ABSTRACT
A wind rotor system to power a rotary air compressor of maximum discharge pressure of 3.53
barg, a free air delivery (FAD) of 0.001179 m3/s at maximum pressure, and a nominal power
requirement of 130W was designed, constructed and tested.
The wind air compressor system included a wind rotor, a transmission mechanism, an air
compressor and a storage reservoir.
The wind rotor was coupled to a selected air compressor and tested at Ahmadu Bello
University, Zaria, Kaduna State, Nigeria.
The compressor discharge pressure and flow rate increased with an increase in the wind
velocity. A discharge pressure of 1.0barg was obtained during the testing period at the rated
wind velocity of 5.10 m/s. A maximum compressor capacity of 0.000833 m3/s at a discharge
pressure of 2.0 barg and a wind velocity of 7.90 m/s was obtained.
At the rated wind velocity of 5.10 m/s, the power output was calculated as 98.56 W.
The overall efficiency increased as the wind velocity increased until it reached a maximum of
27.6 % and then started to decrease gradually thereafter to a minimum of 7.6 %.The actual
efficiency of the system was found to be 24.2% at the rated wind velocity of 5.10m/s
compared to the design efficiency of the system of 35 %.
The installed capital costs for the 130W wind air compressor was N61,150.00.
TABLE OF CONTENTS
Title Page……………………………………………………………………………………….i
Declaration……………………………………………………………………………………………………………. ii
Certification …………………………………………………………………………………………………………. iii
Acknowledgements ……………………………………………………………………………………………….. iv
Table of Contents …………………………………………………………………………………………………… v
List of Tables ……………………………………………………………………………………………………….. ix
List of Appendices ………………………………………………………………………………………………… xi
Nomenclature ……………………………………………………………………………………………………… xiv
CHAPTER ONE ……………………………………………………………………………………………………. 1
INTRODUCTION …………………………………………………………………………………………………. 1
1.1 Background ………………………………………………………………………………………………….. 1
1.2 Statement of the Problem ………………………………………………………………………………… 2
1.3 The Present Work ………………………………………………………………………………………….. 3
1.4 Aim and Objectives ……………………………………………………………………………………….. 4
1.5 Significance of Work ……………………………………………………………………………………… 4
CHAPTER TWO …………………………………………………………………………………………………… 6
LITERATURE REVIEW ………………………………………………………………………………………… 6
2.1 Wind and Wind Energy ……………………………………………………………………………………… 6
2.1.1 The History of Wind Energy …………………………………………………………………………. 7
2.2 Review of Related Past Work ……………………………………………………………………………. 10
2.3 Theoretical background ……………………………………………………………………………………. 12
2.3.1 Available wind power ………………………………………………………………………………… 12
2.3.2 Extractable wind power ……………………………………………………………………………… 13
2.3.3 Compressor power …………………………………………………………………………………….. 14
2.4 Wind Air Compressor System Description ………………………………………………………….. 16
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2.4.1 The wind rotor ………………………………………………………………………………………….. 16
2.4.1.1 Rotor design ………………………………………………………………………………………. 17
2.4.1.2 Material Selection ……………………………………………………………………………….. 26
2.4.2 Shaft Design …………………………………………………………………………………………….. 29
2.4.2.2 Belt and Pulley design………………………………………………………………………….. 30
2.4.2.3 Bearings…………………………………………………………………………………………….. 33
2.4.3 Compressors …………………………………………………………………………………………….. 37
2.4.3.1 Air compressor …………………………………………………………………………………… 37
2.4.3.2 Positive Displacement Compressors ……………………………………………………….. 39
2.4.3.3 Non-positive Displacement Compressors ………………………………………………… 43
2.4.3.4 Selection of Compressor Type ………………………………………………………………. 47
2.5 Pressure Vessels ……………………………………………………………………………………………… 53
CHAPTER THREE ………………………………………………………………………………………………. 54
MATERIALS AND METHODS …………………………………………………………………………….. 54
3.1 The Wind Compressor System ………………………………………………………………………….. 54
3.2 Materials ……………………………………………………………………………………………………….. 55
3.2.1 Material Selection ……………………………………………………………………………………… 55
3.2.2 Wind Speed Data ………………………………………………………………………………………. 57
3.3 Design Theories ……………………………………………………………………………………………… 57
3.3.1.0 Rotor Design …………………………………………………………………………………………. 57
3.3.1.1 Rotor swept Area ………………………………………………………………………………… 57
3.3.1.2 Compressor Power ………………………………………………………………………………. 58
3.4 Design Analysis ……………………………………………………………………………………………… 59
3.4.1 Compressor Selection Considerations …………………………………………………………… 59
3.4.2 Shaft design ……………………………………………………………………………………………… 60
3.4.3 Bearing selection ………………………………………………………………………………………. 61
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3.4.4 Tail vane design………………………………………………………………………………………… 61
3.4.5 Design Considerations ……………………………………………………………………………….. 61
3.5 Design Calculations …………………………………………………………………………………………. 63
