Numerical And Experimental Research Of Radiative Entropy Generation Of High-temperature Heat Transfer System

In electrical power and metallurgy,high-temperature heat transfer system always play an important role.In the high-temperature heat transfer systems,such as coal-fired boilers,industrial furnaces,and internal combustion engines,energy is mainly transferred through the radiation heat transfer process.Moreover,the radiation heat transfer process in the high temperature heat transfer system is always irreversible,which leads to the loss of available work.The radiation entropy generation in the furnace means the irreversibility of the radiation heat transfer.The research of radiation entropy generation can reduce the loss of available work,improve the heat efficiency of the high-temperature heat transfer system,and save energy.In this paper,for the one-dimensional and two-dimensional high-temperature heat transfer systems,the numerical study and experimental research were used to study the radiation entropy production in the heat transfer system.The specific work is as follows:The DRESOR method was used to solve the radiation entropy transfer equation,and the calculation results is verified.The effect of the non-uniformity of the temperature distribution of the medium on radiative entropy generation is studied.Some conclusion can be obtained that radiation entropy generation of the system increases with the increase of the non-uniformity of the medium temperature:the radiative entropy generation increases from 37.2W/(K·m~2) to 52.6W/(K·m~2) when the medium temperature increases from 0K to600K.Moreover,when the medium temperature distribution is non-uniform,higher wall emissivity and lower medium scattering rate should be selected to optimize the radiative heat transfer in high-temperature heat transfer systems.Combining the solution of inverse problem of the medium temperature distribution and the radiation property of the furnace,the radiation entropy generation in the industrial furnace and boiler furnace is analyzed through numerical and experimental research.Some conclusions can be obtained that the medium temperature distribution and heat flux on the wall is the important factor of radiative entropy generation:when the standard deviation of medium temperature changes from 140K to 90K,the radiative entropy generation due to the radiative transfer proceed in the medium changes from 606W/K to 516W/K;when the heat flux on the wall changes from 4.846E6W/m~2 to 5.11E6W/m~2,the heat flux on the wall changes from 1881W/K to 2013W/K.The spectral distribution of the absorption coefficient of the medium in the flame and the spectral distribution of the emissivity of different materials are combined,The non-grey property of the medium and wall is considered,some conclusion can been obtained that in the high-temperature radiation heat transfer system,when the spectral distribution of medium absorption coefficient is similar to the spectral distribution of the wall emissivity,the radiation heat transfer in the system is enhanced,the radiation entropy generation is higher,and the dimensionless entropy generation of the system is lower.