Condensation heat transfer coefficients (HTCs) are rather low compared to thin film evaporation. Therefore, it can be a limiting factor for designing heat transfer equipment. In this work, heat transfer characteristics of water vapor condensation phenomena were experimentally studied on a vertically aligned smooth copper substrate for a range of pressures and temperatures for two different liquid wettability conditions. The heat transfer performance is dominated by the phase change process at the solid–vapor interface along with the liquid formation mechanism. Compared to heat transfer results measured at an untreated copper surface, heat transport is augmented with a thin layer of perfluoro-silane coating over the same substrate. In this work, the effect of saturation pressure on the condensation process at both surfaces has been investigated by analyzing heat transfer coefficients. The results obtained experimentally show an increase in contact angle (CA) with the surface coating. A heat transfer augmentation of about 26% over uncoated surfaces was obtained and surfaces did not show any degradation after 40 h of operation. Finally, current results are compared with heat transfer values reported in open literature.

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Reactive bubble columns are omnipresent in the chemical industry. The layout of these columns is still limited by correlations and therefore improved simulation techniques are required to describe the complex hydrodynamics/reaction interaction. In this work, we focus on the numerical and experimental study of the viscosity influence on bubble motion and reaction using an Euler-Lagrange framework with an added oscillation and reaction model to bring the column layout base closer to a predictive level. For comparison and validation, experimental data in various water-glycerol solutions was obtained in a cylindrical bubble column at low gas hold-up, where the main parameters such as bubble size, motion, and velocities were detected. Glycerol leads thereby to a change in viscosity and surface tension. Further, the surface tension was modified by addition of a surfactant. The bubble oscillating motion in low to higher viscosity could be described using an Euler-Lagrange framework and enables a description of industrial bubble flows. In addition, the simulations were in good agreement concerning reactive mass transfer investigations at higher viscosity of the liquid which led to an overall lower mass transfer compared to the cases with lower viscosity.