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Homework Help: Heat Engine Problem

  1. Mar 27, 2008 #1
    1. The problem statement, all variables and given/known data

    Engine data for a heat engine cycle, ie: Diesel.

    State .........|......1.....|.........2.........|........3........|........4........|
    Pressure(Pa) | 1x10^5 | 11.764x10^5 | 11.764x10^5 | 2.207x10^5 |

    Volume(m^3) |. 0.826 .|..... 0.142 .....|..... 0.25 ......|.... 0.826 ....|

    The gas has a compression and expansion index of 1.4,

    determine the work done in (kJ) in the cycle.


    2. Relevant equations

    I am not sure. But to have an attempt i would say.

    Constant Volume: W = 0

    Constant Pressure: W = P(V_2 - V_1)

    Constant Tempreture: W = P_2 * V_2 * ln (V_2/V_1)


    3. The attempt at a solution

    I have done a P-v diagram, and came up with.

    1-2: Istothermal (Constant Tempreture)
    2-3: Isobaric (Constant Pressure)
    3-4: Isothermal (Constant Tempreture)
    4-1: Ischoric (Constant Volume)

    I am unsure about

    1-2 and 3-4 as it could be a polypropic process (Temp/Press/Vol Change) but i think this has to do with the exp/comp index? but not sure how to figure out?

    I came up with

    -30431.859(kJ)

    I think this is wrong, as this would indicate mins work.

    Do i need to convert PA to KPA or MPA?

    I would welcome any help, advice, or some hints/tips.
     
  2. jcsd
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