Experimental research on savonius turbines for lighting in accordance with wind power along the coast of danang

NGHIÊN CỨU THỰC NGHIỆM ĐỘNG CƠ SAVONIUS PHÁT ĐIỆN CHIẾU SÁNG THE UNIVERSITY OF DANANG, JOURNAL OF SCIENCE AND TECHNOLOGY, NO 6(79) 2014, VOL 1 77 EXPERIMENTAL RESEARCH ON SAVONIUS TURBINES FOR LIGHTIN[.]

THE UNIVERSITY OF DANANG, JOURNAL OF SCIENCE AND TECHNOLOGY, NO 6(79).2014, VOL 1 77

EXPERIMENTAL RESEARCH ON SAVONIUS TURBINES FOR LIGHTING IN ACCORDANCE WITH WIND POWER ALONG THE COAST OF DANANG

NGHIÊN CỨU THỰC NGHIỆM ĐỘNG CƠ SAVONIUS PHÁT ĐIỆN CHIẾU SÁNG PHÙ HỢP

VỚI NĂNG LƯỢNG GIÓ DỌC THEO BỜ BIỂN THÀNH PHỐ ĐÀ NẴNG

Pham Duy Vu

The University of Danang, University of Science and Technology, Email: phamduyvubk@gmail.com

Abstract - Research of illuminated generator engine using wind

energy in accordance with the wind speed range along the coast

of Danang is the goal of the study The author has successfully

designed and manufactured illuminated generator engine that is

suitable for wind speeds along the coast between Danang City (3

÷ 8,5)m/s Fabricated Savonius turbines: wing two- storey type with

ratio of two- storey height is 2:1, 1:1 and 1 wing one-storey type

The experimental results show wing two-story type with height ratio

of 1:1 is the most efficient and rotor diameter d = 416mm suitable

for crowded places like resorts and beaches along the coast In

particular, we have successfully fabricated generators in

accordance with the structure of the Savonius type with capacity

N = 15W

Tóm tắt - Nghiên cứu động cơ phát điện chiếu sáng phù hợp với

dải tốc độ gió dọc theo bờ biền Thành phố Đà Nẵng là mục tiêu khi nghiên cứu Tác giả bài báo đã thiết kế chế tạo thành công động

cơ phát điện chiếu sáng phù hợp với tốc độ gió dọc theo bờ biển Thành phố Đà Nẵng khoảng (3 ÷ 8,5) m/s Chúng tôi đã chế tạo động cơ gió Savonius kiểu 2 tầng cánh với tỉ lệ chiều cao của 2 tầng là 2:1, 1:1 và kiểu 1 tầng Kết quả thực nghiệm cho thấy loại

2 tầng cánh với tỉ lệ chiều cao 1:1 có hiệu suất cao nhất và đường kính cánh quạt d = 416mm phù hợp với những nơi đông người như khu resort, bãi tắm dọc theo bờ biển Đặc biệt, chúng tôi đã chế tạo thành công máy phát điện phù hợp với kết cấu của kiểu quạt gió Savonius đạt hiệu suất trung bình với công suất N =15 W

Key words - savonius engine; renewable energy; wind energy;

wind turbine efficiency; electric motor

Từ khóa - động cơ Savonius; năng lượng tái tạo; năng lượng gió;

hiệu suất quạt gió; động cơ phát điện

1 Introduction

Research of efficiently use of renewable energy

suitable for the locality is one of the criteria for sustainable

development of Danang City Such renewable energy

sources as solar energy, wind energy, biogas and biomass

are being studied for applications; particularly, the

production of electrical power from solar energy, wind

energy is the prior interest

Currently, there is no lighting source along the coast

and coastal rescue stations in Danang, which significantly

affects the development of marine tourism and the safety

of tourists Therefore, the research and manufacture of

generators using wind energy suitable for lighting system

along the coast is useful and practical Manufacturing

equipment should be in conformity with the installation

location along the coast (where there are many passers-by),

easy to install or dismount in case of storms and ensure the

safety of tourists Besides, the installation of wind turbines

in tourist sites also makes people aware of energy saving

and creates scenic beauty of the tourist city

2 Research Method

2.1 Theoretical Basis of Selecting Wind Turbine

Currently, horizontal-axis wind turbines and

vertical-axis wind turbines are commonly used in the world

Horizontal-axis wind turbines are conformable with the

wind velocity from 10 to 17 m/s [4] and often stationed far

from residential areas due to their large diameter propellers

and loud noise Vertical-axis wind turbines is conformable

with low wind velocity (<10 m/s) [4] and small diameter

propellers, and their operation is not dependent on wind

direction

After surveying the advantages and disadvantages of

various types of wind turbines currently used in the world,

we choose the Savonius wind turbine (Figure 1) to use wind energy for lighting This type of turbine is conformable with average wind velocity in Danang City [1] v = 3.3 m/s, and can be easily installed or dismounted without causing any noise and pollution

