Induction melting boundary layer of ice.

In many technical applications, ice grows on metallic surfaces. In most applications this effect is unwanted like the icing on heat exchangers, on power lines or the ice building on the wings of airplanes. The ice influences the properties and the lifetime of some components. In other cases metallic surfaces are designed such that ice grows on them, e.g. in many types of ice slurry generators, ice grows on the surface of a heat exchanger.
Whether the icing is a disadvantage or advantage, in a lot of cases deicing is necessary. Deicing purposes the knowledge of the adhesion force between ice and the surface. Typically, the ice is removed from the surface by some means of mechanical or thermal impact. With a scraper or some other tool the ice can be removed mechanically. The scraping force has to be higher than the adhesion force between the ice and the surface. In order to thermally remove the ice, the temperature of the metallic surface has to rise over the melting point of ice.
In this research there is a combination of the mechanical and the thermal method. The thermal energy to heat up the surface is generated with an induction heater. The total heat energy of induction heating depends on the frequency and the amperage for the induction coil. With a high frequency only a thin skin layer of the metallic surface heats up. The surface temperature rises over the melting point of the ice and the ice at the boundary layer melts off. The adhesion force between ice and the metal decreases until there is a complete liquid layer.
The correlation between adhesion force and an induction heating impulse will be shown.

在诸多工程应用场景中，金属表面均会出现结冰现象。多数场景下该现象并不理想，例如换热器（heat exchanger）、输电线路表面的结冰，或是飞机机翼表面的积冰。结冰会影响部分组件的性能与使用寿命。而在部分特定场景中，金属表面会被特意设计为可形成冰层的结构，例如多数制冰浆发生器（ice slurry generator）中，换热器表面便会生成冰层。
无论结冰带来的是负面影响还是正面效益，诸多场景下均需开展除冰作业。除冰作业需要掌握冰与金属表面之间的粘附力（adhesion force）相关知识。通常而言，可通过机械或热冲击手段去除表面冰层：机械除冰可使用刮冰刀或其他工具，此时所需的刮削力需大于冰与表面之间的粘附力；热除冰则需将金属表面温度提升至冰的熔点（melting point）以上。
本研究将机械除冰与热除冰两种方法相结合，加热表面所需的热能由感应加热器（induction heater）提供。感应加热的总热能取决于感应线圈（induction coil）的工作频率与电流强度：当使用高频电流时，仅金属表面的薄层趋肤层会被加热。当表面温度升至冰的熔点以上时，界面处的冰层便会熔融脱落，随着界面处形成完整的液态水层，冰与金属之间的粘附力会逐步降低直至消失。
本研究将阐明粘附力与感应加热脉冲之间的关联特性。