風力發電機製作 及 相關物理計算 MAKING OF WIND TURBINE AND RELATED CALCULATION - PowerPoint PPT Presentation

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Presentation Transcript

MAKING OF WIND TURBINE

AND RELATED CALCULATION

HKPU

Applied Physics Student

Chka Chun Hang

• 引言

• 理論

• 發電機的設計

• 製作過程

• 相關計算

• 演示

Where do winds come from?風從哪裡來?

• Because of the temperature differences(溫差) around the world

Surface Wind

Convection updraft of rising warm Air

What is wind turbine(風力發電機)?

Wind’s kinetic energy(動能)

->electrical energy(電能)

Theory理論

• By Lenz’s Law (冷次定律)

Induced current(感生電流) opposes(對抗)the change of the magnetic force

Heinrich Lenz

海因里希·冷次

Induced emf-感生電壓

Where ,

• N is the number of turn of coil,

• B is the magnetic field strength

(磁場強度)

• A is the area(面積) of the coil

Brace 支架

Axle 軸

Turbine 渦輪

Rotor 轉片

Coil 電線圈

Supporting Base

Magnet 磁鐵

Material-物料

• Screw(螺絲) x 8Bearing(滾珠軸承)x 2

• Copper wire(漆皮銅線) Chopstick(筷子) x 3

• Water bottle(水樽)Magnet (磁石)x 4

• LED 燈x 1CD case x 1

• )

Making Process-製作過程

• 1. Preparing the material

Making Process-製作過程

• 2.making the frame(骨架) and base

1

2

3

Finished product

Making Process-製作過程

• 3. Assembly(集合) the CD case and the base

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3

4

2

Making Process-製作過程

• 4. making the coil by the copper wire

Making Process-製作過程

• 5. assembly to the CD case

Making Process-製作過程

• 5. assembly to the CD case

Making Process-製作過程

• 6. making the rotor(轉片)

Making Process-製作過程

• 6. making the rotor (轉片)

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3

1

Making Process-製作過程

• 7. making the turbine(渦輪)

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4

Making Process-製作過程

• 7. making the turbine (渦輪)

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Making Process-製作過程

• 8. assembly all the component(部件)

Finish!!

Calculation

Power(功率) of Wind turbine

• kinetic energy of a mass in motions is:

• The power in the wind is given by the rate ofchange of energy:

• As mass flow rate is given by:

Power (功率) of Wind turbine

• Also, the rate of change of distance is given by:

• we get:

• Hence, the power can be defined as:

Power (功率) of Wind turbine

Power coefficient(功率系數),

Cpmax= 0.59

Therefore, the extractable power:

No wind turbine can convert(轉換)more than 16/27 (59.3%) of the kinetic energy of the wind into mechanical energy turning a rotor.

German physicist

Albert Betz

Picture captured from http://www.eoearth.org/article/Betz,_Albert

Power (功率) of Wind turbine

• For this turbine,

假設 ,

• Power Coefficient(功率系數), Cp = 0.5

• Air density(密度), ρ = 1.23 kg/m3

• Area of blades(扇葉), A= 0.04*0.2 = 0.008 m2

Wind speed(風速), v = 20km/h = 5.56 m/sec

所以,

• P = ½*0.5*1.23*0.008*5.563

= 0.423 W

• Since,

Thus,

Induced voltage-感生電壓

• Normally, an AAbattery(電池) is having 1.5V

Factor (影響因素)

Factor(影響因素) of output voltage:

• Wind speed(風速)

• Strength of magnet(磁石強度)

• *The number ofturns of coil, N(線圈圈數)

• *Internal resistance of wire, r(電線內阻)

• Since因為 N->r,Iout

延伸探究

• 內阻同圈數對於輸出電流的連帶關係

• 計算輸出功率

• 計算效率