基于全光谱关联k分布模型的加压富氧燃烧烟气辐射特性研究

Thermal Radiation Characteristics of Gas-particles Mixtures under Pressurized Oxy-coal Combustion based on Full Spectrum Correlated k-distribution

在加压富氧燃烧中,烟气介质的热辐射是炉膛中换热的主要形式之一。气体与粒子的非灰辐射特性导致辐射换热研究需要耗费过多的计算资源,加剧了燃烧、流动及传热多场耦合的难度,忽略气体与粒子非灰特性的双灰体假设模型的计算精度不能满足辐射传热研究要求。全光谱关联k分布模型(Full Spectrum Correlated k-distribution,FSCK)兼顾精度和效率,在非等温非均匀介质的辐射传热中具有很高的应用前景。本文在全光谱关联k分布模型的基础上,结合加压富氧燃烧下的烟气特性,构建适用于加压富氧燃烧气氛下的FSCK气体辐射模型及数据库,并将该模型下的辐射换热计算结果与逐线法及灰气体加权和模型进行比对,对加压富氧燃烧下气体介质的辐射换热特性进行研究;对于吸收散射性介质,将气体与粒子的非灰辐射特性参数进行归一化处理,结合气体FSCK模型与粒子Mie理论,建立了吸收散射性介质全光谱关联k分布计算模型,探究了加压富氧燃烧下包含飞灰颗粒的烟气辐射传热特性。

In pressurized oxy-coal combustion,the heat radiation of gas-particles medium is one of the main forms of heat exchange in furnace.The non-gray radiation characteristics of gas and particles lead to the excessive occupation of computational resources for radiative heat transfer,which is difficult to couple the combustion,flow and heat transfer.The calculation accuracy of the gray body model for gas and particles cannot meet the requirements of precision for radiative heat transfer.Full spectrum correlated k-distribution model(FSCK)takes into account both accuracy and efficiency,and has a high application prospect in the radiative heat transfer of nonisothermal and nonhomogeneous media.Based on the full spectrum correlation k distribution model,the FSCK model and database are established for pressurized oxy-coal combustion.Furthermore,the results of FSCK is compared with the line by line method(LBL)and the weighted-sum-of-gray-gases model(WSGG).The thermal radiation characteristics of gas medium under pressurized oxy-coal combustion are studied.The non-gray radiation characteristic parameters of gas and particles are normalized to optimize heat transfer of the absorbing and scattering medium.Combined with the FSCK model and the Mie theory,a full spectrum correlated k-distribution calculation model considered absorbing and scattering medium is established to indicate the thermal radiation characteristics of gas-particles mixtures under pressurized oxy-coal combustion.