International Journal of Energy Science
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Open Access journal
ISSN (Print) 2218-6026 - ISSN (Online) 2304-3679
Published by Science and Eng Pub Co. [48 journals]
- Internal Model Controller for Variable-Speed Wind Turbines at High Wind
Abstract: Internal Model Controller for Variable-Speed Wind Turbines at High Wind Speeds
Author Rahma OuhibiKhaled Nour
In this paper, an extended Internal Model Controller (IMC) approach is designed for variable speed horizontal wind turbines at high wind speeds. The presented method is based on an inner feedback loop added in conventional IMC structures to provide stable speed tracking and improve the global dynamic system. Firstly, a general wind turbine model and linearization model of considered wind turbine are developed. Then, the extended IMC approach is performed. Finally, a 2MW wind turbine is used to illustrate the good performances bought by the IMC approach by presenting and discussing the simulation results.
- Experience with the Gasification of Low-Grade Coal; A Case Study of
Continuously Changing Temperature inside Gasifier
Abstract: Experience with the Gasification of Low-Grade Coal; A Case Study of Continuously Changing Temperature inside Gasifier
Author Han UhmYoungho NaYong HongDong ShinChang ChoYoung Par
Indonesian brown-coal with high ash content is gasified by two microwave steam-plasmas heating up a reaction chamber of 1145 liters in a swirl-type gasifier for production of hydrogen-rich synthetic gas. With additional heating of the gasifier by a partial oxidation of coal, the inner temperature of the gasifier can be increased from 1100C to 1700C. In this regard, the influence of the gasifier temperature on the gasification efficiency can be investigated in this experiment. The carbon conversion rate and cold gas efficiency are less than 90 percent and 65 percent, respectively, for the inner temperature of the gasifier below 1400C. On the other hand, the carbon conversion rate at the chamber temperature of 1600C is almost 100 percent, ensuring a complete gasification of carbons in a low-grade coal. The cold gas efficiency of the hydrogen-rich synthetic gas at the high inner temperature of the gasifier wall is 84%, very high in a relatively-small gasifier like the experiment here. The total calorific power of the synthetic gas can be easily more than 500kW in this particular experiment.
- On the Use of Concave Heliostats in a Beam-Down Central Receiver System
Abstract: On the Use of Concave Heliostats in a Beam-Down Central Receiver System
Author Erminia Leonard
The beam-down design is standing out as a very promising technology in the field of solar central receiver systems. In this paper, we show that the use of concave heliostats strongly improves the overall performance of the system, allowing for a better concentration of the solar radiation at the receiver. To this aim, the spot at the horizontal plane containing the lower focus of the secondary reflector is analyzed under different conditions, such as secondary reflectors of different eccentricities and solar fields composed of concave or flat heliostats. The performance analysis of a realistic beam-down system is also proposed to stress both the feasibility of the plant and the need of using concave heliostats. This study has been conducted with the use of the CRS4-2 numerical code (an acronym for CRS4 research software for Central Receiver Solar System Simulation S), developed in our laboratory.
- Investigating the Effect of Operating Temperature on the Performance of
TGT Absorber Column
Abstract: Investigating the Effect of Operating Temperature on the Performance of TGT Absorber Column
Author Hamid Reza Mahdipoo
Hydrogen sulfide (H2S) coming from oil and gas refineries, after purifying in amine sweetening unit, is routed to Sulfur Recovery Unit (SRU), wherein converted to elemental sulfur. In order to compensate the low performance of SRU, the remained acid gas is then fed to Tail Gas Treatment (TGT) unit for more processing. TGT unit increases the overall sulfur recovery and therefore, decreases the environmental pollution. The absorber column is an important equipment in the TGT unit. The main function of this column is the selective absorption of H2S in the presence of CO2. In this paper, the effect of operating temperature on the performance of TGT absorber column will be investigated. For this purpose, a typical industrial TGT unit is simulated and then, the results are illustrated and analyzed in terms of technical points of view.
- Study of Environmental Impacts of Wind Power Plants Aiming to Support
Public Policy in Brazil
Abstract: Study of Environmental Impacts of Wind Power Plants Aiming to Support Public Policy in Brazil
Author Wilson Pereira Barbosa FilhoAbílio Cesar Soares de AzevedoAndrea Brandão AndradeAntonella Lombardi CostaRicardo Brant Pinheir
This article presents a study about environmental impacts resulting from the construction and operation of wind power farms. For this matter, a research in national and international literature reviews was carried out, as well as technical visits to wind power plants in several Brazilian states and discussions with the working group about environmental licensing of wind mills in land surface of the Ministry of Environment, which FEAM (Fundação Estadual do Meio Ambiente – Environmental State Foundation) takes part, aiming the formation of plans, projects and wind power programs, according to the provisions of the “Carta dos Ventos” (Charter of Winds). These surveys were carried out in the last three years and used as base for the implementation of relevant work to the theme. The article discusses the impacts in biotic and physical environment, physical and socioeconomic status, identifying the biotic environment, which results from the removal of vegetation, intervention in fauna, degradation of the affected area, changes in the hydrostatic level of aquifer, and still on the socio-economic environment, the issue of noise, visual impact, the corona visual or glare, the electromagnetic interference, the strobe effect and the local interference. The noise and the strobe effect can harm the health of people near the plants, but the distance can avoid such effects. The generation of electricity through wind farms has major advantages in reducing greenhouse gases and CO2 concentration during operation when compared with other sources. However, the environmental impacts coming from the implementation and operation of a wind power plant cannot be neglected.