Solve Thermodynamics Problem: Q12, W12, W21 & Entropy Change

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SUMMARY

The discussion focuses on solving a thermodynamics problem involving a closed system containing 3 kg of R-134a at an initial state of 10 °C and 90 kPa. The system undergoes an isothermal process until it reaches a volume of 0.056 m³, followed by an irreversible return process with a heat transfer of +3.2 kJ. Key calculations include determining the heat transfer (Q12), work done (W12, W21), and the entropy change for each process. Visual aids such as T-s, P-V, and T-V diagrams are recommended for better understanding the thermodynamic cycle.

PREREQUISITES
  • Understanding of thermodynamic cycles and processes
  • Familiarity with R-134a properties and phase diagrams
  • Knowledge of entropy and its calculations in thermodynamics
  • Ability to interpret T-s, P-V, and T-V diagrams
NEXT STEPS
  • Study the properties of R-134a using the REFPROP software
  • Learn about isothermal processes and their implications in thermodynamics
  • Research the calculation of work done in closed systems
  • Explore entropy change calculations in irreversible processes
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Students and professionals in mechanical engineering, particularly those focusing on thermodynamics, as well as anyone involved in HVAC systems or refrigeration technology.

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Homework Statement



A closed system contains 3 kg of R-134a at 10 °C and 90 kPa (state 1), and undergoes an internally reversible, isothermal process until the volume of the R-134a reaches 0.056 m3 (state 2). The system returns to state 1 by an irreversible process and the heat transfer for the return process is +3.2 kJ. Determine Q12, W12, W21 and the entropy change for each process.


Homework Equations





The Attempt at a Solution



I do not know how to go about doing this. Any help will be appreciated. thanks.
 
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Start out by drawing an T-s, P-V, and T-V diagram, to better see the cycle
 

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