A langrangian-based phenomenological model, following the evolution of the individual droplets nucleating at random positions, is applied to the simulation and optimization of hybrid, mixed hydrophobic and hydrophilic surfaces. The proposed mathematical model was originally developed to simulate droplets pattern evolution in the framework of in-flight icing problems and takes into account the surface tension effects (via the advancing and receding contact angle values), the external force balance on the single droplets, as well as the both the condensing and coalescence process. Here, the model is extended to the case of an arbitrary curved substrate surface and a parametric analysis of different cases is carried out, looking for the parameters that help to identify the optimal design for a given set of wettability properties, nucleation site density and wet surface condensation rates. A discussion on the sensitivity of the solutions with respect to the expected high uncertainties on the estimate of some of these parameters in actual practical problems is also presented, in order to assess the effectiveness of the simulation as a design tool. The analysis is carried out for condensation enhancement on both plane surfaces and mini or micro tubes. Comparison with experimental, open literature data ensure the reliability of the approach for both geometries.
Optimization of hybrid hydrophilic-hydrophobic surfaces for dropwise condensation enhancement
Croce G.;D'Agaro P.;Suzzi N.
2019-01-01
Abstract
A langrangian-based phenomenological model, following the evolution of the individual droplets nucleating at random positions, is applied to the simulation and optimization of hybrid, mixed hydrophobic and hydrophilic surfaces. The proposed mathematical model was originally developed to simulate droplets pattern evolution in the framework of in-flight icing problems and takes into account the surface tension effects (via the advancing and receding contact angle values), the external force balance on the single droplets, as well as the both the condensing and coalescence process. Here, the model is extended to the case of an arbitrary curved substrate surface and a parametric analysis of different cases is carried out, looking for the parameters that help to identify the optimal design for a given set of wettability properties, nucleation site density and wet surface condensation rates. A discussion on the sensitivity of the solutions with respect to the expected high uncertainties on the estimate of some of these parameters in actual practical problems is also presented, in order to assess the effectiveness of the simulation as a design tool. The analysis is carried out for condensation enhancement on both plane surfaces and mini or micro tubes. Comparison with experimental, open literature data ensure the reliability of the approach for both geometries.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
