Optimization analysis of rare earth emitter thickness based on radiative transfer equation

A mathematical model was developed based on the radiative transfer equation and energy balance equation to analyze the performance of selective emitter consisted of SiC substrate and Yb2O3 coating,as well as the effect of coating thickness on the emittance inside or outside of the emission band.The calculated results show that the temperature difference between coating surface and substrate makes the emittance lower,which is more obvious as the coating thickness increases.Emittance for the wavelength of 0.98 μm as typical wavelength of the inside the emission band comes to maximum when the coating thickness is 0.25 mm.While for the wavelength of 1.8 μm as typical wavelength of outside,emittance is positively proportional to the coating thickness.According to the principle of high-performance emitter,which indicates high emmittance inside the band and low emmittance outside,the optimal performance of selective emitter is achieved when the thickness of Yb2O3 coating is 0.25 mm.