Arkiduct Propulsion in Large Marine Vessels

<p>Arkiduct devices are based on electrically-driven Archimedes screws, and can be axle-less because they can function like the rotor and stator of an electric motor or generator. They can be used for propulsion and liquid delivery, as well as motors and generators. They are described in reference [1]. This article discusses use of Arkiducts in the propulsion of large marine vessels such as container ships, cruise liners, and tankers, many of which have displacements of over a hundred thousand tons, and can be as much as half a million tons [2].</p><p><strong>Key-words</strong>: Arkiduct devices, large marine vessels, propulsion.</p><p>====================================================================================</p><p>Os dispositivos Arkiduct são baseados em parafusos de Arquimedes movidos a eletricidade, podendo ser sem eixos porque são capazes de funcionar como rotores e estatores de motores elétricos ou geradores. Podem ser usados para propulsão e distribuição de líquidos, bem como motores e geradores. Eles são descritos na referência [1]. Este artigo discute o uso de Arkiducts na propulsão de grandes embarcações marítimas, tais como navios porta-contêineres, navios de cruzeiro e petroleiros, muitos dos quais deslocam mais de cem mil toneladas, chegando a meio milhão de toneladas [2].</p><p><strong>Palavras-chave</strong>: Dispositivos Arkiduct, grandes embarcações marítimas, propulsão.</p>

Design and Fabrication of Graded Copper Inverse Opals (g-CIOs) for Capillary-Fed Boiling in High Heat Flux Cooling Applications

Capillary-fed boiling in microporous copper inverse opals (CIOs) is capable of removing an excess of 1 kW/cm2 at 10–15 °C superheat over small wicking distances ∼ 200 μm. In order to remove heat from large area chips (&gt; 1 cm2), longer capillary wicking distance is desired to reduce the manufacturing complexity of the 3D manifold for liquid delivery and vapor extraction. In this study, we propose graded copper inverse opals (g-CIOs) where smaller pores at the bottom provide high capillary pressure for liquid delivery, while larger pores at the top reduce viscous pressure drop for vapor extraction. This nonhomogeneous wicking material decouples the permeability and capillary pressure in the vertical and lateral directions, resulting in greater CHFs and capillary wicking distances. In this study, we demonstrate the feasibility of fabricating g-CIOs material with up to three different pore diameters (2 μm, 5 μm, and 10 μm) using a multi-step template sintering and copper electrodeposition process. We then leverage and expand upon a well-calibrated experimental model for the prediction of CHF in monoporous CIOs to map the performance metrics for g-CIOs. The model combines a hydraulic resistance network with Darcy’s law and accounts for the nonhomogeneous permeabilities in lateral and vertical directions. Using this model, we study the impact of total wick thickness and graded pore-size combinations on the critical heat fluxes and wicking distances. Our modeling results conclude that a two-layer g-CIOs can potentially reach ∼70% enhancement in the critical heat flux or ∼30% enhancement in the wicking length compared to monoporous CIOs of the same thickness. Our fabrication capability and preliminary modeling results offer the opportunity to design boiling tests with optimized g-CIOs and exploring the potential of dissipating high heat flux for large area cooling applications.

Autonomous atmospheric water seeping MOF matrix

The atmosphere contains an abundance of fresh water, but this resource has yet to be harvested efficiently. To date, passive atmospheric water sorbents have required a desorption step that relies on steady solar irradiation. Since the availability and intensity of solar radiation vary, these limit on-demand desorption and hence the amount of harvestable water. Here, we report a polymer–metal-organic framework that provides simultaneous and uninterrupted sorption and release of atmospheric water. The adaptable nature of the hydro-active polymer, and its hybridization with a metal-organic framework, enables enhanced sorption kinetics, water uptake, and spontaneous water oozing. We demonstrate continuous water delivery for 1440 hours, producing 6 g of fresh water per gram of sorbent at 90% relative humidity (RH) per day without active condensation. This leads to a total liquid delivery efficiency of 95% and an autonomous liquid delivery efficiency of 71%, the record among reported atmospheric water harvesters.