1 1. Introduction Our world as we know it is faced with a major energy problem. In order to enjoy Our world as we know it is faced with a major energy problem. We all enjoy technology and the modern innovations on a day to day basis. Cellular phones, laptops and even basic necessities such as the stove, kettle and geyser are innovations which require electricity.Electricity production in South Africa was not an area of concern during the apartheid era. Focus and attention was only given to the superior race of the time and all others were ignored. The government ensured that white people of the country had their needs taken care of and were living a comfortable lifestyle. This included the constant supply of running water, electricity and easy access to their places of interest.However whilst all attention was given to the superior race, the majority of the country were suffering from discrimination as well as lacked basic necessities. Besides clean running water, they were placed in the furthermost parts of the country which were isolated areas.The government was satisfied with this organization of inhabitants of the country and as long as the superiors had a constant supply of electricity there was little concern for anyone else. Power generation was through coal power stations and the supply exceeded the demand therefore there was little concern towards the future of power generation in South Africa. After the Apartheid era, privileges due to race were abandoned and all South Africans were given an equal opportunity. This meant that the majority of the country which was previously placed in rural areas became urbanized. The need for electricity had started to escalate.In order to accommodate this increase in demand, more coal, an indigenous resource was used and slowly more power stations were being built. By early 2008, South Africa had become a strong economically developing country, with rapid industrialisation.This led to the demand exceeding supply.The leading power generation company in South Africa, Eskom, had embarked on a massive programme to upgrade the countrys electricity infrastructure.A R343-billion five year project to start up two new coal powered stations was the major part of Eskoms project.A nuclear power plant was also on the agenda however, funding from overseas was required. There were also plans of a hydro scheme in the Drakensberg, Kwa-Zulu Natal and re-opening of two open-cycle gas turbines. Energy provides about 15% to the countrys gross domestic product (GDP). Eskom is one of the worlds biggest electricity generators, and provides approximately 95%of South Africas power. The national grid is about 27000 kilometers of power lines. 2 We are privileged to have in this day and age, many innovations however we have used up many of our resources without thought towards the future. The exploitation of non-renewable resources, such as fossil fuels, has proved to be detrimental to the quality of our planet. The consequence thereof is global warming, which is proved by melting of the polar ice caps and the variation in temperature patterns. Many have predicted the end of the world within the next decade due to the excessive use of precious resources and no sense of gratitude or appreciation. We have become greedy for development and improvement in the current technology so much so, we have failed to take care of our resources. Therefore, it is vital that we find ways and means of continually producing the required energy whilst keeping in mind the needs of future generations. According to Creamer Medias Engineering News on 5 April 2012, the power consumption increased by 1.8% in February from a year earlier. However, the production only increased by 0.5%. in January 2012, electricity consumption was 19 676GWh.Eskom contributes 19 410GWh of the 20 292GWh of electricity produced in a month in South Africa. These statistics were provided by Stats SA in this article. Since South Africa is currently facing a major energy crisis and our demand is exceeding the supply, we have experienced load shedding throughout the country and have become liable to an increase in the cost of utility bills.Other methods of trying to decrease the supply have been implemented such as electricity warnings displayed on local television channels. This particular method is effective because most people are at home in the evenings and television has become an integral part of daily life.Winter demands an increased supply of electricity due to heaters and warming elements being constantly used. This causes the demand for electricity to fluctuate according to the needs of the community. Necessities such as street lamps use a lot of power during the evenings and have to be constantly supplied throughout the year. The energy crisis forces us to start taking responsibility of our actions when using resources, therefore a demand for renewable resources.

