Introduction
This design project will focus on the design of an air starting system for a medium sized low speed two- stroke diesel engine. The details of the particular engine are presented below:
Learning Outcomes to be assessed
1. Interpret engineering system requirements and generate a design specification accordingly.
2. Apply a systematic approach to the design process.
3. Communicate design information and data effectively and in accordance with requirements.
4. Demonstrate technical competence in a range of engineering disciplines and their application to
the design of engineering systems.
5. Create computer models of engineering systems and use them appropriately.
6. Demonstrate an awareness of relevant engineering standards and legislation.
Coursework Specification
This design project will focus on the design of an air starting system for a medium sized low speed two- stroke diesel engine. The details of the particular engine are presented below:
The engine/propeller shaft specifications are:
• Engine model MAN B&M 5s50MC
• 5 cylinders, bore 500mm and stroke 1910 mm
• Connecting Rod Length 2190mm
• Reciprocating mass per cylinder 3229kg
• Firing order 1-4-3-2-5
• Mean indicated pressure 19 bar
• Maximum pressure 140 bar
• Rated output MCR 7150kW
• MCR speed 127 rev/min
Engine inertia: The inertia of the individual engine and shaftline components are detailed in reference [1]. Rather than conducting a complex analysis of the entire engine mechanism, a sensible approach would be to model the engine, shafts and propeller as a single object with a combined inertia in the region of 50×103 kgm2. In reality the inertia of the reciprocating components (connecting rod, piston rod, crosshead and piston) are functions of crankshaft angular position, and hence the overall value suggested represents an upper limit. In reality the mean inertia will be less than this and calculation of air requirements based on this value will give rise to an inbuilt safety.
Requirements
You are required to design an air starting system for the above engine. You may assume:
(1) The engine already has a suitable air starting valves that can be operated by suitable air distributor.
(2) The engine is already fitted with suitable cams for operation of the air distributor or alternative arrangement. However, you will need to specify the cam profile, which will sequence the air distribution to each cylinder.
(3) All other services that you would expect to be available are present within the engine room.
(4) The compressors and air receivers required as part of your air staring system can be easily located in close proximity to the main engine, assume a horizontal distance of 5m from air receiver to main engine.
(5) The air starting valve, when open is non-restrictive. E.g. the only frictional losses are associated with the flow of compressed air along the pipeline to the air starting valve and other losses experienced during the air expansion into the cylinder.
Functional Requirements for the air starting system
(1) Your air starting system needs to be able to start the engine in either rotational direction (ahead/astern). However, you do not have to consider the problem of changing the engine valves and fuel injection timing, only the need to change the timing of your air distributor to suit the engine’s intended direction of rotation.
(2) The starting system will be required to deliver a minimum of 12 starts from the air stored in the receivers. This means that sufficient compressed air must be stored in order to guarantee the 12 starts, without the need to run the compressors to recharge the air receivers.
(3) The air starting system must be capable of being operated manually without electrical power supply. (This requirement does not apply to the air compressors, only that the main engine can be started without the need for electrical power). However you may include solenoid operated pneumatic valves so as to enable automatic control, but this is an added extra on top of the basic requirement.
(4) Suitable interlocks must be present so as to prevent erroneous operation of the air starting system.
(5) The system must meet with the expected standards for a marine installation and you will be expected to incorporate and demonstrate the required degree of redundancy within your design.
Completion of this project will require the specification of a range of mechanical and control components, including but possibly not limited to:
• Air compressor(s).
• Air receivers(s).
• Pneumatic valves and pilot valves.
• Flame arrestors or bursting disks.
• Air distributor pilot valves and cam timing.
• Pipe work and pipe specifications.
The components you select will have to be incorporated into a design that is fully validated by modelling/analysis. Components not commercially available will need to be designed.
Design Calculations
In order to start the main engine you are required to achieve an engine speed to 12 rev/minute prior to starting the injection of fuel. In your assessment for meeting this requirement, you will need to make some assumptions with regard to the modelling of your engine and transmission system. For the purpose of this assignment is acceptable to formulate an overall inertia, which represents the components making up the ship’s propulsion system. There is no need to model the inner working of the engine. However, you will need to make sure that your assessment of the required torques are conservative in order for you to guarantee the minimum number of engine starts.
Reporting and submission requirements
Coursework 2 must be submitted via the provided Excel template, with the relevant work inserted into
the correct tabs. The submission will comprise of the following sections:
1. Design specification (definition of the problem), 5%
2. Design philosophy (including design development flowchart), 20%
3. Design calculations:
1. Piping losses, 5%
2. Receiver capacities, 5%
3. Engine starting, 20%
4. System process and instrumentation diagram (P&ID), 25%
5. Operating methodology (sequence), 15%
6. References, 5%.
You are advised that the Department of Maritime and Mechanical engineering operates a zero tolerance approach to late submission of coursework. Any coursework submitted late will be awarded a zero mark unless there are valid mitigating circumstances supported with evidence of the mitigation claimed.
Be advised that loss of computer data will not be accepted in mitigation; it is entirely your responsibility to ensure the secure backup of all electronic data.
Marking Scheme or Guide to Assessment Criteria
See Attached Grid marking scheme.
