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Decoupled Hierarchical Structures for Suppression of Leidenfrost Phenomenon

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posted on 2017-02-21, 00:00 authored by Nazanin Farokhnia, Seyed Mohammad Sajadi, Peyman Irajizad, Hadi Ghasemi
Thermal management of high temperature systems through cooling droplets is limited by the existence of the Leidenfrost point (LFP), at which the formation of a continuous vapor film between a hot solid and a cooling droplet diminishes the heat transfer rate. This limit results in a bottleneck for the advancement of the wide spectrum of systems including high-temperature power generation, electronics/photonics, reactors, and spacecraft. Despite a long time effort on development of surfaces for suppression of this phenomenon, this limit has only shifted to higher temperatures, but still exists. Here, we report a new multiscale decoupled hierarchical structure that suppress the Leidenfrost state and provide efficient heat dissipation at high temperatures. The architecture of these structures is composed of a nanomembrane assembled on top of a deep micropillar structure. This architecture allows to independently tune the involved forces and to suppress LFP. Once a cooling droplet contacts these surfaces, by rerouting the path of vapor flow, the cooling droplet remains attached to the hot solid substrates even at high temperatures (up to 570 °C) for heat dissipation with no existence of Leidenfrost phenomenon. These new surfaces offer unprecedented heat dissipation capacity at high temperatures (2 orders of magnitude higher than the other state-of-the-art surfaces). We envision that these surfaces open a new avenue in thermal management of high-temperature systems through spray cooling.

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