Schiffres Scott N, Malen Jonathan A
Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Rev Sci Instrum. 2011 Jun;82(6):064903. doi: 10.1063/1.3593372.
A novel 3ω thermal conductivity measurement technique called metal-coated 3ω is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases), using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques, including transient hot-wire, steady-state methods, and solid-wire 3ω are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3ω was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity.
一种名为金属涂层3ω的新型热导率测量技术被引入，用于测量液体、气体、粉末和气凝胶。该技术采用微米级金属涂层玻璃纤维作为加热器/温度计，悬浮在样品中。金属涂层3ω在许多关键指标上超过了基于3ω的其他流体传感技术，能够使用较小的温度振荡和较低的寄生传导损耗，对热扩散系数非常低的材料（气体）的小样品进行快速测量。讨论了它相对于现有流体测量技术（包括瞬态热线法、稳态法和实心线3ω法）的优势。提出了一种考虑热边界电阻的广义n层同心圆柱周期性加热解决方案。通过该模型认识到对边界传导率的敏感性得到了提高。通过对热导率跨越两个数量级的气体和液体进行基准研究，成功验证了金属涂层3ω技术。
