7.1. Primacy of Dissymmetry over Free Energy, an Epistemological Issue
There are two lessons associated with the discovery of heat as disorganized energy, the first fundamental theorem and the second fundamental theorem. The first fundamental theorem teaches that heat and work are equivalent as measured in energy and that heat is a form of energy. The second fundamental theorem teaches that heat as disorganized energy is a new kind of phenomenon from mechanical phenomena of reversible nature. In coexistence with mechanical reversible processes,
(i) there is another kind of processes (to be called transformations) that, in distinction from mechanical reversible processes, are processes manifesting nature’s preferred direction, i.e., nature’s dissymmetry;
(ii) one additional detail in association with dissymmetry is that each type of the new processes, to adopt the terms of Cropper [24], can be divided into “processes or transformations of natural direction” and “processes or transformations of unnatural direction”;
(iii) another is the notion of “compensation” or “compensated,” and that an uncompensated process of unnatural direction of the new kind of processes can never occur;
(iv) an additional comment: whereas a mechanical reversible universe allows the conception of a “block-universe,” a deterministic and unchanged universe, a dissymmetric universe allows the conception of transformations in a changing universe.
In short, there are the lesson of energy and the lesson of dissymmetry. While both lessons, i.e., both the first fundamental theorem and the first law and the second fundamental theorem and the second law, are indispensable, the precise roles of the two theorems/laws in the theoretical structure of thermodynamics are subtle issue—for similar reason that the concept of energy is subtle [25]. The treatment of how to combine the two may begin with a premise that supposes the primacy of one of the two lessons over the other as an epistemological presupposition, steppingstone that forms the theoretical argument’s structure and impacts on the kind of conclusions possible—even though the two laws’ status as inexorable laws of nature is never in question.
We already have the example of a premise in the energy conversion doctrine, the principal legacy of Thomson [26], which asserts the primacy of energy over dissymmetry, undergirding the orthodoxy of engineering thermodynamics today. That the “expression has commonly been interpreted to mean that work is extracted from the internal energy U while TS represents energy not available to perform work” represents the premise of primacy of energy over dissymmetry.
The energy conversion doctrine places thermodynamics at home with standard branches of physics that are associated with the causal understanding of what Zwier referred to as the “Consensus View of Physical Causation” (CVPC) [27]. This causal understanding may be described as causality exhibited as “constant conjunction” and “invariable succession” in causal laws of equations of motion in physics. That is, physics describes systems in terms of “an autonomous model of dynamics.” As Zwier wrote, “The completely autonomous evolutions of isolated systems that are familiar from physical theories in which we have complete equations of motion are somewhat foreign to thermodynamic theorizing. This is because we do not have a complete equation of motion for thermodynamic systems” [27: 149] What Zwier perceives something unfamiliar and new in thermodynamics theorizing, however, is not shared by most thermodynamicists. The nonexistence hypothesis of equation-of-motion for energy conversion processes was made earlier by the author in an unpublished Report [28], an earlier submitted paper version of which was reviewed/rejected by leading thermodynamicists (including Gyftopoulos, who signed his review of the submitted paper). One unnamed reviewer simply asserted, “the equation of the change (motion) exists for energy conversion processes.” The reviewers in this instance expressed the orthodox view of physical sciences.
This is an example of Marshall McLuhan’s “old stereotypes” habit [29] in the age of new discovery or invention. As Ulanowicz noted,
Whenever a new tool emerged within an endeavor, practitioners tended to use it in the context of previous habits and remained blind for a while to its full potential. His [McLuhan’s] example was IBM, which saw its purpose as the manufacture of business machines. It wasn’t until its leaders realized they were in the business of processing information that the enterprise began to take off [30].
