EAT342 Tidal Energy Harvest Device Assignment Brief

The Assignment Task

Following the success of a previous study, a team of engineers from the University of Sunderland are continuing their work with a consortium of companies to explore the feasibility of harvesting energy from the sea.

The concept is to develop a system whereby an energy storage device in the form of a ‘clock’ is wound up by the rising and falling of a platform as the tide comes in and out. The energy stored in the clock will be used to power an electric generator. A schematic of this arrangement can be seen in Figure 1. 

The tide will raise and lower a platform approximately twice per day, and the resulting energy is stored in the clock using a flat, coiled spring.

The scope of the project is the size and arrangement of the float, the mechanism to translate its linear movement into rotational movement to wind the clock’s spring in a constant direction (when the platform both rises and falls with the tide). For this feasibility study, we can assume the difference in height between high and low tide is 3 meters. The platform onto which the clock and generator will be mounted is 2.5 meters above mean tide.

1) A design specification for the tidal energy harvesting device assembly (Please note that this is a design specification and therefore needs to provide details of what it is you are required to design. Your specification must, therefore, be written in the future tense. Your specification must include all limitations imposed upon the design by the conditions described or implied above, as well as any further details you deem relevant. It should not include irrelevant details and must not be written as a product specification, i.e. NOT as a document that provides details of an already existing product.

2) A written review, not exceeding 1500 words, of three different materials you believe might be used to manufacture the Clock’s Spring. The associated manufacturing method for each material must also be included. From the three materials and manufacturing methods you review, you need to select the one you deem most suitable for the intended application. This should be done in the form of a discussion listing the advantages and disadvantages of each material and by developing and comparing performance indices based on the conditions and requirements your group set out in your design specification as well as those listed or implied in the brief. Your discussion must take account of the relevant service conditions, cost considerations and most importantly, ethical and environmental considerations. You may make use of CES to help with the material selection process, but this IS NOT essential. If you do use CES, please be aware that the output from the software on its own is insufficient. The software output MUST be accompanied by and supported from the literature with a clear explanation of the method and the findings of the analysis. A weighted Objectives Method is NOT required for this part of the exercise. For this submission, you must also provide a concept sketch (not CAD) of the layout of rack(s), pinion, bearings, shaft etc in the context of the assembly.

3) Based on the criteria you set out in your design specification and the requirements listed or implied in the brief, select the most appropriate material and manufacturing method from which to manufacture the clock’s spring and layout for the transmission design from those proposed by your group members, in 2) above. Your selection must employ the Weighted Objectives Method, and you must provide a brief discussion and rationale for each of the objectives you use. You must also explain the rationale for the scores awarded.

4) Using the material and transmission layout selected by your group in 3) above, determine the required dimension(s) for the clock’s spring. You must also include calculations to convince your customer that the forces generated from the rise and fall of the tide will be sufficient to wind the clock.

Please note that when determining the dimension of the spring, STANDARD-sized bought-in components MUST be available (bearings, etc) to suit your design, and so the dimensions you calculate may need ‘rounding’ to a standard dimension. It is your responsibility to demonstrate that standard-sized, bought-in components are available to support your design. Failure to take this may result in a significant loss of marks. Please note that all calculations and material properties MUST be shown in SI units only.

5) Prepare an engineering layout drawing of the tidal energy harvesting device assembly, including how it is mounted to the dock and the interfaces with the clock. Your drawing must include a border, parts list (with relevant details of all parts both manufactured and bought in) and a data box that provides details of the drawing title, scale and angle of projection.

6) Prepare a plan for the manufacturing methods that might be employed in the manufacture of the spring for the clock from the raw material. In this case ‘raw material’ refers to the material as supplied by the material stockholders. It does not mean manufacturing from the ore. Your manufacturing plan must cover all features included in these components. Please note! No description of the manufacturing processes is required; you are simply expected to suggest the methods and the sequence of operations by which the spring might be finish machined to the required standard. All processes, including any finishing processes, involved in the production of the parts should be included and your reasons for selecting them given.

Marking Criteria

70-79% 3 of the following, 80-89% 4 of the following, 90% and above 5 of the following

• Thorough understanding of all key points and distinguishing features and factors
• Reasons given for all decisions, all aspects understood, very clearly explained and
correct
• All calculations correct, clearly explained and presented
• A clear structure used and good critical analysis
• Demonstration of thorough knowledge across substantive areas
• All issues/aspects addressed thoroughly and clearly

55-69%

• A good understanding of most key points and distinguishing features and factors
• Reasons given for most decisions, most aspects understood, clearly explained and
correct
• Most calculations correct, clearly explained and presented
• A clear structure used and evidence of critical analysis
• Demonstration of a good depth of knowledge across substantive areas
• Majority of issues/aspects addressed thoroughly and clearly

40-54%

• An understanding of most key points and distinguishing features and factors
• Reasons given for some decisions, most aspects understood, explained and correct
• Basis of all calculations correct but containing some errors
• A reasonable structure used and some evidence of reasonable critical analysis
• Evidence of some knowledge across substantive areas
• Most issues/aspects addressed but some not addressed thoroughly or clearly

F – 39% or less

• Little evidence of understanding of the essential features and factors
• Reasons seldom given for decisions, few aspects understood, explained or correct
• Basis of some calculations incorrect and some/all containing errors
• A poor structure used and little evidence of any reasonable critical analysis
• Little evidence of knowledge or understanding across substantive areas
• Irrelevant, unrelated and muddled material.