A study of nucleate boiling near the peak heat flux through measurement of transient surface temperature

Measurements of transient surface temperature during nucleate boiling of water at high heat fluxes support the view of many investigators that a liquid film, herein called the macrolayer, exists beneath an agglomeration of vapor bubbles and it is paramount in transferring heat. The macrolayer repeatedly dries out and reforms. Upon reforming, the surface temperature drops repeatedly for brief periods. This is apparently caused by microlayer evaporation beneath bubbles growing in the macrolayer. Sometimes, a brief quench precedes ebullition. Evaporation from the macrolayer just before it evaporates completely cools the surface effectively and evidence of nucleation then is absent. (author)