Joint Inversion Simulation Study Of Visible And Infrared Radiation In H₂O And CO₂ With Soot

Coal-fired power plants will be the main energy source in China for a long time to come.Oxygen-rich combustion,as one of the effective measures of carbon emission reduction,has been attracting much attention in recent years.In the study of thermal transformation of oxy-fuel combustion technology,radiation heat transfer in furnace plays a leading role.Based on the oxy-fuel combustion condition,the radiative heat transfer characteristics of the oxy-fuel gas phase and the granular phase mixed medium are studied,and the radiative parameters of the medium under the condition are inverted.In order to study the heat transfer problem of mixed radiation in oxy-fuel combustion conditions including CO₂,H₂O and soot,a statistical narrow band（SNB）method was introduced.The radiation transfer equation（RTE）was solved by combining the statistical narrow spectral band（SNB）and the discrete coordinate method（DOM）.A two-dimensional infrared spectral radiation model was developed by combining the statistical narrow band（SNB）method and DRESOR method.In the one-dimensional plate radiation model and two-dimensional infrared radiation model,the influence of CO₂,H₂O gas and soot on radiant heat transfer was studied,and found that one-dimensional and two-dimensional models have similar conclusions:the increase of concentration of single radiant medium and the increase of species of radiant medium could increase the absolute value of radiant heat flow and enhance radiant heat transfer.In the one-dimensional plate radiation model and two-dimensional infrared radiation model,a single radiation parameter was reconstructed for the wet cycle condition of oxy-fuel combustion（maximum temperature 2100K,H₂O gas below 20%,CO₂gas below 80%）,and the relative error of parameter reconstruction was within 2%.Based on the simulation condition of 2-d rectangular section of wet cycle of oxy-fuel combustion,the temperature field and radiation characteristic parameters of oxy-fuel combustion were inverted by combining the existing visible light radiation reconstruction model and infrared spectrum radiation reconstruction model.Based on the visible light radiation reconstruction model,the temperature distribution of the grid and the absorption coefficient distribution of soot assumed by the gray-ness were obtained.Temperature and soot data were used as the inlet parameters of the infrared radiation reconstruction model,and then the concentration distribution of CO₂or H₂O was obtained.The inversion results show that the reconstructed values of temperature and soot are relatively accurate,while the relative error of the reconstructed values of CO₂is within 10%,and that of the reconstructed values of H₂O is mostly within 10%.Parameter reconstruction was carried out after adding 2%and 5%normal distribution measurement error.The reconstructed values of temperature and soot could still maintain high accuracy,while the overall inversion error of CO₂or H₂O increased with the increase of measurement error.Generally speaking,the inversion of CO₂was better than that of H₂O.