title: Decoupled Hierarchical Structures for Suppression of Leidenfrost Phenomenon.
abstract: 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.
authors.affiliation: Department of Mechanical Engineering, University of Houston , 4726 Calhoun Road, Houston, Texas 77204-4006, United States.
authors.forename: Nazanin
authors.initials: N
authors.lastname: Farokhnia
authors.affiliation: Department of Mechanical Engineering, University of Houston , 4726 Calhoun Road, Houston, Texas 77204-4006, United States.
authors.forename: Seyed Mohammad
authors.initials: SM
authors.lastname: Sajadi
authors.affiliation: Department of Mechanical Engineering, University of Houston , 4726 Calhoun Road, Houston, Texas 77204-4006, United States.
authors.forename: Peyman
authors.initials: P
authors.lastname: Irajizad
authors.affiliation: Department of Mechanical Engineering, University of Houston , 4726 Calhoun Road, Houston, Texas 77204-4006, United States.
authors.forename: Hadi
authors.identifier: 0000-0002-0554-4248
authors.initials: H
authors.lastname: Ghasemi