Visualization of flow boiling heat transfer using temperature sensitive paint with high spatial and temporal resolution

•A new method for visualization of boiling surface temperature profiles has been developed using a temperature-sensitive paint (TSP) film structure and pulsed LED excitation to enhance emission intensity.•The temperature of the heat transfer surface in forced flow boiling was visualized with a spatial resolution of 64 µm and measurement speed of 2 kHz.•The unsteady changes in the temperature and the heat transfer coefficient due to expansion of the dry patches at the bottom of the nucleated small bubble and slug bubble were evaluated.