Advanced Thermophysical Properties Measurements Using Heater-Integrated Fluidic Resonators

Abstract

Measurement of thermophysical properties of liquids on microscale has been developed with increasing interest in thermal management or energy storage/transport systems. Thermal conductivity, heat capacity, and density are required to predict heat transfer performance, however, simultaneous measurement of thermophysical properties of small-volume liquids has been rarely studied. Recently, we have proposed new metrology for the three intrinsic properties simultaneously by heater-integrated fluidic resonators (HFRs) in an atmospheric pressure environment, which consist of a microchannel, a resistive heater/thermometer, and a mechanical resonator. Thermal conductivity is measured from a temperature response by using a resistive thermometer upon heating, and the specific heat capacity is obtained from the volumetric heat capacity along with the density by the resonance densitometer. In this paper, we show improvement in thermophysical properties measurement performance with HFRs by switching the environment around the sensor to the vacuum. It is validated by numerical analysis that the dynamic range of thermal conductivity is expanded by ~50 times and the sensitivity of heat capacity is increased by ~2 times. This improves the resolution of thermal conductivity and heat capacity with the same measurement resolution in vacuum environment.