Thermodynamics Help- Proving Carnot Cycle

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SUMMARY

The discussion centers on analyzing a Carnot cycle involving air as the working substance, with specific processes including adiabatic compression, isobaric expansion, and adiabatic expansion. The efficiency of the cycle is expressed as efficiency = 1 - (v1/v4)^γ(v4/v3), where γ represents the ratio of specific heats (Cp/Cv). Participants emphasize the importance of understanding the implications of isothermal and isobaric processes within the context of a Carnot cycle, noting that such conditions suggest the presence of a partially liquefied working substance. The net work done by the cycle is also a key point of inquiry, requiring further exploration of pressure and volume relationships.

PREREQUISITES
  • Understanding of Carnot cycle principles
  • Knowledge of thermodynamic processes: adiabatic and isobaric
  • Familiarity with the concepts of specific heat ratios (Cp/Cv)
  • Ability to interpret P-V and T-V diagrams
NEXT STEPS
  • Study the derivation of Carnot cycle efficiency formulas
  • Learn how to plot P-V and T-V diagrams for thermodynamic cycles
  • Investigate the implications of isothermal and isobaric processes in thermodynamics
  • Explore the relationship between pressure, volume, and work done in thermodynamic cycles
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Students and professionals in thermodynamics, mechanical engineers, and anyone involved in the study of heat engines and efficiency calculations.

Spoolx
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1. Please help with the following question.

Given:

A Heat engine goes through a Carnot Cycle as the following states:

State 2 to 3: air compresses adiabatically (pressure increasing)

State 3 to 4: air expanded under isobaric process

State 4 to 1: air goes under adiabatic expansion process

State 1 to 2: air goes under an isobaric compression

Expression :

efficiency = 1-(v1/v4)^gamma(v4/v3)

Find:

1: Plot P-V and T-V diagram of the cycle

2: Prove that the efficiency of this cycle given by expression (1)

3: Determine the net work done by this cycle as function of pressure and volume.

Thank you

2. efficiency = 1-TL/TH
efficiency = 1-(v1/v4)^gamma(v4/v3)

3. I have done the graphs correctly, I am not expecting anyone to do it for me, just some guidance on the right direction to start.
 
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What does it tell you that it's a Carnot cycle with the isothermals also isobars?

(I hope γ is latent heat, otherwise I'd be stumped too. Usually γ is Cp/Cv. If this is the case here, then the cycle could not be a Carnot since for a Carnot the top & bottom curves are not isobars. You can only have isobars and isotherms simultaneously if the working substance is part liquiod and part vapor. So we must be dealing with partly liquefied air. At least that's my understanding.)
 
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