HEAT AND MASS-TRANSFER PROCESSES IN CONNECTED SATURATED HE-II BATHS

We report on a preliminary experiment designed to study combined heat and mass transfer processes associated with two-phase vapour/He II flo w systems. The experiment consists of two separate baths connected by two channels, the upper one being for vapour flow and the lower one co ntaining He II. Thus, the experiment simulates a two-phase flow with c onstant and known void fraction. Heat transfer between the two baths i s governed by the counterflow process in the lower tube and vapour mas s flow in the upper tube. Steady state and dynamic models, based on th e energy and momentum equations, agree well with experimental results. We also explore the use of a porous plug in the lower channel to comp ensate for the level changes in the two baths. (C) 1997 Elsevier Scien ce Ltd.