Experimental Study of Rewetting of a Superheated Plate with Structured Capillary-Porous Coating by Flowing Liquid Film

The experimental results on rewetting of the surface of a superheated vertical copper heater and a heater with a structured capillary-porous coating (applied by means of directed plasma spraying) by liquid nitrogen film are presented. It is shown that presence of the capillary-porous coating fundamentally influences the temperature variation and reduces the duration of overall plate cooling by more than three times. The high-speed videofilming of the transient processes was carried out and data on the character and structure of the rewetting front were obtained. Analysis of the synchronized measurements of the plate temperature and the high-speed video of transient processes shows that the higher cooling rate in the presence of structured capillary-porous coating is related to the development of intensive boiling in the rewetting front at sufficiently higher plate temperature.