The use of nuclear power plants is an existing design and is being implemented in South Africa. However, it poses an extreme health risk if failure occurs. This has recently occurred in Tokyo,Japan.After the Fukushima disaster where a tsunami followed an earthquake and disabled the power supply. All three cores of the nuclear power plant were largely melted and therefore high radioactive releases.Japan used nuclear power since 1970 and it contributed 30%to the annual power generation in the country.This disaster has therefore caused an expected shortage of electricity in the near future. Synthetic fuels, oils and gas have been provided by South Africa leading company on the JSE stock Market, Sasol.Sasol has a plant in Secunda, Mpumalanga where it coverts gas to more environmentally friendly liquids. 3 The planet provides many natural phenomena and it is important that we utilize these existing forms of resources. Such phenomena are wave power, solar and wind energy. Whilst many methods and designs have been made in respect to these phenomena, it is also possible to improve on modern innovations to provide suitable amount of power.We are consistently improving technology and it has become important to keep the environment and power usage in mind. The planet requires responsible inhabitants presently and in future generations. Renewable energy is the solution to the energy crisis and will have a positive impact in the future. According to Creamer Medias Engineering News on 5 April 2012, the power consumption increased by 1.8% in February from a year earlier. However, the production only increased by 0.5%. in January 2012, electricity consumption was 19 676GWh.Eskom contributes 19 410GWh of the 20 292GWh of electricity produced in a month in South Africa. These statistics were provided by Stats SA in this article. Ref: www.enginneringnews.co.za/article/february-power-consumption www.world-nuclear.org/info/fukushima_accident_inf129.htmlwww.southafrica.info/business/economy/infrastructure/energy.htm#plan 4 1.1Speed Bumps Speed bumps have the connotation of coffee spills and thus discomfort to a journey, but we would like to change this in a positive manner. Besides slowing down a vehicle, we aim to use the weight of the car as it passes the speed bump to generate electricity. For this, we have chosen to use a hydraulic system whereby the force generated from the weight of the car will cause a piston to be pushed down and thus fluid flow towards a hydraulic motor which will allow the production of electricity once coupled to a generator. We have chosen this method as it is reliable, does not require a lot of maintenance and the fluid is incompressible.Speed bumps are operational throughout South Africa and implementing a system to generate electricity within a speed bump will be resourceful and very effective. The electricity generated could be used to power up street lamps and nearby facilities. The system will allow a decrease in the power required from the national grid, and if it is implemented around the country a significant amount of electricity demanded will be adhered to. 1.2Traffic Tunnels Traffic tunnels see a large amount of vehicles passing through it every day. These vehicles displace large amount of wind as they pass through the air traveling at speeds of around 45km/h to 120km/h. All this wind energy that is been created by the passing vehicle is simply getting lost.The conceptual design that is in the report is an idea to capture the wind that passing vehicles are displacing and convert it to mechanical energy and then into electrical energy to power tunnels,lights, extractor fan and traffic signs etc. The conceptual design uses a vertical turbine as it is more compact and has a lower starting speed than the everyday horizontal wind turbine. The reason we went with a drag vertical turbine, is that it required less space for operation and can be implanted into current traffic tunnels or knew tunnels can be designed around the idea of having these vertical turbine running down the side of the wall. RENEWABLE POWER GENERATIONSPEED BUMPS TRAFFIC TUNNELS HYDRAULIC SYSTEM WIND TURBINE 5 2. Literature review 2.1Speed Bumps The project required a lot of research and self study. Research was the first step in the design process because it was vital to read up on existing designs and to appreciate the ideas of others. Research enabled us to find ideas and basic designs which already existed. Each design used the basic concept of converting kinetic energy into electrical energy. These designs included the use of a pneumatic system due to its simplicity and relatively safe working pressures. However, components could be damaged due to contamination of the air in a dirty environment. In order for the system to function, high pressures of air in large volumes would be needed; some of this volume may be lost due to compression of the vehicle therefore producing a less efficient system. Air is drawn from the atmosphere therefore a filter is required as well as a compressor to ensure the air is at a high pressure. A cooler and air treatment unit would also be required as air contains water vapour and this needs to be condensed. A mechanical design was also an option but proved to be inefficient. The rack and pinion, crank shafts and gear trains which would be involved would require constant maintenance. Damage to key components would be caused from low impact high frequency traffic pulses which would be converted to a high speed rotational movement.Bearings would be needed for a crank shaft which would lead to problems with balancing and since the loads will be variable, vibrations would become challenging.Electromagnetic induction could also be used for the design but there would be a fluctuating frequency of movement within a coil to generate electricity. This fluctuation would render the system inefficient. Regenerative braking was another design approach which could be taken but we preferred a system within the speed bump itself.There are many complications with the friction brake on an incline, two-wheel drive vehicles and wet surfaces.Therefore a hydraulic system would be used whereby the inconsistency of traffic would be compensated for by the use of an accumulator. A hydraulic system is known for high impact force applications and is best suited design for our project. It will operate at all temperatures and it is closed off to the environment, preventing contamination. (Ref 2) Research was also required for the understanding of system components and the reasons for selecting these specific components. There are many different innovations that can be used for a broader function but in order to gain maximum efficiency it is important to narrow down the choices for specific requirements. In order to attain this it was important to thoroughly research the required components, its materials, availability and cost.Specific companies had to be researched and catalogues attained in order to meet system requirements. There were also standards which were used for components such as piping, bearings, bolts etc. 6 2.2 Traffic Tunnels Vertical axis wind turbine can catch the wind from all direction and at a low speed than horizontal axis turbine. There have been two distinct types of vertical axis turbine. The Darius and the Savonius types. The Darius turbine was researched and developed by the Sandia National Laborites in the 1980s. Horizontal axis wind turbine are typically more efficient at converting energy to electricity than vertical axis wind turbine. However, smaller vertical axis turbine are more suited to urban areas as they tend to be more silent and reduce the risk associated with slower rates of rotation. There was blog about a Arizona student that came up with an idea to use a horizontal wind turbine that would be placed above a high way that will recapture energy caused by moving cars on a freeway. (Ref: http://green.autoblog.com/2007/05/01/highway-wind-turbines-to-capture-energy-from-passing-vehicles/). By doing more research we were able to come up with a conceptual design. We found that a vertical wind turbine that is been manufactured and install in urban areas. We were able to take that idea and design our vertical wind turbine, to be installed in existing as well as in new tunnels that will use the wind energy and convert it to mechanical energy. (Ref: http://www.silentwindturbine.com/) 7 3. Conceptual Design 3.1 Speed humps The conceptual design was basic ideas which the group had sketched and decided upon a final design. Constraints were placed on the design and targets set out.We experienced constraints such as the size of the system which would be able to fit into a standard 2mx 500 mm speed bump. The consistency of traffic along the road where speed bumps are in existence was very influential in the design. Inconsistent traffic would allow very little power to be generated whilst consistent traffic will be very useful and increase the efficiency of the system.The need for such a system was prevalent in DUT itself. There is a constant flow of traffic around Steve Biko Campus due to taxis, buses and cars which transport students to and from campus on a daily basis. However in the evenings, students use the library and there is not sufficient lighting to increase safety. Therefore we decided that the electricity produced would be used to power up street lamps in and around campus. Generation of 10kW of electricity would power up 100 streetlamps since 100W of electricity is used by a single streetlamp.The system could be used at toll gates and used to power up signs and streetlamps around the area.The conceptual design can be found in the annexure. 3.2 Traffic Tunnels The conceptual design the group chose to go with was a four blade vertical turbine that will capture the wind produced by passing vehicle in a closed tunnel. The total height of the unit would be 1.5m and this is under the maximum high in a traffic tunnel. The plan is to design a curved blade that will capture more wind and force the wind downwards towards the gear box so it can also be used a cooling unit. The blade would have two support spaced at either end of the blade and would be 1m apart. The supports would be bolted to the main drive shaft. The gearbox will house the gears as well as act as a support for the blade assembly. The reason for a gearbox and not to connect the drive shaft straight to the generator is that blade as a low speed and in order for the generator and our system to be more efficient, the speed need to increase and a gearbox was the only way with less loss. The gear of choice is a spur gear and the reason for this is it can change the vertical motion to a horizontal so there is less height. The system we designing can be used to power the lights in the tunnel which will make the tunnel self maintained as well as the power can be used to power local businesses or houses near the tunnel 8 4. Design 4.1. Speed Bumps The hydraulic system which will be used will make use of the weight of the car as it passes over a speed bump. The natural phenomena of gravity allows the use of weight, this downward force will be used on pistons. There will be 8 pistons used to acquire maximum force from the movement of the car. The strategically placed pistons will transfer the force into a pressure of fluid. The fluid will flow along piping through to an accumulator. The accumulator will store the energy until a suitable working pressure is reached. Once this pressure is reached, the fluid will flow towards the hydraulic motor passing a nozzle which would allow an increased velocity. The increased velocity will be important for functioning of the hydraulic motor. A generator will be coupled to the motor and once electricity is produced it will be stored in battery banks. This electricity will now be used when needed. The system also contains many valves to control flow and pressure. Check valves will be used to ensure flow in one direction and ball valves serves as isolation valves. These valves will allow maintenance of the system. Since this is a closed system, after flowing through the hydraulic motor, the fluid will pass through a filter and thereafter back to the reservoir. The purpose of the filter is to eliminate any impurities which have contaminated the hydraulic fluid from the components in the system. Shazeem Tulsi 9 4.1.1Fluid selection Hydraulic fluids are abundantly used in industry. These fluids are required to transmit motion and generate motion efficiently when a pressure is applied. Hydraulic fluid is also required to lubricate moving parts, provide a means of cooling, carry away contamination and prevent wear and corrosion.Viscosity, a measure of a fluids resistance to motion, is one of the most important properties of hydraulic fluids. The fluid must provide a good seal at motors, valves etc so that pressures may be maintained. Leakages within the system will result in a loss of pressure, affect control aspects instantaneously and the overall efficiency. Liquids that have a low viscosity and thus too thin, will allow rapid wear of moving parts and parts affected by a heavy load. However, fluids which are too thick having a high viscosity will cause internal friction and thus slow down provide unnecessary pressure drops. The lubricating power, chemical stability, toxicity demulsibility is also very important. The liquid should also be free from acids and therefore become corrosive resistant. Another important factor when choosing a hydraulic fluid is filterability. Cleanliness is defined as the amount of dirt particles oil can tolerate without losing performance. Filters are very common in hydraulic systems and improved cleanliness allows for longer lasting filters.There are many types of hydraulic fluids but the most common is mineral oil (petroleum based).(ref3) White mineral oil was chosen for the design due to its low viscosity and adheres to the FDA Regulation. It proves to be beneficial and suitable for the system with regards to the above mentioned requirements of a hydraulic fluid. (Annexure 1) 4.1.2 Motor selection One of the major components in the design is a hydraulic motor. Hydraulic motors are used to convert flow of a liquid under high pressure into mechanical rotation.A hydraulic motor is known as the reverse of a hydraulic pump, instead of creating a movement of liquid by mechanical parts acting upon it, a hydraulic motor causes rotation by the movement of liquid. There are many types of motors namely, gear, vane, gerotor and radial piston motors. The gear and vane motor have a low initial cost and high rpm. A gerotor motor has low-to-medium speed and medium-to-high torque. For the system we needed a motor which would function at a low speed yet develop high power. Therefore a radial piston motor was chosen. The motor that was initially chosen was the GM05 (60) motor which would be supplied by SAI Hydraulics. They are a reputable company with respect to the manufacture of hydraulic motors in South Africa. However due to changes the motor specifications did not meet the system requirements therefore the motor is now a KPM HMB 100 from BMG Hydraulics. (Annexure 2) Shazeem Tulsi 10 4.1.3Return mechanism-Spring It was very important to have a mechanism which would allow the pistons to return to its original position after a vehicle has passed. Efficiency, reliability and maintenance were very important for this design. Due to these factors a spring was chosen as the return mechanism. A spring will allow for easy maintenance as it can be replaced when needed. The spring would have a pin which would allow the replacement of the spring. There are many types of springs which can be used based on the material.Music wire proved to be inefficient as it has a small wire diameter range. This range makes it suitable for small load operations. It operates at temperatures up to 120C.Hard-drawn wire is the cheapest type of spring however it is used where life, accuracy and deflection are extremely important.Chrome-silicone is the best type of material for high stresses and endurance but is extremely expensive. The chosen spring type is Chrome Vanadium. A chrome vanadium spring is most popularly used. It is an alloy spring steel for conditions involving high stress. It has a good fatigue resistance and endurance. The spring would also be excellent for shock and impact loads and withstand temperatures up to 220C. The diameter range is greater than music wire and is also cost effective.This spring would undergo inconsistent compression and expansion due to the inconsistency in traffic. Therefore its property of excellence in shock and impact loads is beneficial for the design. Cost is a very important factor and is another reason for choice of spring. (ref 4) 11 4.1.4Piping For a hydraulic system, pipe design is of significant importance. Component selection in a process system is priority however it is also important for smaller equipment such as piping which, if failure occurs can cause major damage to the larger equipment and thus extra cost to the system. It is known that most process system failures occur at points within the piping, flanges, valves, fittings etc. Therefore it is vital to select components which are compatible with one another.Material selection of piping is based on liquid properties and flow characteristics. These include viscosity, density, temperature, Reynolds number and velocity. Material suitability is also based on valid codes and applications and requires reviewing for safety purposes. The commonly used code is American Society of Mechanical Engineering (ASME) Code for Pressure Piping, B31. The environment has to be taken into consideration to avoid corrosion and temperature changes of the pipeline or fluid. Temperature changes can lead to thermal expansion and therefore damage to the system. Pipe sizing is also considered in the process system. Process efficiency can be increased by ensuring that the liquid flow is optimal. There is an allowable pressure drop which is influenced by the requirements of the process, safety and vibration limitations. Pressure drop is the allowable loss in pressure due to frictional losses along the pipeline. This friction is resistance of flow and therefore reduces process efficiency. Pressure drops are inevitable within a system however large pressure drops depict that the resistance to flow is unfavorably large. Typical pipingPictures compliments of Valves Africa PTY (LTD) Shazeem Tulsi 12 4.1.5 Valves In any hydraulic system it is very important to control flow. This can be done by regulating flow or directing the flow by operating in positions such as fully opened, fully closed or partially obstructs the flow. Valves can either be manually operated or automatic where a change in pressure or temperature will actuate the valve.There are different types of valves for different uses. Some of these include globe, butterfly, check and ball valves.Valves may have two or three ports in which one or two of the ports are inlet or outlet. In our system it was very important to control the direction of flow since it requires oil to flow in one direction. Flow which is bi-directional could cause damage to system components. Therefore check valves were needed for this function. Check valves are two-port valves which allow flow in one direction. This means that they have two openings, an inlet and outlet. They are automatically controlled and are cost effective simple and small in size.For a selection of a valve, the cracking pressure is vital. This is the minimum upstream at which a valve will operate. Check valves are designed on the basis of the cracking pressure and thus selected accordingly. Check ValvePictures compliments of Valves Africa PTY (LTD) Shazeem Tulsi 13 Another valve which was crucial for efficient operation of the system over a period of time is an isolation valve. This valve would have a lever to allow the flow to be stopped and therefore replacement of the system components can occur for regular maintenance of fault in the system.All isolation valves were chosen which have the same size as the pipe diameter therefore not allowing any pressure drop. Valves have been selected according to working pressures, pipe diameter, availability and durability. Isolation ValvePictures compliments of Valves Africa PTY (LTD) Shazeem Tulsi 14 Flange pipe joint Hydraulic pipe joints are generally oval flanges which are fastened by use of two bolts.Oval flanges are used for small diameter pipes that are upto175mm diameter. Flanges are generally cast integral with the pipe ends and are used to carry fluid pressure ranging from 5 to 14Mpa. Flange joints are the most widely used pipe joint. The joint can be made leak proof by placing packing between the flanges. The pipe can also be strengthened for higher pressures and large diameters by placing ribs between the bolt holes. Socket or a couple joint This type of pipe joint is one of the most common joints however it is mostly used for pipes carrying water at low pressures. Shazeem Tulsi 15 Nipple joint A small piece of pipe threaded outside is screwed in the internally threaded end of each pipe therefore decreasing the area of flow. Union joint This joint allows for disengaging pipes by a simple coupler nut. Spigot and socket joint Used for underground piping. It had an advantage of flexibility and can adjust due to the change in level of earth which is caused by climate and environmental conditions. Expansion jointAn expansion joint is mainly used for pipes which carry steam at high pressures. It accommodates for expansion and contraction due to change in temperatures. Ref: A Textbook of Machine Design by R.S.KHURMI AND J.K.GUPTA (pdf) Shazeem Tulsi 16 4.1.6 Control Pressure Switch A pressure switch is a switch mechanism that will initiate an electrical connection when a specific amount of pressure is placed on the switch.It is typically a contact switch which means it fits into a container of liquid and measures the pressure. A pressure switch is made up of two parts, a transducer and a switch. The transducer identifies increasing and decreasing pressures or even multiples of pressure points. Once a specific pressure is reached, it will send a signal to the switch unit. The switch unit will now convert this signal to electrical energy. This energy then allows the next part of the process to occur.In this project the hydraulic switch is used in combination with the accumulator. The accumulator will build up and release pressure and may even experience multiples of the basic pressure. Due to inconsistency in traffic the fluid flow is not constant and therefore the accumulator will be subjected to varying pressures. The pressure switch will allow the fluid to be stored in the accumulator until a pressure of 5.12MPa is reached. Once this pressure is released it will allow the fluid to flow towards the next component being the nozzle. Pressure switches are available with various ranges and different settings, therefore selection of these switches are based on each application specification. Availability and standards is also important when selecting this component. Liquids vary in viscosity and therefore the pressure switch should be functional for the liquids viscosity. However, most pressure switches can accommodate majority of hydraulic fluids. The pressure switch selected for this application is adjustable from 12-150 Bar with a repeatability of 2% of setting. The model is IPH-150 from BMG Hydraulics. www.thomasnet.com/articles/instrumentswww.wisegeek.com/what-are-pressure-switcheswww.bmghydraulics.net Shazeem Tulsi 17 4.1.7Rectifier Circuit A rectifier circuit is required for conversion of AC to DC from the generator for storage in batteries. A rectifier circuit has the purpose of converting an incoming ac signal from a power source to a pulsating dc current. This means that the rectifier takes current which is flowing alternately in both directions and modifies it so that it only flows in one direction. This is illustrated in the figures below. DIAGRAMS There are two types of rectifiers:Half Wave rectifiers Full Wave rectifiers A half wave rectifier circuit is very simple and cheap to produce. It makes use of a diode to either use the positive or negative half cycles to have an output voltage as positive or negative dc component. Since only half the signal is used the circuit is inefficient, 18 wasting energy in the other half of the waveform, it is used in low-current, non-critical applications. The diagram below shows the half wave rectifier circuit. A full wave rectifier circuit It would be more efficient to use both halves of the input waveform and have more energy available at the output. The output is now positive pulsating dc where the frequency has doubled therefore a smoother output.Within this type of rectifier circuit there is the full-wave centre-tapped rectifier and the full-wave bridge rectifier A full wave bridge rectifier has advantages over the centre-tapped rectifier such as; no centre tapped transformer is required, the output voltage is double the secondary voltage of the transformer and the circuit uses more efficient diodes.The four diodes in a diamond shape serves well to provide ac rectification. It is similar to resistors in a Wheatstone bridge.Using the diagram below, we can understand the operation of the circuit. During the positive-half cycle, shown in red, the transformer pushes electrons through theforward-bi1.ased D3, and then through the load resistor.Forward biased D2 has electrons flowing through it and then to the top of the transformer winding. This is a complete circuit therefore current can flow. During this, D1 and D4 are reversed biased and do not conduct any current.Shazeem Tulsi 19 Now, during the negative half- cycle, D1 and D4 are forward-biased and D2 and D3 are revers-biased. Therefore electrons flow through D1 and D4 as shown by the blue arrows. With this type of arrangement the diodes keep switching the transformer connections to the resistor. The resistor can be replaced with a filter and have a regulator follow to allow for a smoother output voltage. Ref: 1) www.Play-hookey.com/ac_theory/ps_rectifiers.html2) Introductory Electronics for EngineeringMartin PodgesISBN 0 7021 5214 5 3) Electronic Devices conventional Current version Eighth editionThomas L FloydISBN 0 13 615581 2

