According to the internal thermal emission of the medium,a new method,pseudo source adding method,is presented to analyze the apparent emissivities of semi-transparent medium layers.By this method,the apparent emissivity formulae are derived for two different cases,in one of which,the semi-transparent emitting surface is considered to be specularly reflecting,and the diffuse reflection is considered in the other.The substrate surface of the layer is supposed to be diffuse and opaque for the two cases.The comparison with the results by the Monte Carlo method is also given.

The coupled heat transfer processes of radiation, conduction and convection in semitransparent planar slab are analyzed. An inverse method is presented for estimating the unknown boundary incident radiation heat flux in semitransparent planar slab with transparent boundaries from the knowledge of the radiation intensities exiting the boundaries. The effects of anisotropic scattering, absorption coefficient, scattering coefficient, fluid temperature outside the boundaries, convection heat transfer coefficients, conduction coefficient of semitransparent media and slab thickness on the accuracy of the inverse analysis are investigated. The results show that this method is praticable.

The discrete ordinate approximation method of three-dimensional radiative transfer equation in absorbing scattering medium is expounded. The selection of quadrature sets of in-scattering term are analysed. The causes about the formation of false scattering and ray effect and its influence on the accuracy of solutions are also analysed. By detailed comparison, it is shown that false scattering and ray effect exact not only in discrete-ordinates method, but also in zone method, discrete transfer method, etc., and the influence of false scattering and ray effect on solution accuracy of radiative transfer equation can be reduced by decreasing grid size and increasing the number of solid angle discretation. The process of radiative heat transfer in a three-dimension rectangular furnace is simulated using discrete ordinates method. By comparison with zone method and discrete transfer method, it is found that discrete ordinates method has a good accuracy, and recently is one of the best method to simulate the process of radiative heat transfer in furnace.

The Monte-Carlo method is applied to calculate the stray light of an infrared optical system.The system's geometrics tructure and the physical kinds of its elements are standardized.Some relevant probability models are established and a ray tracing approach is employed which can speed the calculation effectively.On the basis of those,an universal computer program is developed,and the stray light of an infrared camera has been analyzed.

Combined with the radiosity intensity of diffusely reflecting surfaces,the improved ray tracing method is reversely employed to analyze the apparent spectral emissivity of a body of semi-transparent medium having some diffuse surfaces.The radiosity intensities of a diffusely reflecting surface are obtainde by iteratively solving the energy balance equations of all discrete zones and using the ray tracing method reversley.The apparent emissivity results obtained by this method are separately compared with the exact solutions of the semi-transparent slabs and the numerical values of disc bodies of semi-transparent medium gained by Monte-Carlo method,and the apparent emissivity of a disc body is investigated.

Combined with spectral band model, control volume method and discrete transfer (DT) method are employed to investigate numerical calculation dealing with the transient combined radiation-conduction heat transfer in three dimensional cylindrical semi-transparent medium. The first and the third nonlinear boundary conditions are both considered. Compared with Zone method and improved Monte-Carlo approach, the calculated results by this method are reliable and more precise.