Figure 1 Savonius wind turbine

Figure 2 Comparison of the moment of layers [5]

The Savonius wind turbine (Figure 1) was invented by

a Finnish engineer named J.Savonius in 1920 It consists of

Direction of rotation

Wind direction

78 Pham Duy Vu

a rotating shaft (axis of rotation) and two half cylindrical

(or elliptical) blades arranged in “S” shape Convex side of

one of the half cylinder and the concave side of the other

are facing the wind stream at a time The basic driving

force of the Savonius rotor is drag This drag is parallel to

the wind direction The drag coefficient of a concave

surface is larger than the convex surface Hence, the half

cylinder with concave surface facing the wind will

experience more drag force than the other half cylinder,

thus forcing the rotor to spin

For designing a Savonius Wind engine, the factors

affecting momen values are the layer numbers, layer ratio,

height, fan-blade diameters According to the research

result by Md Nahidul Islam Khan [5], at the same wind

velocity the two-layer fan blade has the highest

performance (figure 2) According to the research result

by Peter Werner [3], the fan blade height is twice as much

as the layer diameter As a result, for this design we choose

the two-layer fan blade with diameter of 400 mm

equivalent to the height of 800mm

2.2 Calculating Capacity Factor of Wind Turbines

Figure 3 Geometrical parameters of Savonius blades

+ Select wind speed ratio to calculate the capacity, v,

m/s

+ Select the right diameter of the blades, m

+ Capacity of the turbine is determined by the formula

[3]:

Pq= Cp.kk v3.π.R.H, W (1)

Where

- kk: Air density, kg/m3

- Cp: maximum capacity ratio

- Cm: torque coefficient

- : Tip-speed ratio

- R: Radius of Savonius blade, R = D / 2

-H: Height of blade, H is given by the empirical formula

[3] H = 2D

- Interstitial space between the blades: e = R / 5.5

- Diameter of a convex surface of Savonius blade: d =

R + e / 2

3 Research Results and Comments

3.1 Designing and Manufacturing 2 Types of Savonius

Turbines

Based on the geometrical parameters of Savonius

blades in Figure 1 and the formula (1) the research team has manufactured three types of blades with the same diameter, but different in the number and the height of storeys (Figure 4)

+ Type 1 (Figure 4a): 2 storeys, ratio: 1:2, height of lower storey: H1 = 540mm, height of upper storey: H2 = 260mm

+ Type 2 (Figure 4b): 2 storeys, ratio: 1:1, height of lower storey: H1 = 400mm, height of upper storey: H2 = 400mm

Table 1 Parameters of designing 2 types of blades

1

2

3

4

5

6

7

height of lower storey height of upper storey Radius of rotor Diameter of blade Interstitial space, e Interstitial space, a Inclined angle between two storeys

H1

H2

R

d

e

a



mm

mm

mm

mm

mm

mm degree

540

260

200

220 3,7

0

90

400

400

200

220 3,7

0

90

Figure 4a Type 1

Figure 4b Type 2

THE UNIVERSITY OF DANANG, JOURNAL OF SCIENCE AND TECHNOLOGY, NO 6(79).2014, VOL 1 79

Comments:

After a lot of experiments with the wind velocity from

3 to 8.5 m/s, we draw the following conclusions:

+ Wind velocity for the blades to spin is: type 1: v = 3.4

m/s, type 2: v = 3 m/s

+ With the same wind velocity, type 2 starts faster and

more stable

+ Corresponding to the wind velocity, the torque of

type 2 is the largest

Thus, the manufacturing of type 2 wind turbines is

conformable with the average wind velocity along the coast

of Danang Concurrently, the operation of the blades with

diameter D = 400mm will cause no harm to people around

and be installed or dismounted easily in case of storms

3.2 Designing and Manufacturing Generators

+ The research team selected the type of generator

conformable with the design of Savorius blades, and

carried out the steps of designing, manufacturing and

experimenting, as showwn in Figure 5

+ Actual electrical capacity: Nt = UI, W (2)

