Liquid Crystal Thermography and Infrared Thermography Application in Heat Transfer Research on Flow Boiling in Minichannels

This study investigated FC-72 boiling heat transfer in minichannels using two non-contact temperature measurement techniques: liquid crystal thermography (LCT) and infrared thermography (IRT). These methods were applied simultaneously to measure temperature distributions on the heated wall surface of minichannels, formed by a thin metal foil. The temperature data facilitated the calculation of local heat transfer coefficients at the foil-working fluid contact surface. Calibration of the liquid crystal colour response to temperature was conducted prior to the use of LCT. According to a comparison of the heat transfer coefficients and Nusselt numbers determined using LCT and IRT measurements, comparable temperature distributions are provided, with the average relative differences in heat transfer coefficients determined using these techniques remaining below 15%. The findings highlight the advantages of non-contact temperature measurement in minimising system disturbances while providing precise data for understanding flow boiling heat transfer mechanisms. Such results can contribute to the design of minichannel heat exchangers.