农村生活垃圾生物质热解和燃烧气相数值模拟

GAS PHASE NUMERICAL SIMULATION OF PYROLYSIS AND COMBUSTION OF RURAL DOMESTIC WASTE BIOMASS

为模拟周围湍流气体中生物质颗粒的热化学转化和交互作用,提出了生物质热解和燃烧的数值模拟方法。反应混合气模拟气相质量、动量和能量交换的气体粒子交互作用包括在双向耦合项中。通过双向耦合对生物质颗粒转化时间影响的分析发现:颗粒体积分数大于10-5。在恒定体积分数下,由于在较小颗粒的情况下总热交换面积较高,双向耦合的影响随着颗粒尺寸的减小而增加。由于较高的气体温度,DNS模型包含的气相均相反应而减少了生物质热解时间。相反,包括气相反应由于颗粒表面氧浓度较低而增加了生物质的燃烧时间。

A numerical simulation method was proposed towards the pyrolysis and combustion process of biomass in order to simulate the thermochemical conversion and interaction effect between biomass particles in turbulent channels.Gas particle interactions,involving mass,momentum and energy exchange,were included in a bi-directional coupling term.The volume fraction of particles was found to be higher than 10-5 by analyzing the effect of bi-directional coupling on the transformation time of biomass particles.At a constant volume fraction,the effect of bi-directional coupling increased with the decrease of particle size due to the high total heat exchange area in the case of small particles.In DNS model,homogeneous gas phase reactions reduce the pyrolysis time of biomass due to high gas temperature.On the contrary,in the gas phase reaction,the combustion time of biomass increased due to the low oxygen concentration on the surface of particles.