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• Microscale and nanoscale boiling processes are investigated using LBM and MD. • Successive nucleate boiling enhancement is holistically obtained. • Underlying microscale and nanoscale enhancement mechanisms are revealed. Nucleate boiling enhancement from surfaces in energy industries is of fundamental significance for improving energy conversion and thermal management efficiency. This study investigates the microscale and nanoscale boiling processes on the hybrid wettability micropillar structured surface (MPS) to continuously enhance nucleate boiling. The microscale and nanoscale boiling processes and underlying enhancement mechanisms are studied by Lattice Boltzmann Method (LBM) and Molecular Dynamics (MD) simulations, respectively. It is revealed that MPS designed with a hydrophilic bottom surface and a hydrophobic top surface decorated with nanopillars can improve nucleate boiling throughout the microscale and nanoscale boiling process. The microscopic boiling process of the hybrid wettability MPS shows that the synergistic effect of wettability and surface structure is attributed to nucleation boiling enhancement due to higher bubble nucleation density and higher bubble departure frequency. The nanoscale boiling process on hydrophobic nanopillar structured surfaces (NPS) shows further nucleate boiling enhancement. The NPS with a nanopillar height of 1.6268 nm is in the Wenzel state with higher heat flux and lower thermal resistance, resulting in faster boiling onset and shorter separation time, while the hydrophobic NPSs in the Cassie state leads to a deterioration in the nucleate boiling. [ABSTRACT FROM AUTHOR]

• Air-steam condensation on inclined plate surface is experimentally investigated. • At 15°, flow pattern evolves into developed ridge regime under all conditions. • Visualization study of condensation water film flow patterns underneath the plate. • In large space, condensation driven by buoyancy natural convection. China Gen III NPPs is designed with PCS. When PCS starts running, the water level in IRWST may lower down due to the condensate loss on containment roof through raining, the loss of condensate will affect the effectiveness and response time of PCS. To observe the raining phenomenon and eventually evaluate heat removal capacity and response time of the PCS, a containment dome slice experimental facilities was constructed to get the lose part of the condensate. The test plate surface is 1.5 m × 0.6 m, suspended in diameter 2.5 m, high 4.5 m pressure vessel. A canon camera was set to record the images and videos of the condensation flow phenomenon through 6 viewports on the pressure vessel. Raindrop faction and flow phenomena in the presence of air under different angle were investigated under the condition of pressure ranged from 0.2 to 0.6 MPa and air concentration ranged from 14 to 69%. [ABSTRACT FROM AUTHOR]

• Steam condensation on a downward-facing plate with inorganic zinc coating. • The effects of key parameters on condensation heat transfer. • An empirical correlation for condensation heat transfer coefficient prediction. Steam condensation on the containment vessel is a significant cooling strategy to cope with the design basis accidents in the third-generation reactors with passive safety features. Aiming to evaluate the heat removal capacity of steam condensation, a number of condensation experiments have been conducted on a horizontal plate with the same surface condition as CAP1400 containment vessel. The effects of surface sub-cooling, air concentration, bulk pressure and different steam injecting models on condensation heat transfer have been experimentally investigated. In the experiments, the condensation heat transfer coefficients (within the range of 77–1297 W/m2 K) on the downward-facing plate are successfully obtained under the conditions of bulk pressure ranging from 0.154 to 0.607 MPa, air molar fraction ranging from 1.1% to 82.9% and surface sub-cooling ranging from 12.6 to 49.3 °C. In addition, an empirical correlation for heat transfer prediction has been developed based on the experimental data in this work. Besides, the experimental data have also been compared with four existing empirical correlations proposed by Uchida, Tagami, Dehbi and Liu, respectively. The comparing results show that most of condensation heat transfer coefficient data on the test plate could be overestimated by these four correlations. [ABSTRACT FROM AUTHOR]

• Description of condensate flow pattern on the horizontal and inclined plate. • The effect of surface inclination angle on condensation process was analyzed. • A semi-empirical model was established to predict the condensation heat transfer coefficients. Steam condensation heat transfer is the primary cooling strategy of the passive containment cooling system in some of the third generation reactors. In this study, a series of experiments were performed to investigate the steam condensation on a 1.5 × 0.6 m2 rotatable inorganic zinc surface, with surface inclination angle from horizontal to 60°. The condensate flow on the condensing surface at different inclination angles is photographed and analyzed. The results show that the effect of inclination angle on condensation heat transfer coefficient could be influenced by air fraction. Furthermore, considering the existence of air and overpressure, a semi-empirical correlation based on Nusselt model is developed to precisely predict the steam condensation heat transfer coefficient on the inorganic zinc surface. Since the surface condition of the experimental condensing surface is the same as that of the actual containment vessel, the experimental results would have certain reference values to the containment response analysis of the postulated accidents. [ABSTRACT FROM AUTHOR]