Our example here is the discovery of equivalence of heat and work, i.e., correlation of heat and work. But correlation is not necessarily causation. The discovery is encapsulated fully by the dualistic lessons of energy and dissymmetry, of which energy and CVPC are the previous habits thinking carried over from conceptualization in the reversible world of physics while dissymmetry is the discovery in the new irreversible world, the essence of which is captured by interventionist conceptualization.
We may surmise that orthodox engineering thermodynamics follows the orthodoxy of CVPC, thus, if one question CVPC, one may question orthodox engineering thermodynamics. This is exactly what Zwier did in making the case of interventionist causation, a theory of causation by the philosopher James Woodward [31]. In her thesis, she wrote,
Yet CVPC relies entirely on an autonomous model of dynamics in which everything about the evolution of a system can be predicted purely by knowledge of its beginning state and its internal dynamical rules. For a theory such as thermodynamics, where we have no fully-developed autonomous dynamics, CVPC is wholly inadequate…
I have argued in this chapter that interventionist reasoning is evident not only of the process of discovery of thermodynamic theory, but in the very structure of the theory itself. We can see the interventionist underpinnings in the Clausius submanifold that forms the skeleton of thermodynamic theory and in the “driving forces” which turn out to be interventionist causes of their respective conjugate variables. Interventionist causal claims, in which one variable is said to cause another in a given context, can be formulated and assessed quite naturally using standard “textbook” thermodynamic language and explanations. [27: 158]
In view of Zwier’s philosophical argument and the thermodynamics investigation of this paper, we make the case for supplanting the premise of the primacy of energy with the premise of primacy of dissymmetry over free energy: the structure of thermodynamic theory outlined in this paper is the most important result from the new premise, the missing interventionist conceptualization, instead of the energy conceptualization, may be the deeper reason why Clausius’ “idea of equivalence of transformations is difficult to grasp and is not even mentioned in most thermodynamics textbooks.” The new premise will lead to conclusions, including those drawn from the Carnot/Clausius account, that are radically different from conventional conclusions drawn from the energy conversion doctrine account (see summary of which in Sect. 7.3 and Sect. 8).
7.2. Helmholtz Free Energy and Gibbs Free Enthalpy; Entropy Growth Potentials
Coopersmith referred to “the conflict between Carnot and Joule” as Thomson’s problem [25: 284]. With his second fundamental theorem [23: 111–135] as the more precise version of Carnot’s theory, Clausius in 1854 succeeded in coming to the resolution of Thomson’s problem [25: 284]. I call this the Carnot·Clausius account. Clausius’ 1854 Fourth Memoir then led to the development by Gibbs the Gibbsian equilibrium thermodynamics [10]. It is the equilibrium thermodynamics based on the Gibbs-Carathéodory fundamental relation and the Gibbs-Carathéodory equation that provides the most satisfactory CORE theoretical structure of thermodynamics. This paper is an attempt to achieve unification of the Carnot·Clausius account and equilibrium thermodynamics on the bedrock of this core. Sect. 6 is one element of this project. Note that the Carnot/Clausius account is in terms of heat and work and dissymmetry in the account is in terms of transmission of heat, whereas dissymmetry in the equilibrium thermodynamics account is in terms of thermodynamic potentials. There is a disconnect in our treatment of the complete project. The disconnect can be filled by investigating the dissymmetry in the two thermodynamic potentials, Helmholtz free energy and Gibbs free enthalpy, manifested as heat release transformation.
In the context of multicomponent reactive systems, the Helmholtz free energy, , and the Gibbs free enthalpy, , can be interpreted similarly: the former represents a body’s internal energy (e.g., as released as heat in combustion taking place in a bomb calorimeter), subtracted by energy that is not available, and the latter represents a body’s enthalpy (e.g., as released as heat in combustion taking place in a isobaric combustion chamber), subtracted by enthalpy that is not available. For our purpose here, we shall use the latter example for discussion.
