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• Nanoscale liquid film evaporation was investigated using MD simulations. • The effects of dispersive and electrostatic forces on evaporation were investigated. • Interface model dependent evaporation rates were observed. Thin-film evaporation is relevant for electronics cooling, water desalination, and some energy conversion processes, and the overall performance of such applications relies on the adequate understanding of heating-induced phase-change mechanisms. Given the importance of polar compounds, such as alumina, for nanoporous membranes in water desalination, the effects of electrostatic forces on thin-film evaporation were investigated in this paper by means of molecular dynamics simulations. The influence of the electrostatic interactions was assessed by modelling the alumina-water interactions using two approaches: i) accounting for electrostatic and dispersive van der Waals (vdWs) forces between the solid and liquid atoms (LJ+Coulombic model), and ii) considering only dispersive vdWs interactions (LJ model). Additionally, a theoretical model based on the Schrage relationships was developed to compare theory and simulations. The results showed considerable differences in the evaporation rates obtained from the two interfacial models. For the LJ+Coulombic model, the liquid films were 40% thicker, and the maximum evaporation mass flux was lower than the LJ model by a factor of two. The theoretical Schrage relationships deviated from the simulation evaporation fluxes with errors of 2.2-18.1% and 24.0-57.9% for the LJ+Coulombic and LJ models, respectively. These observations suggest that the partial charges in the solid affect the evaporation behavior of water if the films are ∼5 nm or thinner. Moreover, the significant deviations in the evaporation behavior demonstrated the importance of a robust interfacial modelling approach to investigate thin-film evaporation in polar interfaces. [ABSTRACT FROM AUTHOR]

• Hybrid cold plates combining fractal channel manifolds and microjets were analyzed. • A parametric analysis of the cooling performance was conducted using 3-D CFD simulations. • The geometry of the channels was optimized for low pressure drop in laminar flows. • A metric was introduced to assess both, thermal and hydraulic performance. • The tradeoff between thermal and hydraulic performance was targeted for optimization. A parametric optimization of a novel hybrid configuration of liquid-cooled heat sinks is presented herein. Such a hybrid design encompasses a combination of channels and microjets for optimal performance of chip scale high-power density electronic packages. Fractal flow channel geometries were used to create variants consisting of 16, 32, and 64 channels and a corresponding number of microjets in the impingement cavity. In addition to the conventional coplanar setup, where channels and area enhancing features align with the main flow direction, an out-of-plane network of channels was created to allow for removal of the cooling fluid in the opposite direction of the impinging jets. The parametric analysis was performed via 3-D CFD simulations to investigate the tradeoff between hydraulic and thermal resistances in jet cooling systems. The thermal resistance of the heat sinks was estimated and the pressure losses were calculated for every design. Observations of the flow patterns were used to inform on the optimization process of the architecture of the flow channels. A metric able to merge thermal and hydraulic performance was defined, such that the thermo-fluid characteristics of a liquid cooled heat sink are represented using one parameter. The utilization of this parameter led to a unique performance assessment of the proposed hybrid liquid-cooled heat sinks and allowed to identify an optimum design, which yields the lowest thermal resistance with minimum pumping power input. [ABSTRACT FROM AUTHOR]