EN0751 Interdisciplinary Engineering Project Shell Eco Marathon

Appendix 51: Ethanol Research

The easy option would have been to use petrol as the fuel for the internal combustion engine however, due the fact that petrol engines emit large amounts of pollutant gasses, they are having an adverse effect on the environment. Therefore, a greener alternative would be more beneficial for the project.

Bioethanol fuel is most commonly produced through the sugar fermentation process, although it can be manufactured by reacting Ethylene with steam. The crops grown for the sugar needed to produce ethanol are known as “Energy Crops”, because they are grown specifically for energy use. These crops include sugar cane, maize, corn and wheat. Ethanol or ethyl alcohol (C2H5OH) is a clear colourless liquid which is biodegradable, low in toxicity and causes little environmental pollution if spilt. Ethanol burns to produce carbon dioxide and water. Its high octane fuel has replaced lead as an octane enhancer in petrol. ^[3]

Bioethanol has many advantages over conventional fuels such as petrol and diesel. Firstly, being a renewable resource (since crops can simply be replanted) there is no issue of resources depleting, unlike conventional fuels. Road transport accounts for approximately 25% of greenhouse gas emissions in the UK, and with these emissions rising at an alarming rate global warming is increasing, causing unrepairable damage worldwide. ^[4] When ethanol is burned it produces Carbon Dioxide and Water, however, some of these emissions will be reduced as the energy crops absorb the CO2 they emit while growing. Energy crops, such as sugar, beet, and maize can be grown in the UK meaning there would be a higher level of fuel security and less reliance on the main oil producing nations.

Bioethanol is also biodegradable and far less toxic that fossil fuels. In addition, using bioethanol in older engines can help reduce the amount of carbon monoxide produced by the vehicle thus improving air quality. ^[5] Bioethanol production is not without its limitations. In theory bioethanol is carbon neutral, but this doesn’t include transporting the fuel, or producing the ethanol from the crops.

As well as this, in countries such as Brazil, where Bioethanol is widely implemented, rainforests are being destroyed in order to grow these crops. In cases such as this, using bioethanol is responsible for causing more greenhouse emissions as opposed to that of oil. Another issue of using Bioethanol is on a moral level. Land for growing crops for food would instead be used for producing fuel which could cause food shortages and increased food prices. Ethanol contains approximately 34% less energy per unit volume than petrol, and therefore, in theory, burning pure ethanol in a vehicle reduces the miles per gallon by 34% compared to burning pure gasoline. Since ethanol has a higher octane rating, the engine can be made more efficient by raising its compression ratio. ^[5] Bioethanol presents a potential challenge for the ICE used for this project, but it is a challenge which has more positives than negatives. Using green fuel is what sets NUCLEUS apart from the majority of teams competing.

Appendix 52: EFI/ECU Research

This is achieved through the reading of sensors while adjusting the engine operation mode to ensure optimum performance. A majority of the components needed have been ordered with the Ecotrons EFI kit. Example of sensor technologies including position, pressure, temperature, humidity, vibration, force and ultrasonic are used for a wide range of transportation applications. The demands on automotive sensors are divided into electrical, mechanical, climatic and chemical requirements that depend on the electrical load and positioning conditions in the vehicle. Modern automobiles have several separate computer systems, each designed to control a specific aspect of the vehicle's operation. Each component has a controller, such as the engine, transmission, dashboard electronics, ABS braking system, tracking control, etc.

The engine controller reads various sensors including coolant temperature, engine speed, oxygen intake, throttle position, and so on.

Various control modules are connected together using an in-vehicle network. There are many different ways of implementing this network, but one of the most common is CAN. The network allows individual control modules to send and receive information from other modules at high speed while the vehicle is in operation.

