鉛直同心二重円筒内高温気体の自然対流熱伝達に関する研究

抄録

Water cooling panels are adopted as a vessel cooling system of a High Temperature-engineering Test Reactor (HTTR) to cool the reactor core indirectly by natural convection and thermal radiation. In order to investigate heat transfer characteristics of high temperature gas in a vertical annular space between the reactor pressure vessel and the cooling panels of the HTTR, we carried out experiments and numerical analyses on natural convection heat transfer coupled with surface-to-surface thermal radiation in a vertical annular space of a double coaxial cylinder. In the present experiments, Rayleigh number based on the height of the vertical space was set to be 2.0 × 10⁷ < Ra < 5.4 × 10⁷ for helium and 1.2 × 10⁹< Ra < 3.5 × 10⁹ for nitrogen. The numerical results were in good agreement with the experimental ones regarding the temperature on the heating and cooling walls, and so on. As a result of the experiments and the numerical analyses, a heat transfer coefficient of natural convection coupled with surface-to-surface thermal radiation was obtained as functions of Rayleigh number, radius ratio, temperature and emissivities on the heating and cooling walls.