FURTHER ELABORATION OF SINGLE BUBBLE EXPANSION MODEL AND ANALYSIS OF PRESSURE RESPONSE WITHIN WATER-GLYCEROL SYSTEM

A dangerous sharp pressure raise would happen when high pressure subcooled water was injected into higher temperature glycero under atmosphere pressure. For vapor bubble which was generated in water-glycero interaction, its expansion was controlled mainly by two factors: the external heating and the internal pressure. The previous work has proved roughly that the internal pressure dominated the process of bubble expansion from a theoretical way. In order to obtain a precise expansion model, the external heating model has been improved. And the system pressure response during the injection has been established to evaluate the system safety in this study. Firstly, a new temperature distribution profile based on analytical solution of transient sphere heat transfer equation was applied to evaluate the thermal conduct rate between bubble and glycero; Furthermore, the effect of the heat convection in the bubble which would enhance the expansion rate was studied by a CFD simulation. Compared with internal pressure, the expansion rate driven by external heating model was ignorable. Based on the internal pressure expansion model, the pressure raising of water- glycero system after water injection was solved. The growing bubble occupied the space of the glycero, resulting the existing inert gas compressed and the system pressure rose rapidly. Overall, the bubble expansion is confined by its growth as a response to the system pressure. The pressure response can be described as an ordinary differential equation. A two-stage controlled system pressure response model was developed by a numerical program. The calculated results complied with literature data of system pressure well.