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oldsloguy
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Are the concepts of exergy and Gibbs Free Energy related? What are the differences between them? Thanks in advance for any help.
oldsloguy said:Are the concepts of exergy and Gibbs Free Energy related? What are the differences between them? Thanks in advance for any help.
Topher925 said:Eh, sort of. The Gibbs free energy is the amount of available work for an isothermal and isobaric process. Exergy is more of a measurement of total available work until a system reaches equilibrium with its surroundings. You can't replace one with the other, but they are similar in concept.
I believe, hopefully someone else can verify this, that GFR [tex]\geq[/tex] Exergy of a system for an isothermal and isobaric process or system.
oldsloguy said:I'm also posting this question in the physics forum to see if anyone there can help.
Andy Resnick said:
OOP, sorry. My thinking was that some people might not look at all of the different forums. BTW what is a "PM" and how do I do it?stewartcs said:Don't double post. If in doubt PM a Mentor and they will help you decide where to put it (or move it).
CS
oldsloguy said:OOP, sorry. My thinking was that some people might not look at all of the different forums. BTW what is a "PM" and how do I do it?
oldsloguy said:Thanks for the responses. So would it be fair to say that the Gibbs Free Energy would be a specific case of the more general Exergy. That is that for isothermal and isobaric processes the GFE and Exergy would be equal and computed in the same manner?
Topher925 said:a systems equilibrium may not allow all available energy to be extracted, which can be determined by the GFE, still assuming an isobaric and isothermal process of course.
Exergy is a measure of the maximum amount of work that can be extracted from a system while it comes to equilibrium with its surroundings. Gibbs free energy, on the other hand, is a measure of the maximum amount of work that can be extracted from a system while it is kept at constant temperature and pressure. In other words, exergy takes into account the non-equilibrium state of a system, while Gibbs free energy only considers the equilibrium state.
Entropy is a measure of the disorder or randomness of a system. Exergy, on the other hand, is a measure of the useful energy that can be extracted from a system. These two concepts are related in that the higher the entropy of a system, the lower its exergy will be. This is because as a system becomes more disordered, it becomes less useful for performing work.
Yes, exergy can be negative. This occurs when the exergy of a system decreases as it comes to equilibrium with its surroundings. This is often the case in real-world systems, where there is always some amount of energy loss due to irreversibilities.
Gibbs free energy is used as a thermodynamic potential that determines the direction in which a chemical or physical process will occur. In a closed system at constant temperature and pressure, a decrease in Gibbs free energy indicates that the process is thermodynamically favored and will occur spontaneously.
Exergy is often used in engineering to evaluate the efficiency and sustainability of energy systems. By considering the exergy of a system, engineers can identify areas where energy losses occur and work to improve the overall efficiency of the system. Exergy analysis is also used in the design of more sustainable and environmentally friendly processes and systems.