Study on local heat transfer in the vicinity of the contact line under vapor bubbles at pool boiling

The results of an experimental study of the dynamics of local heat transfer at nucleate pool boiling of liquids are presented. Experimental data on the nucleation site density and the evolution of the temperature field underneath individual vapor bubbles were obtained by high-speed infrared thermography with high spatial and temporal resolutions. Deionized water and ethanol at the saturation line under atmospheric pressure were used as working liquids. Evolution of the distribution of the local heat flux rate in the region of an individual nucleation site has been constructed based on numerical simulation. It has been shown that the maximum rate of the local heat flux is observed in the region of the liquid microlayer during the period of vapor bubble growth and reaches a value exceeding the average heat flux rate by $15$–$20$ times. Based on the results, the thickness of the microlayer underneath the vapor bubble during the period of the bubble growth was estimated. The estimates satisfactorily agree with experimental literature data obtained with the use of laser interferometry.