MULTIPHASE MEDIA AND PHASE CHANGE 2
HEAT TRANSFER DURING GAS HYDRATE FORMATION IN VERTICAL GAS-LIQUID SLUG FLOW WITH SMALL BUBBLES IN LIQUID PLUGS
T. Elperin, A. Fominykh
The Pearlstone Center for Aeronautical Engineering Studies
Department of Mechanical Engineering
Ben-Gurion University of the Negev
P.O. Box 653 Beer Sheva 84105 Israel
A model of heat transfer during gas hydrate formation at a gas-liquid interface in gas-liquid slug flow with liquid plugs, containing small bubbles is suggested. Under the assumption of perfect mixing of liquid in liquid plugs, recurrent relations for temperature value in the n-th liquid plug and heat and mass fluxes from the n-th unit cell of gas-liquid slug flow are derived. The total mass and heat fluxes in gas-liquid slug flow during gas hydrate formation are determined.
UNSTEADY METHOD OF EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER IN POROUS MATERIALS
Galitseisky B. M., Loshkin A. L.
Moscow Aviation Institute, Russia
In the present work there are suggested the method for a determination of internal heat transfer coefficient based on solving the inverse unsteady heat transfer. The solution is obtained by the perturbation method. The methods are proposed, how to determine experimentally the interpore heat transfer coefficient. The experimental setup realizing the proposed method is described. It is shown that the affect of porous structure nonuniformity on heat transfer is of the some value as the effect of material porosity. Therefore, heat transfer intensity can be controlled by means of a variation of a porous material structure non-uniformity degree. There is suggested a semi-empirical model for a calculation of heat transfer coefficients and hydraulic resistance.
HEAT EXCHANGE ENHANCEMENT DUE TO UPPER CRUST CRACKING OF CONTINUOUS MASS DEBRIS
A. V. Moskovchenko, V. F. Strizhov
Russian Academy of Sciences, Nuclear Safety Institute,
52 Bol'shaya Tul'skaya, 113191 Moscow, Russia
The special mechanism of in-vessel debris cooling is considered which is rather important in the case of week fragmentation of melt core relocation to the lower head. Under such conditions upward heat transfer via boiling at the upper debris surface may be enhanced due to cracks formation and coolant penetration along the crack walls. In this work the possible stationary states of the upper crust temperature field were studied. Dependencies of the main problem parameters (upward heat flux; heat flux transfered via boiling in cracks; upper crust thickness) on the characteristic distance between cracks and the depth of water penetration along crack walls were obtained.