Title: Novel Sensors and Measurement Techniques for Thermal Properties in Extreme Environments
Program: Doctor of Philosophy in Materials Science and Engineering
Advisor: Dr. David Estrada, Materials Science and Engineering and Electrical and Computer Engineering
Committee Members: Dr. Joshua Eixenberger (Co-Chair), Physics; Dr. Austin Fleming, Electrical and Computer Engineering and Materials Science and Engineering; Dr. Todd Otanicar, Mechanical and Biomedical Engineering; and Dr. Jessica Koehne, Materials Science and Engineering
Advancements in thermal properties analysis is crucial for improvement of existing and next generation reactors, space exploration, and environmental safety. Extreme environments pose a great hurdle for instrumentation to measure real time thermal properties due to the extreme temperatures, high radiation, and variable electromagnetic environments. Nevertheless, measurement systems are tremendously important for the design, performance, and safety considerations of nuclear fuels, space crafts, and deep sea/deep earth drilling. Thermal properties may change significantly in these environments creating challenging problems for temperature and thermal conductivity measurement systems. A recent focus has surrounded improvements in such systems for accurate determination of temperature and thermal properties to increase efficiencies, reduce costs, calibrate models, and tackle problems previously unfulfilled. Here we report on various devices and techniques for measuring temperature and thermal conductivity in harsh environments. First, a novel 1-wire line heat source probe and measurement technique were developed to monitor the temperature rise of the sample via the temperature dependent resistance of the probe’s heater wire and using a multilayer analytical model in tandem to extract the thermal conductivity of the sample. Second, a more robust 2-wire probe geometry was developed that improves upon the 1-wire approach. This geometry allows the use of a thermocouple as a dual temperature and thermal conductivity probe. Analytical models for both geometries were verified against COMSOL Multiphysics finite element analysis and experimental measurements. Finally, a third device is proposed for temperature measurements; a printed niobium/molybdenum (Nb/Mo) high temperature irradiation resistant thermocouple (HTIR-TC). This device will have the durability necessary for surviving extreme radiation and temperatures while being compact and versatile in design. These innovative approaches provide feasible methods for extracting temperature and thermal conductivity in extreme environments.