3.6 The Wind compressor system design ………………………………………………………………….. 74
3.6.1 Design calculations ……………………………………………………………………………………. 74
3.6.2 Design drawings ……………………………………………………………………………………….. 74
3.7 System Component Construction ……………………………………………………………………….. 75
3.7.1 Rotor Blades …………………………………………………………………………………………….. 75
3.7.2 Rotor Hub ………………………………………………………………………………………………… 75
3.7.3 Rotor Shaft ………………………………………………………………………………………………. 75
3.7.4 Bearings ………………………………………………………………………………………………….. 75
3.7.5 Belt and Pulley …………………………………………………………………………………………. 76
3.7.6 Mounting Plate …………………………………………………………………………………………. 76
3.7.7 Tail vane………………………………………………………………………………………………….. 76
3.7.8 Tower ……………………………………………………………………………………………………… 76
3.8 Cost Evaluation ………………………………………………………………………………………………. 76
3.9 Installing and testing the system ………………………………………………………………………… 78
3.9.1 Testing Set up …………………………………………………………………………………………… 78
3.9.2 Testing Procedure ……………………………………………………………………………………… 79
3.10 Calculations………………………………………………………………………………………………….. 79
3.10.1 Energy Pattern factor determination for Zaria ………………………………………………. 79
3.10.2 Power Output and Overall efficiency determination for wind air compressor …….. 81
CHAPTER FOUR ………………………………………………………………………………………………… 84
RESULTS AND DISCUSSIONS ……………………………………………………………………………. 84
4.1 Test results and discussions ………………………………………………………………………………. 84
4.1.1 Results ……………………………………………………………………………………………………….. 84
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4.1.2 Discussion of results ……………………………………………………………………………………… 90
CHAPTER FIVE …………………………………………………………………………………………………. 92
SUMMARY, CONCLUSIONS, LIMITATIONS AND RECOMMENDATIONS …………… 92
5.1 Summary ……………………………………………………………………………………………………….. 92
5.2 Conclusions ……………………………………………………………………………………………………. 92
5.3 Recommendations …………………………………………………………………………………………… 93
5.4 Contributions to knowledge ………………………………………………………………………………. 93
REFERENCES ……………………………………………………………………………………………………. 94
APPENDIX A ……………………………………………………………………………………………………… 97
APPENDIX B ……………………………………………………………………………………………………… 98
APPENDIX C ……………………………………………………………………………………………………… 99
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CHAPTER ONE
INTRODUCTION
1.1 Background
Nigeria, a developing nation of 140 million (2006 census) with a growth rate of 3.20 %
(Energy Commission of Nigeria, 2013), has an installed production capacity of about 6,000
MW of power as at 2009 (Sambo, 2009). In 2012, the installed production capacity stood at
9,955.4 MW with an average availability of 5, 516.38MW (Energy Commission of Nigeria,
2013). The estimated daily power generation as at December, 2009 was about 3,700MW
while the peak load forecast for the same period was 5,103 MW, based on existing
connections to the grid (Nigeria Vision 20-2020, 2010). The Business day Newspaper of 21st
July, 2009 reported that manufacturers alone require about 2,000MW to power their factories,
based on installed capacities as at 2009. The power requirements of the nation have been
projected at 28,360MW by 2015 at a modest economic growth of 7% (Sambo, 2009). There
is, therefore, a need to bridge this energy gap.
“Fossil” fuel driven machines are used all over the country to augment supply to meet these
power requirements. The Energy Commission of Nigeria estimated that fuel driven machines
provide about 42% of the power needs of the country between the year 2000 and 2004
(Sambo, 2008). The Nigerian Tribune Newspaper of 21st August, 2009 estimated a daily
diesel consumption of 13 million litres. The Vanguard of October, 2010 reported that the
Central Bank of Nigeria (CBN) estimated that about $13bn (N1.989trillion) per annum is
expended on diesel for power generation. The use of fossil fuels adds to the carbon emissions
in the world with their devastating effect such as global warming and acid rain to mention a
few. It is an established fact that fossil fuels are an irreversible source of energy and their
supply is depleting. In fact, the continued unrest in the Middle East creates an oil shortfall
around the world. From February to April, 2011, crude oil prices have surpassed $120/bbl
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with oil prices reaching the $5 mark in the United States. Oil demand increase is expected to
be about 40% over the next 20 years. Oil supply increase in the world is not likely to be 50%
over the next 30 years (Cambridge Energy Research Associate(CERA), 2011). There is,
therefore, a need for reliable, available systems to power light commercial applications such
as production of compressed air for pressurizing tyres, powering pneumatic tools for paint
spraying, drilling, etc.
