Simultaneous measurements of thermal conductivity and thermal diffusivity of liquids under microgravity conditions

A transient short-hot-wire lechnitltLr is proposed and used to measure tile thermal conductivity and thermal diffusivity of liquids simultaneously. The method is based on tile numerical evaluation of unsteady heat conduction from a wire with the same length diameter ratio and botmdary condflions as those in the expcriment.s. To ct~nfirm tile applicability and accuracy of this method. measurements were made for lixe sample liquids with known thermophysical properties and were performed under both normal gravity and microgravity conditions. The results reveal that the present method determines both the thermal conductivity and the dillusivity within 2 and 5"0. respectively. The microgravity experiments clearly indicate that even trader normal gravity conditions, natural-convection ellcots are negligible Ibr at least I s after the start of heating. This method would be particularly suitable fi.w a valuable and expensive liquid, and has a potential for application to electrically conducting andor corrosive liquids when the probe is ellectively coated with an insulating and anticorrosivc n l t l t e l ʹ i t l l .