Critical Heat Flux for Flow Boiling of Water at Low Pressure on Smooth and Micro-Structured Zircaloy Tube Surfaces

Flow boiling of a liquid is characterized by a high heat transfer from the heated surface into the fluid. However, the nucleate boiling regime is limited by the occurrence of the critical heat flux (CHF) leading to a possible thermal damage of the heated surface. The influence of tube surfaces structured with elevations in nano- and microscale, micro-channels, and porous or oxidized layers on CHF was experimentally investigated in a low pressure steam/water test facility.