Characterization of Thermochromic Liquid Crystals for Multi-Color Transient Heat Transfer Experiments

Abstract

This study focuses on the calibration of non-encapsulated spray-able thermochromic liquid crystals (TLC). The TLC is calibrated on a copper block with thermistors and is recorded with cameras at 0°, 15°, 30°, and 45°. The influence of viewing angle on the perceived peak temperature is investigated as well as the long-term stability of TLC characteristics. Typical transient heat transfer experimenters utilize only the green peak temperature. In this work, it is demonstrated that the calibration of TLC yielding two distinct color peaks (for the red and green signal) are feasible and can be accurately obtained. The multi-color technique is an improvement of the traditional single-color technique used in transient heat transfer experiments. This multi-color technique enables two independent measurements of the surface temperature and will double the yield of usable data in future transient heat transfer experiments. The technique can be further expanded to incorporate multiple TLC mixtures and multi-band multi-color techniques can also be employed.