Effect of a low-thermal-conductive coating on the dynamics of rewetting of overheated plate by falling liquid film

Resumo

The experimental results of rewetting of overheated vertical copper heater with a low-thermal-conductive coating by a falling nitrogen film are presented. It is shown that the presence of the coating affects significantly the feature of the temperature curves and decreases the total plate cooling time by more than fourfold. The experimental data obtained earlier showed that the rewetting front propagating over the copper plate without coating was one-dimensional. It is revealed by comparison of the experimental data that the presence of the low-thermal-conductive coating results in the appearance of the front of a cellular structure with regular boiling jets, characteristic of rewetting of overheated thin plates. The synchronized measurements of the plate temperature and high-speed video recording of the transition processes show that the higher rate of cooling in the presence of the coating is associated with the development of intense boiling in the rewetting front at a much higher temperature of the plate.