Thermodynamic polytropic compression

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SUMMARY

The discussion centers on the calculation of volume V3 during a polytropic compression process, specifically using the equation P2V2^n = P3V3^n. The user is attempting to understand how the textbook arrives at V3 = 0.0169 m³ given P2 = 500 kPa, V2 = 0.05364 m³, P3 = 2000 kPa, and n = 1.2. The correct formula to derive V3 is V3 = (V2^n * P2 / P3)^(1/n), which confirms the textbook's result.

PREREQUISITES
  • Understanding of polytropic processes in thermodynamics
  • Familiarity with the ideal gas law
  • Knowledge of pressure-volume relationships
  • Basic algebra for manipulating equations
NEXT STEPS
  • Study the derivation of the polytropic process equation
  • Learn about different values of the polytropic index n and their physical significance
  • Explore applications of polytropic processes in real-world thermodynamic systems
  • Practice solving problems involving polytropic compression and expansion
USEFUL FOR

Students studying thermodynamics, engineers working with gas compression systems, and anyone looking to deepen their understanding of polytropic processes.

Vathral
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Homework Statement


I'm reading through my textbook and doing examples on polytropic process. I see this step and cannot figure out how the textbook gets V3 = 0.0169 m3

P2V2n = P3V3n
(500 kPa)(0.05364 m3)1.2 = (2000 kPa)V31.2
V3 = 0.01690 m3

Homework Equations


Not sure what to add other than it is a polytropic compression process


The Attempt at a Solution


I've tried multiplying the left side so its 26.821.2 then diving it it by 2000 to get rid of it from the right side to leave V3 alone. Tried subtracting 1.2 by 1 and tried again...no dice.
 
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Vathral said:

Homework Statement


I'm reading through my textbook and doing examples on polytropic process. I see this step and cannot figure out how the textbook gets V3 = 0.0169 m3

P2V2n = P3V3n
(500 kPa)(0.05364 m3)1.2 = (2000 kPa)V31.2
V3 = 0.01690 m3

Homework Equations


Not sure what to add other than it is a polytropic compression process


The Attempt at a Solution


I've tried multiplying the left side so its 26.821.2 then diving it it by 2000 to get rid of it from the right side to leave V3 alone. Tried subtracting 1.2 by 1 and tried again...no dice.

Solve for V3:

V_3 = \left(\frac{V_2^nP_2}{P_3}\right)^{1/n}

CS
 

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