Surface Modification of AI Alloy 2014 by Electrochemical Deposition of Ni

The surface of Aluminum alloy AA 2014 was modified by electrochemical deposition of Ni and its effect on corrosion performance was evaluated. Standard Watt's bath with varying potential, current and time was employed for deposition. The Ni-coated samples were heat treated to improve coating characteristics. Corrosion behavior was studied by electrochemical testing and microstructural characterization was performed using scanning electron microscopy. Microhardness was also undertaken. Experimental results indicate that electrochemical deposition combined with heat treatment can be used to improve the surface properties of Al alloys

Surface Modification of AI Alloy 2014 by Electrochemical Deposition of Ni

The surface of Aluminum alloy AA 2014 was modified by electrochemical deposition of Ni and its effect on corrosion performance was evaluated. Standard Watt's bath with varying potential, current and time was employed for deposition. The Ni-coated samples were heat treated to improve coating characteristics. Corrosion behavior was studied by electrochemical testing and microstructural characterization was performed using scanning electron microscopy. Microhardness was also undertaken. Experimental results indicate that electrochemical deposition combined with heat treatment can be used to improve the surface properties of Al alloys

Offshore wind speed and wind power characteristics for ten locations in Aegean and Ionian Seas

This paper utilizes wind speed data measured at 3 and 10 m above water surface level using buoys at 10 stations in Ionian and Aegean Seas to understand the behaviour of wind and thereafter energy yield at these stations using 5 MW rated power offshore wind turbine. With wind power densities of 971 and 693 W/m2 at 50 m above water surface level, Mykonos and Lesvos were found to be superb and outstanding windy sites with wind class of 7 and 6, respectively. Other locations like Athos, Santorini and Skyros with wind power density of more than 530 W/m2 and wind class of 5 were found to be the excellent sites. Around 15–16% higher winds were observed at 10 m compared to that at 3 m. Lower values of wind speed were found during summer months and higher during winter time in most of the cases reported in the present work. Slightly decreasing (∼2% per year) linear trends were observed in annual mean wind speed at Lesvos and Santorini. These trends need to be verified with more data from buoys or from nearby onshore meteorological stations. At Athos and Mykonos, increasing linear trends were estimated. At all the stations the chosen wind turbine could produce energy for more than 70% of the time. The wind speed distribution was found to be well represented by Weibull parameters obtained using Maximum likelihood method compared to WAsP and Method of Moments.http://www.ias.ac.in/jess/ai201

Analysis of a multi-megawatt grid connected wind farm

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.No abstract available, please open full text articlemp201

Wind power potential assessment for seven buoys data collection stations in Aegean Sea using Weibull distribution function

This paper utilizes three hourly measured values of wind speed and direction from seven buoys data collection stations in Aegean Sea to study the wind speed and power characteristics applying the Weibull shape and scale parameters. Specifically, the site dependent, annual and monthly mean patterns of mean wind speed, Weibull parameters, frequency distribution, most probable wind speed, maximum energy carrying wind speed, wind power density and wind energy density characteristics have been studied. The Weibull distribution was found to represent the wind speed distribution with more than 90% accuracy in most of the cases. Slightly decreasing trends were observed in annual mean wind speed values at Lesvos and increasing at Mykonos. The mean values of wind speed, scale parameter, most probable wind speed, maximum energy carrying wind speed, wind power and wind energy density values showed higher values during winter time and lower in summer time. Mykonos was found to be the best site from wind power harnessing point of view. Moreover, the correlation between the percentages of times the wind speed was above cut-in-speed and the measured mean wind speed for the three selected sites and the correlation between the aforementioned percentages and the scale parameter c were examined and were found linear.http://jrse.aip.org/ai201

Extraction of the inherent nature of wind speed using wavelets and FFT

Due to technological advancement, availability of multi-megawatt wind turbines, ease of installation and maintenance, economic compatibility and commercial acceptance, wind power is being used globally for both grid-connected and off-grid applications. The wind power is intermittently available due to the fluctuating nature of the wind and hence needs to be understood well. Its variability was studied in this paper both in time and spatial domain. The present work utilized daily mean values of wind speed from different meteorological stations spread over the Kingdom of Saudi Arabia in conjunction with wavelet transform and fast Fourier transform power spectrum techniques to understand the dynamic nature of the wind at nine stations. The study found that wind speed changed by ± 0.6 to ± 1.6 knots over a long period of about 10 years depending on the locations. The long-term mean wind speed of 5.6, 8.9, 6.25, 8.1, 6.0, 7.1, 6.0, 8.6 and 7.3 knots was obtained at Abha, Dhahran, Gizan, Guriat, Hail, Jeddah, Riyadh, Turaif and Yanbu, respectively.Research Institute of King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia.http://www.journals.elsevier.com/energy-for-sustainable-development/hb2014ai201

Review of 600kw to 2500kw sized wind turbines and optimization of hub height for maximum wind energy yield realization

The percent increase in energy production with corresponding increase in hub-height for wind energy conversion system (WECS) from different manufacturers was compared in this study. It was seen that an increase of 10m in hub-height from 40 to 50m resulted in an increase of 3.17% in energy production for wind turbines from Nordex, while a change of 3.48% from Vestas, and so on. The overall mean increase in energy production was found to be 2.92% while changing the hub-height from 40 to 50 m. Further increase of 10m in hub-height from 50 to 60 m, showed an increase of 7.55%, 7.90%, 7.88%, 8.25%, 8.14% and 7.75% for WECS from Nordex, Vestas, DeWind, GE, Bonus and Enercon respectively. The overall mean increase in energy production was found to be 7.91% for this change of hub-height from 50 to 60 m. Similarly, an increase of 3.02% in energy production was obtained for an additional of 10m increase in hub-height i.e. from 70 to 80 m. On the average the maximum increase in energy production of 7.91% was obtained while changing hub-height from 50 to 60 m.http://www.elsevier.com/locate/rserai201