Thermodynamics Help- Proving Carnot Cycle

In summary, the conversation discusses a given problem involving a heat engine going through a Carnot Cycle with four different states, and the expressions for efficiency and net work done for this cycle. The individual is seeking guidance on how to plot the P-V and T-V diagrams and how to prove the efficiency of the cycle. They also mention that the cycle may not be a true Carnot cycle due to the presence of isobars and isotherms.
  • #1
Spoolx
38
0
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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  • #2
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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1. What is a Carnot cycle?

A Carnot cycle is a theoretical thermodynamic cycle that represents the most efficient way to convert heat into work. It consists of four reversible processes: isothermal expansion, adiabatic expansion, isothermal compression, and adiabatic compression.

2. How does a Carnot cycle work?

In a Carnot cycle, a working fluid is used to absorb heat from a high-temperature source at a constant temperature, expand and do work, and then release heat to a low-temperature sink at a constant temperature. This process is reversible, meaning that the working fluid can be brought back to its original state by reversing the direction of each process.

3. Why is the Carnot cycle considered to be the most efficient?

The Carnot cycle is considered to be the most efficient because it operates between two constant temperature reservoirs, and the heat transfer only occurs when there is a temperature difference. This means that all of the heat supplied to the working fluid is converted into work, resulting in the maximum possible efficiency.

4. How does one prove the efficiency of a Carnot cycle?

The efficiency of a Carnot cycle can be proven mathematically using the Carnot efficiency equation: Efficiency = (T_high - T_low) / T_high, where T_high is the temperature of the high-temperature source and T_low is the temperature of the low-temperature sink.

5. What are the practical applications of the Carnot cycle?

The Carnot cycle has practical applications in the design of heat engines, such as steam turbines and internal combustion engines. It also serves as a standard for comparing the performance of real-world thermodynamic systems. In addition, the principles of the Carnot cycle are used in the development of refrigeration and air conditioning systems.

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