Measuring the Thermal Conductivity of Flowing Liquid Samples Using the Three Omega Method

Abstract

The thermal conductivity of a liquid is generally measured under conditions that suppress bulk flow in the sample. However, in situ measurement of the thermal conductivity of a flowing liquid would be useful in various scientific and engineering applications. This work demonstrates that a thermal wave technique, such as the three omega method, can effectively measure the thermal conductivity of flowing liquid if the frequency range is adjusted such that the thermal boundary layer is sufficiently thinner than the momentum boundary layer. A new dimensionless number was defined to assess the convection effects, and a criterion for thermal conductivity measurements was obtained for water flowing in a circular tube.