic oxidation for VOCs, de Rivas et al, 17 respectively, performed the experimental studies on VOCs over six various kinds of Ce-Zr catalysts, which indicated the catalysts with mole ratio 0.15:0.85 and 0.5:0.5 have the best stability.…”