An ac calorimetric method for measuring thermal diffusivity of liquids

By applying ac calorimetry, three methods are proposed for thermal diffusivity measurements in liquids. In these methods the distance between an ac-heat source and a thermometer in liquid is changed and the decay of the ac-temperature wave is observed as a function of the distance. From the relation of the ac-temperature amplitude vs distance, the thermal diffusivity of the liquid can be determined directly. These methods are also capable of measuring the heat capacity per unit volume and the thermal conductivity.