Robust Heat Flux Sensors for Power Plant Extreme Environments

Direct heat flux measurements in extreme environments are valuable for the optimal performance of combustion systems, particularly when thermocouple- and optics-based diagnostics are inadequate. We report on the development of a robust heat flux sensor using the Transverse Seebeck Effect (TSE). Elicited through intentional misalignment of anisotropic single crystals with respect to the direction of heat flow, the TSE can generate an electric field perpendicular to the applied heat flux and can facilitate rugged devices with less complex constructions. In this work, we detail the design and characterization of an extreme environment-tailored heat flux sensor leveraging the Seebeck coefficient tensor anisotropy and high melting point of Rhenium single crystals. Experimental characterization of the sensor demonstrated its linear response to heat flux and that the transduction mechanism is based on the TSE. Through independent modulation of the sensor package temperature and incident heat flux, we obtain temperature-dependent calibration data consistent with a model that incorporates the impact of the surrounding package on the heat flow through the transducers.