Stirling cycle: Why neglect isochoric heat transfers?

In summary, to prove the Carnot efficiency of the Stirling cycle, one must ignore the isochoric heat transfers. Although they have the same absolute value, they are still contributing to heat energy lost to the cold reservoir during the isothermic compression. Additionally, during the isochoric stages, the working substance is in contact with a regenerator, not the cold reservoir, and the transfer of heat to the cold reservoir is the same as in the Carnot cycle.
  • #1
greypilgrim
521
36
Hi.

To prove that the Stirling cycle has Carnot efficiency, one needs to neglect the isochoric heat transfers. Sure they have the same absolute value (but different signs), but it's still heat energy lost to the cold reservoir during the isothermic compression.
 
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  • #2
greypilgrim said:
To prove that the Stirling cycle has Carnot efficiency, one needs to neglect the isochoric heat transfers. Sure they have the same absolute value (but different signs), but it's still heat energy lost to the cold reservoir during the isothermic compression.
I'm not sure I understand your question. During the isochoric stages, the working substance is in contact with a regenerator, not the cold reservoir. The transfer of heat to the cold reservoir is the same as in the Carnot cycle.
 

Related to Stirling cycle: Why neglect isochoric heat transfers?

1. What is the Stirling cycle and how does it work?

The Stirling cycle is a thermodynamic cycle that is used in Stirling engines to convert heat energy into mechanical work. It consists of four processes: isothermal compression, isochoric heat transfer, isothermal expansion, and isochoric heat transfer. During the cycle, a working gas is alternately heated and cooled, causing it to expand and contract, which drives a piston and creates mechanical work.

2. Why is isochoric heat transfer neglected in the Stirling cycle?

Isochoric heat transfer, also known as constant volume heat transfer, occurs when there is a transfer of heat between a system and its surroundings at a constant volume. In the Stirling cycle, this process is often neglected because it is difficult to maintain a constant volume in the engine. Additionally, the amount of heat transferred during this process is usually small compared to the other processes, so it is not significant in the overall efficiency of the engine.

3. What are the consequences of neglecting isochoric heat transfer in the Stirling cycle?

The main consequence of neglecting isochoric heat transfer in the Stirling cycle is a decrease in the efficiency of the engine. This is because the heat transferred during this process is not used to do work, so it is essentially wasted. Neglecting isochoric heat transfer can also affect the performance and durability of the engine, as it can cause temperature imbalances and stress on the components.

4. Are there any situations where isochoric heat transfer is not neglected in the Stirling cycle?

In some special cases, isochoric heat transfer may be considered in the Stirling cycle. For example, in certain high-temperature applications, such as solar power generation, isochoric heat transfer may be used to increase the overall efficiency of the engine. This requires careful design and control of the engine to maintain a constant volume throughout the cycle.

5. How does neglecting isochoric heat transfer affect the performance of Stirling engines?

Neglecting isochoric heat transfer can have a significant impact on the performance of Stirling engines. It can decrease their efficiency and power output, as well as increase their operating temperature and stress on the components. This can lead to reduced reliability and durability of the engine. Therefore, it is important for engineers to carefully consider the effects of isochoric heat transfer when designing and optimizing Stirling engines.

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