Comparison of a two-wavelength pyrometer system and spectral pyrometry for high-temperature measurements

Abstract

A pyrometer system is an optically passive, non-intrusive method that uses thermal radiation law to determine temperature. It combines electronic and optical instruments to detect low-level signals of radiation measurements. Surface high-temperature measurements are successfully obtained using a two-wavelength pyrometer system. This study used a pyrometer system to achieve high stability, minimize errors due to changing emissivity, and remove background noise from the radiation measurement for surface high-temperature measurements. Temperature measurements were also obtained from Planck’s model, and the results were compared with logarithmic assumption. The precision of these measurements is improved through variable optimization of the instruments, validation of the data, and calibration of the pyrometer system. The 16 temperature measurements were obtained (800–1600°C temperature measurement range) with a correlation coefficient above 97%. The response time between temperature readings is within 785 µs. Furthermore, the high-temperature measurements were obtained with higher stability (±2.99∘C at 1600°C) and less error (less than 2.29% for Si sensor). In addition, the error of the temperature measurement was reduced from 5.33% to 0.86% at 850°C by using Planck’s model compared with using logarithmic assumption. A cooling system temperature is also optimized to reduce the error temperature reading. It was found to be at 10°C that the uncertainty was reduced from 2.29% at ambient temperature to 1.53% at 1600°C. The spectral pyrometry system was also used in comparison with the two-wavelength pyrometer system to confirm that the calibration curves of the spectral pyrometry can be used to determine temperature measurements.