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Optics, Energy and fuels
A singlemode-no-core-singlemode (SNS) fiber structure optical sensor for detecting the solid-liquid phase change in a phase change material: C18H38 n-alkane material (n-octadecane) is proposed and demonstrated. The transmission-type sensor probe consists of a short section of no-core fiber sandwiched between two sections of a singlemode fiber. Phase changes in n-octadecane are accompanied by large step-like variations of its refractive index (RI). Such a large discontinuous change of the n-octadecane’s RI during its phase transition, leads to the corresponding step-like change in the transmitted optical power that can reliably indicate the phase change of the sample in the vicinity of the sensor. In addition, the proposed sensor can detect whether the sample is in solid or liquid phase based on a single power measurement, can detect supercooling, and is resistant to bending and strain disturbances during the measurements. The results of this work also illustrate that the proposed sensor can be applied to detect liquid-solid phase changes in other materials with thermo-optic properties similar to n-octadecane.
Han, W., Rebow, M., Lian, X., Liu, D., Farrell, G., Wu, Q., & Semenova, Y. (2019). SNS optical fiber sensor for direct detection of phase transitions in C18H38 n-alkane material. Experimental Thermal and Fluid Science, 109854. DOI:10.1016/j.expthermflusci.2019.1098...
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