C+ programming software is almost universally used for the power train (engine/gearbox), braking, steering, body (windows, seats, heating) generally automotive ECUs (Electronic Control Units) are based on lower power microcontrollers for reasons of cost, power and weight. Apart from any other considerations, lower power microcontrollers don't need cooling equipment like high spec computers. This allows the Powertrain Control Module (PCM), antilock brake/traction control/stability control system, electronic steering, electronic suspension, automatic climate control system, keyless entry system, lighting control modules and other systems and modules to all be interconnected electronically.

The sensors from the ECU can determine the mixture required.

Appendix 53: Steering Details

The wheel hub is the innermost part of the wheel connecting the axle to the wheel, into which the spokes are also inserted. The spokes act to take tension load of the vehicle, and arranged whereby ensuring equilibrium is reached due to the number of bearings attached causing displacement at the centre of the wheel through careful alignment of the spokes. ^[11]

Those that are thinner are more inclined to snap under load, yet the thicker the spoke, the heavier each one is. The more spokes there are, the more durable the wheel will be. ^[12]

http://www.translationdirectory.com/glossaries/glossary323.php ^[13]

In respect of applying the component to the vehicle, great care needed to be taken to ensure that the wheels were capable of supporting the vehicle load, while staying in motion and manoeuvring around corners. Attention needed to also be placed on the weight of the steering system, so as to fit in line with the maximum required weight of the overall vehicle, as per rules and regulations dictated by Shell. The rear wheel measures at a diameter of 24’, while the original intention was to obtain 18’ front wheels with a thickness of 35mm. Upon further investigation, advice led to a change in the proposed suggestion, thus deciding on fitting front of the vehicle with 16’ wheels, boasting a 20mm thickness. The rear wheel axle is a part of the whole rear wheel assembly, bolted under the derailleur hangers, holding the weight of the car thus keeping the axle securely in place.

The front wheel axle is a part of the stub axle assembly on each side of the car, where the front wheels slide and lock in place with the help of nuts on the outer side, securing it in place.

Appendix 54: Electric Start Details

This was too large and heavy to sit on the engine crankshaft, while able to allow a chain to connect it to the drive shaft. After consultation with the lab technicians, an electric starter motor for a larger Honda gx160 engine was selected. This particular electric starter motor was chosen as it was smallest size available.

The ring was held on to the original plate by cold shrinking and so, with the application of heat, expanded to a point where a small impact with a hammer was able to remove it from the plate. It could then be bolted onto a new smaller and thinner aluminium flywheel, with the driving sprocket mounted in the middle. The new flywheel was much thinner than the supplied cast iron one and reduced the overall weight of the kit by over 2.5kg. A significant improvement.

The flywheel was made by removing the ring with the teeth on from the original cast iron flywheel. This ring was then attached to a new, bespoke aluminium piece manufactured in house.

Appendix 55: Fuel Tank Details

As the engine already has a tank attached to it, modifications were made so as to allow an alternative tank to sit in place of the original one. For the initial engine tests, a new mount was machined from an aluminium plate and fitted. Doing so allows space for the electric starter motor and repositioned exhaust pipe. Once all engine tests have been completed the glass tank will be fitted. A new mount has not as yet been machined due to exact layout of the EFI system being unknown.

Appendix 56: Air Tank Details

Many tanks found online fit with the size requirements for the vehicle but had huge pressure ratings- a basic paintball gun air system has a pressure rating of 4500psi ^[8].

The shell requirement states roughly around 72.5 (5 Bar). As such, these would not only be very heavy, but would also be vastly over engineered to the needs of the project.

Appendix 57: Project Outcomes

At the time of writing the overall project, in collaboration with group B, is incomplete, though the university remains on track to be able to take a vehicle down to London at the end of May to compete in the event.

Delivery is expected w/c 27/03/2017.

Appendix 58: Project Planning

As a whole group of 10+ members, project planning is a key element in ensuring project success. Without clear tasks assigned, and timescales calculated for each individual component, the aims and objectives would not be achieved. For a fully modified powertrain to adhere to SEM rules and regulations, and to be in full working order, a number of tasks needed to be completed before the deadline on 24.04.17. Once done, the powertrain then needs to be combined with the chassis, body and all other components of the vehicle. A bill of materials, paired with a Gantt chart, estimating cost, and completion date ensured the project was on track to be completed before the final deadline. This can be seen in project appendices 7-10.

