A Modified 3-Omega Technique to Measure Thermal Conductivity in Liquids, Gases, and Powders

A novel modified 3ω thermal conductivity measurement technique called metal coated 3ω is introduced for use with liquids, gases, and powders. This technique employs a micron-scale metal coated glass fiber. Metal coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics including fraction of heat generated entering fluid, signal strength per temperature oscillation intensity and thermal boundary sensitivity. The advantages of this technique to Transient Hot-Wire (THW) and steady-state techniques are also discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. The technique is validated through a benchmark study of gases and liquids.