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Estimation of Long-term Power Demand of Oil and Gas Installations using Hybrid Models
Get PDFA methodology to forecast power demand of oil and gas installations which uses publicly production available data, parametric models and data-driven Gaussian regression methods is presented. The methodology also captures the expected fuel gas consumption and energy ratio. The proposed methodology is tested on the Brage field on the Norwegian Continental Shelf. It is shown that the general oil and water production behaviour as well as fuel gas consumption trends can be predicted. However, the forecast inherits a significant uncertainty due to the publicly available dataset lacking metadata and a complete description of the energy sinks. © 2024 Elsevier B.V. Author keywords Forecast; Gaussian Process Regression; Oil and Gas; Power demandacceptedVersio
Computational Modelling of Electric Arc Behaviour in Direct-Current Smelting Furnaces Using Hydrogen as a Reductant
Get PDFIn this work, the authors present results from a computational multiphysics model for direct-current plasma arcs operating in open bath electric smelting furnaces. Plasma thermodynamic and thermophysical properties of a range of mixtures of hydrogen and water vapour that might be expected in the gas space of a smelter using pure hydrogen as a reductant are discussed, with most properties seen to be strong functions of the plasma temperature and composition. The properties are combined with the multiphysics model and used to generate predictions of the arc behaviour, with both quasi-steady state and fully transient simulations conducted. The electrical performance of the arc was found to be highly dependent on the hydrogen:water ratio in the freeboard gas, with larger hydrogen fractions causing the arc to become less stable and more electrically resistive.publishedVersio
Forced surge motion of a floating bridge pontoon to evaluate the hydrodynamic damping properties
Get PDFDedicated model tests were carried out to investigate the hydrodynamic force coefficients in surge for a pontoon that is designed to support a floating bridge. The experiments were carried out by oscillating the pontoon at various Keulegan–Carpenter (KC) numbers and oscillation periods in forced motion. A pontoon designed for the floating bridge in Bjørnarfjorden, Norway, is investigated herein. Several numerical simulations are performed to supplement the experiments. The estimated damping coefficients in surge are of significant importance at the first horizontal resonant mode of the floating bridge, which may be excited due to swell sea in the fjord. The first horizontal resonant mode of the floating bridge is around 15–16 s. The model tests were conducted with and without turbulence triggers. A finding from the model tests were that turbulence triggers did not prove to be necessary to eliminate model scale effects in oscillatory flow. The KC-dependent added mass and damping coefficient in oscillatory flow is investigated. The added mass and damping coefficients are clearly KC-dependent. The wave radiation damping in surge is small at the tested oscillation periods, and the damping in surge is dominated by the damping due to flow separation. Numerical simulations using a hybrid potential flow-CFD solver with linear free-surface conditions, PVC3D, are carried out with both linear and nonlinear body-boundary conditions. The simulations with nonlinear body-boundary conditions predict the hydrodynamic force coefficients with reasonable accuracy, whilst the simulations with linear body-boundary conditions fail to predict the hydrodynamic coefficients with the desired accuracy — both used to investigate the viscous damping which arises due to flow separation along the pontoon body.publishedVersio
Hardware-in-the-Loop platform based on Smart Meters for Demonstrating Advanced Distribution Management Systems
Get PDFAs the number of distributed energy resources grows, distribution system operators are facing significant challenges in monitoring and controlling their distribution networks. This evolution of the distribution power grid has led to the development of new techniques for monitoring and validating the state of the distribution grid. This paper presents a test-bed with smart meters that serve to validate power distribution smart grid techniques, including topology identification, distribution state estimation, and advanced control such as optimal power flow. The test-bed uses an emulated cyber-physical environment incorporating the actual smart meters that are used on distribution power grids. We also describe an example of application i.e. topology identification which is described and experimental results are shownHardware-in-the-Loop platform based on Smart Meters for Demonstrating Advanced Distribution Management SystemsacceptedVersio
Ghost fishing efficiency in swimming crab (Portunus trituberculatus) pot fishery
Get PDFAbandoned, lost, or otherwise discarded fishing gear (ALDFG) is a global challenge that negatively affects marine environment through plastic pollution and continued capture of marine animals, so-called “ghost fishing”. In different pot fisheries, ghost fishing related to ALDFG is of concern, including pot fishery targeting swimming crab (Portunus trituberculatus). This study quantified the ghost fishing efficiency by comparing it to the catch efficiency of actively fished pots of the commercial fishery. The results showed that the ghost fishing affects both target and bycatch species. On average, the ghost fishing pots captured 12.53 % (confidence intervals: 10.45 %–15.00 %) undersized crab and 15.70 % (confidence intervals: 12.08 %–20.74 %) legal-sized crab compared to the actively fished pots. Few individuals of several bycatch species were also captured by ghost fishing pots. The results of this study emphasized the need to develop new management strategies for reducing marine pollution by ALDFG and associated negative effects in this pot fishery.publishedVersio
Selected papers from the 15th International Conference on Industrial Applications of Computational Fluid Dynamics, Trondheim, Norway, June 11–13, 2024
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Alterations of river flow caused by three types of hydropower plants in Slovenia and Croatia