The team as a whole learnt how to work together on a project. A misconception for a lot of people is that working in team is easy, however, what is not communicated is how a team can work together successfully.

A big key in a successful project is communication. When someone stops communicating and updating others on how their task is panning, subsequent tasks can be impacted as require a prior task to be completed before continuing.

In respect to the other outcomes, however, it is possible to have a view on the progress so far, with an insight on possible outcomes based on the research carried out followed by testing of equipment.

The engine has been tested and is able to run on ethanol, albeit with a 20% methanol content due to it being available in university at the time. The main components of the engine have all been connected and are ready to be mounted directly onto the chassis.

The main aim of the second eco marathon project group was to produce a lightweight, safe and aerodynamic body and chassis system for the vehicle.

This primarily involved:

1. 
   Providing the structure of the vehicle, by designing and manufacturing a chassis to specific design constraints.
   
2. 
   Producing an aerodynamic body counterpart that meets specific design constraints.
   

For Body design, as it a team it was our economic and ecological responsibility to ensure high fuel efficiency. The Body Specific Design Requirements were as follows:-

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  Produce a design with a drag factor <0.10
  
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  Integrate with chassis and steering designs
  
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  Produce a design that is capable of being manufactured
  
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  House the wheels inside the body
  

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  Ensure Structural Safety by rigorous FEA testing
  
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  Structure Weight vs FoS analysis. (If FoS was unnecessarily large, potential weight saving adjustments were outlined)
  
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  Dimensional compatibility with Body, Powertrain and all other components.
  
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  Aerodynamic Performance (Simulated by Body Design)
  

The complete chassis and body system were computationally analysed throughout the project to ensure that the project aim was met. Designs of the whole system went through numerous iterations, to ensure the best design was agreed upon.

Alongside analysis, correct materials selection was imperative to ensure the groups aim was met. CES EduPack software was used to inform the decision on the best material group to be selected for both the chassis and the body.

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  Lightweight (Low Density).
  
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  High Yield Strength (Elastic Limit).
  
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  Affordable, aligned with the budget constraint of £150.
  

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  Lightweight
  
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  Reasonable impact resistance
  
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  Able to manufacture internally
  

The project is still in the manufacturing phase, after spending too long in research and development. As such, the current project output is not at the desired state. At this stage, the chassis is in the process of being externally manufactured and the body is in the early stages of being internally manufactured

Appendix 60: SEM 2017 Project Management Summary and Constraints

Summary

A research period lasted approximately 3 weeks at the beginning of the project where both groups contributed to compile general information regarding the SEM rules, categories and prototype vehicle entries. The team was then assigned a project leader in order to manage work loads and create an organised structure.

With the team split into a powertrain group and chassis and body group, budget and time constraints were two key parts in assuring success in this project. The group initially lacked communication and this was a major issue which had to be addressed. A group leader was assigned using a democratic vote and a budget report and Gantt chart to manage the project were created. With the prototype category selected, phase 1 of the registration process was completed. After this phase 2 was completed and phase 3 prepared for. The manufacturing of the car is still in progress and should be completed before 24^th of April.

• 
  Short timescale (8-10 months) for large project with little or no prior experience from team members
  
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  Budget of circa £10000 would limit the materials and equipment used by the team (i.e Carbon fibre could not be used due to a high quote of £9000)
  
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  University purchasing protocol meant for delays during processing payments, this was an issue which was not entirely clear before the project commenced
  
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  Winter break where university was shut meant for lack of progress in a crucial stage of research and purchasing of equipment
  
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  Risk assessment forms and university regulations limit the work which can commence on site
  
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  Complex technical project in comparison to other interdisciplinary projects undertaken within the same module