The role of enhanced coated surface in pool boiling CHF in FC-72

 The purpose of Critical heat flux (CHF) experiments was to determine the role of various types and thickness of enhanced coated surface on a horizontal, vertically oriented ribbon heaters made of Ti and Steel 1010 of different thickness. Saturated pool boiling in FC-72 at atmospheric pressure was used in the experiment. The microstructure and surface topography are important factors in pool boiling CHF. In conditions of highly wetting FC-72 and increased roughness, CHF increased by 6 to 12%. However, CHF increased by 29% with greater topographic unevenness of the surface and lower roughness, which was obtained by etching Steel 1010 in H₂SO₄ acid. CHF also increased when the content of metals and metal oxides particles in the coating were increased. The CHF ratio of enhanced coated surface to a ribbon heater featuring a standard surface finish is up to 2.3. In addition, the asymptotic CHF of these uncoated heaters was considerably exceeded. Received on 17 January 2000