Energy Engineering - Journal Articles
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Item A fully-coupled analysis of the spar-type floating offshore wind turbine with bionic fractal heave plate under wind-wave excitation conditions(Elsevier Ltd., 2024-08-05) Huang, Haoda; Liu, Qingsong; Iglesias, Gregorio; Yue, Minnan; Miao, Weipao; Ye, Qi; Li, Chun; Yang, Tingting; National Natural Science Foundation of ChinaAs shallow coastal areas for the installation of wind turbines approach saturation, wind turbines will need to be installed in deeper areas, requiring floating rather than seabed-fixed substructures. Considering factors such as economy and safety, floating offshore wind turbines (FOWTs) have become the major focus for offshore wind research and development. In the case of spar-type FOWTs, stability in the heave direction poses a challenge. With this in view, in this work a heave plate with bionic fractal structures is mounted on the bottom of the spar-type FOWT. The bionic fractal heave plates are innovatively proposed to further improve the dynamic response of the FOWT. In this study, the aero-hydro-mooring dynamic method of the FOWT is established to develop a reliable numerical solution model through the DFBI module using computational fluid dynamics software STAR-CCM+. The results of fully-coupled simulations of the original FOWT, the FOWT with heave plate (HP-FOWT) and FOWTs with 3∼5-layer bionic fractal heave plate (3∼5BFHP-FOWTs) are presented. Increases in average thrust and power of 0.44 % and 0.99 %, respectively, prove the optimal aerodynamic responses of the 5 BFHP-FOWT. As for the hydrodynamic responses, the average heave response amplitudes of the HP-FOWT and 3∼5BFHP-FOWTs are significantly lower than the original FOWT. The maximum reduction (25.03 %) is obtained by the 5BFHP-FOWT. The bionic fractal heave plate will slightly reduce the stability of the pitch response. For the standard deviation of the heave, surge, mooring lines 1 and 2 responses, the 5BFHP-FOWT decreases by 17.97 %, 11.44 %, 17.50 %, and 8.25 % respectively, showing the best stability improvement among the HP-FOWT and BFHP-FOWTs. Furthermore, the vortices in the bionic fractal heave plates are analyzed in detail at the Z = ±0.25 m section of the flow field. Only when the specific fractal layer number is 5, the number and curl of the vortices in the fractal structure increase significantly, showing excellent effect of the energy absorption.Item Integrating short term variations of the power system into integrated energy system models: A methodological review(Elsevier Ltd., 2017-03-27) Collins, Seán; Deane, John Paul; Poncelet, Kris; Panos, Evangelos; Pietzcker, Robert C.; Delarue, Erik; Ó Gallachóir, Brian Pádraig; SFI Research Centre for Energy, Climate and Marine; Vlaamse Instelling voor Technologisch OnderzoekIt is anticipated that the decarbonisation of the entire energy system will require the introduction of large shares of variable renewable electricity generation into the power system. Long term integrated energy systems models are useful in improving our understanding of decarbonisation but they struggle to take account of short term variations in the power system associated with increased variable renewable energy penetration. This can oversimplify the ability of power systems to accommodate variable renewables and result in mistaken signals regarding the levels of flexibility required in power systems. Capturing power system impacts of variability within integrated energy system models is challenging due to temporal and technical simplifying assumptions needed to make such models computationally manageable. This paper addresses a gap in the literature by reviewing prominent methodologies that have been applied to address this challenge and the advantages & limitations of each. The methods include soft linking between integrated energy systems models and power systems models and improving the temporal and technical representation of power systems within integrated energy systems models. Each methodology covered approaches the integration of short term variations and assesses the flexibility of the system differently. The strengths, limitations, and applicability of these different methodologies are analysed. This review allows users of integrated energy systems models to select a methodology (or combination of methodologies) to suit their needs. In addition, the analysis identifies remaining gaps and shortcomings.Item Tidal stream energy potential in the Shannon Estuary(Elsevier Ltd., 2021-12-18) Fouz, D. M.; Carballo, R.; López, I.; Iglesias, Gregorio; European Regional Development Fund; Xunta de GaliciaThe tidal and river in-stream energy resource in the Shannon Estuary (W Ireland) is investigated using of high-resolution numerical modelling and spatial analysis. Although freshwater discharges are large, their influence on the available resource is found to be all but negligible, the tide being the main driver of estuarine circulation. The Tidal Stream Exploitability (TSE) index is adapted to the analysis of estuaries with non-depth-limited areas (TSEndl), such as the Shannon Estuary, and then used to select the hotspots with potential for a tidal stream farm. For this purpose, a new depth penalty-limiting function is defined to avoid overestimating the available energy potential in areas with depths greater than those required for tidal energy converter operation. Seven hotspots are identified based on the revised index. The approach followed in this study illustrates the applicability of high-resolution numerical modelling and spatial analysis for identifying the most appropriate areas for tidal stream energy conversion. Finally, the potential of tidal stream energy to contribute to the much-needed decarbonisation of the energy mix in Ireland is emphasized.Item A holistic methodology for hydrokinetic energy site selection(Elsevier Ltd., 2022-04-25) Fouz, D. M.; Carballo, R.; López, I.; Iglesias, Gregorio; European Regional Development Fund; Xunta de GaliciaHydrokinetic energy can contribute to diversify and decarbonise the energy mix in many coastal regions, in particular estuaries. These are typically areas of high environmental value and with intense socioeconomic activity. The aim of this work is to provide a comprehensive methodology for selecting the optimum locations for hydrokinetic energy exploitation, by considering all the relevant aspects which affect the decision-making process, and improve the current available procedures. The methodology is centred around a novel holistic index, the Integrated Hydrokinetic Energy (IHE) index, which considers: (i) the exploitable resource, (ii) the costs of installation, and (iii) the socioeconomic and environmental aspects. The approach is illustrated through a case study in the Shannon Estuary, on the west coast of Ireland. It is shown that the application of this methodology facilitates the planning and reduces the uncertainties in the development of a hydrokinetic farm project.Item The structural modification and rehydration behaviours of milk protein isolate powders: The effect of granule growth in the high shear granulation process(Elsevier Ltd., 2016-05-30) Ji, Junfu; Cronin, Kevin; Fitzpatrick, John; Maguire, Pierce; Zhang, Hongzhou; Miao, Song; Department of Agriculture, Food and the Marine, IrelandThe effects of granule growth in high shear granulation on the structures and rehydration abilities of milk protein powders were investigated. In this study, milk protein isolate, as a model powder, was agglomerated in a high shear granulator. The formed granules with different sizes were used to compare the densities, granule shapes and subsequently the wettability, dispersibility and solubility. It is found that the small nuclei showed the most compacted structures. Then the primary agglomerates coalesced to create irregular secondary structures with lower density and higher porosity until the final agglomerates formed. The densely packed structures allowed the granules to be more easily wetted by water. The large granules showed quicker release of materials into water until reaching a critical size, where more mechanical energy is potentially required for further granule break down. All the agglomerated MPI granules solubilised much more slowly than the standard MPI powder.