A study on self-rewetting fluids for heat transfer in microgravity

In a number of water alcohols solutions the surface tension is an increasing function of temperature. Such mixtures are generally referred as self-rewetting fluids because convection driven by a reverse Marangoni effect is direct from cold to hot region along liquid-vapour interface. Within two phase heat transfer device, like heat pipes, liquid condensed is spontaneously driven to the hot evaporator improving the thermal performances and increasing the maximum heat flux. The research activities focused on numerical simulation and experimental laboratory for thermal characterization of heat pipe filled with self-rewetting fluids. Measurements of thermo-physical properties, in particular surface tension, have been carried out for several binary and ternary mixtures. A comparison between heat pipe filled ordinary and self-rewetting fluids has been carried out. Flow visualization of self-rewetting fluids has been obtained using optical diagnostic systems.