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The application of computational fluid dynamics (CFD) in wind turbine design and analysis is becoming increasingly common in research on wind energy, resulting in a better knowledge of the aerodynamic behaviour of rotors. Due to the deformation of blade airfoils on account of icing, a significant drop in aerodynamic performance brings wind turbines to lose considerable portions of their productivity. Estimating power degradation due to icing via 3D simulation, although it is essential to capture the three-dimensional turbulence effects, is very costly in computational resources despite technological development it then becomes unfeasible when it comes to different operation scenarios to estimate icing originated power losses. The Quasi-3D simulation based on the CFD-BEM method is a practical alternative for generating wind turbines power curves. It showed effectiveness in predicting performance up to a certain level. More than few studies in the literature have adopted this approach to generate the power curve for both clean (un-iced) and iced-up wind turbines. However, the methodology was not adequately presented and discussed for wind turbine icing. This paper reviews the results of almost all the up-to-date published papers that approached this method, summarizing the findings and federates the research in that field to conclude with concrete facts and details that advance research in this domain.

Dust collection systems represent a significant portion of a wood product manufacturer’s total electricity use. The system fan works against the static pressure of the entire system—the blast gates, the ductwork, and the upstream or downstream cyclone and/or baghouse. A poor system design (e.g., sharp elbows or undersized ductwork) increases the total amount of static pressure in the system, the fan’s performance curve shifts, increasing the total brake horsepower required by the fan (up to the maximum point on the curve). Additionally, system designers may oversize a dust collection system to ensure adequate dust capture and transport, either to accommodate system expansion or simply to be conservative. Since theoretical fan energy use increases with its velocity cubed, this can be an expensive safety net. This paper presents a comprehensive literature review about industrial cyclone dust collectors energy saving in relation to management, technologies, and policies. Energy-saving technologies like high-efficiency motors (HEMs), variable-speed drives (VSDs), leak detection, and pressure drop reduction have all been examined. Based on energy saving technologies results, it has been found that in the industrial sectors, a sizeable amount of electric energy, and utility bill can be saved using these technologies. Finally, various energy-saving policies were reviewed.

The application of computational fluid dynamics (CFD) in wind turbine design and analysis is becoming increasingly common in research on wind energy, resulting in a better knowledge of the aerodynamic behaviour of rotors. Due to the deformation of blade airfoils on account of icing, a significant drop in aerodynamic performance brings wind turbines to lose considerable portions of their productivity. Estimating power degradation due to icing via 3D simulation, although it is essential to capture the three-dimensional turbulence effects, is very costly in computational resources despite technological development it then becomes unfeasible when it comes to different operation scenarios to estimate icing originated power losses. The Quasi-3D simulation based on the CFD-BEM method is a practical alternative for generating wind turbines power curves. It showed effectiveness in predicting performance up to a certain level. More than few studies in the literature have adopted this approach to generate the power curve for both clean (un-iced) and iced-up wind turbines. However, the methodology was not adequately presented and discussed for wind turbine icing. This paper reviews the results of almost all the up-to-date published papers that approached this method, summarizing the findings and federates the research in that field to conclude with concrete facts and details that advance research in this domain. &nbsp

