Discussion:
Second Law of Thermodynamics and Misleading Education
Add Reply
Pentcho Valev
2017-11-17 18:03:59 UTC
Réponse
Permalink
Raw Message
Heat engines able to violate the second law of thermodynamics are COMMONPLACE. This would be obvious if misleading education had not diverted the attention from relevant examples. It is universally taught that all heat engines are NON-ISOTHERMAL, that is, two temperatures, high and low, are always NECESSARY:

"In thermodynamics, a heat engine is a system that converts heat or thermal energy - and chemical energy - to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state temperature. A heat "source" generates thermal energy that brings the working substance to the high temperature state. The working substance generates work in the "working body" of the engine while transferring heat to the colder "sink" until it reaches a low temperature state." https://en.wikipedia.org/wiki/Heat_engine

"A necessary component of a heat engine, then, is that two temperatures are involved. At one stage the system is heated, at another it is cooled." http://physics.bu.edu/~duffy/py105/Heatengines.html

Not true. There are heat engines functioning in ISOTHERMAL conditions - the two temperatures are not necessary. For instance, the work-producing force can be activated by some chemical agent, not by heating. The analysis of isothermal cycles in which such heat engines produce work shows that the engines are essentially perpetual-motion machines of the second kind.

There is a clear and unambiguous formulation of the second law of thermodynamics given by Sadi Carnot himself:

"A cold body is necessary"

That is, heat cannot be cyclically converted into work unless some temperature gradient is present - a hot body, source of heat, and a cold body, receiver of heat, must be available. The problem is that in 1824 Carnot deduced "A cold body is necessary" from a postulate that eventually turned out to be false:

Carnot's (false) postulate: Heat is an indestructible substance (caloric) that cannot be converted into work by the heat engine.

Unpublished notes written in the period 1824-1832 reveal that, after realizing that his postulate was false, Carnot found "A cold body is necessary" implausible:

Sadi Carnot, REFLECTIONS ON THE MOTIVE POWER OF HEAT, p. 225: "Heat is simply motive power, or rather motion which has changed form. It is a movement among the particles of bodies. Wherever there is destruction of motive power there is, at the same time, production of heat in quantity exactly proportional to the quantity of motive power destroyed. Reciprocally, wherever there is destruction of heat, there is production of motive power." p. 222: "Could a motion (that of radiating heat) produce matter (caloric)? No, undoubtedly; it can only produce a motion. Heat is then the result of a motion. Then it is plain that it could be produced by the consumption of motive power, and that it could produce this power. All the other phenomena - composition and decomposition of bodies, passage to the gaseous state, specific heat, equilibrium of heat, its more or less easy transmission, its constancy in experiments with the calorimeter - could be explained by this hypothesis. But it would be DIFFICULT TO EXPLAIN WHY, IN THE DEVELOPMENT OF MOTIVE POWER BY HEAT, A COLD BODY IS NECESSARY; why, in consuming the heat of a warm body, motion cannot be produced." http://www.nd.edu/~powers/ame.20231/carnot1897.pdf

Generally, a cold body is not necessary, that is, the second law of thermodynamics is false. The cold body is only TECHNOLOGICALLY necessary as it makes heat engines fast-working. Heat engines working under isothermal conditions (in the absence of a cold body) are commonplace but are too slow and impuissant to be of any technological importance. Except, perhaps, for the case where water is placed in an electric field - the non-conservative force (pressure) that emerges between the cathode and the anode, able to convert ambient heat into work, seems to be quite vigorous:

Wolfgang K. H. Panofsky, Melba Phillips, Classical Electricity and Magnetism, pp.115-116: "Thus the decrease in force that is experienced between two charges when they are immersed in a dielectric liquid can be understood only by considering the effect of the PRESSURE OF THE LIQUID ON THE CHARGES themselves." http://www.amazon.com/Classical-Electricity-Magnetism-Second-Physics/dp/0486439240?tag=viglink21401-20

"However, in experiments in which a capacitor is submerged in a dielectric liquid the force per unit area exerted by one plate on another is observed to decrease... [...] This apparent paradox can be explained by taking into account the DIFFERENCE IN LIQUID PRESSURE in the field filled space between the plates and the field free region outside the capacitor." http://farside.ph.utexas.edu/teaching/jk1/lectures/node46.html

Tai Chow, Introduction to Electromagnetic Theory: A Modern Perspective, p. 267: "The strictly electric forces between charges on the conductors are not influenced by the presence of the dielectric medium. The medium is polarized, however, and the interaction of the electric field with the polarized medium results in an INCREASED FLUID PRESSURE ON THE CONDUCTORS that reduces the net forces acting on them." http://www.amazon.com/Introduction-To-Electromagnetic-Theory-Perspective/dp/0763738271

Liquid Dielectric Capacitor


"The Formation of the Floating Water Bridge including electric breakdowns"


Pentcho Valev
Pentcho Valev
2017-11-17 22:48:56 UTC
Réponse
Permalink
Raw Message
NON-ISOTHERMAL heat engines - apparently do not violate the second law of thermodynamics:

Loading Image...

