title: Criticality in the slowed-down boiling crisis at zero gravity.
abstract: Boiling crisis is a transition between nucleate and film boiling. It occurs at a threshold value of the heat flux from the heater called CHF (critical heat flux). Usually, boiling crisis studies are hindered by the high CHF and short transition duration (below 1 ms). Here we report on experiments in hydrogen near its liquid-vapor critical point, in which the CHF is low and the dynamics slow enough to be resolved. As under such conditions the surface tension is very small, the experiments are carried out in the reduced gravity to preserve the conventional bubble geometry. Weightlessness is created artificially in two-phase hydrogen by compensating gravity with magnetic forces. We were able to reveal the fractal structure of the contour of the percolating cluster of the dry areas at the heater that precedes the boiling crisis. We provide a direct statistical analysis of dry spot areas that confirms the boiling crisis at zero gravity as a scale-free phenomenon. It was observed that, in agreement with theoretical predictions, saturated boiling CHF tends to zero (within the precision of our thermal control system) in zero gravity, which suggests that the boiling crisis may be observed at any heat flux provided the experiment lasts long enough.
authors.affiliation: Service des Basses Températures, UMR-E CEA/UJF-Grenoble 1, INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: T
authors.initials: T
authors.lastname: Charignon
authors.affiliation: Laboratoire de Mécanique des Solides, CNRS-UMR 7649, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, France.
authors.forename: P
authors.initials: P
authors.lastname: Lloveras
authors.affiliation: Service des Basses Températures, UMR-E CEA/UJF-Grenoble 1, INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.
authors.forename: D
authors.initials: D
authors.lastname: Chatain
authors.affiliation: Laboratoire de Mécanique des Solides, CNRS-UMR 7649, Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, France.
authors.forename: L
authors.initials: L
authors.lastname: Truskinovsky
authors.affiliation: Departament d'Estructura i Constituents de la Matèria, Universitat de Barcelona Martí i Franquès 1, Facultat de Física, 08028 Barcelona, Catalonia, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Vives
authors.affiliation: Service des Basses Températures, UMR-E CEA/UJF-Grenoble 1, INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.|Physique et Mécanique des Milieux Hétérogènes, UMR 7636 ESPCI, CNRS, Univ. Paris-Diderot, Univ. P.M. Curie, 10 rue Vauquelin, 75005 Paris, France.
authors.forename: D
authors.initials: D
authors.lastname: Beysens
authors.affiliation: Service de Physique de l'Etat Condensé, CNRS UMR 3680, IRAMIS/DSM/CEA Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: V S
authors.initials: VS
authors.lastname: Nikolayev