Shazeem Tulsi 20 4.1.6.3 P&ID Diagram Process and Instrument Diagram is a diagram which shows all process fluid lines, instrumentation, instrumentation signals and equipment. Instrument identification is extremely important in understanding a control loop. Standards such as The Instrumentation, Systems and Automation Society (ASI) of the United states of America is used in industry. A circle with two or more letters is used to label instruments and the number corresponds to the tag number.In the case of faults, the tag number allows for efficient documentation at replacement.The function of the instrument is indicated by the second letter in the circle. Below is a basic Process and Instrumentation Diagram of the design for the hydraulic system. PistonBladder AccumulatorIsolation valveCheck ValveHydraulic motor Filter Reference:van Vuuren G, An Introduction to Process instrumentation, 3rd Edition, quad Technologies. Durban, 2002 www.googleimages.com 03 May 2012 Shazeem Tulsi 21 Generator selection A GL-PMG-5000 generator was selected due to the fact that it needs a minimum of 3.5 rpm to keep the shaft rotating and it is cost effective. This generator is made of alloy steel which has anti-corrosion treatment and it has a life time of more than twenty years which means there is less maintenance required. Graphs depict the power and voltage achieved. It can It can be seen from the above graph that 300 rpm cant be achieved so 250 rpm was selected and from the graph approximately 70KW power is generated Using 200 RPM a voltage of nearly 650 V is achieved 22 4.1. Traffic Tunnel Design The vertical blade turbine design that was chosen is a drag turbine. This uses the thrust force of the wind to push the wind turbine and make it rotate about it axis. This is a way of converting wind energy into mechanical energy.This concept has been adapted to use the wind produced by cars traveling @ 45Km/h to 100Km/h.The reason for going with this design is because other vertical turbine needed a large working diameter to operate efficient. By going with the drag turbine we would need less space which made the turbine more efficient an allow it to be incorporated into current traffic tunnels or into knew tunnels that are still be designed. How this turbine works it that it captures the wind energy as the vehicles pass it and turns a shaft. The shaft is then connected to a gearbox where the low speed of the blades is converted to a higher out speed by means of a gearbox. The gearbox allows the generator to rotate at maximum speed without having the blades turn fast. The electricity that the generator generates is then stored in numerous batteries. Lendell Beaumont 23 The idea is to take the vertical turbine an place it on the one side of double flowing traffic or two place it in the centre so it receives wind from both lanes traveling in opposite directions The above images display the available space in a box tunnel or an arch tunnel. Our design has an outer diameter of 1m and a height clearance of 1800mm. Lendell Beaumont 24 4.1.2.Energy in Wind

