基于辐射传输方程的稀土辐射器厚度优化分析

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

对以碳化硅为基底、氧化镱为表面涂层的选择性辐射器进行优化分析,基于热辐射传输方程和能量平衡方程建立数学模型,研究带内、带外光谱发射率与涂层厚度的变化关系.结果表明:涂层内外温差对发射率有削弱作用,而且涂层厚度越大这种削弱作用越明显.以0.98μm为典型波长的带内辐射,在涂层厚度为0.25mm时发射率有最大值;以1.8μm为典型波长的带外辐射,发射率随涂层厚度增加而单调增大.依据高性能辐射器应同时具备较高的带内发射率和较低的带外发射率的原则,综合分析得出稀土辐射器氧化镱涂层的最优厚度为0.25mm.

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.