Investigations of rewetting phenomena at steam generation on surfaces with porous coatings

Abstract
The results of the experimental investigation of elemetary processes and wetting pheomena at boiling on surfaces with porous coatings are presented. Porous coating transform the heat transfer laws, change the values of critical heat flux and generates the new mechanisms of moisture exchange. The main of them are discussed : coating friction effect, asimutal heat pipe effect, drops wetting effect and bulk wave rewetting in channels with porous coating. The importance of the drops wetting for stratified and intermittent flows in horizontal steam generating channels is proven experimentally. Preliminary estimations are done of the velocity and size distributions of secondary drops generated by porous coatings. Wave rewetting mechanisrns are investigated on model experiments at second heat transfer crisis.