Get PDFStudy region Eight rivers in Slovenia and Croatia that are tributaries of the Danube River or the Adriatic Sea Study focus The different types of hydropower plants alter river hydrology at several temporal scales and to a varying degree, respectively, but impacts have hardly been quantified in an integrative way structured by hydropower plant type. Hence, we analysed hydrological data from rivers affected by 13 HPPs belonging to 3 operational types, namely run-of-river (RoR), storage (ST), and diversion storage (DST). Daily discharge data in pre- and post-impact periods were compared by applying the Ecodifference and Indicators of Hydrologic Alteration methods. In addition, sub-daily discharge data were analysed for potential alterations induced by hydropeaking. New hydrological insights for the region Studied HPP types caused mostly strong but varying alterations of flow regime. To facilitate comparisons, the three existing impact indicators were integrated into a composite Holistic Score of River Hydrology Impact. Holistic Score of River Hydrology Impact showed that DST HPPs caused most severe impacts in residual river reaches, followed by ST HPPs, while RoR HPPs had less severe impact. Environmental flows were not provided to five of six residual river reaches. We detected hydropeaking in 9 HPPs, but probably underestimated their impacts, as sub-daily discharge was only available for 58% of the gauging stations in the study area.Alterations of river flow caused by three types of hydropower plants in Slovenia and CroatiapublishedVersio
Physicochemical properties of La0.5Ba0.5Co1-xFexO3-δ (0 ≤ x ≤ 1) as positrode for proton ceramic electrochemical cells
Get PDFWe report on essential properties of materials in the series La0.5Ba0.5Co1-xFexO3-δ as positrodes for proton ceramic electrochemical cells (PCECs). The unit cell and thermochemical expansion coefficient (TCEC) of these cubic perovskites decrease with iron content x, the TCEC of La0.5Ba0.5FeO3-δ going as low as 11⋅10-6 1/K. The materials behave as LaMO3 perovskites with small band gaps and Ba acting as acceptors compensated by electron holes and oxygen vacancies. The electrical properties are dominated by p-type conduction with high large polaron mo- bilities for the Co-rich compositions at low temperatures, shifting towards small polaron mobilities with increasing Fe content. X-ray absorption spectroscopy (XAS) shows that Co is in a high spin state and takes on the main part of the cation oxidation state changes, and that hole states are in orbitals overlapping with the O 2p states, confirming the large polaronic behaviour, while holes on Fe are more localised at the cation. Hydration is more pronounced in inert atmospheres, as hydration of oxygen vacancies is easier than hydrogenation and in- creases with Fe content, in line with the commonly accepted finding that delocalization of holes disfavours protonation. Fe-rich compositions benefit from lower TCEC and higher hydration and hence expected proton permeability, at the cost of lower electronic conductivity. The surfaces are hydrophobic irrespective of Fe content, suggesting weak chemisorption of the underlaying water layer, possibly giving relatively many available surface sites for oxygen adsorption, but limited surface proton conductance – both of importance to positrodes for operando PCECspublishedVersio
Application of suspended inter-array power cables in floating offshore wind farms
Get PDFThe aim of the present study is to propose an engineering approach of designing suspended inter-array power cable configuration for offshore wind farms. To achieve this, a spar type and a semi-submersible type floating offshore wind turbines (FOWTs) are modeled in the dynamic analysis software OrcaFlex. The accuracy of these models is validated against reference studies. Several different cable configurations connecting two spar FOWTs are assessed based on Fitness Factors using static and dynamic analyses. The non-linear bending behavior and the marine growth effects are considered in the analyses. The number of buoys is found to be the main parameter affecting the maximum effective tension and the minimum bending radii of the cables. The buoy spacing determines whether the cable touches the seabed, floats fully submerged, or floats at the sea surface. The influence of the cable length and the marine growth on the observed cable tensions and curvatures is small for the investigated configurations. The optimum cable configuration found for the two spar FOWTs is employed to connect two semi-submersible FOWTs. The influence of the floater type on the suspended power cable tension and curvature is found to be negligible. Analysis of power cable behavior in an offshore wind farm layout shows that a two-turbine setup with different environmental load directions can be used as a representative case for the suspended power cables design of the entire wind farm.publishedVersio
High resolution depth profile scanning of plankton organisms—VERTILICE
Get PDFKnowledge of the vertical migration pattern of sea lice (Lepeophtheirus salmonis) copepodites is necessary for designing efficient measures to prevent lice infestations on farmed Atlantic salmon (Salmo Salar) in sea-cages. However, data can be challenging to acquire at a large scale under realistic circumstances without interfering with the natural behavior of the specimen. A mesocosm platform was built to help acquire this data consisting of a sensor package in an underwater housing being pulled up and down along a 11-meter-long transparent tube containing planktonic organisms while collecting image-, temperature- and spectrometer data. The platform was placed at a salmon farm and the acrylic tube was filled with L. salmonis copepodites and was pre-programmed to run a profile scan twice per hour for four consecutive days. Using a fully convolutional neural network, the copepodites were automatically counted – creating a depth profile of detected lice and measured light specter. The final results showed a diurnal migration pattern throughout the test period. • Capable of acquiring vertical density profiles of any aquatic species between 0,5 – 10 mm down to 11 m below the surface. • Fully automated and can be left unintended for weeks while collecting data.publishedVersio