Study on the combustion mechanism of molten sodium

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13450082
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: YOSHIZAWA Yoshio Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Professor, 原子炉工学研究所, 教授 (00016627)
• Co-Investigator(Kenkyū-buntansha): KATO Yukitaka Tokyo Institute of Technology, Research Laboratory for Nuclear Reactors, Professor, 原子炉工学研究所, 助教授 (20233827)
• Project Period (FY): 2001 – 2003
• Keywords: sodium / pool combustion / counter flow diffusion flame / aerosol / radiation heat transfer

Research Abstract

The combustion of melting sodium is difficult and different from flame phenomenon widely known in the conventional basic combustion science because product is a solid phase. (1) There appears suction on the reaction zone. (2) The process of diffusion and removal of the solid phase product from the reaction zone is complicated. (3) The radiation heat transfer by the solid phase product has an important effect. In this study, the combustion of sodium is clarified from the viewpoint of the basic combustion science. The behavior of the radiation heat transfer by floating solid phase product (aerosol) was examined in detail and the effect of the radiation heat transfer by aerosol is discussed widely. The radiation heat transfer model based on the transport equation as an absorbing emitting medium was used. The followings were clarified by the numerical analysis based on above discussions ; surface combustion rate and flame height from the sodium pool, the effects of melting sodium temperature, atmosphere temperature, atmosphere oxygen concentration and emissivity of sodium surface. A sophisticate experimental sodium combustor was made. It is substantially a counter flow diffusion flame burner. The burner is surrounded with a pair of honeycomb which composes a radiation feedback burner. The premixed flame of the methane is formed on the honeycomb surface and the space between honeycomb is kept as a controlled high radiation field. Counter flow diffusion flames on the melting sodium pool surface were observed. The results agreed approximately with the analysis. In addition, an axi-symmetric flow field near the stagnation point of the counter flow was analyzed including detailed examination of the aerosol. The phenomena was clarified by comparing with the experimental results.