Hidden Heat Reservoirs and Violations of the 2nd Law of Thermodynamics

In summary, the conversation discusses how the 2nd law of thermodynamics is explained through a diagram and how it relates to the Clausius and Kelvin-Plank statements. The diagram shows two systems, one violating the Clausius statement and the other following it. However, when the boundary is drawn around the two systems and the cold reservoir, it violates the Kelvin-Plank statement. The conversation then poses a scenario where a boundary is drawn around the right system and the cold reservoir, leading to a violation of the Kelvin-Plank statement due to a hidden internal energy source.
  • #1
cmcpeek
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I have a quick question concerning the 2nd law of thermodynamics. So my textbook uses an illustration to explain how the violation of the Clausius statement of the 2nd law implies a violation of the Kelvin-Plank. But while looking over the diagram I stated thinking about a certain situation. In the diagram two systems are shown communicating thermally with the same reservoirs. The on on the left is in violation of the Clausius statement while the one on the right is thermodynamicaly sound as its own system. But when you draw the boundary line around the two cycles and the cold reservoir, it violates the Kelvin-Plank statement, which is perfectly okay. However, what if a system boundary were drawn around the cycle to the right and the cold reservoir, making a system consisting of those two entities. It would seem that the system would be communication thermally with only one reservoir (the hot one) yet generate a net output of work, which violates the Kelvin-Plank statement. Any insight would be appreciated.
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  • #2
Cannot load the image.
I cannot see but it sounds like you have a system with a hidden internal energy source: the heat reservoir inside the box.
It still counts.
 

FAQ: Hidden Heat Reservoirs and Violations of the 2nd Law of Thermodynamics

What is the 2nd Law of Thermodynamics?

The 2nd Law of Thermodynamics states that in any natural thermodynamic process, the total entropy of a closed system will always increase over time. In simpler terms, it means that the disorder or randomness of a system will always increase unless energy is added to it.

What is entropy?

Entropy is a measure of the disorder or randomness in a system. It is a thermodynamic property that indicates the amount of energy that is unavailable to do work in a system. The more disordered a system is, the higher its entropy.

How does the 2nd Law of Thermodynamics relate to heat transfer?

The 2nd Law of Thermodynamics states that in any natural thermodynamic process, the total entropy of a closed system will always increase. This means that heat will always flow from a hotter object to a colder object, and not the other way around. This is because the heat transfer from a hotter object to a colder object increases the overall disorder or entropy of the system.

Can the 2nd Law of Thermodynamics be violated?

No, the 2nd Law of Thermodynamics is a fundamental law of physics and cannot be violated. It has been experimentally proven to hold true in all natural processes, and it is an essential concept in understanding the behavior of systems in the universe.

How does the 2nd Law of Thermodynamics relate to everyday life?

The 2nd Law of Thermodynamics applies to all natural processes, including those that occur in everyday life. For example, the 2nd Law explains why hot coffee will eventually cool down, why ice cubes will melt in a warm room, and why a dropped object falls to the ground instead of floating in mid-air. It is a fundamental principle that governs the behavior of energy and matter in our universe.

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