The quantities U, I are measured during the time of

generating electricity

3.3 Experiment Results

Savonius turbines using wind energy to generate

electricity are manufactured in the Thermal Workshop of

Danang University of Technology (7) and have been

experimentally installed along Nguyen Tat Thanh Street,

Danang xCity

Table 2: Parameters of designing generator

1

2

3

4

5

6

7

8

9

Diameter of rotor

Diameter of stator

Average potential

difference

Average electric

current

Average rotational

speed

Size of magnetic field

Wavelength of

magnetic field

Diameter of conductor

wire

Average capacity

D1 D2

U

I

n

axbxc

L

d

P

mm

mm

V

A

Revs per min

mm

mm

mm

W

300

300

20

1,2

400

40x60x8

60

0,6

24

Figure 5a Stator of generator

Figure 5b Rotor of generator

Figure 6 Diagram of Savonius wind turbine principle

Figure 7 Savonius turbine N=15W

3.3.1 The Results of Experimental Research

In performing experiments with different wind speeds,

we can measure current intensity and electrical potential difference Based on the formulae of (1) and (2), corresponding to each wind speed value, we can calculate the capacity of blades, the actual electric capacity and the efficiency of wind turbine for generating electricity The experiment results are listed in Table 3

Mach nap

Stator Rotor

Cánh Savonius Bóng đèn Savonius

Accumulator Accumulator

circuit

80 Pham Duy Vu

Table 3 Parameters of experimenting wind turbine for generating electricity

Wind

velocity

v(m/s)

Capacity

of bladesPq (W)

Actual Electrical capacity

Nt (W)

Efficiency

of equipment

tb

Wind velocity

v (m/s)

Capacity

of blades

Pq (W)

Actual Electrical capacity

Nt (W)

Efficiency

of equipment

tb

3.3.2 Comments on the results of experimental research

+ From the results of experimental research, we can

create the graph of the relationship between the potential

difference of equipment and wind velocity, as shown in

Figure 8

Figure 8 Relationship between the efficiency

of equipment and wind velocity

+ Comments:

- When the wind velocity is from 3 - 8.5 m/s, the

efficiency of Savonius turbines for lighting is 2753 %

- Within the velocity from 3,7  5,8 m/s, the turbine

has an efficiency of 40  53 % If the wind velocity

increases, the efficiency does not increase

- When the wind velocity is greater than 7m/s, the

efficiency gradually reduces

Experimenting data show that the type of Savonius

wind turbine which has just been designed, manufactured

and installed is conformable with coastal areas with low

wind speed and the average efficiency of 38%

4 Conclusion

+ Based on the research results of Md Nahidul Islam Khan [5] and results of experimental research above, we see that the choice of two-storey Savonius wind turbine with the height of each storey H = 400 mm, diameter D =

400 mm, is conformable with the wind speed along the coast of Da Nang city (3 to 8.5) m/s

+ Savonius turbines operate with minimum wind speed

of 3m/s

+ The research team has selected the suitable generator for the type of Savonius blades The generated power source to charge batteries for lighting produces an actual capacity of 15W

+ The average efficiency of a Savonius generator

is 38%, corresponding to the wind velocity from 3 to 8,5m/s

+ From the research results, we have reason to carry out further research on the application of wind energy to lighting along the coast of Danang City

REFERENCES

[1] Lê Quang Nam, “Tiềm năng các nguồn năng lượng tái tạo tại thành

phố Đà Nẵng”, Tạp chí Khoa học và công nghệ, Đại học Đà Nẵng,

số 9(58), 2012, quyển II, từ trang 25 đến trang 32

[2] Nguyễn Hồng Thanh, Thiết kế máy điện, Nhà xuất bản khoa học và

kỹ thuật Hà Nội, 2006

[3] Peter Werner, Năng lượng gió và ứng dụng chương trình đào tạo

hợp tác quốc tế Việt Nam - CHLB Đức về Năng Lượng Gió, ĐHBK

Đà Nẵng 16-20/11 năm 2009

[4] Wind Energy Resource Atlas Of Southeast Asia, The World Bank

Asia Alternative Energy Program - True Wind Solution, LLC

Albany Newyork, September 2001

[5] Md Nahidul Islam Khan, M Tariq Iqbal, Michael Hinchey, and

Vlastimil Masek - Memorial University, Performance of savonius

rotor as a water current, St John’s, Newfoundland, Canada: turbine

2009

(The Board of Editors received the paper on 20/05/2014, its review was completed on 24/06/2014)

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