We know that

Where m = mass (kg)V = velocity (m/s)Energy (Joules) = kg m2 / s2

Energy in a finite mass of air moving at a certain velocity:

Kinetic Energy of a finite mass of air

Power produced by a finite mass of air:Energy (Joules) / time = power (Watts) Let us assume that the finite mass of the air in consideration is passing through a hoop where it transfers its energy to an imaginary plate place at the entrance of the hoop. Mass of air going through the hoop per second: Where: A = cross sectional area of the hoop = air density (mass/volume) Power of a mass of wind blowing through a HOOP at a certain rate (velocity):

Energy Conversion Efficiency:We cannot convert all of the power in the wind to Mechanical (then electrical) power. According to Belts, Maximum theoretical power conversion efficiency (wind to mechanical) is 59% (0.59, Beltz limit).Maximum mechanical power extracted from wind blowing through a HOOP at a certain rate (velocity):

The losses are typically caused by aerodynamic drag, frictional losses due to high wind velocity and wind turbulence.

Lendell Beaumont 25

Torque on the shaft created by the wind Where: T = Torque F = Force r = radius

Lendell Beaumont 26 4.1.2.Blade The blade is the most important part of the design. It needs to be light but also rigid to avoid shattering as this could cause major damage in a tunnel. To install anything into a tunnel we had to keep to the tunnel specification. The blade would need to take pressure created from the wind as well as centrifugal forces as it taking a linear velocity and turning it into an angular motion. The blade is of a simple design we it is just a flat plate that get pushed by the wind. Although it looks simple the size and strength had to work out to make it very efficient as weight is a big problem when making the blades move. As you can see in figure 1 the different material that was tested gave different deflection readings. Although steel gave the least deflection it was too heavy and the weight alone single it out as it will not work. Other material like aluminum and fiberglass was tested. The aluminum gave nice low reading but again it was still too heavy. The fiberglass was light but it deflection was too high as it will shatter in a tunnel if something goes wrong. It was found by fusing fiberglass and aluminum together we could come up with a stronger and lighter material of the two as you can see on figure 1 below. 4.1.2.3.Results Figure 1 Deflection of the Blade The maximum shear stress occurs along the neutral axis where abending moment occurs. As you can see in the graph below when using aluminum or steel they experience a much lower stress than that of the composite material. This is due to the fact that it is one solid piece and does not have any joints. Although in the graph the steel or aluminum is the best they still have a weight factor that prevents us from using it. If you look at the composite material is subjected to a max shear stress of 2.5MPa in the fiberglass. This is well acceptable as the maximum shear stress the fiberglass can take before failure is -0.0001-0.00008-0.00006-0.00004-0.0000200 0.1 0.2 0.3 0.4 0.5Deflection Distance Deflection On a Blade Caused by 90N Force AluminumSteelFibre GlassComposite MaterialLendell Beaumont 27 Graph 1 Shear Stress against distance from centered 4.1.2.3.Manufactoring Process The manufacturing process to make the blade is the most important. The process sees bonding of the aluminum piece to the outer fiberglass. The process is done a few steps. First the aluminum piece is cut into the correct size. Then it is taken to a press where the wholes for the bolts to go through are press out. An alloy base is casing holds one layer of fiberglass Epoxy is pour on to the fiber glass and is spread out equally. A 2nd layer of fiberglass is laid on top of the epoxy and epoxy is then poured over the fiberglass. This is done for 3 layers to get a required thickness of 3mm. After the 3 layer of fiberglass is laid down, epoxy is again laid down. The epoxy helps join the fiberglass together as it acts as an adhesive. The aluminum core is then laid onto of the epoxy and the same procedure follows backwards for laying the fiberglass. The top casing is then put on to the entire mold. The casing with mold inside is then taken to a press that heats the casing and press all the material together. The heat helps to melt the epoxy, so it gets distributed evenly and the pressure push out any air spaces. The mold is then removed and left to cool down. The excess fiberglass is shaved off by a bench grinder and the wholes are punched through the fiberglass to allow for the bolts to go through -0.006-0.004-0.00200.0020.0040.006-3.00E+05-2.00E+05-1.00E+050.00E+001.00E+052.00E+053.00E+05Distance m Shear Stress Shear Stress vs distanceCompositeAluminiumSteelLendell Beaumont 28 4.2.3.ConnectingArm 4.2.3.1.The support beam would have to accommodate the following effect to be used: Will be subjected to a force pushing it down due to gravity Would be subjected to a centrifugal force Would need to be light The material need to be coated to protect it from corrosion There will be two loads acting on the x-axis as well as the y-axis. These two loads will cause bending and shearing in the welds. Therefore the material would have to be strong to with stand these stresses and must be light so the blade can turn will a little amount of wind. 4.2.3.2.Results The maximum Yield strength for steel is 250MPa, Ultimate strength is 400MPa There will be a moment on the x-axis as 0.42Nm and8.1Nm in the y-axis The first step taken was to calculate the second moment of inertia for the x-axis and y-axis for two different size materials. The stress was then calculated as well as the bending in the flat bar. In the table below you can see the stress of the beam at different places on the beam. It can be seen that the 3mm plate is much higher than the 6mm plate but it is still bellow the maximum strength of the material. 3mm thick6mm thick

