气固两相流表观发射率的实验研究

Experimental Study on Apparent Emissivity of Gas-solid Flow

气固两相流的辐射换热是其传热的主要方式之一,准确计算气固两相流的辐射换热需要掌握其发射率。结合工程实际,设计搭建了固相颗粒群表观发射率的测定实验台,提出了一种气固两相流发射率的简便测试方法。在此基础上,系统研究了颗粒温度、颗粒浓度及颗粒粒径等因素对固相表观发射率的影响。测试结果表明,在实验范围内,气固两相流的表观发射率与固体浓度正相关;颗粒群的表观发射率随颗粒温度的升高而降低,颗粒粒径的影响可以忽略。根据实验数据提出了考虑颗粒浓度、温度的颗粒群表观发射率经验关联式,与前人的实验结果吻合得很好,表明其具有良好的可靠性。

The emissivity of the gas-solid two-phase bed is critical to accurate calculation of the radiation heat transfer in the high-temperature gas-solid two-phase flow. In this paper,an experimental platform for testing the apparent emissivity of solid particles was constructed and an indirect measurement method of the apparent emissivity of solid particles at different concentrations was carried out. The effects of particle temperature,particle concentration and particle size on the apparent emissivity were studied systematically. The experimental results showed that the larger the particle concentration was,the higher the apparent emissivity would be,while the apparent emissivity decreased with the increase of particle temperature,but the effect of particle size on the emissivity was not significant. Based on the experimental data,the empirical correlation of the apparent emissivitywas established,whichwas the function of temperature and the suspension density of solid. The comparison between the empirical correlation and the data from literature confirms its availability.