Temperature Determination Using Multispectral Radiation Thermometry Algorithms for Aluminum Alloys

Abstract

Multispectral radiation thermometry (MRT) was applied to predict the aluminum surface temperature. Experiments were conducted to measure the spectral intensity values for five different aluminum alloys, AL1100, AL2024, AL5083, AL6061, and AL7005, at 600 K, 700 K, and 800 K. The experimental work is coupled with six MRT emissivity models encompassing mathematical and analytical functions to infer surface temperature. Assessment of the MRT emissivity model is subject to parametric effects of number of wavelengths, alloy composition, and temperature. Results show that increasing wavelength number does not significantly improve measurement accuracy while applying MRT. If the emissivity model can represent well the real emissivity behaviors, a more accurate inferred temperature can be achieved. Overall, most models achieve high accuracy in temperature prediction, except two emissivity models. One particular emissivity model provides the best compensation for the aforementioned parametric influences.

Acknowledgments

The author is grateful for the support of the National Science Council of Taiwan (with project number NSC-95-2221-E-006-393). The author also thanks J. King Aluminum, Inc. (JKAI), in Taiwan for the supply of steel samples and Dr. Jongmook Lim of the Spectraline, Inc., for technical assistance and instrument support.

Chang-Da Wen is an assistant professor of mechanical engineering at the National Cheng Kung University, Taiwan. He received his M.S. degree in mechanical engineering from the University of Michigan, Ann Arbor, MI, USA, and the Ph.D. degree in mechanical engineering from Purdue University, West Lafayette, IN, USA. His research interests are in the areas of thermal/fluid sciences. Special interests include radiation thermometry, electronic cooling, two-phase flow and heat transfer, thermal management, material processing, surface analysis, and specialized heat transfer projects. He is a member of ASME, CSME, and STAM and was a recipient of the NCKU ME Excellent Teacher Award for 2007 and 2008.