First of all, it is possible to consider the latter example in the same manner as the two examples in Sect. 6, the reversible manifestation of entropy growth as driving force for useful work. The detail can be found in a 1992 paper [32]. Here a summary of the discussion is reproduced: Consider a mixture of 1
of
and ½
of
. A reversible “combustion” heat engine may be constructed along the same lines as a Carnot heat engine. It also consists of four steps (see
Figure 8): an isentropic compression,
→ 1; an isothermal process at peak temperature, 1 → 2 → 3; an isentropic expansion, 3 → 4; and finally, an isothermal heat transfer process at
, 4 →
P0. This final isothermal process will be a heat rejection process if (
) is positive, or a heat absorption process if (
) is negative. Instead of combustion step, the key step of the reversible engine cycle is the isothermal processes at peak temperature, 1 → 2 → 3 (see also Figure 10 of [
32] for examples of different peak temperatures).
The isothermal process at peak temperature is made up of two phases (see. 3 of [32]). After separating each component of the mixture () through corresponding semipermeable membranes into individual manifolds (mixture at 1 becoming components at 1(a), 1(b), …), each component undergoes an isothermal expansion, 1 (a) → 2(a), 1(b) → 2(b), … (the first phase). This is followed by a reversible heat release reaction process (the second phase): components at 2(a), 2(b), … are collected through semipermeable membranes into a Van’t Hoff reaction box where reversible reaction takes place, releasing heat and producing an equilibrium mixture at “3.” Note that pressure at state 3 is selected on the condition of ). (Note that even though point 3 and point 1 overlap each other in the figure, they represent different pressures.) In that case, heat released in the reaction box exactly matches the heat required for maintaining the isothermal expansion processes of the two individual components.
This arrangement transfers the chemical affinity “released” reversibly in 2 → 3 to the enhancement of mechanical spontaneity manifested as isothermal expansions in 1 → 2. Note that heat rejection (area under P0→R0, see Figure 10 of [32]), therefore the thermal efficiency of the reversible heat engine, is independent of the peak temperature . It is noted that a reversible combustion heat engine operating with different peak operating temperatures as shown in Figure 10 of [32] produces the same useful work equal to Gibbs free energy since the heat rejection remains the same.
In this sense, “Gibbs free enthalpy” corresponds to the situation that, of the “combustion heat” released in a spontaneous event, only a minimum amount of heat has to be theoretically subtracted (in fact, if the () of another mixture is negative we’ll have a situation of heat addition instead of subtraction). So, we should be talking about this “work,” which equals the maximum amount of heat that can be extracted, as derived from “available heat,” (see p. 28, lines 18-20).
From these previous examples, whether it is the Carnot-Clausius cycle, or the two examples in Sect. 6, or the example of
Figure 8, the logical name for the work obtained
reversibly should be
available or
free heat that nature’s dissymmetry makes them possible. Only, when
irreversible steps are involved intrinsically in the practice of producing work, the use of free energy or free enthalpy makes some kind of sense, as we shall discuss.
The practice of combustion technology is intrinsically irreversible; the technology led to the invention of steam engines and Carnot’s theoretical investigation. Consider the schematic diagram of
Figure 9, in which a combustion chamber is depicted. The figure is in reference to
Figure 3 and
Figure 8: combustion process of a reactant mixture at
and
enters the chamber with enthalpy
The mixture is transformed into the burned product at
with enthalpy
. These notations are consistent with those in
Figure 8. Heat transmission takes place in the chamber from burned product to the working fluid of the Carnot heat engine—with working fluid of state “3” entering the chamber with an operating temperature designed at
. The working fluid receives heat,
, corresponding to step 3 → 4. The exiting working fluid of state “4” enters the adiabatic expander of the Carnot engine at state “4”. These notations are consistent with those in
Figure 3.
