Transient thermochromic liquid crystal technique (TLC) has been widely used for measuring surface temperature distribution and local heat transfer coefficient (h). For flow inside ducts, the mass-flow-averaged temperature (T-m) and the adiabatic wall temperature (T-aw) are often used as mainstream reference temperature. They are difficult to measure and a systematic error is often introduced into the results. In the present study, a novel method is developed to resolve the mainstream reference temperature from the measured temperatures at several locations using non-dimensional temperature analysis. TLC experiments of a square channel with vertical ribs, 450 ribs or V-shaped ribs are carried on, with relative CFD simulations. It is showed in the results that using the non-dimensional temperature analysis method, Nusselt number based on T-m, can be adjusted by 4-15%, especially when there is large spanwise temperature variations. The systematic error of transient experiments is reduced. T-aw and h can be solved in the experiments using mixed liquid crystals whether mainstream temperature history is an ideal step or not. (c) 2014 Elsevier Ltd. All rights reserved.