180.93MPa45.47MPa

-179MPa-44.5MPa

179MPa44.5MPa

-181MPa-45.5MPa From this we decided to go with the 3mm plate as weight is a big factor for our design and it will stand up to the condition. Lendell Beaumont 29 4.2.3.3.ManufacturingProcess The parts of the beam would be fabricated separate and will be brought together in a jig and welded. The process will be listed below: 4.2.3.3.1.There are two piece made from 5 X 30mm flat bar. The bar is supplied in 3m lengths. 4.2.3.3.2.The flat bar would be cut into 3m length so it can be easier handled 4.2.3.3.3.The bar is taken to a punch machine where two holes 12mm in diameter are punched in ever 100mm length piece. 4.2.3.3.4.The 3m length bar is then taken to a galantine where it is cut into it 100mm length. 4.2.3.3.5.A slot of 22 x 50mm is cut into each 100mm flat as this is where the round pipe would be welded on. 4.2.3.3.6.A round pipe of nominal bore 15mm will be cut into 250 mm long pieces with the use of a bench jig saw. 4.2.3.3.7.The round pipe will be placed into a jig and 5 flat plate will be placed in the jig Refer to figure bellow figure4.2.3.3.8.The pieces will be tacked together and turned over so the bottom can be tacked together. 4.2.3.3.9.The tacked piece will be removed and fully welded with a 3mm weld all round.4.2.3.3.10. The same process from 3.3.1 to 3.3.5 will be done for the 30 x 250mm flat plate. Lendell Beaumont 30 4.2.4 Drive Shaft 4.2.4.1.Shaft Requirements The shaft will need to withstand shear stress caused by the twisting of the shaft as well as circumferential stress Must support the weight of all five blades The material selected needs to be corrosion protected The material needs to be light and rigid 4.2.4.2.Results The shaft would be made from a 40 mm nominal bore hollow pipe.The cleats that holds the blade support to the shaft will be made of a 60 nominal bore hollow pipe and the cleats will be made from 6 x 30mm flat bar. The maximum Yield strength for steel is 250MPa, Ultimate strength is 400MPa The maximum torque created by the blades would be 54NM From the calculation done on the circumferential stress the maximum shear would be 17.5KPa. When compare to the maximum value of 250MPa the shaft is suitable for the job. The shaft would be 1200mm long. The blades on the shaft would be spaced at 72 degree intervals as this allows the blades to receive maximum wind and there will always be a blade facing the direction of the wind. 4.2.4.3.Manufacturing Process Due to the length and the arrangement of the cleats it was neaseary to fabricate each piece separate and then do an assembly of the entire component at the end. 4.2.4.3.1.The flat bar for the cleats are supplied in 6m lengths. Therefore each length will be cut into 3mm length to make it easy to handle 4.2.4.3.2.Each cleat is 30 x 50mm4.2.4.3.3.2 Holes will be punched into each cleat as per fabrication drawing 4.2.4.3.4.The cleats will then be cut into 50mm lengths 4.2.4.3.5.A 60mm nominal bore hollow pipe will be cut into 50mm length with the use of a band saw for accuracy 4.2.4.3.6.The 50mm nominal bore punch will be placed into a jig 4.2.4.3.7.The five cleats will be placed into the jig 4.2.4.3.8.All components will be tacked Lendell Beaumont 31 4.2.4.3.9.The components will be turned over and tacked before removing and full welded 4.2.4.3.10.A second jig will hold the completed components after welding 4.2.4.3.11.The cleats will be equally spaced and the 50mm nominal bore pipe will be slide in 4.2.4.3.12.The pieces will be tacked together before removed and fully welded Lendell Beaumont 32 4.2.5.Coupling 4.2.5.1.Requirements Needs to transfer the shaft torque to the gearbox shaft Need to light but strong and rigid Need to with stand shearing 4.2.5.2. Results The coupling was designed around the shaft diameter.The maximum torque created by the rotating shaft was 104Nm When the calculation was done to find the maximum torque the coupling can with stand. It was found that the coupling that was design around the shaft diameter can with stand a maximum torque of 375Nm that 3 time greater than the 104Nm created by the shaft. Therefore the coupling will work. The coupling also acts a support for the blade assembly. 4.2.5.3.Manufacturing Process 4.2.5.3.1.The coupling will be machined from a solid piece of of steel so there are no joints and welds.4.2.5.3.2.This will make the coupling stronger and will reduce shear. 4.2.5.3.3.The coupling will then be welded to the 40mm nominal bore shaft to complete the shaft assembly. Lendell Beaumont 33 4.2.9.Gear Box Agearboxisimportantintheturbinebecauseitchangestheaxisofrotationfromthe rotor to the generator as well as providing the required gear ratio for the generator. Thegearratiowasdecideduponthedesignspecificationsofthegeneratorandthe available torque and speeds developed by the turbine blades trough the rotor.The gears itself, were calculated by selecting the teeth numbers giving the required gear ratio.AllthenecessarycalculationsweredoneusingSolidEdgeinputparameterbased on: Thegearboxistobefloormountedandservesassupportfortherotorshaft.Forthis reason,thematerialofthegearboxcasinghastobecapabletowithstandthestresses caused by the wind blowing the blades.4.2.10 Generator Thegeneratorisatri-phasestarconnectedacoutput.Thisconfigurationallowsthe generator to start producing electricity at low speeds, making it an advantage for the wind turbine.ThecurrentsuppliedbythegeneratorisDC,meaningthatthereisarectifier converting the tree-phase AC from the windings to single phase DC output. Thegeneratorusedisrated1800wattsat450rmp.Duetothenatureofthewindspeed inside the tunnel, an estimated torque of 8.1Nm is expected from the rotor.The gearbox, withits2,8gearratiosuggeststhatthegeneratorwillbeeasilysuppliedwiththerated speed because the average rotor speed is 573rpm. 4.2.11 Charge Controller Charge controller is a device that limits the input of current from the generator to charge the batteries. Although the current has to go through the battery charger before going to the battery, it allows the battery charge not overcharge the batteries by limiting current going to it. 4.2.12Battery Charger For a system voltage 48V and battery capacity of 52AH, 6A battery charger was selected because it is common practice to charge batteries with only 10% of its amp hour capacity. 4.2.13 Inverter InvertersconvertDCpowertoAC.Atthesametimetheychangethevoltagestoredin the battery system to a more suitable AC voltage which is the type of power most tunnel equipment use. For the battery bank used, a 48VDC to 220VAC at pure sine wave inverter is to be used for low voltage system supply.Lowerpowerinvertersarecheaper.Suitableinverterpowershouldbeselectedoncethe loadpowerrequirementisidentified.The300wissuitablefortheprojectbecausemost sensitive equipment such as computers monitors and sensors run on low power. 34 Fig: Grid tie System example DC Generator Utility Grid Battery Charger Grid Tie Inverter Battery BankCritical Load AC AC Load 35 5 Calculations 5.1 Speed Bumps 5.1.1. Pipe Stress Calculations Maximum tangential stress at the inner surface of the pipe: t (max) =2 22 2) ( ) (] ) ( ) [(i oi or rr r p+p = Internal fluid pressure in the pipe(MPa) =2 22 2) 8 ( ) 10 (] ) 8 ( ) 10 [( 4 . 5+ri = Inner radius of the pipe = 24.6MPa ro = Outer radius of the pipe. Minimum tangential stress at the outer surface of the pipet(min) = 2 22) ( ) () ( 2i oir rr p = 2 22) 8 ( ) 10 (] ) 8 )( 4 . 5 ( 2 = 19.2MPa Ultimate tensile stress is 400MPa and using a factor of safety 3:1, the allowable tensile strength is: w= fety factorofsato = 310 4006 = 66.67MPa The minimum yield strength of mild steel is 250N/mm2 which is equivalent to 250Mpa. Since the tensile strength in the pipe (24.6MPa) is less than the yield strength and the allowable tensile strength, the pipe will not fail.