6160Eng Engineering Design 3
Grade descriptors and feedback sheet for: Student name:
Design of a marine engine air starting system Lecturer(s): E. Blanco-Davis & G. Phylip–Jones
Assessed Element Below 40% 40 to 49% 50 to 59% 60 to 69% >70% Mark Weight Weighted
% Mark
1) Design Specification (definition of the problem), 5% Very limited Basic description Reasonable description with some detail Very good with much detail Excellent description with much detail 0.05
2) Design philosophy (including design development flowchart), 20% Very limited Basic description Reasonable description with some detail Very good with much detail Excellent description with much detail 0.2
3) Design calculations:
a. Piping losses, 5%
b. Receiver capacities, 5% c. Engine starting, 20% Very limited Basic description Reasonable description with some detail Very good with much detail Excellent discussion with much detail 0.3
4) System process and instrumentation diagram (P&ID), 25% Very limited Basic description Reasonable description with some detail Very good with much detail Excellent description with much detail 0.25
5) Operating methodology (sequence), 15% Very limited Basic description Reasonable description with some detail Very good with much detail Excellent description with much detail 0.15
6) References, 5%. Very limited Basic description Reasonable description with some detail Very good with much detail Excellent discussion with much detail 0.05
Total Mark / 100
Comments
Recommended reading
• [1] Magazinovic G. (1998) “Shaftline Design Considerations for Five-Cylinder Low-Speed Propulsion”, Plants, 13th Symposium on Theory and Practice of Shipbuilding.
• Jackson L. Morton T.D (2005) ‘‘Reeds Vol 8: General Engineering Knowledge’’, 80713682649.
• McGeorge H.D (1991) “General engineering knowledge”, 0750600063.
• Pounder, C.C. (1998) ”Pounder’s Marine Diesels”, 075062583.
• https://www.youtube.com/watch?feature=player_detailpage&v=AiLdwtPh8xg
Extenuating Circumstances
If something serious happens that means that you will not be able to complete this assignment, you need to contact the module leader as soon as possible. There are a number of things that can be done to help, such as extensions, waivers and alternative assessments, but we can only arrange this if you tell us. To ensure that the system is not abused, you will need to provide some evidence of the problem. More guidance is available at http://www.ljmu.ac.uk/corporate/SPR/60399.htm.
Any coursework submitted late without the prior agreement of the module leader will receive 0 marks.
Academic Misconduct
The University defines Academic Misconduct as ‘any case of deliberate, premeditated cheating, collusion, plagiarism or falsification of information, in an attempt to deceive and gain an unfair advantage in assessment’. The School takes Academic Misconduct very seriously and any suspected cases will be investigated through the University’s standard policy (Academic Misconduct Policy). If you are found guilty, you may be expelled from the University with no award.
It is your responsibility to ensure that you understand what constitutes Academic Misconduct and to ensure that you do not break the rules. If you are unclear about what is required, please ask.
Reference ENR-PP-LA-3-07
Document title Template for Coursework
Revision 2.0
Date 21/01/2016
Author GPJ/EBD
Cheating includes:
(i) any form of communication with, or copying from, any other source during an examination;
(ii) communicating during an examination with any person other than an authorised member of staff; (iii) introducing any written, printed or other material into an examination (including electronically stored information) other than that specified in the rubric of the examination paper;
(iv) gaining access to unauthorised material in any way during or before an assessment;
(v) the use of mobile phones or any other communication device during an assessment or examination;
(vi) the submission of false claims of previously gained qualifications, research or experience in order to gain credit for prior learning;
(vii) the falsification of research data, the presentation of another’s data as one’s own, and any other forms of misrepresentation in order to gain advantage;
(viii) the submission of work for assessment that has already been submitted as all or part of the assessment for another module without the prior knowledge and consent of the Module Leader for the subsequent assessments.
Plagiarism is defined as the representation of the work, artefacts or designs, written or otherwise, of any other person, from any source whatsoever, as the student’s own. Examples of plagiarism may be as follows: (i) the verbatim copying of another’s work without clear identification and acknowledgement
including the downloading of materials from the Internet without proper referencing of materials; (ii) the paraphrasing of another’s work by simply changing a few words or altering the order of presentation, without clear identification and acknowledgement;
(iii) the unidentified and unacknowledged quotation of phrases from another’s work;
(iv) the deliberate and detailed presentation of another’s concept as one’s own.
Collusion includes:
(i) the conscious collaboration, without official approval, between two or more students in the preparation and production of work which is ultimately submitted by each in an identical or substantially similar form and/or is represented by each to be the product of his or her individual efforts;
(ii) collusion also occurs where there is unauthorised co-operation between a student and another person in the preparation and production of work which is presented as the student’s own.
For more information you are directed to following the University web pages:
• • Information regarding academic misconduct:
• • Information on study skills:
• • Information regarding referencing:
http://www.ljmu.ac.uk/studysupport/81924.htm http://www.ljmu.ac.uk/studysupport/ http://www.ljmu.ac.uk/studysupport/69049.htm
Reference ENR-PP-LA-3-07
Document title Template for Coursework
Revision 2.0
Date 21/01/2016
Author GPJ/EBD
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