CONCEPTUAL DESIGN OF MINI WIND TURBINE FOR HOUSEHOLD APPLICATION

CHOW JIA LE

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

i

ABSTRACT

Wind turbine is a device that using the renewable energy to produce electrical power. It converts the wind energy to become electricity by rotating the rotor blade. In international or domestic market, small size wind turbines normally have their market value which can produce electricity for household application. Hence, the purpose of this project is to design a mini size wind turbine which able to use it for household application. Through this project, case study on current trend of small size wind turbine is carried on. Three conceptual design of mini size wind turbine are proposed with power generation analysis using CFD software. Material selection and Finite Element analysis are conducted to determine the best material for it. Cost estimation and weight calculation are done to determine the feasibility of making the designed product.

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ABSTRAK

Turbin angin adalah alat yang menggunakan tenaga boleh diperbaharui untuk

menghasilkan kuasa elektrik. Ia menukarkan tenaga angin untuk menjadi tenaga elektrik

oleh putaran bilah pemutar. Dalam pasaran antarabangsa atau domestik, turbin angin saiz

kecil biasanya mempunyai nilai pasaran mereka yang boleh menghasilkan tenaga elektrik

untuk permohonan rumah. Oleh itu , tujuan projek ini adalah untuk membentuk turbin angin

saiz mini yang dapat menggunakannya untuk aplikasi rumah. Bersama-sama projek ini,

kajian kes kepada trend semasa turbin angin kecil saiz dijalankan. Tiga reka bentuk konsep

turbin angin saiz mini dicadangkan dengan analisis penjanaan kuasa menggunakan perisian

CFD. Pemilihan bahan dan FEA analisi dijalankan untuk memilih bahan yang terbaik untuk

itu. Anggaran kos dan pengiraan berat juga dijalankan untuk menentukan kemungkinan

membuat produk yang direka.

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ACKNOWLEDGEMENT

First of all, I would like to thank my supervisor, Dr Tee Boon Tuan, who had given me advices, guidance, and strong support to help me in completing my project. He has assisted me in using CFD software for my project analysis. Besides, he has given good advices and solution when I was facing problem when completing this project. I would like to thank to my parents for their lovely support and encouragement throughout the process to complete this project. I would also thank to my beloved friend, course mates, housemates and lecturers who help me in completing this project. Finally, my acknowledgement to those people who directly or indirectly assist and help me in finishing this project.

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CONTENT

CHAPTER CONTENT

PAGE

DECLARATION

ABSTRACT i

ABSTACK ii

ACKNOWLEDGEMENT iii

TABLE OF CONTENT iv

LIST OF TABLES viii

LIST OF FIGURES ix

LIST OF SYMBOLS xiii

LIST OF ABBREVIATIONS xiv

CHAPTER 1 INTRODUCTION

1.1 Background 1

1.2 Problem Statement 2

1.3 Objective 3

1.4 Scope Of Project 3

CHAPTER 2 LITERATURE REVIEW

2.1 Overview 4

2.2 Brief History of Wind Turbine 4

2.3 Wind Turbine 6

2.3.1 Types of Wind Turbine 6

2.3.2 Horizontal Axis Wind Turbine (HAWT) 6

2.3.3 Vertical axis wind turbine (VAWT) 7

2.3.4 HAWT VS VAWT 8

2.3.5 Small Scale Wind Turbine 9

v

2.4 Lift and Drag Force 9

2.5 Components of Wind Turbine 10

2.5.1 Blades 10

2.5.2 Number of Blades 11

2.5.3 Airfoil 11

2.5.4 Untwisted and Twisted Blade 11

2.6 Betz Limit 12

2.7 Energy in the Wind 13

2.7.1 Power Available in the Wind 14

2.7.2 Tip Speed Ratio 14

2.8 Comparative Analysis of Small-Scale Wind Turbine

Design For The Low Rate Wind Speed

16

2.9 Design and Development of Horizontal Small

Wind Turbine Blade for Low Wind Speeds

20

2.10 Feasibility Study of Micro-Wind Turbines for

Powering Wireless Sensors on a Cable-Stay

Bridge.