Ref: www.csmsteel.com A Textbook of Machine Design by R.S.KHURMI AND J.K.GUPTA (pdf) Shazeem Tulsi 36 5.1.2 Reynolds Number and Bernoullis Equation A 20mm diameter pipe was chosen: Since Q =A.V Q= volumetric flow rate (m3/s) V =AQ A= Area (mm2) V =2 3) 10 20 (40084 . 0tV= Velocity (m/s) = 26.73m/s Re=uvd Re=Reynolds Number But u = v x v- kinematic viscosity (cSt) = (25 x 10-6) (870)- density (kg/m3) = 0.02175 kg/ms u- dynamic viscosity (kg/ms) Therefore:Re =) 02175 . 0 () 10 20 )( 73 . 26 )( 870 (3 = 21384 = 2.1384 x 104 Since using commercial steel pipe:c= 4.5 x 10-5c- surface roughness (mm)(Moody Diagram) Relative roughness = dc = 3510 2010 5 . 4 = 2.25 x 10-3 Shazeem Tulsi 37 Using the Moody Diagram, figure 1.7: Friction factor (f) = 0.013 Shazeem Tulsi 38 Now Bernoullis principle could be used: l fh h ZgVgPZgVgP+ + + + = + +222 2121 12 2 P- Pressure (Pa)- Density (kg/m3) V- Velocity (m/s) Z- Height (m) Hf- frictional losses (m) Hl- other losses (m) The Darcy- Weisbach Equation: Hf = gdflv242 And:Hl = gkv22k- loss coefficientR- centre line radius d- inside diameter Table 1K values for pipe bends and elbows 90 Bends dR K 1.00.4 1.50.32 2.00.27 3.00.22 4.00.20 Table 2 K values of valves Type K Foot valve with strainer 2.5 Globe valve completely open10 Angle valve completely open 5 One way valve swing type2.5 ball type 70 Gate valve Completely open0.19 open 1.15 open 5.6 open 24 Shazeem Tulsi 39 From point 1 to 2: l fh h ZgVgPZgVgP+ + + + = + +222 2121 12 2 ) 81 . 9 ( 2) 73 . 26 ( 27 . 0) 81 . 9 ( 2) 73 . 26 )( 5 . 2 () 10 20 )( 81 . 9 ( 2) 73 . 26 )( 25 . 2 )( 013 . 0 ( 4) 81 . 9 ( 273 . 26) 25 . 0 () 81 . 9 ( 273 . 26) 81 . 9 )( 870 (10 4 . 52 232 222 6+ ++ + = + +gP P2 = 2.723MPa Note: hl is the loss due to a 90 bend and due to an isolation valve which is the swing type check valve. From Point 2 to 3: l fh h ZgVgPZgVgP+ + + + = + +323 3222 22 2 ) 81 . 9 ( 2) 5 . 25 )( 5 . 2 () 10 20 )( 81 . 9 ( 2) 5 . 25 )( 10 800 )( 013 . 0 ( 4) 81 . 9 ( 25 . 25) 81 . 9 ( 25 . 25) 81 . 9 )( 870 (10 12 . 5232 3 232 6++ + = +gP P3 = 3.82MPa Since: V= 602 N tN- number of revolutions (rev/min) N = t 260 V = t 2) 60 )( 5 . 25 ( = 243.51 rev/min Therefore, the orifice will have to increase the velocity in order to gain a constant 250 rev/min as needed by the motor specifications.V = 602 N tV needed = 26.18 25.5 = 60) 250 ( 2t =0.68 m/s = 26.18 m/s Shazeem Tulsi 40 From Point 3 to 4: l fh h ZgVgPZgVgP+ + + + = + +424 4323 32 2 ) 10 20 )( 81 . 9 ( 2) 18 . 26 )( 10 100 )( 013 . 0 ( 4) 81 . 9 ( 218 . 26) 81 . 9 ( 218 . 26) 81 . 9 )( 870 (10 82 . 332 3 242 6+ + = +gP P4 = 3.74MPa 0.1MPa = 1 Bar Therefore, 3.74MPa = 37.4Bar Q = A. V lpm- litres per minute=) 18 . 26 ].( ) 10 20 (4[2 3 t = 0.00822m3/s= 493.2 lpm Shazeem Tulsi 41 5.1.3Motor Equations Torque = rpmpressure flow 91 . 15 Torque (Nm) = 25091 . 15 4 . 37 2 . 493 Flow (lpm) = 1173.88Nm Pressure (Bar) Power =9543rpm torque = 9543250 88 . 1173 = 30.75KW Displacement =rpmflow 1000 = 2501000 2 . 493 = 1972.8cm3/rev The motor will meet specifications of the system. Shazeem Tulsi 42 5.1.4 Orifice Design From above calculations the velocity needed from the orifice 0.68m/s. Pressure drop = 3.82MPa 3.74MPa = 0.08MPa Therefore H =gP = ) 81 . 9 )( 870 (10 08 . 06 = 9.37m of OilQact = A.V = 4t(20 x 10-3)2(0.68) = 2.136 x 10-4m3/s Since Qact = CdA11 ) (2201AAgh = (0.6)( 4t(20 x 10-3)2 ) 1 )10 20() 3 . 9 ( 2203Ag Therefore do = 5.6mm Shazeem Tulsi 43 5.1.5Tank Calculations Since displacement =1972.8cm3/rev and N=250rpmTank volume = 1972.8 x 250= 493200 cm3 = 493.2 l Due to standards, tank volume= 630 l Volume = 1000H W L L, W, H (cm) = 100068 90 150 = 918 l The tank would be subjected to standard pressure. Shazeem Tulsi 44 5.1.6 Design of oval flange pipe joint The force trying to separate the two flanges has to be resisted by the stress produced in the bolts It is important to use the outside diameter of packing and it is assumed that the packing is 5mm.Therefore, D1= 20+ 2(5)=30mm The force separating the two flanges due to fluid pressure is given by: F =4t(D1)2p = 4t(30)2(5.4) = 3817.04N Since two bolts will be used the force in each bolt is: Fb= 204 . 3817 = 1908.52N We also know that the load in the bolt: Fb =4t(dc)2tbwhere tb is the maximum tensile stress in the bolt1908.52 = 4t(dc)2 (100) dc = 5.11 say 6mm Shazeem Tulsi 45 Nominal diameter of bolts: d =84 . 0cd = 84 . 06 = 7.14 say 8mm Outer diameter of the flange: Do =D + 2t + 4.6 d = 20 + 2 4 + 4.6 8 =64.8 say 65 mm Pitch circle diameter of the bolts: Dp =Do (3t + 20 mm) = 65 (3 4 + 20) = 33 mm Tf from diagram Ref: A Textbook of Machine Design by R.S.KHURMI AND J.K.GUPTA (pdf) Shazeem Tulsi 46 5.2.3.Piston Cylinder calculations Volume= Piston troke

=

= 128 cm3 Vretraction = Vext Vrod

= 128

(

)= 82 cm3 Vtotal =

(

) troke =

(

) 0.065 =209.3 cm3 F2F1 F3 0.5m0.6 m 0.7m

1.8 m The motor vehicle is traveling in the direction as shown by the above arrow Consider the four small shapes as piston cylinders. The maximum speed for the hump is 40km/h and the minimum weight that will push down the cylinder is 1000 kg and since the fluid level is very small the fluid resistance to flow value can be neglected.

=8.2and

=6.2 1)Force1=

=

()

=9911 N 2) Force2= mg = = 9810 N

3)Force3=

=

()

= 9868 N 4)Velocity=

= 11.1 m/s Zamani Bhulose 47 Assumptions: the motor vehicle velocity will be constant when it crossesthe hump 5)The time taken for the car to press down the piston rod can be calculated by: t1=

=

= 0.063 sec t2=

= 0.0541 sec t3=

=0.045 sec 100mm diameter of a cylinder was selected The pressure in the cylinder can be calculated

1)P1=

=

= 5.04MPa 2)P2=

= 5MPa 3)P3=

= 5.03MPa Flow rate from each piston must be calculated, the volume for the all cylinders is the same and the fluid level is 75mm from the bottom of the cylinder. Volume=Area =

= 128

m4 So using the calculated time, flow rate can be found 1)Q1=

=

=0.002

/s Zamani Bhulose 48 2)Q2=

=0.00236

/s 3)Q3=

= 0.0028

/s 65mmpipe Flow rate in the cylinder = flow rate in the pipe 1)Vpipe=

=

= 2 m/s 2)Vpipe2=

=2.7 m/s 3)Vpipe3=

= 3.2 m/s Using Bernoullis equation, pressure in the pipe can be calculated. It a 20mm diameter mild steel pipe which is 400mm long and friction factor is found to be 0.001. The specific gravity for mineral oil is 870 kg/m3. Since the height difference and V1 is very small. It can be negligible.

