Transient boiling phenomena of high-temperature clod of grains in low boiling point liquid

Abstract

Vapor explosion is thought to occur under liquid-liquid contact condition. In addition, it is reported that a mass of grains and water also cause the transient boiling phenomena. However, it is not clearly defined that the phenomena with the grains are vapor explosion. Thus we focused on the transient boiling phenomena with clod of grains. The objective of the present study is to clarify the behavior and specific quality of transient boiling phenomena with the clod. We heat the clod which consist of grains less than 100 μm and inject it into the tank filled with water. The boiling behavior and pressure data were obtained by a high speed camera and a pressure transducer. From experimental results, it is confirmed that the vapor explosion similar to the liquid-liquid condition occurred by the clod. In addition, it is clarified that the vapor film holding time increased as the water temperature increased. Furthermore, it is also clarified that the occurrence condition of vapor explosion can be estimated by TIZ (Thermal Interaction Zone) which is used to define the occurrence condition of vapor explosion in liquid-liquid condition. In contrast, we found that the occurrence of vapor explosion with the clods is influenced by the hardness of the clods which is the characteristics of the clod of grains. From these results, it is also clarified that the process of disengagement of the grains is the trigger mechanism of vapor explosion with the clod. These results indicate that the vapor explosion with solid-liquid contact condition which is not assumed in the previous work can occur.

Keywords

• thermal hydraulics
• heat transfer
• boiling
• pressure fluctuation
• vapor explosion
• clod of grains
• tiz(thermal interaction zone)
• trigger mechanism