24

2.11 Summary and Comparison of Study 28

CHAPTER 3 METHODOLOGY

3.1 Overview 29

3.2 Flow Chart 29

3.3 Parameter Study 30

3.3.1 Blade Performance Initial Estimation

3.2.2 Sizing of Blades

3.3.3 Number of Blades

3.3.4 Airfoil Selection

3.3.5 Wind Behaviour

31

31

32

32

32

3.4 Concept Generation

3.4.1 Morphology Chart

3.4.2 Conceptual Design

32

32

33

3.5 SOLIDWORK 33

3.6 Computational Fluid Dynamic (CFD) Simulation 33

vi

3.7 Material Selection Procedure 34

3.8 Finite Element Analysis (FEA) 35

3.9 Detail Design 35

CHAPTER 4 CONCEPTUAL DESIGN AND ANALYSIS

4.1 Introduction 36

4.2 Concept Generation

4.2.1 Construction of Morphological Chart

4.2.2 3D Modelling Conceptual Design

4.2.3 Weight Decision Matrix

36

36

37

39

4.3 Analysis and Simulation

4.3.1 3D Wind Turbine Simulation among

Different Design

4.3.2 Analysis on Design A

4.3.3 Analysis on Design B

4.3.4 Analysis on Design C

41

41

44

46

48

4.4 Material Selection of Wind Turbine Blade 50

4.5 Finite Element Analysis (FEA) Among Different

Material

53

4.6 Detail Design of Product 57

4.7 Cost Estimation of Product

4.7.1 Hub

4.7.2 Rotor Blade

4.7.3 Nacelle

4.7.4 Generator

4.7.5 Bearing

4.7.6 Wind Vane

4.7.7 Shaft

4.7.8 Total weight and material cost estimation

58

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63

4.8 Discussion 64

CHAPTER 5 5.0 Conclusion and Recommendation 65

vii

REFERENCE 67

APPENDIX 70

viii

LIST OF TABLES

TABLE TITLE PAGE

2.1 Summary and Comparison of Study 28

4.1 Basic parameter of wind turbine rotor 37

4.2 Weight decision matrix for three design 40

4.3 Evaluation Schema for Designing Alternatives or Objectives 40

4.4 Computational conditions of 3D simulation 42

4.5 Torque analysis of conceptual design 43

4.6 The mechanical properties and criteria of wind turbine blade 50

4.7 The comparison of different materials for rotor blade 52

4.8 The Material properties of polypropylene (PP 30% long glass

fiber)

54

4.9 The material properties of aluminium 55

4.10 The material properties of HS carbon fiber 56

4.11 The general properties of material used for hub 58

4.12 The general properties of material used for rotor blade 59

4.13 The general properties of material used for rotor blade 60

4.14 The total weight and cost of product 63

ix

LIST OF FIGURES

FIGURE TITLE PAGE

2.1(a) The concept of windmill-like device that described by Heron

the Alexandria in his Pneumatica (a) The horizontal like

windmill drive disk and raise pinton in an air pump (Spera,D,

2009)

5

2.1(b) The concept of windmill-like device that described by Heron

the Alexandria in his Pneumatica (b) The vertical like windmill

rotor. (Spera,D, 2009)

5

2.2 The upwind and downwind turbine with wind direction. Source:

(google image)

7

2.3 The Savonius (left) and Darrieus (right) rotor wind turbine.

Source: (google image)

7

2.4 Lift and drag force (Cengel,2010) 9

2.5 The twisted airfoil (upper) and untwisted airfoil (below)

(Hsiao,al. etc 2013)

12

2.6 Tip speed ratio against the power coefficient with different WT

Available from (Hau,2006)

13

2.7 The tip speed ratio consideration (Peter J, 2012) 15

2.8 Specification of prototype (Ali Musyafa, 2012) 16

2.9 The recorded data through the testing(Ali Musyafa, 2012) 17

x

2.10 Pitch angle against rotational speed per minute (RPM) with

prototype testing. (Ali Musyafa, 2012)

18

2.11 Wind speed against power coefficient with prototype testing

(Ali Musyafa, 2012)

18

2.12 Tip speed ratio against power coefficient (Ali Musyafa, 2012) 19

2.13 Cl/Cd against angle of attack (AOA) among different airfoil

(Navin, 2014)

21

2.14 The modification of NACA 4115(Navin, 2014) 21

2.15 Cl/Cd against angle of attack (AOA) with NACA 4415 and

modified airfoil (Navin, 2014)

22

2.16 Cl/Cd against angle of attack (AOA) with all tested airfoil

(Navin, 2014)

22

2.17 Average wind speed (left) and wind rose diagram (right) (Park,

2012)

24

2.18 The tabulated data of total power consumption wireless

remote(Park, 2012)

