超臨界水中における気体の拡散現象の測定

抄録

This study attempts to develop a clean and high efficiency combustion system utilizing reactions in supercritical water. This study is aimed at the establishment of the measuring techniques of transport properties of gas and observing techniques of reaction zone in supercritical water. The refractive index of water in supercritical region was measured first because previous values were not available. The measurements were made under the conditions from ambient temperature to 420°c and from atmospheric pressure to 27MPa. The results showed that the index was constant at the whole range of the condition within experimental errors. The mass diffusivity of gas in supercritical water was measured on the assumption that the mixture was an ideal mixture. Nitrogen was employed as an alternative media of oxidizer gases in this experiment to avoid the effects of reaction. The mass diffusivity of nitrogen in supercritical water was calculated from the fringe shift measured by a Mach-Zehnder interferometer. The value of the measured diffusion coefficient was intermediate between gas and liquid's one. The effect of excess volume phenomena on the diffusivity was discussed using the experimental results.