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Acknowledgements Conclusion The project required the design of a 20W wind turbine; the final product was capable of producing up to 35-40W of power, therefore,

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Presentation on theme: "Acknowledgements Conclusion The project required the design of a 20W wind turbine; the final product was capable of producing up to 35-40W of power, therefore,"— Presentation transcript:

1 Acknowledgements Conclusion The project required the design of a 20W wind turbine; the final product was capable of producing up to 35-40W of power, therefore, overall the project was a success. The Lenz2 type wind turbine works very well in low wind conditions; it is self starting at about 4mph winds and can maintain its rotation at low speeds. Design and Fabrication of a Solar-Wind Hybrid Power System Abstract Rural coastal communities in developing countries along the equator lack electricity due to the expenses involved with connecting them to the power grid. An affordable local solution, such as on-site micro power generation, would benefit these communities and fulfill their basic lighting and ventilation needs. This project involves the development such a system; consisting of a vertical axis wind turbine integrated with a solar panel to generate direct current (DC) power. Prad Pathirana Advised by Prof. Richard Wilk Lenz2 Wind Turbine The Lenz2 turbine design is a gyro mill type wind turbine with three scoops at 120 o to each other. Although the scoops have an aerodynamic design its mainly a drag based wind turbine, like the Savonius turbine. An advantage that the Lenz2 has over the Savonius turbine is the fact that it can reach much faster rotational speeds. SymLab 4 was used to model lenz2 blades under different wind speeds and showed promising results as seen in figure 10. References 1.NASA. 18 Mar. 2009. 2."Topic Ten : Local Winds." WRGB CBS 6 Albany. 10 Nov. 2008. 3.Elliot, D., and M. Schwartz. Wind Energy Resource Atlas of Sri Lanka and Maldives. Rep. National Renewable Energy Laboratory. 17 Mar. 2009. 4."SymLab | Symscape." Symscape | Computer-Aided Engineering for All. Fall 2008. Introduction and Background This project was motivated by the predicament of rural coastal communities in Sri Lanka that have no access to the power grid. Sri Lanka happens to be a developing island nation with vast stretches of coastline. Many of the communities along the coast have very poor living standards and one of their main concerns is the lack of electricity for lighting and other uses. Currently, they use kerosene lamps as a source of lighting and car batteries to power basic electronics. These are the cause of both fire, and other health hazards. Children from these coastal communities tend to study with kerosene lamps for lighting; mishaps and fires are common place. Coastal areas in Sri Lanka have two sources of energy that are yet to be harnessed; the high incident solar radiation, and the convection wind flows that occur due to the proximity to the ocean. This project involves development a system that will harness these two free sources and supply the power to light and ventilate these small houses. Figure 1: Solar energy incident on surface 1 Sri Lanka Figure 2 : Sea breeze and land breeze 2 Figure 3 : Wind data map 3 Table 1: Load and power generation calculations Initial Tests and Calculations Power (W) # Usage (hrs) Energy (W.hrs) Houses LED636108 3 houses supplied Fan101 100 Total power required with LED bulbs per day208 CFL1436252 2 houses supplied Fan101 100 Total power required with CFL bulbs per day352 Solar Panel5016300 Power Output Wind Turbine201 400 Total power supplied by system per day700 Ametek 38VDC Motor Testing The ideal wind turbine generator would reach high voltage levels at low RPMs, while at the same time the torque should remain relatively low. The Ametek 38VDC motor showed the best characteristics and the results of its motor test is shown below in table 2. The table was truncated for the sake of clarity. Tach (V) Speed (RPM) Torque (oz-in) Gen Voltage Out (V) 2.39114.9010.144.00 3.15151.4410.655.30 3.66175.9611.156.30 6.84328.8513.3511.20 7.04338.4613.6912.00 7.41356.2513.8612.70 12.50600.9617.4121.20 13.25637.0218.0822.40 14.35689.9018.9323.90 Table 2: Ametek 38VDC motor test results Size the Load Different types of lighting such as CFL and LED were considered. A small DC fan will be used for ventilation. It was assumed that the house will be lit for six hours a day, on average; with three lighting fixtures providing the entire lighting requirement for these small dwellings. The wind turbine was assumed to generate 20W of power for 20 hours, while the solar panel generated 50W for 6 hours per day. The resultant power supply and demand is tabulated in table 1. Wind Tunnel Testing A blade testing apparatus that can be mounted on to the wind tunnel was designed and built. Through this apparatus the rotational speed of different blade designs at varying wind speeds was measured; as well as torque and power generated by the mini-turbine. Figures 4a- b shows the design schematic and the final apparatus. Figures 4a-d: Design Schematic, Savonius blade, pulley, bevel gear arrangement 5a) Rotational Speed 5b)Power 5c)Torque Figures 5a-c: Rotational Speed, Power, Torque measures for a Savonius type blade under different wind speeds. 4a 4b 4d4c These results predicted that a larger scale Savonius type wind turbine would self start at very low wind speed, but it may have structural issues at very high wind speeds. Figure 6a-b: Lenz2 Wind turbine simulated in SymLab at 15 mph wind in x direction a)Shows the entire pressure coefficient spectrum b)Shows the areas with higher pressure coefficient Overall Design As shown in figure 7, the two components generating power are the solar panel and the wind turbine. They are connected to a charge controller which would be connected to the battery pack. The vertical axis wind turbine is connected to a sprocket and chain with a four to one transmission ratio. This was sized depending on the expected power and torque of the VAWT. The VAWT will drive an Ametek 38VDC motor that would generate a certain voltage and current. If the said voltage is below 13V or excessively higher from that number, the voltage will be converted up or down to 13.3V using a Linear LTM4605ev buck/boost converter. The charge controller will protect the battery from surges and make sure it does not get overcharged. The battery used for testing purposes was a 12V - 12Ah Maintenance- Free Rechargeable Sealed Lead-Acid Battery. Figures 7: Overall Design Schematic 6a6b Final Wind Turbine Design Testing the Wind Turbine The finished wind turbine was assembled on top of the Union College facilities building as seen in figure 8c. Now, its ready for field testing. Performance tests were carried out on a particularly windy day(16mph average). The experimental setup is seen in figure 9a-b. The voltage generated by the DC motor averaged at about 5-7V at low-medium winds; and it reached up to 14V. The buck/boost converter regulates the voltage to 13.3 Volts. After the charge controller this voltage dropped back down to about 12.5V. The current delivered to the battery reached up to 2.9A. Therefore, by multiplying current by voltage, the power generated in the system is about 37W. Figures 8a-c: Design Schematics of the wind turbine, and the final finished product assembled on top of the facilities building 8a8b 8c Figures 9a-b: Yellow multi-meter measures V generated, Green-1 measures current supplied to the battery, Green-2 measures V regulated to the battery. Inside the box you can see the charge controller and the buck/boost voltage converter circuit. VVAPower (W) Min0000No wind Max1412.62.936.54Medium-high wind Average512.61.2515.75Medium-low wind Table 3: Multi-meter readings Future Work Integrate a solar panel to the system. Test the entire system performance over time using a data acquisition device; while keeping track of wind speed. Develop electrical system such that multiple batteries can be charged; while, allowing certain batteries in the battery pack to discharge. Experiment with higher gear ratios. Test other generators and compare data. Prof. Richard Wilk, Prof. James Hedrick, Prof. John Spinelli, Prof. William Keat, Paul Tompkins, Stanley Gorski, Rhonda Becker, Malysa Cheng, Kevin Donovan, James J. Howard, Roland Pierson Department of Mechanical Engineering, Union College, NY Senior Project - 2009


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