往复热循环多孔介质“超焓燃烧”特性

Excess enthalpy combustion characteristics in reciprocal porous media combustion system with heat recirculation

对稀薄低热值气体在往复式热循环多孔介质燃烧系统的"超焓燃烧"特性进行了研究。在模型验证的基础上,阐明了系统"超焓燃烧"产生机理,分析了换向半周期、燃气热值、二次风比等工况参数与气固两相的热容比、对流传热系数、光学厚度等物性参数对系统"超焓燃烧"特性的影响,并给出了相应的变化规律;着重指出"超焓燃烧"在燃气热值较低(H0<3.48)才能产生,且随着燃气热值降低,超焓现象越明显;稳定燃烧时,燃烧效率受各参数影响相对较小,基本保持在非常高的水平,验证了多孔介质燃烧的高效性。

Excess enthalpy combustion characteristics of low heating value gas were numerically investigated in a novel model of reciprocal porous media combustion system with heat recirculation. Based on the comparison of the model with the experimental results, the effective of the model was verified, and the mechanism of excess enthalpy combustion in the system was clarified. The influence of the conditional and material characteristic parameters on the excess enthalpy characteristics were analyzed including half period, heating value, secondary air ratio, heat capacity ratio, optical thickness, convective coefficient etc. The excess enthalpy combustion can be obtained in the system when the dimensionless heating value is no more than 3.48. The lower the heating value, the higher the level of the excess enthalpy is. The results also showed that the combustion efficiency was seldom influenced by those parameters and kept a high level at the steady combustion state, which further proved the high effectiveness of porous media combustion.