Kelvin -Planck Statement in Law of Thermodynamics

Kelvin Planck Statement:

It is impossible to transport heat from one body to another without generating any other effects on the cycle, according to Kelvin Planck’s assertion. When heat is conveyed, it has uncontrollable side effects that are sometimes beyond one’s control. In other words, it is impossible to build an engine just for the purpose of converting heat into work.

This statement plays a great role in the second law of thermodynamics.

How did Kelvin and Planck statements come together?

Understanding the two separate statements, namely the Kelvin statement and the Planck statement, brought the Kelvin Planck statement together. Lord Kelvin and Planck were the ones who gave it.

To deduce the mechanical effect of things, Kelvin stated that it is impossible to cool any matter below the greatest cooling temperature.

Planck, on the other hand, maintained that given a reversible system, the total accumulation of entropies will always remain constant.

The Kelvin – Planck assertions were created by combining these distinct claims.

Kelvin Planck statement example:

Wilhelm Ostwald invented the perpetual motion machine of the second kind (PMMSK), which was a fictional machine designed just to convert heat into work without creating any other effects.

Statement of The second law of thermodynamics:

The second law of thermodynamics indicates that heat can be used for more than just determining work; it can also have other consequences. In terms of work, heat would have more than one effect. It’s simply not doable. The Kelvin statement is another name for the second rule of thermodynamics. The kelvin statement can be used to express some of humanity’s most pressing issues. Despite all of the fancy and advanced technological features, a reliable heat engine has yet to be developed.

The possibility of developing a flawless engine is determined by the first rule of thermodynamics, while the second law of thermodynamics completely prohibits it.

Why and how did the Second Law of Thermodynamics emerge?

The first law has some flaws when it comes to analysing the thermodynamic system. One of these flaws is that it is unable to explain why some thermodynamic processes occur in a specific direction and cannot be reversed. Such a process is carried out from left to right, while the reverse process cannot be carried out from right to left. The fact that the first law of thermodynamics does not distinguish between the properties of different kinds of energy is another flaw. Work and heat transmission are equivalent in this sense, according to the first law of thermodynamics’ energy balance. In actuality, it is well recognised that the work, when compared to heat transfer, has a greater quality in practical applications. Work is a useful form of energy, but heat must go through a thermodynamic process to become useful, such as being fed into a thermal engine that turns a portion of this energy into useful work.

The second law of thermodynamics was created to compensate for the first law’s flaws. It was used to forecast how a thermodynamic process would proceed. Furthermore, a reference for comparing diverse energy with varied quality is provided utilising the exergy idea, which is one of the consequences of the second law of thermodynamics.

In thermodynamics, reversible processes are those that may be carried out in both directions, that is, 1 2 and 2 1 without requiring any additional energy from the environment. Irreversible processes, on the other hand, are those that only go in one way and cannot be reversed without the input of extra energy. Irreversibilities control the direction of the thermodynamic process. There are a variety of sources of irreversibilities in real-world processes, including finite temperature differences, friction, chemical potential differences, dissipative processes, abrupt expansion, hysteresis, and nonelastic expansion of materials.

There are various formulations that serve as a foundation for additional study before any analytical approach for applying the second law of thermodynamics to energy systems. These are the expressions:

• The Kelvin-Planck statement : It is impossible to build a thermal engine that operates in a thermodynamic cycle and generates electricity with only one thermal reservoir.
• Clausius’s statement: It is impossible to transfer heat from low-temperature heat sources to a higher-temperature medium without supplying extra energy from an outside source.

The Kelvin-Planck statement expresses the second law of thermodynamics in terms of heat engines, whereas the Clausius statement expresses the second law of thermodynamics in terms of refrigerators and heat pumps. These two claims are equal since it can be demonstrated that if one is violated, the other is violated as well, and vice versa.

Conclusion :

The statement of Kelvin Planck is a perfect example of the second law of thermodynamics. It is evident from this statement that a heat engine cannot have a thermal efficiency of 100%. A system that converts work into comparable heat, on the other hand, is possible.