Study Of The One-dimensional Non-gray Gases Radiative Heat Transfer Coupled With BRDF Wall

As a fundamental heat transfer way, radiative heat transfer is widely presented in various engineering and technical fields, such as in electric, meteorological, aerospace,chemical and etc., many problems which are related to infrared radiation characteristics are emerged, the accurately predict the gases characteristics is the key to solve the radiative heat transfer. Meanwhile, the boundary surface within a radiative heat transfer analysis cannot simply assumed to be blackbody, diffuse or specular, the bidirectional reflectance distribution function(BRDF) of the surface of the materials can describe the walls' emission and reflection very well, which is very important and meaningful to accurately calculate gases radiative heat transfer. The details are as follows:The non-gray gases radiative heat transfer is calculated by statistical narrow band model and discrete ordinate method under different walls. The influence of different physical length, concentration of medium and different medium on gases radiative heat transfer under BRDF walls, blackbody and diffuse is also investigated. First of all, gases radiative heat source and net radiative heat flux is analyzed under diffuse wall, the results show that with the decrease of physical length, radiative heat source change greatly near walls. In this situation, the error of radiative heat source and heat flux will be enlarged under different walls. Then the calculation of heat transfer with different concentration of medium and different medium under diffuse walls are also carried out. The results show that with the concentration of medium increase, the values of heat source and flux will be enlarged. It is also show that the radiating capacity of CO2 is largest than H2 O and CO, the radiating capacity of H2 O is larger than CO. At last, we select the Minnaert model as the BRDF function, the calculation of heat transfer with different physical length and concentration of medium is analyzed under blackbody, diffuse, gray BRDF wall and non-gray BRDF wall,respectively. It is shown that the difference of heat source will be enlarged, so is heat flux,because the more radiative intensity arrive walls under the small physical length. The capacity of medium's absorption will be enlarged with the increasing of the concentration of medium. At the same time the radiating capacity of medium will be also enlarged, so theradiative intensity arrive the wall will be enlarged, in this situation the error will become larger under different walls, so it is very important and meaningful to accurately grasp the radiative properties of the wall in radiative heat transfer.The calculation of the gases radiative heat transfer coupled with BRDF walls is studied in air combustion and oxy-fuel combustion. The influence of four different walls on the gases radiative heat transfer in dry flue gas recycle and wet flue gas recycle modes,respectively. The results show that it will bring large error under simple assumption of the radiative properties of the walls on the calculation of radiative heat and net radiative heat flux, and with the increase of concentration of the radiative participating medium, the error will be enlarged.