1)

+

+

=

+

+

+

=

+

+

+

P2 =16.096MPa

Although there were valves but still the pressure did not change that much Zamani Bhulose 49 5.2.3.Structural analysis Using the total weight of a fully loaded 84 sitter bus and plus the account for an overload, the maximum force of 200KN was used for testing the structure. Using Appendix a W15018 I beam column was selected Ixx=9.19

m4

To solve for bending moment at the centre of the beam, let assume there is a hinge at the centre, i.e. the bending moment will equal to zero. Since the frame is symmetrical, one half of a frame can be considered. VA=VB=99.9KN

=0 HA0.653 +VA0.9 q 0.9

=0 HA=68.8KN=HB Using modified Castiglianos method, bending moment at the centre can be found. By applying unit force at C The horizontal reactions can be calculated VA=VC=

=0

0.9 + Hc0.653 =0 HC=0.69KN=HA From the table W150and W200Wide flange columns were selected, which gives moment of inertia for the both columns as, 20.4mm4 and 9.19mm4 respectively. EI1=

4.284

EI2=210

1.9299

Using modified castiglianos numerical method, deflection at the centre can be found

=

dx=2*

(

)

(

)+ =0.007mm Zamani Bhulose 50 Since deflection is equal to bending moment over stiffness, the bending moment at the centre is calculated. BMB=17.89KNm To check whether the structure wont fail, the moment of resistance must be more than the bending moment at the centre. Moment resistance equation=0.9

, where e=

The yield stress is 250MPa for mild steel. Since the I beam column cross section is symmetrical is at the centre which is =75mm e=

=

Using equation for moment resistanceMresistance=0.9

=27KNm This is greater than 17.89KNm therefore the structure wont fail Calculating the compression stress

=

=

= 149MPa Since this is less than the yield stress for mild steel the structure wont break. The maximum stress at the cross section for the I beam column can be calculated using the following formula.

max=

Q=A= (b

= (90

) = 496

m3 I=6.293

m4

max=

=

= 197MPa Using equations (5-48b) from (Gere, 5th edition, p.g. 360) minimum shear stress is calculated as follows.

=

(

) =

(

= 159MPa The shear force in the web is calculated as follows Vweb=

(

) 51 =

( ) = 184.3KN The beam resistance factor (BRF) is calculated BRF=

= 92% this is good

=

=

= 200MPa The structure wont fail since the shear stress in web is 1.5% more than the maximum shear stress.

Moment of inertia= (

)

=(

( )

)

= 23.048

m4 Zamani Bhulose 52 5.2.3.Spring Calculation Table 1.2 From table 1.2, Chrome-vanadium material spring that has 8mm spring wire diameter and 60mm mean diameter is selected. Table 1.2 From table 1.3, modulus of elasticity and rigidity is found to be 203.4 and 77.2 GPa. The total number of turns is 11. Figure 3 www.lesjoforsab.com,06April2012 1)Sut =

=

= 1.4227 GPa 2) allowable = 0.45(Sut) Zamani Bhulose 53 = 1.4227 0.45 = 619.5 MPa 3)Spring Force =

=

= 2075.98 N 4)Solid length (Ls) = Na

= 9 = 72 mm 5)Spring constant(K) =

=

= 16.6 KN/m 6)Deflection of spring(Y) =

=

= 125 mm 7)Original spring length(Lo) = Y+Ls = 125 = 197 mm 8)Pitch =

=

= 21 mm 9)Maximum outside diameter(D)=D+d = 60+8 = 68 mm For stability L0 <

*()

+ If both the ends of the spring are hinged than =1 If the selectedis 1 than the value found is 159 mm and since Lo=197mm the spring will buckle since L0 must be < than 159mm. So if =0.707 using the above equation L0 5

= 1.4, which is less than five thus this is suitable Figure shows the discharge of the accumulator Zamani Bhulose 56 www.groveengineering.com Assumptions: there is no change in temperature between point 1 and point 3 (Isothermal compression) P1v1=P3V3 V3=

= 2.86 litres Assumptions: there is an adiabatic expansion process between point 2 and point 3 P3V3n=P2V2n V2 =(

)

=(

)

= 3.4 litres Zamani Bhulose 57 Oil filters Oil filters will be required to remove unwanted contaminants from oil, since the system will be exposed to dirt. Sensitive components like hydraulic motors require clean oil and this can increase the life of all other equipments in the hydraulic system. Types of filters Rejected1)Centrifugal filterThis type of filter uses the rotation of a rotor to remove unwanted impurities from the oil although they are most efficient but the rotor needs to rotate very fast so that it can contaminants can be removed. Selected1)Bypass filter In this type of oil filter oil is filtered in small segments, this means most oil goes straight to the tank and the small proportion of oil is sent through the filter this reduces the oil that becomes staggered in the filter and it also increases the life of the filter, hence the maintenance cost is reduced. Zamani Bhulose 58 Traffic Tunnel 5.2.1Blade The blade has two supports at either end to reduce the bending. 5.2.1.1Blade deflection

When changing fiberglass to Aluminum you multiply it by

I of composite material

[

(

)] (

)

Lendell Beaumont 59

22. Aluminum@ 0.25 deflection

Steel @ 0.25m deflection

Fiberglass @ 0.25m deflection

Composite Material (aluminum and fiberglass) @ 0.25m deflection

5.2.1.2 Shear stress created in the blade

Lendell Beaumont 60 5.2.3.Connecting Arm On the x-axis there will be a moment caused by the blade weight of 0.42Nm and on the y-axis a moment of 8.1Nm caused by the wind force. First step was to calculate the second moment of inertia

3mm6mm

180.93MPa45.47MPa

-179MPa-44.5MPa

179MPa44.5MPa

-181MPa-45.5MPa 3mm6mm

Lendell Beaumont 61 5.2.3 Drive Shaft The angular velocity of the shaft is 573Rpm as calculated in the blade design.

Circumferential Stress

Max torque the shaft can with stand D = 50mm d = 40mmModulus of elasticity = 80GPa (

)

(

)

(

)

Lendell Beaumont 62 5.2.4Coupling The shaft diameter is d = 50mm

Outside diameter

Lendell Beaumont 63 5.2.5Spur gear selection Agearboxisimportantintheturbinebecauseitchangestheaxisofrotationfromthe rotor to the generator as well as providing the required gear ratio for the generator. Thegearratiowasdecideduponthedesignspecificationsofthegeneratorandthe available torque and speeds developed by the turbine blades trough the rotor.The gears itself, were calculated by selecting the teeth numbers giving the required gear ratio.AllthenecessarycalculationsweredoneusingSolidEdgeinputparameterbased on: -Simple bending stress -Material strength at minimum factor of safety -Based on standards -Load based on torque Thegearboxistobefloormountedandservesassupportfortherotorshaft.Forthis reason,thematerialofthegearboxcasinghastobecapabletowithstandthestresses causedbythewindblowingtheblades.Thegearboxismaterialisaluminumbecauseit aluminum made for gearbox application makes lighter and strong gearboxes. Desired gear ratio is determined by torque from rotor shaft and generator starting torque

,

, therefore:

