Document Type: Full Lenght Research Article
Faculty of Mechanical &amp; Energy Engineering, Shahid Beheshti University, A.C., Tehran, Iran
Vapor film formation and growth due to contact of a hot body and other liquids arises in some industrial applications including nuclear fuel rods, foundry and production of paper.
The possibility of a steam explosion remains in most of these cases which may result in injuries and financial damage. Since this phenomenon is important, this study deals vapor layer forming, growth and its internal pressure are investigated. A mathematical model of a molten spherical droplet immersed in water is developed, and results of the numerical solution are discussed. The effects of changing various characteristics (e.g. hot body size, temperature, and hydrostatic effects, as well as temperature of bulk fluid) are investigated. These parameters impact the vapor layer size, vapor internal pressure, and the saturated temperature at the interface between vapor & liquid phases. Finally, conclusions indicate that internal vapor pressure jump, being up to several times larger than that of the initial condition. These pressure pulses and related vapor layer thickness variations could cause thermal fragmentation of the droplet which in turn results in strong pressure shock build-up due to small pieces of the droplet in contact with the water, which could then escalate to become a propagating large scale vapor explosion. The vapor explosions could be hazardous and endanger the system safety.