25

2.19 The micro scale wind turbine tested in wind tunnel (Park, 2012) 25

2.20 The power output of different number of blades(Park, 2012) 26

2.21 The power output with different wind speed(Park, 2012) 26

3.1 Flow chart of methodology 30

3.2 Flow chart of material selection 34

4.1 The morphology chart of wind turbine blade design 37

4.2 Horizontal Axis Wind Turbine rotor conceptual design A 38

4.3 Horizontal Axis Wind Turbine rotor conceptual design B 38

4.4 Horizontal Axis Wind Turbine rotor conceptual design C 38

4.5 Weight Decision Matrix of small size wind turbine 39

4.6 Meshing of Design A, B and C 41

xi

4.7 Computational domain of wind turbine simulation 41

4.8 Blade velocity vector of rotor blade design A 44

4.9 The pressure contour on rotor blade design A 44

4.10 The generated torque of blade in Design A 45

4.11 The blade velocity of Design B 46

4.12 The pressure contour front and behind of Design B 46

4.13 The torque generated by Design B 47

4.14 The blade velocity of design C 48

4.15 The pressure contour of design C 48

4.16 The torque generated of design C 49

4.17 The single blade geometry of Design B 53

4.18 The meshing of single blade for FEA testing 53

4.19 FEA test by using polypropylene as material 54

4.20 FEA test by using aluminium as material 55

4.21 FEA test by using HS carbon fiber as material 56

4.22 The detail design of mini size horizontal axis wind turbine 57

4.23 The assembly of mini size wind turbine 57

4.24 The volume and design of hub 58

4.25 The volume and design of rotor blade 59

4.26 The volume and design of rotor blade 60

4.27 The wind turbine generator (Sorce : ebay) 61

4.28 The 30mm internal diameter bearing (Sorce : ebay) 61

xii

4.29 The volume and design of wind vane 62

4.30 The volume and design of shaft 62

xiii

LIST OF SYMBOL

W = Watt

v = volume

V = Velocity

L = Length

𝑝 = density

FD = Drag Force

FL = Lift Force

𝐿𝑓 = Lift coefficient

𝐿𝐷 = Drag coefficient

Pa = Pascal

s = second

Cp = power coefficient

P = Power

A = Area

𝜆 = tip speed ratio

𝜔𝑚 = rotational speed

𝑅 = radius

xiv

LIST OF ABBEREVATIONS

WT Wind Turbine

HWAT Horizontal Axis Wind Turbine

VAWT Vertical Axis Wind Turbine

RE Renewable Energy

MWT Mini Wind Turbine

CFD Computational Fluid Dynamic

DC Direct Current

NACA National Advisory Committee for Aeronautics

FEA Finite Element Analysis

1

CHAPTER 1

INTRODUCTION

1.1 Background

Wind energy is a kind of renewable and sustainable energy that produced by natural

phenomena. The Earth is surrounded by atmospheric air which not only protect us from

ultraviolet solar light but also forming a flowing air motion in the Earth. Wind is formed

when there is a changes in pressure and temperature of air. Thus, the kinetic motion of air

form wind energy which can be changed to other form of energy, either mechanical energy

or electrical energy. The wind power device that used to produce electricity is normally

called as wind turbine.

Generally, wind turbines are classified as two different kinds. A turbine with a shaft

mounted normally to ground is known as vertical axis wind turbine (VAWT) while turbine

mounted horizontally parallel to ground is called as horizontal axis wind turbine (HAWT).

VAWT can be attributed as low tip speed ratio and difficulty in controlling rotor speed, but

it still has the market requirement as it can operate without additional mechanism to face the

wind and generator can be installed on ground. On the other hand, HAWT designs become

the mainstream development because it has better rotor control through pitch and yaw

adjustment. (Schubel, 2012)

Unfortunately, although the wind turbines produce electricity by using clean energy,

but it has its limitation. Large scale wind system plants mostly being built far away from

urban area because they require large area for installation, noise problem and high cost. Thus,

mini wind turbines are starting to be built in the country or house that near to shore area.

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These turbines can operate under low wind speed, producing small amount of electricity

which can provide for small household electrical device. (Kekezoglu, 2015)

1.2 Problem Statement

In recent years, Malaysia’s government has attempted to develop renewable energy

(RE) in order to reduce the consumption of non-renewable energy such as coal, petroleum

or natural gas. Those factories that use coal or petroleum to produce energy will emit lot of

harmful gases such as carbon dioxide, or sulphur dioxide which can affect the environment

and ecosystem. Thus, RE is suggested to use for saving our Earth.

