Search results for "turbine"
showing 10 items of 198 documents
An experimental study of double-to-single-loop transition in stirred vessels
1999
The velocity characteristics of the flows in a fully baffled vessel of diameter T = 290 mm stirred by a Rushton impeller of diameter D = T/3 were investigated by means of laser-Doppler anemometry measurements. The effects of clearance and rotational speed on the flow patterns in the vessel were studied. It was found that at impeller clearances from the bottom of the vessel (C) around 0.2 T the characteristic double-loop flow pattern undergoes a transition to a single-loop one with the impeller stream direction becoming partly axial and being inclined at around 25 to 30° to the horizontal. The impeller stream inclination varied with radial distance from the impeller, as well as with angular …
Cost-Benefit Analysis for Hydropower Production in Water Distribution Networks by a Pump as Turbine
2014
AbstractThe use of microhydroelectric plants in urban pipe networks, based on the combination of a pump as turbine (PAT), two regulating valves, and two pressure meters, is proposed along with simple automation rules. Its economic benefit is tested on a small pipe network, where the network geometry as well as the demand coefficient variation in time and space have been inferred from previously collected data and existing analysis. A similar analysis has been also carried out for different scenarios in which the reduction of pipe installation cost due to a diameter reduction is compared with the increased benefit in energy production. The case study shows that a small increment of the pipe …
A probabilistic rainfall model to estimate the leading-edge lifetime of wind turbine blade coating system
2021
Rain-induced leading-edge erosion of wind turbine blades is associated with high repair and maintenance costs. For efficient operation and maintenance, erosion models are required that provide estimates of blade coating lifetime at a real scale. In this study, a statistical rainfall model is established that describes probabilistic distributions of rain parameters that are critical for site-specific leading-edge erosion assessment. A new droplet size distribution (DSD) is determined based on two years’ onshore rainfall data of an inland site in the Netherlands and the obtained DSD is compared with those from the literature. Joint probability distribution functions of rain intensities and dr…
The good process or the great illusion? A spatial perspective on public participation in Danish municipal wind turbine planning
2021
This paper explores the nature of public participation in Danish municipal wind power planning. Although the procedure for involving citizens embedded in the environmental impact assessment (EIA) procedure for wind power projects is often praised for its participatory character, the approach is not without problems. In this paper, we identify the limitations and potentials of the public space provided for citizen involvement. By means of Gaventa’s terminology suggesting a continuum of public spaces for participation, the paper shows how the planning process can be approached from different spatial perspectives – each of them illuminating different forms of power, resistance and opportunitie…
Effectiveness and safety of a new helmet CPAP configuration allowing tidal volume monitoring in patients with COVID-19.
2021
Abstract Background High generated tidal volumes (Vt) have been correlated with higher risk of self-induced lung injury and worse clinical outcome. This study aimed to evaluate the effectiveness and safety of a new helmet continuous positive airway pressure delivered (h-CPAP) configuration allowing Vt monitoring in patients affected by COVID-19. Methods This prospective observational study was performed in the respiratory intermediate care unit of University Hospital in Turin, Italy, between March 24th, and June 15th, 2020. Included patients were treated with CPAP via a single-limb intentional leak configuration by a turbine-driven ventilator, provided with a dedicated patch. Effectiveness …
A novel soft-stall power control for a small wind turbine
2017
In this paper, the problem of Soft-stall power control design for a small wind turbine is considered. Passive stalling and furling methods are widely used to limit the output power of small wind turbines at above-rated wind speed conditions. However, these methods have substantial limitations, for instance, related to tracking the maximum power at some wind speed levels, limited variable speed operation and introducing unbalanced forces on wind turbine blades. Soft-stall power control is a promising technique to overcome above limitations and improve the performance of small wind turbines. Small wind turbines have a comparatively low moment of inertia value, and it is possible to make fast …
Evaluating the Performances of Small Wind Turbines: A Case Study in the South of Italy
2012
AbstractAmong renewable energy resources, wind energy became more attractive in the last decade. Wind farms installations dramatically increased in areas where climatic conditions, topography and environment have allowed their development. The installation of wind turbines, usually carried out in remote areas, recently began to cover areas identified by a complex terrain such as urban and suburban zones. Although these new sites’ choices are characterized by lower productivity there is increasing interest in wind energy production in both urban and suburban area. In this work the authors have carried out an energy analysis developed from a sample of small wind turbines available on the mark…
The risk management in the international contracts of marine renewable energy : focus on offshore wind farms
2022
At a time when climate change is becoming the main concern, the renewable energy sector is developing extremely rapidly. In order to add other sources to the existing ones and to increase electricity production while ensuring its stability, the sea has quickly been considered as an attractive alternative. However, the creation of a new industry is a major challenge and marine renewable energy projects are very expensive and risky. The concept of risk was created specifically regarding the management of human activities at sea. The example of offshore wind energy allows us to go back to the origins of the notion of risk by considering it from the point of view of the company, and to analyse …
Condition Assessment and Analysis of Bearing of Doubly Fed Wind Turbines Using Machine Learning Technique
2023
Condition monitoring of wind turbines is progressively increasing to maintain the continuity of clean energy supply to power grids. This issue is of great importance since it prevents wind turbines from failing and overheating, as most wind turbines with doubly fed induction generators (DFIG) are overheated due to faults in generator bearings. Bearing fault detection has become a main topic targeting the optimum operation, unscheduled downtime, and maintenance cost of turbine generators. Wind turbines are equipped with condition monitoring devices. However, effective and reliable fault detection still faces significant difficulties. As the majority of health monitoring techniques are primar…
Offshore wind turbine operations and maintenance: A state-of-the-art review
2021
Abstract Operations and maintenance of offshore wind turbines (OWTs) play an important role in the development of offshore wind farms. Compared with operations, maintenance is a critical element in the levelized cost of energy, given the practical constraints imposed by offshore operations and the relatively high costs. The effects of maintenance on the life cycle of an offshore wind farm are highly complex and uncertain. The selection of maintenance strategies influences the overall efficiency, profit margin, safety, and sustainability of offshore wind farms. For an offshore wind project, after a maintenance strategy is selected, schedule planning will be considered, which is an optimizati…