Numerical study on the radiative efficiency and its sensitivity to effective thermal conductivity and emittance of a cylindrical porous burner

Improving the radiative efficiency ( η ) of porous media burners is crucial for enhancing energy utilization, yet the influence of key material properties under practical operating conditions requires clearer quantification. This study systematically investigates the impact of effective thermal conductivity (λ eff ) and emittance (ε r ) of porous shell on η , as well as their sensitivities. We employ an axisymmetric two-dimensional numerical model based on the volume average method with reduced kinetics, coupled with local sensitivity analysis across a wide parameter range. The results demonstrate that η is consistently enhanced by reducing λ eff or increasing ε r . For instance, at an equivalence ratio of 0.86 and a flow rate of 26 slm, η increases from 0.35 to 0.41 as λ eff decreases from 7.5 to 0.175 W/m·K for ε r = 1. Sensitivity analysis reveals a strong but non-linear dependence: the sensitivity to λ eff is most pronounced when λ eff ≤ 1.5 W/m·K, and to ε r when ε r ≤ 0.6, with both dependencies leveling off beyond these thresholds. This work concludes that selecting emitter materials with low λ eff and high ε r is paramount for optimizing radiative performance, thereby providing direct guidance for the design of high-efficiency combustion systems. • Radiative efficiency ( η ) sensitivity to effective thermal conductivity (λ eff ) and surface emissivity (ε r ) is conducted; • Strong dependence and sensitivity of η to λ eff and ε r is validated by local sensitivity analysis; • An increase in ε r or decrease in λ eff always leads to an increase in η ; • The sensitivity of η to λ eff is decreased when λ eff is smaller, following by a soft variation with λ eff ; • The porous emitter with small λ eff and great ε r is recommended to achieve high η .