THE PROCESS OF HEAT AND MASS-TRANSPORT AT THE CRITICAL-POINT OF PURE FLUIDS

The effects of fast isentropic temperature propagation, called the ''p iston effect,'' or ''critical speeding up,'' and slow mass diffusion, called ''critical slowing down,'' are investigated. A temperature prop agation experiment in a spherical cell filled with pure SF6 at critica l density was performed during the Second German Spacelab Mission D2 i n 1993. The results evidently confirm the presence of the piston effec t both in the one-phase region and in the two-phase region. The numeri cal simulations are in remarkable good quantitative agreement with the experimental results.