FAST THERMALIZATION IN SUPERCRITICAL FLUIDS

Heat transport in supercritical fluids in the absence of gravity is sh own to occur in a fast manner. Interferometric observations of the hea t transport in supercritical CO2 at different densities and temperatur es around the critical point show two interrelated mechanisms. A diffu sing thermal boundary layer and fast adiabatic density increase in the bulk fluid via propagation of pressure waves have been evidenced. The border of the expanding thermal layer acts as a piston. The growth of the thermal boundary layer can be described using a simple scaled fun ction and the bulk density increase is shown to be an adiabatic proces s. Near the critical point, the diffusing boundary layer can become un stable.