Role of Taylor instability on sublimation of a horizontal slab of dry ice

Sublimation of a horizontal slab of dry ice (approximately equal to 190 K) placed beneath a pool of warm water or benzene (278 to 340/sup 0/K) was observed experimentally. Data for the heat transfer coefficient were obtained in both steady and quasi-static states. The heat transfer coefficient for this pseudo film boiling process is found to be strongly dependent on the pool temperature. In the temperature range of stable film boiling, the heat transfer coefficient depends on the laminar or turbulent nature of the gas film. However, when the pool temperatures such that a stable film can no longer be maintained, and the overlying liquid starts to freeze at the interface, the heat transfer coefficient data are correlated with the parameter c/sub p/..delta..T/sub f//h/sub sf/ for the liquid. Post-experiment visual observations of the dry ice surface show the presence of valleys and ridges arranged in a nearly square array spaced about one Taylor wavelength apart. An application of the present study to the fast reactor hypothetical accident situations in which a pool of molten fuel may be formed on horizontal steel surfaces is discussed.