Extreme Temperature Distributed Sensing for Modular Energy Systems
Luna Innovations and research team members at Ohio State University have developed a single-mode sapphire sensor for distributed temperature and flow measurement to address the extreme environments encountered in energy applications. The single-mode sapphire fiber sensor is designed to also detect and localize fouling and deposits that accumulate on its surface over time. The single-mode sapphire is created by imparting an internal cladding in the fiber through an irradiation process in a research nuclear reactor developed at Ohio State University. Triton and alpha particles are implanted in the fiber. Single-mode or reduced-mode performance in the optical fiber is verified by imaging a beam of infrared light transmitted through the fiber. The single-mode sapphire fiber is interrogated using optical frequency-domain reflectometry (OFDR) and spectral back scatter analysis to yield these distributed measurements. The OFDR technique can operate on the natural Rayleigh backscatter or with fiber Bragg gratings (FBGs). Type II FBGs were written in the fiber using a femtosecond laser to improve the signal-to-noise ratio over Rayleigh scatter based measurements. The fiber is integrated in a sensor assembly for measurements in a high-temperature furnace. Temperature accuracy was on the order of 5°C for measurements ranging from room temperature to over 1000°C. Spatial resolution of 11 mm was attained and enabled visualization of the temperature gradients along a fiber passing through a furnace. The effects of cooling flow were characterized for steady operation, with the intent to leverage this data in future work to infer velocity profiles of high temperature flows. Dynamic cooling flow tests showed that the presence of simulated deposits on the outside of the sensor resulted in slower time response in the vicinity of the deposit. This technique could be used to determine the presence and location of deposits along the length of the sensor assembly. The newly developed sensor will be applicable to fossil energy production, nuclear energy production, and gas turbine engines or generators. During Phase II, Luna plans to extend operation to 1700°C, reduce the unit cost to produce sensors, and ruggedize the system for energy applications. The ability to obtain distributed temperature, distributed velocity profiles, and self-diagnosis of deposits/fouling thickness with a single sensor in extreme temperatures up to 1700°C is unique among all research in the field.
- Research Organization:
- Luna Innovations, Roanoke, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- SC0018767
- OSTI ID:
- 1506968
- Type / Phase:
- STTR (Phase I)
- Report Number(s):
- 3582-DOE-1T; 3582-DOE-1T
- Country of Publication:
- United States
- Language:
- English
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