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Homework Help: Work/Efficiency of the Engine

  1. Apr 5, 2009 #1
    1. The problem statement, all variables and given/known data

    A six-stroke engine (Otto-cycle) with 78.4 mm bore, 83.3 mm stroke, 10.7 compression ratio.
    Suppose the initial state in the stroke is 1.0 atm (at room temperature).

    1. Calculate the work done during an engine cycle.
    2. Calculate how muck energy is released to air.
    3. Estimate the efficiency. (5500rpm)

    2. Relevant equations

    1. I found a http://www.grc.nasa.gov/WWW/K-12/airplane/ottoa.html" [Broken].
    2. Haven't found yet.
    3. Haven't found yet.

    3. The attempt at a solution

    1. I use the equation mentioned in the above website.
    But I don't know the ratio of specific heats.
    There are gasoline and air in a stroke, which value should I use?
    2. I think the energy generated by the engine is distributed to (1) the kinetic energy of the car. (2) the friction energy in the engine. (3) the remaining energy which I need to find.
    How to find these?
    3. I think the efficiency is the (the kinetic energy of the car)/(work done during an engine cycle). If I can solve question 1&2, I think the efficiency can be derived.

    Thanks for your help!
    Last edited by a moderator: May 4, 2017
  2. jcsd
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