(), teeths

, chosen. Factor of safety for both pinion and gear are high for the face width chosen, therefore it can be used. 64 65 66 Afonso Luis 67 5.2.6Battery Bank Sizing Battery Bank Sizing The Objective is to design a power supply system to provide at least 10% of running load of tunnel to help reduce costs bringing benefits to the environment as well. Taking10%ofthetotal17.3KwloadofTheWatervalBoventunnel(previouslythe NZASM tunnel) located just outside Waterval Boven on the N4, the battery bank for the system is calculated. StepProcessCalculation 1Total daily use in Watt-hours Wh17.3 KW x10% x 24h = 1730 Wh/day 2IdentifyDaysofAutonomy(backupdays); multiply Wh/day by this factor. 0.67 Days of Autonomy: 1730 x 0.67 = 1159.1 Wh 3Depth of Discharge (DoD) in percentage50% DoD: 1159.1 / 0.5 = 2318.2 Wh 4MinimumAmp-hour(Ah)capacityofbattery bank. 2318.2 Wh/48V = 48.3 Ah Theautonomyof0.67(16/24)waschosenbecausetheturbineswillbeproducing electricity on a daily basis, but for an estimated period of 10 to 12 hours When the traffic islowest(8:00PMto8:00AM)notmuchenergywillbeproduced.Thebatteryisthe required to handle the load for 16 hours (4 hours more than the non-charging period). Althoughthebatteryisdeepcycletype,a50%depthofdischargeisadvisableforlong life. Low temperature affects the battery charging capacity and is not a reason to worry in mostofSouthAfricanterritorygiventhespecificationofthebatteryfromthe manufacturer.Forthisreasontemperatureeffectonthebatterieswasleftoutinthe calculation. High temperature however, is a factor that reduces the life of the batteries. Number of batteries needed:

The chosen battery voltage is 12 volts, therefore:

Therefore it needs 8 batteries to build a system to store 1.73 watts of power for 12 hours, being 2 strings of batteries connected in parallel and 4 batteries in each string. Afonso Luis 68 Fig: System sizing estimator example (at http://www.freesunpower.com/battery_designer.php)

Afonso Luis 69 Maintenance Speed bumps Regular maintenance on system components will be required. All components have been chosen such that they have high levels of endurance. The oil will be passed through a filter therefore removing impurities and can be used for many cycles within the system.Effect of ageing on pipesLumps of rust against inner walls of steel pipes are caused by corrosion. Therefore pipe surfaces are rough and the effective cross sectional area of pipes are reduced.(Ref5) Piping Vapour pressure and Cavitation When pressure in the fluid drops below vapour pressure and causes heating of the liquid, bubbles are formed. When the liquid and bubbles move to a region of high pressure, the bubbles collapse and form liquid once again. This causes small shock wave which iscaused by condensation has a greater effect on local stresses (MPa) on the surface of component parts, thus causing metal fatigue and therefore erosion. These affects leads to decrease in the efficiency of components and the entire system. (ref 6) For the system it was important to choose a pipe diameter which would allow for maximum flow and thus maximum pressure to be transmitted from the pistons through to the hydraulic motor. However the pipe diameter should also be able to handle high pressures and flow and not break due to these constraints. Initially a 16mm diameter pipe was chosen but was changed due to these stresses to a 20 mm diameter pipe Shazmeen Tulsi 70 Traffic tunnels Gearbox Installation For the gearbox to be installed it is recommended that the foundation for it is appropriate. The ground inside the tunnel is made of concrete, therefore screws can be attached to the ground so that nuts are used to tight generator and gearbox support. Thewholesystemtobeinstallednexttotheroadwillbedividedinto3main components: rotor shaft with its blades, gearbox and generator. Necessary bolts, nuts will andcirclipswillbeusedtoassemblyitonsite.Fromtherecablingwilltakepower generated to the Battery bank storage place where other equipment will also be placed. Maintenance Given the nature of the location where the turbine is to be installed it is essential for the systemtobeeasytoassembleinstallandmaintaintoavoidlongtimeexposureof technicianstotrafficaccidents.Althoughsafetymeasuresforthoseworkingonthe installation can be provided, it is important to notice that traffic should not be disrupted for very long time.Forreasonsmentionedabove,partsweredesignedforeasyassemblyandlonglife,by reducing the complexity of parts to be assembled by: -reducing the number of bolts and nuts to be tightened -selecting materials resistant to corrosion -choosing surface polished gears to reduce wear -choosing long service lubrication method . 6. Safety Standard safety protocol shall be adhered to. The system may only be accessed by selected company personnel therefore restricted access. Afonso luis 71 7.Costing 7.1Speed Bumps QUANTITYCOMPONENT SUPPLIER MODEL NUMBERUNIT COSTSUB TOTAL 1Hydraulic MotorBMG HydraulicsHMB 100R10000.00R10000.00 420 x2.5mm Hydraulic tube 6m BMG HydraulicsR38.40p/mR921.60 2RHD Check ValveBMG HydraulicsR396.00R792.00 12HP Full Bore ValveBMG HydraulicsBKH 20SR306.00R3672.00 1Elbow Adapter BMG HydraulicsW20SR60.00R60.00 10-250Bar Pressure GaugeBMG HydraulicsR485.00R485.00 1Pressure Switch 12-150Bar BMG HydraulicsIPH-150R455.00R455.00 600lMineral Oil Selona White Mineral Oil R17.65/kgR10590.00 Shazmeen Tulsi 72 7.2Traffic Tunnel Cost for one Blade and shaft assembly Bill of Quantity ThicknessSizeQty requiredRateTotal 3mm2500x1500 3mm30mm5300mmR 18.6R 98.58 6mm30mm1000mmR 21.78R 21.78 pipe40NB1200mmR 100R 120.00 pipe50NB150mmR 124R 18.60 pipe15NB3750 mmR 50R 187.50 Grand TotalR 446.46 Labor

Labor supplied by SFUNDELE ENGINEERING CC SkillQty TimeRateTotal Boiler Maker12 R 205R 410 Welder22 R 300R 1200 Semi Skill12 R 150R 300 Grand TotalR 1910 There for to fabricate a complete blade assembly will cost R 2356.46 Afonso Luis 73 The main components of the system are -Generator model GL-PMG-1800 PMG supplied by Ginlong Technologies, sold by Green Joule. Fig: Generator full specification (available athttp://www.ginlong.com/wind-turbine-pmg-pma-permanent-magnet-generator-alternator-GL-PMG-1800.htm) 74 -Batteries : GP12260 12V 26Ah Battery Cells Per Unit6 Voltage Per Unit12 V Capacity26 Ah at 20hr-rate to 1.75V per cell @ 25C (77F) Weight (kg)Approx. 8.45 kg. (18.63 lbs.) Maximum Discharge current (A) 350 A (5sec.) Internal Resistance Approx. Approx. 11 m Operating Temperature Range Discharge-15~50(5F~122F) Charge-15~40(5F~104F) Storage-15~40(5F~104F) Nominal Operating Temperature Range 25C 3C (77F 5F) Float charging voltage13.5 to 13.8 VDC/unit Average at 25C (77F) Recommended Maximum Charging current limit 7.8 A Equalization and Cycle Service 14.4 to 15.0 VDC/unit Average at 25C (77F) Self-Discharge It should be more than 75% of the capacity that before storage after stocked for 6 months at ambient temp. 25 TerminalB1/B3/B3B-L terminal or Recessed type to accept M5 bolt Table: Specifications (available at http://www.csb-battery.com/english/01_product/02_detail.php?fid=5&pid=15) -Battery Charger : 300W, BCxx-300 model available at http://www.dcpowersa.co.za -Inverter: IPS-5kW-48 model pure sine wave (5KW 48VDC to 220VAC).Available at Carima product catalog (http://www.carima.co.za/sites/default/files/pricelist_solar_20120423.pdf) Equipent / Part Unit Price (R) QuantityTotal Battery5708045600 Inverter8333.331083333.3 Battery Charger781.52107815.2 Generator1800010180000 Total316748.5 75 PAYBACK PERIOD CONCLUSION AND RECOMMENDATION 8.References 1- www.enginneringnews.co.za/article/february-power-consumption 2-Team 7- Dailhousie University, Department of Mechanical Enginnering 3- Engineer handbook 4- J.E Shigley- C.R Mischke 5- Application of Fluid Mechanics Part 1 C.F Meyer 6-Application of Fluid Mechanics Part 2 C.F Meyer For Traffic Tunnels Formulae came from: Mechanics of materialsSeventh edition SI Edition James M. Gere Barry J. Goodno Publisher : CENGAGE Learning 76 Precise referencing will be done in final report