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Heat Engine Problem

  • Thread starter EngNoob
  • Start date
38
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1. Homework Statement

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. Homework 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.
 

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