phase of heat released from the energy system, i.e., only indirect energy conversion
would be physically possible. This is clearly not true.
In the literature, the available energy (free energy) concept was, for obvious
reason, attributed to Gibbs [7]. But, the well-deserved attribution to Gibbs was often
taken as Gibbs as the originator of the concept, instead of one who gave a general
idea its concrete form. That perception is contradicted by the analysis in Chap. 4 of
this essay/disquisition, as well as other writers who held a real vantage point on this
topic: The source of Gibbs’ insight is traced by Daub, as he noted in a historical
study on entropy and dissipation, to Kelvin, “Although Gibbs never once mentioned Thomson in his work, he was indebted, I believe, to Thomson’s concept of
dissipation of energy via the good offices of Maxwell and his Theory of Heat.
Maxwell, in turn, was indebted to Gibbs in the revision of his treatment of available
and unavailable energy in his Theory of Heat, thereby uniting the two traditions of
entropy and dissipation” [4:351]. Daub’s reading of the history of thermodynamics
is fully consistent with the historical study of Kelvin’s biographers [8]. Finally, the
clearest attribution to Kelvin is, in a review of Tait’s Thermodynamics, [9] the
statement by Maxwell, “Thomson, the last but not the least of the three great
founders [Clausius, Rankine, and Thomson], does not even consecrate a symbol to
denote the entropy, but he was the first to clearly define the intrinsic energy of a
body, and to him alone are due the ideas and definitions of the available energy and
the dissipation of energy.”
These conceptual developments contributed to how engineers understand the
“heat!mechanical energy” transformation. In this part of thermodynamics history,
in the 1940s and 50s, Joseph Keenan assumed the leadership role in applying
second law analysis to engineering applications [10]. This eventually became
known as the theory of exergy, the term was introduced by Rant in his 1956 article,
[11].
The theory of exergy was an important phase in the long-term conceptual
contribution to be derived from the entropy principle to engineering thermodynamics. In a significant way, the theory of exergy represents an outcome resulting
from the inference of the combined entropy and energy principles. Scientists, i.e.,
physicists and chemists, etc., have no use of the energy principle, needing only the
conservation of energy and entropy principles. Engineers, however, in formulating
the theory of exergy by applying the entropy principle, have very much in their
mind that the bedrock of their enterprise is the energy principle, while the entropy
principle as incorporated in exergy analysis is only a tool to make their undertaking
more effective.
7.2.1 Why Exergy?
My analysis on the development of the idea of available energy may be summarized: Kelvin started the general idea of available energy, Gibbs provided the
general idea its concrete form, and, in the following I shall show, the formulation of
the theory of exergy transformed/united streams of ideas into one general
168
7 Free Energy, Exergy, and Energy …
would be physically possible. This is clearly not true.
In the literature, the available energy (free energy) concept was, for obvious
reason, attributed to Gibbs [7]. But, the well-deserved attribution to Gibbs was often
taken as Gibbs as the originator of the concept, instead of one who gave a general
idea its concrete form. That perception is contradicted by the analysis in Chap. 4 of
this essay/disquisition, as well as other writers who held a real vantage point on this
topic: The source of Gibbs’ insight is traced by Daub, as he noted in a historical
study on entropy and dissipation, to Kelvin, “Although Gibbs never once mentioned Thomson in his work, he was indebted, I believe, to Thomson’s concept of
dissipation of energy via the good offices of Maxwell and his Theory of Heat.
Maxwell, in turn, was indebted to Gibbs in the revision of his treatment of available
and unavailable energy in his Theory of Heat, thereby uniting the two traditions of
entropy and dissipation” [4:351]. Daub’s reading of the history of thermodynamics
is fully consistent with the historical study of Kelvin’s biographers [8]. Finally, the
clearest attribution to Kelvin is, in a review of Tait’s Thermodynamics, [9] the
statement by Maxwell, “Thomson, the last but not the least of the three great
founders [Clausius, Rankine, and Thomson], does not even consecrate a symbol to
denote the entropy, but he was the first to clearly define the intrinsic energy of a
body, and to him alone are due the ideas and definitions of the available energy and
the dissipation of energy.”
These conceptual developments contributed to how engineers understand the
“heat!mechanical energy” transformation. In this part of thermodynamics history,
in the 1940s and 50s, Joseph Keenan assumed the leadership role in applying
second law analysis to engineering applications [10]. This eventually became
known as the theory of exergy, the term was introduced by Rant in his 1956 article,
[11].
The theory of exergy was an important phase in the long-term conceptual
contribution to be derived from the entropy principle to engineering thermodynamics. In a significant way, the theory of exergy represents an outcome resulting
from the inference of the combined entropy and energy principles. Scientists, i.e.,
physicists and chemists, etc., have no use of the energy principle, needing only the
conservation of energy and entropy principles. Engineers, however, in formulating
the theory of exergy by applying the entropy principle, have very much in their
mind that the bedrock of their enterprise is the energy principle, while the entropy
principle as incorporated in exergy analysis is only a tool to make their undertaking
more effective.
7.2.1 Why Exergy?
My analysis on the development of the idea of available energy may be summarized: Kelvin started the general idea of available energy, Gibbs provided the
general idea its concrete form, and, in the following I shall show, the formulation of
the theory of exergy transformed/united streams of ideas into one general
168
7 Free Energy, Exergy, and Energy …