Interfacial frosting is ubiquitous in daily life and has many industrial applications. Owing to the poor heat transfer performance induced by packed air pockets, the frost layer usually manifests itself as a thick porous medium, which compromises the operational effectiveness of heat exchangers. Despite extensive studies spanning centuries, condensation frosting has achieved significant advancement only in the last decade. These advancements include the discovery of new physical features during condensation frosting that were too fast or too small to be captured and the development of new anti-/defrosting techniques. This study aims to provide a comprehensive up-to-date review on condensation frosting, particularly its progress in the last decade. The stages of condensation frosting, namely, condensation nucleation, growth of condensed microdrops, icing nucleation, formation of frost halos, frost spreading via ice bridging, and the final densification process, are introduced chronologically. Recent engineering efforts to solve the frosting problem, either by anti-frosting or defrosting, are also discussed. This review sheds light on the existing understanding of condensation frosting and promotes the development of anti-/defrosting techniques.

Droplet impact is ubiquitous in numerous applications and plays an important role in fields such as anti-icing, pesticide spraying, and inkjet printing. With the advancement of high-speed imaging and surface fabrication technologies, an increasing variety of multifunctional surfaces have been developed and utilized, deepening our understanding of the dynamic characteristics and energy changes during droplet impact. This paper first introduces the basic parameters of droplet impact, including the maximum spreading coefficient, contact time, and a list of relevant dimensionless numbers. Next, the kinetic and dynamic characteristics of droplet impact on single-functional and multifunctional surfaces are discussed. Multifunctional surfaces, typically possessing two or more different functionalities, exhibit unique motion phenomena such as lateral migration, self-splitting, and self-rotation due to their anisotropy during droplet impact. This paper categorizes these multifunctional surfaces based on their topological and chemical characteristics, including surfaces with micro-physical structural adjustments, macro-special shaped multifunctional surfaces, and externally coupled multifunctional surfaces. The kinetic and dynamic behaviors of droplet impact on these surfaces are described in detail, providing theoretical models and practical applications. This work aims to provide theoretical support and technical guidance for the optimized design of multifunctional surfaces and their applications across various fields through a comprehensive exploration of droplet impact dynamics.

Enhancing the vaporization efficiency of evaporators is crucial for improved energy management and heat transfer enhancement. To explore efficient evaporation methods, this study proposes a novel technique that actively introduces microbubble clusters to intensify the vaporization of the working fluid. Experiments were conducted using a microbubble generator fabricated from microporous titanium foam mesh. The effects of key parameters, including operation mode (continuous heating/no heating), average pore size of the titanium foam (2, 5, 10 μm), and gas flow rate (1-15 NL/min), on the evaporation performance (vapor output, liquid temperature drop) were quantitatively investigated. The associated bubble dynamics were analyzed via high-speed visualization. The results indicated that under the no-heating condition, the introduction of microbubble clusters with an average pore size of 10 μm and a flow rate of 15 NL/min led to a temperature drop of 30 ℃, while the corresponding vapor output increased by 38 times compared to the case without bubbles. Under the continuous heating mode, microbubbles with the same parameters caused a temperature decrease of approximately 15 ℃ and enhanced the vapor output by a factor of 1.7. Mechanistic studies reveal that the microbubble clusters substantially increase the vapor-liquid phase change interface area. The agitation caused by the rising bubbles and the alteration of vapor partial pressure due to the presence of non-condensable gas collectively accelerate the vaporization process at the interface, thereby enhancing the evaporation efficiency. This method requires no external fields or surface modifications, offering a simple and effective new approach for enhanced evaporation.