Estimation for mass transfer coefficient under two-phase flow conditions using two gas components

ABSTRACT

For proper source term evaluation, we constructed the theoretical model to estimate the mass transfer coefficient of gaseous iodine species under two-phase flow conditions, which complicates the direct experimental measurements. The mass transfer speed is determined by the product of the overall mass transfer coefficient and the interfacial area. Using the ratio of two gas components, the interfacial area, which is an important parameter that is difficult to measure, can be canceled out and the ratio of their overall mass transfer coefficients can be obtained. This ratio is expected to be equal to the ratio of their diffusion coefficients. Therefore, the unknown mass transfer coefficient such as iodine species can be estimated using the diffusion coefficients of two gas components and the reference mass transfer coefficient such as O₂. We carried out the experiments using the bubble column to confirm this relationship. From the results in this study, we confirmed that the ratio of the overall mass transfer coefficient was in good agreement with the ratio of diffusion coefficient under the bubbly flow conditions. Using this relationship confirmed in this study, we estimated the mass transfer coefficient of I₂, one of the iodine species.

KEYWORDS:

• Source term
• severe accident
• iodine
• pool scrubbing
• revolatilization
• organic iodine
• mass transfer coefficient
• bubbly flow

Disclosure statement

No potential conflict of interest was reported by the author(s).