RESUME: Ce projet s'inscrit dans des etudes pour approfondir la connaissance du givrage atmospherique afin d'adapter les eoliennes aux conditions d'exploitation en climat nordique. L'objectif principal est de developper des techniques pour evaluer, a long terme, l'impact du givrage sur le fonctionnement des turbines eoliennes et d'optimiser les techniques de degivrage. Plusieurs etudes complexes doivent etre effectuees avant de proposer un modele precis, capable de realiser une simulation tridimensionnelle du givrage sur des pales des eoliennes en rotation. Pour atteindre les objectifs, nous avons utilise des logiciels commerciaux de CFD et l' interface conviviale de MS Excel pour valider un cas test des simulations de l'accumulation de glace sur un cylindre. Ces methodes sont destinees a etre appliquees a la simulation en 3D de l'accumulation de glace sur les eoliennes, etant donne que l'etude du givrage du cylindre, pour lequel des resultats analytiques et experimentaux nombreux sont disponibles pour validation, est fondamentale et prerequise pour ce domaine de recherche. La capacite d'un objet a capturer des gouttelettes d'eau dans un ecoulement est appelee l'efficacite de collection. Une evaluation de l'efficacite de collection sur un cylindre a ete simulee en utilisant une approche Eulerienne basee sur les modeles de turbulence multiphasiques dans ANSYS-CFX. Les resultats ont ete valides avec des resultats des approches Lagrangiennes et Eulerielmes dans FLUENT ainsi qu'avec des resultats experimentaux obtenus a partir d'etudes anterieures. Les resultats ont demontre l'efficacite des modeles multiphasiques du logiciel CFX a simuler les fractions volumiques d'eau et a definir la zone de collection et les limites d'impact autour du cylindre. Pareillement, un logiciel pour calculer les trajectoires des gouttelettes d'eau interceptees dans un ecoulement d'air par un cylindre a ete realise sous Excel avec un code VBA (Visual Basic for Applications). Cette interface permet de demontrer les differents scenarios pouvant aider a valider les simulations avec CFX. Les deux simulations realisees avec Excel et CFX ont demontre une coherence entre le comportement des lignes de courant, des trajectoires et des forces agissant sur les gouttelettes. --ABSTRACT: This project has been conducted in the context of intensifying the knowledge of atmospheric icing on wind turbines to be adapted in Nordic conditions. The main objective is to develop techniques to evaluate the long-term impact of icing on the performance of wind turbine projects and to optimize the de-icing techniques. Several upstream complex studies are to be conducted prior to propose a precise model capable of achieving a three-dimensional simulation of icing on wind turbine rotating blades. In order to overcome these difficulties, we made use of the high capacity of commercial CFD software, together with the friendly user interface of MS-Excel. The validation of these tools for the ice accretion past a cylinder is the prerequisite for applying these tools for the 3D simulation of icing over wind turbines, given that the study of cylinder icing is fundamental in several areas of icing research. The ability of an object to capture water droplets presented in an air flow is caIled collection efficiency. Evaluation of the collection efficiency over a cylinder has been simulated using Eulerian approach based on multi-phase turbulence models in CFX. The results have been validated with those of Lagrangian and Eulerian approaches in FLUENT as weIl as with experimental results obtained from previous studies. The results showed that the use of ANSYS-CFX multi-phase models was effective in simulating water volume fractions through the domain and in defining the collection zone and the impingement limits around the cylinder. In addition, a code to calculate the trajectories of supercooled water droplets in the air intercepted by a cylinder has been achieved using MS-Excel sheets supported with VBA (Visual Basic for Applications). This interface has been used to demonstrate different scenarios that can help to validate similar simulations using CFX. In both Excel and CFX simulations, the streamlines and trajectories have demonstrated similar behaviour which is consistent with the forces acting on water droplets.

In the context of global campaign to mitigate climate change effects, researches on wind turbines industry have known a constant growth during the last few years. Wind velocity is so important for wind turbine productivity and very significant wind resources are available in cold regions where icing effects are also significant. Ice accretion increases the risks of unbalanced mass resulting in losses of annual power production, in vibration problems and in security risks. This coincides with the most abundant days of wind in the year. At the WERL (Wind Energy Research Laboratory), in collaboration with the TechnoCentre Eolien and the AMIL (Anti-icing Materials International Laboratory), numerous studies have been conducted to avoid this problem. In this paper we made use of these studies to simulate a test case of icing around a cylinder as described in Lozowski et al. [1]. We emphasize on the fact that these studies cannot provide very accurate local results due to numerous simplifications. We, therefore, developed at the WERL an interactive interface to simulate the trajectory of water droplets in an airstream until collision on a cylinder. This interface is based on MS-Excel worksheets supported with VBA code (Visual Basic for Applications) using a fourth order Runge-Kutta resolution scheme. The interface provides flexibility to demonstrate various scenarios that can help to validate the subsequent evaluation of collection efficiency based on multiphase CFX simulation.

Several research activities have been realized to improve the design of turbines and their resistance to extreme conditions like ice accretion. This phenomenon triggers the degradation of turbine performance and increases vibration problems. In an aim to mitigate this problem, it is important to predict the shape, type and extent of ice accretion in order to apply optimised de-icing strategies. This article proposes one such upstream study inscribed in a more global study being conducted at the Wind Energy Research Laboratory on ice accretion - CFX based modelling of water droplets flow in an airstream until impingement on a cylinder. This model makes part and parcel of a more elaborate project whereby thermodynamics and phase change equations will be applied on each water droplet to simulate the new geometry due to ice accretion. This article emphasis on the intrinsic parameters in multiphase modelling, the factors affecting local and global water droplets collection, models simplifications, the analytical equations used in the model, the obtained results and the options for further improvement of the model.