A bubble growth model for nucleate boiling in thin, falling, superheated, laminar, water films

Falling film boiling of refrigerants over nanostructured and roughened tubes: Heat transfer, dryout and critical heat flux

“…The falling film heat transfer enhancement ratios, Kff, where the falling film HTCs at a Γr of approximately 0.13 kg/m/s were compared with the pool-boiling HTCs from our previous study [38] are shown in Figure 15 The polished tube had some of the lowest enhancement ratios, while the roughened tube had some of the highest enhancement ratios. This is consistent with the theory that falling film enhancement is driven by increased microlayer evaporation from trapped and sliding bubbles [8,66]. The greater nucleation site density of the roughened tube compared to the polished tube would allow it to have more sliding bubbles and thus a greater enhancement ratio.…”