The wind pump, used for centuries to lift water, but largely abandoned after the introduction
of engine-driven pumps (generally fuelled by diesel or kerosene) and electric pumps, is now
being reconsidered as one of several alternative technologies that can be used for these light
applications. The classic multi bladed windmill that was a familiar sight in the Great Plains of
the US until the 1940s is still being manufactured today. However, engineers have recently
begun to make improvements to the design of these pumps, and adapt them for use in
developing countries specifically for water lifting.
Automotive industries in Nigeria on the average pressurise one and a half million tyres each
year based on registered cars in Nigeria as provided by the Federal Road safety Corps in its
2013 annual report. This is currently achieved using air compressors mostly powered by
fossil fuel fired generators. Typical cost for the purchase of the fuel is inhibitive especially
with the partial removal of subsidy by the government in December, 2013.. The fuel
unavailability in Nigeria is also an inhibiting factor.
In view of the above, the use of renewable energy sources such as wind, solar, biomass, etc to
produce “clean” and sustainable energy for domestic uses is considered timely and necessary.
1.2 Statement of the Problem
Hundreds of vulcanisers litter the Nigerian streets today with car air condition compressors
converted to air compressors for car tyre pressurising. These compressors are mostly powered
by 3 hp engines powered by fossil fuels. A walk around revealed about 20 of these 3 hp
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engines in use in surrounding environs (about a geographical area of 4km2) of Ahmadu Bello
University, Zaria main campus of Samaru. It is clear that these vulcanisers do not have any
other source of energy apart from these engines. Each of these engines requires about 6 litres
of petrol. The green house emission is estimated at about 300 kg of CO2 gas per day (1litre of
petrol produces about 2.3 kg of CO2 when burnt) (Lawrence and Thomas, 2011). This is
besides the noise emission as well as the economic drain on the country for this domestic use
of a “highly” subsidised resource. It is also worthy of note that majority of these vulcanisers
cannot even afford these fossil fuel fired compressors.
Equally, other heavy users of compressed air such as car service stations, car assembly
factories such as Peugeot Automobile Nigeria (PAN), furniture factories, etc. produce their
own enormous quarter of emissions from their fossil fuel powered compressors.
In summary, the present scenario leads to a huge greenhouse gas emission with its
devastating effect, noise pollution, and “wastage” of a “highly” subsidized resource.
1.3 The Present Work
Past Works on wind energy utilization reviewed, that involved the use of Compressed air,
concentrated on its use as an energy storage medium in an electric power supply grid.
Most of the reviewed works focus on the production of electricity from the wind, which is
then converted to mechanical power for air compression using an electric air compressor.
Also none of the works reviewed have used wind energy for air compression for day to day
uses to the best of my knowledge.
This work utilised the wind as an energy source to produce “clean” compressed air. The
produced compressed air was then stored in reservoirs for sale in “units” of compressed air to
various users. The design was for operation in Zaria, Kaduna state.
The focus was on direct conversion of wind energy to mechanical power in the shaft of an air
compressor. The losses associated with the conversion first to electric power and then to
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mechanical power were avoided. The costs of electrical components necessary for conversion
to electric power were also eliminated.
1.4 Aim and Objectives
The aim of this work is to design, construct and test a wind air compression system of 130 W
for the purpose of producing compressed air of 3.45 barg in Zaria, Kaduna State.
The specific objectives are:
i. to carry out a design analysis for the wind rotor and a suitable transmission system for
the wind compressor system.
ii. to select appropriate materials for the wind compressor system.
iii. to construct and/or procure the components of the system.
iv. to evaluate the performance of the system.
v. to estimate the cost of a prototype of the system.
1.5 Significance of Work
The use of wind power as a replacement for fossil fuels would make Nigeria’s energy use
greener which would reduce our carbon emissions. This would substantially reduce Nigeria’s
contribution to global warming.
The burning of fossils fuels also results in the formation of sulphur and nitrogen oxides which
are released. These compounds combine with atmospheric moisture to form acids, leading to
‘acid rain’. This can lead to destruction of forests and the progressive erosion of rock and
masonry structures, both natural and man-made. The use of wind energy as an alternative
helps reduce this impact.
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This work would reduce noise pollution in the Nigerian society.
It would help to increase Nigeria’s industrial output.
It would serve as a source of income for the “compressed air from wind” investors.
It would free the scarce resource of local vulcanisers for more profitable use helping with the
governments’ poverty reduction program.
The work will reduce domestic use of fossil fuels (a highly subsidised resource in Nigeria)
for compressed air production, allowing its use for more pertinent purposes like power
production in remote locations for medical purposes example.
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