Determination of Interior Surface Temperature Using Luminance Measurement of Thermochromic Liquid Crystals

• Published in: Experimental heat transfer Vol. 21; no. 2; pp. 133 - 142
• Main Authors: Senin, S., Langebach, J., Karcher, Ch
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.04.2008; Taylor & Francis
• Subjects: Applied sciences; Exact sciences and technology; Ground, air and sea transportation, marine construction; heat transfer; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; luminance measurement; Physics; Road transportation and traffic; temperature measurement; Thermal instruments, apparatus and techniques; thermochromic liquid crystals; Thermometry; Temperature measurement; Internal source; Motor car; Luminance; Road vehicle; Test facility; Lighting; Vehicle light; Liquid crystal devices; Calibration; Experimental study; Thermochromism
• ISSN: 0891-6152; 1521-0480
• DOI: 10.1080/08916150701815754

This paper presents a new method to measure interior surface temperature distributions. An image-resolved luminance measurement camera is used to capture light transmitted through thermochromic liquid crystals (TLC). These crystals change their optical properties with temperature. The experiments clearly show a unique relationship between temperature and the luminance value of the TLC. A calibration function is detected to transform the measured luminance distribution into corresponding temperatures. The developed method is applied to a model of an automotive headlamp. The data are compared with results obtained by using standard techniques such as infrared camera and thermocouple measurement. By that, a reasonable accuracy of the developed method of about ± 0.7°C can be determined. Knowing the temperature on both inner and outer surfaces, the heat transfer can be evaluated.