Measurement of Temperature Distribution Using Liquid Crystal Thermography Technique Over the Absorber Plate of Solar Air Heater

Recently, the thermochromic crystals are widely used in the non-instructive studies of the heat transfer and fluid mechanics. The optical properties of this chromic materials are mostly dependent on the temperature of the plate in a probable and repeatable means. The liquid crystal thermography (LCT) technique is an advanced technology to examine the heat transfer dispersal over the complex structured absorber plate of the solar air heater. This technique is capable of providing the measurement of the temperature field up to a high accuracy, especially for the surfaces having complex flow field. The color pattern obtained from the surface using LCT gives the profile of the temperature distribution. The foremost thing in the overall step in determining the color–temperature relationship of chromic materials is the calibration process. The calibration procedure of LCT has been discussed in detail in this article. The major four parameters, like bandwidth of TLC, lighting angle, thickness of the coating, and quality of coating influence the uncertainty in the temperature measurement, and the TLC calibration curve of hue–temperature has been discussed in this paper. The uncertainty in the measurement has also been disserted.