Heat added to the Carnot engine,
, depends on the design selection of the working-fluid peak temperature,
,
The selection of the peak temperature is a critical design factor: a too high temperature lowers for the Carnot heat engine while a too low peak temperature lowers the thermal efficiency of the Carnot engine. Both combustion irreversibility and a poor design selection of peak temperature impact significantly on the end performance result of work production. However, these considerations are not the present focus of the paper, which addresses the teaching of the Carnot cycle and the Carnot-Clausius cycle.
We train on the role of heat reservoir for the operation of Carnot cycle, particularly on the impact of the heat reservoir temperature on the efficiency of the Carnot cycle. The “real value of the Carnot cycle” is often described this way, “Thermal efficiency increases with an increase in the average temperature at which heat is supplied to the system or with a decrease in the average temperature at which heat is rejected from the system,” wrote Cengel and Boles in the textbook Thermodynamics, an Engineering Approach Sixth Edition [33]. We ask in what roles the heat reservoir plays in leading to the conclusion that a decrease in the average temperature at which heat is rejected from the system causes greater fraction of to be transformed into work.
Demarcation of heat transmission as the driving force of the Carnot engine in accordance with the Carnot-Clausius cycle can be generalized. The demarcated treatment of
high temperature heat-energy as a “driving force” of
heat transmitted from
to
, can be generalized to the consideration of a “driving force” in association with
a source-system, whether it is a composite system considered in Sect. 6 (two such systems considered there: Eq.(41) and Eq.(42)) or the example immediately below in this subsection. We referred to, in this generalization, the “driving force” as Entropy Growth Potential,
EGP. [
7: Sects. 8.3 to 8.5] The value of
EGP is determined by the
total entropy growth or entropy production of the source-system and the environment the system interacts with (referred to as “source-system”
“the environment-reservoir”
),
That is,
is the total entropy growth of universe in a spontaneous event. Correspondingly, there is a reversible event. It has been argued in [
7] that the two events define a set of infinite possibilities (the set is referred to as Poincare Range) that share “
a property common to all possibilities” ([34], also see [
7: 197]). By letting,
and naming it Entropy Growth Potential, we acknowledge EGP to be the common property of all possibilities within the set of a Poincare Range.
While the entropy growth of each event is different from other events, every event in the set has the same entropy growth potential, which represents the maximum (potential) useful work of each and every event in the set, corresponding to,
The actual useful work produced by each specific event is less than the maximum useful work of a specific value in association with the specific entropy growth.
For the case of the Carnot-Clausius cycle, (46) takes the form,
Note that in this case
, in accordance with (45), is a function of
, and equals to
It follows that
is,
Instead of looking at demarcation identifies the dual roles the heat reservoir plays, as a heat sink for the EGP driving force and as a heat source-reservoir for the heat extraction mechanism made possible by the driving force. Reason for the decrease in heat rejected from the Carnot-Clausius cycle in association with lower heat reservoir temperature is the combined result of a stronger increase in EGP, the driving force in (37) , and a proportional decrease in extracted heat resulted from lower heat reservoir temperature in (37) and (47)—rather than that a lower heat reservoir temperature favors the heat extraction process.
Now we consider the direct application (sans heat exchange as shown in
Figure 9) of burned product derived from combustion of a reactant mixture at adiabatic flame temperature with enthalpy
. Instead of discharging the burned product at a designed value of peak temperature as implied in
Figure 9 for heat to be added to the Carnot cycle at approximately constant peak temperature, the burned product is designed to discharge ideally at
, the surroundings temperature. This can be done either as an “internal combustion heat engine” with fuel-air-reactant/burned-product as the working fluid, or as an “external combustion engine” with a fluid other than the fuel-air-reactant/burned-product, e.g., steam, as the working fluid. In the latter case, the idealization of a cycle is defined by the minimization of heat transmission irreversibility by keeping the temperature difference between burned product and working fluid small.