Wind energy is one of the clean and renewable energy that can convert to electricity.

However, the geometrical problem and insufficiency place for installing big wind turbine

lead Malaysia less efficiently using the wind turbine system to get the electricity. Malaysia

is located in lower pressure belt region which facing low wind speed problem causes

investors are not interest in building wind turbine at here. (Belhamadia, 2014) The cost of

installing a big wind turbine is high and required professional technician and engineers to

install it. Thus, mini wind turbine (MWT) for household application is proposed in this

project. MWT is not only smaller in size, but also save cost as less material used and efficient

to product some electricity that may help in small electric devices such as low energy garden

light. Besides, it can promote the concept of green technology which is affordable and

leading to an eco-friendly environment.

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1.3 Objective

The objectives of this project are as follows:

1. To develop and propose a mini wind turbine design that can generate electricity

for household application.

2. To conduct conceptual analysis on the structure and feasibility of mini wind

turbine.

1.4 Scope of Project

The scope of this project are as follows:

1. Study the current designs of mini (small scale) wind turbine along with the market

requirement.

2. Design mini size horizontal axis wind turbines using SOLIDWORK software.

3. Simulation of wind turbine component using Computational Fluid Dynamic

analysis (CFD) and Finite element analysis (FEA).

4. Compare and propose the best conceptual design of mini wind turbine.

4

CHAPTER 2

LITERATURE REVIEW

Literature review is focused on the previous study on the mini wind turbine to obtain

knowledge and information present study. In this chapter, journals and articles that related

with designing mini wind turbine are reviewed. Different parameters in designing wind

turbine such betz limit, tip speed ratio, power generated are discussed in it.

2.2 Brief History of Wind Turbine

Before the invention of electrical power, the wind turbine actually is modified from

windmill. Windmill is a mechanical system device that convert kinetic energy from wind to

mechanical kinematic energy with rotational motion. There are a lot of discussion or

argument for the true inventor of windmill, but the most ancient manuscript that related with

the windmill was Heron of Alexandria as one in his Pneumatica idea of 2000 years ago.

According to the description in Pneumatica as “ the construction of an organ which when

the wind blows the sound of a flute shall be proceed.” After that, Woodcroft [1851] and

Schmidt [1899] used their creativity and imagination based on the description of Horn to

draw the system which shown in Figure 2.1(a) and 2.1(b). ( David A, Spera,2009)

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Figure 2.1 : The concept of windmill-like device that described by Heron the Alexandria in

his Pneumatica (a) The horizontal like windmill drive disk and raise pinton in an air pump

(b) The vertical like windmill rotor. (Spera,D, 2009)

There are different types of windmill existed in the whole world. The first recorded

windmill was found in Sistan, an Eastern part of Persia on the tenth century. This is

documented by trusted writer with supported ancient drawings that correspond to the

remaining of old mills and to modern use. The recorded windmill was like vertical axis type

which put the millstone below the rotor and grind reeds.

The first horizontal axis windmill existed in Europe during the Middle Ages. ( Spera,

D,2009) Then, the German crusaders bring their windmill’s making skill to Syria around

1190 according to the reports. (Monthorst, 2002) This skill immigration lead the windmill

technologies are spreading to the world.

After few years of evolutions, the wind turbines with generator were invented. At the

19th century, the DC electrical energy is just beginning to use, thus only direct current

available. The inventor and builder, Charles F. Brush built a windmill with 12 kW of DC

power for charging storage batteries in year 1888.(Spera, D,2009) This invention lead the

initial step in developing the wind turbine with installation of electrical generator. After this,

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different size and kind of wind turbines been developed and modified until becoming those

modern type of wind turbine that using now in this 21th century.

2.3 Wind Turbine

2.3.1 Types of Wind Turbine

Wind turbines come in different designs with varying output and efficiencies but all

of them are converting kinetic energy from wind to mechanical or electrical energy. There

are several types of modern wind turbines operating in this world. Basically, the wind

turbines are classified as two major type which are horizontal axis wind turbine (HAWT)

and vertical axis wind turbine (VAWT).

