No. of cylinder calculaions

Discussion in 'Diesel Engines' started by Rhys2908, Dec 10, 2016.

  1. Rhys2908
    Joined: Oct 2016
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    Location: UK

    Rhys2908 Junior Member

    I'm currently doing a question that asks to calculate the number of cylinders of a marine diesel engine.

    Given the following equation, how can I achieve this?
    Power at MCR = 6500 kW
    Bore = 460mm
    Stroke/Bore ratio = 4.2
    Maximum brake mean effective pressure = 19bar
    RPM = 129

    Thank you
     
    Rhys2908, Dec 10, 2016
    #1
  2. gonzo
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    gonzo Senior Member

    What is the thermal efficiency?
     
    gonzo, Dec 10, 2016
    #2
  3. Rhys2908
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    Rhys2908 Junior Member

    We don't have thermal efficiency but we have the following:
    fuel consumption = 173 g/kWh
    the air-to-fuel ratio is 51
    the temperature of the exhaust gas exiting the engine is 237oC
    the engine radiation losses percentage is 0.6%
    the turbocharger compressor absorbed power is 42% of the engine brake power
    the turbocharger mechanical efficiency is 96%
    The used fuel lower heating value is 42700kJ/kg
    The engine room temperature is 38oC
     
    Rhys2908, Dec 10, 2016
    #3
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    This may be one of those problems designed by academics. They make assumptions that they don't explicitly say. I always have a hard time with them. The thermal efficiency is the ratio between the actual power produced to the theoretical one.
     
    gonzo, Dec 11, 2016
    #4
  5. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    One assumes you realise when all else fails - Google is your friend? :p

    It is imperial units but shows the methodology:

    http://www.designchambers.com/wolfhound/wolfhoundRACHP.htm
     
    Ad Hoc, Dec 11, 2016
    #5

  7. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    The answer is eleventy. Give or take some.
     
    Mr Efficiency, Dec 11, 2016
    #6
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