Because the burned product is designed to discharge ideally at
, this case represents the more effective combustion application of fossil fuel. In this case,
, in accordance with (45), becomes, in view of (44),
As it has been noted, the logical name for the work obtained reversibly should be available or free heat. The use of free energy or free enthalpy makes some kind of sense only when irreversible steps are involved in the practice of producing work, such as combustion, whether it is internal combustion or external combustion. Eq. (50) shows, of the enthalpy released by combustion, , a minimum fraction of which is not available, therefore, must be subtracted from the released enthalpy. For the reversible example of Gibbs “free enthalpy,” , calling unavailable can be problematic since the term may be negligible or even negative (in the latter case, enthalpy is to be added to the release enthalpy rather than to be subtracted). In the case involving irreversible steps, irreversibility ensures the amount of enthalpy to be subtracted to be significant. It is useful to call the “released enthalpy subtracted by a sizable unavailable fraction” free flame enthalpy, the word flame serving to remind us of the context of irreversible combustion involved in its meaning.
Thermodynamics began with a focus on the relation between heat and work and with Carnot’s innovation of investigating this relation in terms of reversible processes. Analysis in this paper and particularly in this subsection suggests, however, that this historical background of thermodynamics contains, by linking heat and the discussion of reversibility so closely, a misleading notion of the true nature of reversibility. Any discussion of heat necessitates involvement of heat release that is intrinsically irreversible. “Reversible” use of heat, such as Carnot cycle or the Carnot-Clausius cycle, only idealizes the part involving heat transmission, leaving the irreversible heat release hidden from consideration.
True reversibility for the whole processes is represented by examples in Sect. 6 and the example of
Figure 8. These are examples that require no heat sink or sizable heat sink. For the example of
Figure 8, due to the reaction being driven by infinitesimal affinity rather than large affinity of typical combustion reactions, the required heat sink, if any, is of moderate size. For the examples in Sect. 6, these are examples of
pure spontaneity, EGP of which is independent of
because
requires no heat discharging to the surrounding. No heat sink is required.
In these latter cases, the heat reservoir serves solely as a heat-source, with the whole processes requiring no heat sink. It follows that the temperature of a heat-source reservoir can be any arbitrarily one,
, because
EGP is not dependent of
,
For these examples, referring as available or free energy is misleading. Instead, it should be referred to as .
In addition to examples in Sect. 6 and the example of
Figure 8, the application of renewables is examples requiring no sizable heat sink. The reversible realization of all these cases represents “transformations of heat into work” in which heat extraction from the surroundings, rather than heat discharge into which, is the dominant mechanism. The real lesson of the equivalence of heat and work is the requirement of heat reservoir for serving as a heat-source, whereas a heat reservoir serving as a sizable heat sink is the result of fossil fuel combustion practices rather than the result of physics as the consequence of the equivalence theorem. Demand of a sizable heat sink is an option, resulted from the technological choice, rather than a necessity, in accordance with physics.
Calling heat discharged to heat sink waste heat may be misleading, [35] but the necessity of sizable heat-sink for the disposal of heat manifests irreversibility involved in heat release in fire. The teaching that the equivalence theorem demands, cumulatively, prodigious production of heat to be disposed represents both an incorrect scientific interpretation of the theorem and a mistakenly pessimistic fate facing the Anthropocene with mankind indoctrinated by the Prometheus myth of fire necessitating the planetary environment as a heat sink.
