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12 results on '"Garivalis, Alekos Ioannis"'

5. Critical heat flux enhancement in microgravity conditions coupling microstructured surfaces and electrostatic field

Author

Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Garivalis, Alekos Ioannis, Manfredini, Giacomo, Saccone, Giacomo, Di Marco, Paolo, Kossolapov, Artyom, Bucci, Matteo, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Garivalis, Alekos Ioannis, Manfredini, Giacomo, Saccone, Giacomo, Di Marco, Paolo, Kossolapov, Artyom, and Bucci, Matteo

Abstract

AbstractWe run pool boiling experiments with a dielectric fluid (FC-72) on Earth and on board an ESA parabolic flight aircraft able to cancel the effects of gravity, testing both highly wetting microstructured surfaces and plain surfaces and applying an external electric field that creates gravity-mimicking body forces. Our results reveal that microstructured surfaces, known to enhance the critical heat flux on Earth, are also useful in microgravity. An enhancement of the microgravity critical heat flux on a plain surface can also be obtained using the electric field. However, the best boiling performance is achieved when these techniques are used together. The effects created by microstructured surfaces and electric fields are synergistic. They enhance the critical heat flux in microgravity conditions up to 257 kW/m2, which is even higher than the value measured on Earth on a plain surface (i.e., 168 kW/m2). These results demonstrate the potential of this synergistic approach toward very compact and efficient two-phase heat transfer systems for microgravity applications.

Published
2023

11. The multiscale boiling investigation on-board the International Space Station

Author

Sielaff, Axel, Mangini, D., Kabov, O., Raza, M. Q., Garivalis, Alekos Ioannis, Zupančič, Matevž, and Golobič, Iztok

Subjects
pool boiling, strižni tok, shear flow, električno polje, udc:66.02:66.046.7, vrenje v bazenu, multiscale boiling, večnamenski eksperimenti vrenja, mikrogravitacija, Mednarodna vesoljska postaja, International Space Station, microgravity, electric field
Abstract

This publication lays the foundation for the description of the Multiscale Boiling Experiment, which was conducted within two measurement campaigns on the International Space Station between 2019 and 2021. The experiment addresses fundamental questions about two-phase heat transfer during boiling processes. For this purpose, single or few subsequential bubbles are selectively ignited on a heated substrate using a short laser pulse. A detailed investigation of the phenomena is possible, as the boiling process is temporally slowed down and spatially enlarged in microgravity. Within the Multiscale Boiling Project, the undisturbed growth of the bubbles, the influence of a shear flow, and the influence of an electric field are investigated within the same test facility using FC-72 as working fluid. Within the project, thirteen research groups from eight countries are collaborating. Over 3000 data sets have been generated over an 11-month measurement period. In the context of this publication, besides the motivation and necessity of such investigations, the basic structure of the experiment, the objectives of the investigations, and the organization are described. Finally, first results of the investigations are presented. Therefore, this publication has the primary aim to serve as a basis for many further planned publications and present the project as a whole.

Published
2022

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