Showing papers by "Jacopo Buongiorno published in 2018"
TL;DR: In this paper, the authors present an experimental methodology that enables accurate measurement of fundamental subcooled flow boiling quantities, such as nucleation site density, bubble growth and wait time, and bubble departure diameter, up to the Critical Heat Flux (CHF) limit.
74 citations
TL;DR: The microscopic length found in the simulations is a kind of numerical slip length in the vicinity of the contact line, which can be used to realize grid-independent simulations that could be matched to microscopic physics in the region of validity of Cox's theory.
49 citations
TL;DR: In this article, the volume-of-fluid (VOF) method is used to reproduce the hydrodynamics of hemispherical bubble growth at the wall, and resolve the formation of the microlayer with an unprecedented resolution.
33 citations
TL;DR: In this paper, a pre-oxidized, low-carbon steel heaters were tested in a flow boiling loop using the IVR water chemistry, i.e., DI water with addition of boric acid and sodium tetra-borate.
28 citations
TL;DR: In this article, the effects of rolling motion and static tilt on the engineered safety systems are investigated using a RELAP5-3D (version 4.3.4) model of OFNP-300.
Abstract: The Offshore Floating Nuclear Plant (OFNP) integrates an advanced light water reactor into a cylindrical, double-hull, floating platform. It offers a series of potential benefits in economics and safety. The 300-MW(electric) version, named OFNP-300, uses an ocean-based direct reactor auxiliary cooling system (DRACS) to remove decay heat from the core passively and indefinitely during loss of feedwater or loss of off-site power events. In the ocean, the OFNP platform may roll during storms or even statically tilt following asymmetric flooding of underwater compartments. The effects of rolling motion and static tilt on the engineered safety systems are investigated in this paper using a RELAP5-3D (version 4.3.4) model of OFNP-300. The oscillations of the platform are described as the superposition of sinusoidal motions for the six degrees of freedom, i.e., heave, roll, pitch, yaw, sway, and surge. The plant’s thermal-hydraulic responses to two postulated accidents, i.e., loss-of-coolant accident (LO...
27 citations
TL;DR: In this article, the authors developed and demonstrated a strategy for drastically reducing the thermal conductivity of a flexible, closed-cell polychloroprene foam to 0.031 ± 0.002 W m−1 K−1.
Abstract: Closed-cell foams are widely applied as insulation and essential for the thermal management of protective garments for extreme environments. In this work, we develop and demonstrate a strategy for drastically reducing the thermal conductivity of a flexible, closed-cell polychloroprene foam to 0.031 ± 0.002 W m−1 K−1, approaching values of an air gap (0.027 W m−1 K−1) for an extended period of time (>10 hours), within a material capable of textile processing. Ultra-insulating neoprene materials are synthesized using high-pressure processing at 243 kPa in a high-molecular-weight gas environment, such as Ar, Kr, or Xe. A Fickian diffusion model describes both the mass infusion and thermal conductivity reduction of the foam as a function of processing time, predicting a 24–72 hour required exposure time for full charging of a 6 mm thick 5 cm diameter neoprene sample. These results enable waterproof textile insulation that approximates a wearable air gap. We demonstrate a wetsuit made of ultra-low thermally conductive neoprene capable of potentially extending dive times to 2–3 hours in water below 10 °C, compared with <1 hour for the state-of-the-art. This work introduces the prospect of effectively wearing a flexible air gap for thermal protection in harsh environments.
13 citations