Recent experiments for laminar and turbulent film heat transfer in vertical tubes Original Research Article

This study reviews experimental local heat-transfer data for laminar and turbulent film heat transfer for downward condensing films, under the influence of interfacial-waviness and shear–stress effects. Local laminar-wavy-film heat transfer and transition to turbulence are significantly influenced by local wave characteristics, which depend not only on the film developing length, but also on the film-formation method. The results demonstrate that the dimensionless film thickness, incorporating shear stress, provides a more appropriate length scale to estimate laminar-wavy-film heat transfer, as well as transition to turbulence. For turbulent films, a phenomenologically-based local heat-transfer correlation has been proposed, treating the near-wall and near-interface regions in series, to derive a `two-layer resistance modelʹ, based on the investigation of turbulence structure across sheared gas–liquid interfaces.