"All materials react to heat in some way. But this new shape-changing polymer reacts to temperatures as small as the touch of human skin to contract - in the process lifting as much as 1,000 times its own weight." http://gizmodo.com/this-new-shape-changing-polymer-can-lift-1-000-times-it-1759165438

"Stretchy Science: A Rubber Band Heat Engine. Learn how a rubber band can turn heat into mechanical work with this simple activity. [...] Your blow dryer essentially turned your rubber band into a heat engine - a machine that turns thermal energy into mechanical work." https://www.scientificamerican.com/article/bring-science-home-rubber-band-heat/

ISOTHERMAL analogs - pH-sensitive polymers - do violate the second law of thermodynamics:

"pH sensitive or pH responsive polymers are materials which will respond to the changes in the pH of the surrounding medium by varying their dimensions. Materials may swell, collapse..." https://en.wikipedia.org/wiki/PH-sensitive_polymers

Loading Image...

"When the pH is lowered (that is, on raising the chemical potential, μ, of the protons present) at the isothermal condition of 37°C, these matrices can exert forces, f, sufficient to lift weights that are a thousand times their dry weight." http://www.google.com/patents/US5520672

A. KATCHALSKY, POLYELECTROLYTES AND THEIR BIOLOGICAL INTERACTIONS, p. 15, Figure 4: "Polyacid gel in sodium hydroxide solution: expanded. Polyacid gel in acid solution: contracted; weight is lifted." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367611/pdf/biophysj00645-0017.pdf

The following four-step isothermal cycle, if carried out quasi-statically (reversibly), clearly violates the second law of thermodynamics:

1. The polymer is initially stretched. The operator adds hydrogen ions (H+) to the system. The force of contraction increases.
2. The polymers contracts and lifts a weight.
3. The operator removes the same amount of H+ from the system. The force of contraction decreases.
4. The operator stretches the polymer and restores the initial state of the system.

The net work extracted from the cycle is positive unless the following is the case:

The operator, as he decreases and then increases the pH of the system (steps 1 and 3), does (loses; wastes) more work than the work he gains from weight-lifting.

However electrochemists know that, if both adding hydrogen ions to the system and then removing them are performed quasi-statically, the net work involved is virtually zero (the operator gains work if the hydrogen ions are transported from a high to a low concentration and then loses the same amount of work in the backward transport). That is, the net work involved in steps 1 and 3 is zero, and the net work extracted from steps 2 and 4 is positive, in violation of the second law of thermodynamics.

Pentcho Valev
Pentcho Valev
2017-11-18 07:55:44 UTC
Réponse
Permalink
Raw Message
If a catalyst affects the forward and the reverse reactions differently - e.g. accelerates the one more than the other and so shifts the chemical equilibrium - the second law of thermodynamics is violated. Wikipedia explains why in the following idiotic way:

Wikipedia: "The second law of thermodynamics describes why a catalyst does not change the chemical equilibrium of a reaction. Suppose there was such a catalyst that shifted an equilibrium. Introducing the catalyst to the system would result in a reaction to move to the new equilibrium, producing energy. Production of energy is a necessary result since reactions are spontaneous only if Gibbs free energy is produced, and if there is no energy barrier, there is no need for a catalyst. Then, removing the catalyst would also result in reaction, producing energy; i.e. the addition and its reverse process, removal, would both produce energy. Thus, a catalyst that could change the equilibrium would be a perpetual motion machine, a contradiction to the laws of thermodynamics." https://en.wikipedia.org/wiki/Catalysis

As a result of the idiotic education, nobody - not even the editors of Nature - knows that the second law is straightforwardly violated in this case:

Loading Image...

Yu Hang Li et al. Unidirectional suppression of hydrogen oxidation on oxidized platinum clusters https://www.nature.com/articles/ncomms3500

Pentcho Valev

Loading...