Is 600J the Minimum Heat Transfer to Maintain Entropy in a Thermodynamic Cycle?

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In summary, the conversation discusses a closed cycle involving a working substance that performs external work and exchanges heat with various reservoirs. The question is posed about the minimum heat that must be transferred to a reservoir at a specific temperature. After some discussion, it is determined that the minimum heat is 600J, as the entropy change of the system must be positive and heat rejection is necessary to comply with the second law of thermodynamics.
  • #1
Bigfoots mum
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Hi, i just want to check my reasoning on this problem.

A working substance is taken around a closed cycle that involves performing some external work. It absorbes heat Q1 = 1000J from a resevoir at T1 = 1000K, and heat Q2 = 2000J from a resevoir at T2 =2000K. The only other exchange of heat is with a resevoir at T3 = 300K.
What is the minimum heat that must have been transferred from the substance to the resevoir at T3 ( explain your reasoning)?

Now i think the minimum heat is 600J, as the entropy change of the system must be >= 0, and we must have heat rejection otherwise we'd violate the 2nd law. Is this ok?
Thanks
 
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  • #2
Hi Bigfoots mum, welcome to PF. Your reasoning looks good to me.
 

1. What is the Entropy Problem?

The Entropy Problem refers to the concept of disorder or randomness in a system. It is a measure of the amount of energy in a system that is no longer available to do useful work. In other words, it is a measure of the amount of disorder or randomness in a system.

2. Why is the Entropy Problem important?

The Entropy Problem is important because it is a fundamental concept in thermodynamics and is used to understand the behavior of energy and matter in various systems. It also has implications in fields such as information theory, chemistry, and biology.

3. How is Entropy related to the Second Law of Thermodynamics?

The Second Law of Thermodynamics states that the total entropy in a closed system will always increase over time, or remain constant in ideal cases where the system is in equilibrium or at a constant temperature. This means that the Entropy Problem is closely related to the Second Law of Thermodynamics and is used to explain why certain processes are irreversible.

4. Can Entropy be reversed?

Theoretically, yes, it is possible to decrease the entropy of a system. However, this can only be achieved by expending energy and work. In most cases, the amount of energy required to decrease entropy is much greater than the amount of disorder or randomness that is reduced, making it impractical.

5. How is the Entropy Problem applied in real-world situations?

The Entropy Problem is applied in various fields such as physics, chemistry, and biology to understand the behavior of energy and matter in different systems. It is also used in engineering and technology to design more efficient systems and processes, and in environmental science to study the impact of human activities on the natural world.

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