2.3.2 Horizontal Axis Wind Turbine (HAWT)

Horizontal Axis Wind Turbine (HAWT) is a turbine that the rotational axis of have

to be oriented parallel to the wind to produce power. It can be single or many blades but 2

or 3 blades are common used and most efficient. The peak efficiency of HAWT with 3 blades

is high which about 50% efficiency, leading it become wind turbine industry mainstream

product. (Hau, 2006) The HAWT can be determined as two types which are upwind turbine

and downwind turbine. The rotor of upwind turbines is in the front of the unit, with same

position with the propeller driven airplane. A tail installed at the behind the WT as yaw

mechanism become one of the characteristic of it. While the rotor of downwind turbine is

located at the back side of turbine. The nacelle with electric generator is designed for find

the wind direction, so the yaw system is neglected. The wind direction go through the upwind

turbine and downwind turbine can be seen from Figure 2.2. (Power-talk.net, 2010)

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Figure 2.2: The upwind and downwind turbine with wind direction. Source:

(google image)

2.3.3 Vertical Axis Wind Turbine (VAWT)

Vertical axis wind turbine (VAWT) is the turbine that the rotational axis is

perpendicular to the wind direction. The generator is set up on ground become one of the

advantages of it because climbing to high position is not necessary when maintaining the

electric generator. It does not required yaw system. Wind speeds available are lower as its

proximity to ground. (Javier Castillo, 2011) There are many kinds of VAWT such as

Savonius and Darrieus or giromill. Savonius rotor is drag type VAWT while Darrieus rotor

is life type VAWT. Figure 2.3 shows the different designed of modern VAWT that are being

used now.

Figure 2.3: The Savonius (left) and Darrieus (right) rotor wind turbine

(google image)

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2.3.4 HAWT VS VAWT

Horizontal axis wind turbine (HAWT) dominates the majorities of the wind industry.

According to Hau (2006), more electricity can be generated compare with VAWT with given

same amount of wind. It points into the wind direction to produce electrical power, enabling

them to simplify their design and eliminate the difficulties caused by the gyroscopic on the

rotor of a conventional machine when tracking the wind. The designing of removable adjust

angle of attack in HAWT cause them to maximize the wind power energy generated. Besides,

the cost of HAWT is cheaper in price compare to VAWT because it is higher production

volume which HAWT is the major trend in market demand of whole world. Although there

are many advantages, but according to research of Ozgener (2007), he proves that the HAWT

is hard to start near ground area. It should have installed on high ground to operate at high

efficiency. The tall tower and long blades are difficult in transportation from one place to

another due to it is required specific installation procedure.

On the other hand, the vertical axis wind turbine (VAWT) have better receiving

effect compare with HAWT due to the direction of inertial force and stable gravity, that

according from the studies done from Tabassum and Probert (1987). Thus, the blades can

receive fixed load and fatigue longevity is longer than HAWT. According to Kalantar and

Mousavi (2010), the electrical components such as electric generator are installed near on

ground, this make it easier path to repair or maintenance. This type of turbine does not

required pointed into the wind or strong wind because it can operate under slow wind speed.

But there are also have some disadvantages of VAWT. Most of the turbines are only half

efficient as HAWT due to effect of dragging force. The airflow near the ground and other

objects will create a turbulent flow which lead vibration of whole wind turbine.

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2.3.5 Small Scale Wind Turbine

Basically, small scale wind turbines are used in housing area to generate some

electricity for supplying the household application, and it is installed on the roof of building

or urban area. Thus, the size of it should be small. As example, for the small size of HAWT,

it can be categorized as micro (1 kW), mid-range (5 kW) and mini wind turbine (20 kW). Its

swept area should not more than 200 m2, which mean the radius of blades are not more than

8m according to the International Electro technical Commission (IEC) 61400-2. (IEC, 2006)

2.4 Lift and Drag Force

Lift and drag force are important in designing the airfoil of wind turbine. The force

that exerts by the flowing fluid is called drag. Drag force actually is the combination force

of pressure and wall shear forces in the flow direction. The component of pressure and wall

shear forces normal to the flow that tend to move the body direction is called lift force as

shown in Figure 2.4. (Cengel, 2006). The lift force is used to overcome gravity in

aerodynamic, and higher lift force will lift the heavier mass.

Figure 2.4: Lift and drag force (Cengel,2010)

Besides, lift and drag force coefficient are useful in determining the performance of

airfoil. The equations are defined as :

Lift coefficient: 𝐿𝑓 = 𝐹𝐿

1/2𝑝𝑉2𝑐 (2.1)

Drag coefficient: 𝐿𝐷 = 𝐹𝐷

1/2𝑝𝑉2𝑐 (2.2)