Research on radiative heat transfer in sodium combustion. Modeling, verification and development of a radiative properties measuring method

A quantitative evaluation of a radiative heat transfer is an important issue in sodium combustion, because a large amount of aerosol particles that are produced as a result of the combustion exists in a combustion region. The JNC cooperative research scheme on the nuclear fuel cycle with Hokkaido University has been carried out to develop a radiation heat transfer model, based on a diameter, number density and statistical and spatial distribution of aerosol particles, and an optical property measurement method. The following conclusions are obtained in this research. Computational program of the Monte Carlo method has been developed. This program evaluates a radiative transmission intensity based on an optical property. Using this program, an optical property (complex index of refraction) can be estimated from experimental conditions and results such as a diameter of particle and radiative transmission intensity. Measurement of the radiative transmission and the distribution of radiative transmission intensity has been carried out using magnesium oxide aerosol, which optical property is identified. It is validated that the estimation scheme from the experimental results represents the correct optical property of magnesium oxide. A new model of absorption and scattering coefficients that are adopted in the gas-flux radiation model has been developed using the Mie scattering theory. In this model, an influence of particle distribution on the radiative heat transfer can be evaluated. A one-dimensional benchmark calculation between the Monte Carlo method and the gas-flux model shows that the new model with the Mie scattering theory is applicable to the radiative heat transfer evaluation. (author)