An automated non-contact wall temperature measurement using thermoreflectance

This work presents a novel implementation of wall temperature measurement by thermoreflectance. The implementation relies on imaging light reflected from an interface between a transparent wall and liquid, and processing the resulting digital images to measure the diameter of the resulting light ring. The system is relatively simple to implement and the validation data indicate that the output is nearly linear over a wide range of temperatures. A detailed uncertainty analysis was performed, showing that uncertainties of ±1.1 K or less are possible for measurements in water using the multiple point calibration. Measurement uncertainties of less than ±0.1 K are readily attainable using fluids with high coefficients of thermal expansion.