7.3. The Dissymmetry Premise, the Driving Force of the Irreversible World
Cropper, the chemist and historian of physics, made the observation on Thomson,
In his discursive way, Thomson touched on every one of the major problems of thermodynamics. But except for his temperature scale and interpretation of the energy concept, his work is not found in today’s textbook version of thermodynamics. Although he ranks with Clausius and Gibbs among thermodynamicists, his legacy is more limited than theirs. The comparison with Clausius is striking. These two, of about the same age, and both in possession of the Carnot legacy, had the same thermodynamic concerns. Yet it was the Clausius thermodynamic scheme, based on the two concepts of energy and entropy and their laws, that impressed Gibbs … left no doubt about the conceptual foundations of his theories, and gave Gibbs the requisite clues to put together the scheme we see today in thermodynamics texts. [36: 90]
It is true that in physics and chemistry the textbook version of thermodynamics follows the scheme of Clausius and Gibbs. But Thomson’s legacy on engineering thermodynamics and technology is supreme as evidenced by the unchallenged acceptance of the theory of exergy, which is based on the universal dissipation of free energy or exergy (a proposition that is shown to be falsified in Sect. 4). Other highlights of Thomson’s legacy are these widely accepted truisms: Joule’s assertion of conversion of heat to work (which Thomson initially hesitated to accept); heat cannot be 100% converted into mechanical energy; the notion that “free energy makes the world go ‘round.” In a nutshell, the legacy of the energy premise that the free-energy portion of disorganized energy is the driving force causing changes/transformations in nature.
But that legacy is directly challenged by Clausius’ second fundamental theorem, which Clausius stated in the 1865 Ninth Memoir as,
The second fundamental theorem, in the form which I have given to it, asserts that all transformations occurring in nature may take place in a certain direction, which I have assumed as positive, by themselves, that is, without compensation; but that in the opposite, and consequently negative direction, they can only take place in such a manner as to be compensated by simultaneously occurring positive transformations {23: 364].
Examples of positive transformations, which can be called conversions since they are transformations that take place by themselves, are heat transmission from high temperature to low temperature; dissipative conversion of work into heat; reaction of reactant into product. The opposite of “dissipative conversion of work into heat” is the “transformation of heat into work,” as asserted by Joule and advocated by the post-1850 Thomson. But missing from this general “understanding” is the precise nature of these transformations: such negative transformations, without being “compensated by simultaneously occurring positive transformations.” are impossible in accordance with the second fundamental theorem. It is positive transformations that cause (autonomously or interventionistically) changes in nature, whether they are spontaneous changes (autonomously) or changes of negative transformation kind (interventionistically), i.e., all processes in the irreversible world, possible. The second fundamental theorem, the bedrock of the second law [22], transmutes the discovery of heat by NWCJ, the disorganized form of energy, into the discovery of dissymmetry of spontaneous transformations. That is the dissymmetry premise, the primacy of dissymmetry over free energy, which asserts dissymmetry manifested by entropy growth to be the real driving force of the irreversible world—in which real transformations happen and are made to happen.
Some notable clarifications/comments that can be drawn from the dissymmetry premise are:
The deceptive association of high temperature heat as an “energy driving force” of a Carnot engine is due to the fact that entropy growth potentials, EGPs, in these cases requires a heat sink for the disposal of heat released at high temperature: other examples, especially of pure spontaneity kind, in the paper make it clear that that situation is a manifestation of one kind of entropy growth rather than an intrinsic feature of every EGP; the universal feature of harnessing dissymmetry manifested by entropy growth is heat extraction instead of heat disposal.
The second law asserts the inexorable increase of entropy, but the law—the premise emphasizes—does not directly or automatically assert the inexorable change of any other variable. Some examples of common misconceptions are found in the present paper.
That includes that processes towards equilibrium are spontaneous but not inexorable (i.e., universal), i.e., an assertion of dissymmetry is not that of unidirectionality (unidirectional means processes opposite to that of unidirectional is not possible, while dissymmetry in processes towards equilibrium allows processes moving away from equilibrium only that they must be made to happen interventionistically).
A related point to Point 3 should be emphasized that far-from-equilibrium is the precondition for extracting free energy. There has been a lot of talk about extracting free energy, including the advocation of acceleration in extracting free energy by techno-optimists. Without safeguarding the Far·From·Equilibrium precondition, the accelerating extraction of free energy as advocated by techno-optimists will kill the goose that lays the golden eggs.
Discussion in more detail in reference to Points 3 to 4 will be given in another venue, a hint of which is found in Sect. 8.