Discussion:
Isothermal Heat Engines Violate the Second Law of Thermodynamics
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Pentcho Valev
2017-02-12 00:48:40 UTC
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Systems converting heat into work at constant temperature, e.g. that of the surroundings, are commonplace, but, if they can do this CYCLICALLY, they violate the second law of thermodynamics. In other words, they contradict the Kelvin-Planck statement of the second law of thermodynamics:

"The Kelvin-Planck statement (or the heat engine statement) of the second law of thermodynamics states that it is impossible to devise a cyclically operating device, the sole effect of which is to absorb energy in the form of heat from a single thermal reservoir and to deliver an equivalent amount of work. This implies that it is impossible to build a heat engine that has 100% thermal efficiency."

The problem is that the Kelvin-Planck statement is practically unfalsifiable. How can one prove that the forbidden device is possibble after all? By building one and showing it to a jury? But there can be various technological and other reasons (that have nothing to do with the second law of thermodynamics) why the device would not work, and yet it could still be a genuine perpetual-motion machine of the second kind.

Here I am going to convert the above unfalsifiable statement of the second law of thermodynamics into an easily refutable version.

For a closed system (exchanges energy but not matter with the surroundings) the first law of thermodynamics defines the internal energy change, dU, to be:

dU = dQ - dW = dQ - FdX /1/

where dQ is the heat absorbed, dW is the work done by the system on the surroundings, F>0 is the work-producing force and dX is the respective displacement.

Let us consider a system with two work-producing forces, F1 and F2 - here is an oversimplified illustration:

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We assume that the system does work slowly, virtually reversibly. The work done by this system on the surroundings is:

dW = dW1 + dW2 = F1dX1 + F2dX2 /2/

Is W a function of the displacements X1 and X2? If yes, the second law of thermodynamics (Kelvin-Planck version) is obeyed - at the end of any cycle W returns to its initial value and no net work is done on the surroundings.

The following theorem is relevant:

Theorem: W is a function of X1 and X2 if and only if the mixed partial derivatives are equal:


"Mixed Partial Derivatives"

Since F1 and F2 are in fact the first partial derivatives, the theorem can be expressed in the following way:

Theorem: W is a function of X1 and X2, that is, the second law is obeyed, if and only if:

dF1/dX2 = dF2/dX1 /3/

where "d" should be the partial derivative symbol - when X2 varies, X1 is fixed and vice versa.

In terms of our system with two work-producing forces, the Kelvin-Planck version of the second law now states:

EQUIVALENT TO KELVIN-PLANCK VERSION: The partial derivatives dF1/dX2 and dF2/dX1 are equal.

That is, if experiments show that the two sides of /3/ are equal, the second law is confirmed. If, however, experiments unambiguously show that the two sides of /3/ are not equal - e.g. dF1/dX2 is positive and dF2/dX1 negative - the second law of thermodynamics is false and will have to be abandoned.

Consider the so-called "chemical springs". There are two types of macroscopic contractile polymers which on acidification (decreasing the pH of the system) contract and can lift a weight:

http://www.google.com/patents/US5520672
"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.ncbi.nlm.nih.gov/pmc/articles/PMC1367611/pdf/biophysj00645-0017.pdf
POLYELECTROLYTES AND THEIR BIOLOGICAL INTERACTIONS, A. KATCHALSKY, p. 15: "FIGURE 4: Polyacid gel in sodium hydroxide solution: expanded. Polyacid gel in acid solution: contracted; weight is lifted."

Polymers designed by Urry (U) absorb protons as their length, Lu, increases, whereas polymers designed by Katchalsky (K) release protons as their length, Lk, increases. See discussion on p. 11020 in Urry's paper:

http://pubs.acs.org/doi/abs/10.1021/jp972167t
J. Phys. Chem. B, 1997, 101 (51), pp 11007 - 11028, Dan W. Urry, "Physical Chemistry of Biological Free Energy Transduction As Demonstrated by Elastic Protein-Based Polymers". p. 11020: "Stretching causes an uptake of protons" for Urry's polymers, and "stretching causes the release of protons", for Katchalsky's polymers.

Let us assume that two macroscopic polymers, one of each type (U and K) are suspended in the same system. At constant temperature, IF THE SECOND LAW IS TRUE, we must have

dFu / dLk = dFk / dLu

where Fu>0 and Fk>0 are work-producing forces of contraction. The values of the partial derivatives dFu/dLk and dFk/dLu can be assessed from experimental results reported on p. 11020 in Urry's paper. As K is being stretched (Lk increases), it releases protons, the pH decreases and, accordingly, Fu must increase. Therefore, dFu/dLk is positive. In contrast, as U is being stretched (Lu increases), it absorbs protons, the pH increases and Fk must decrease. Therefore, dFk/dLu is negative. One partial derivative is positive, the other negative: this shows that the second law of thermodynamics is false.

Pentcho Valev
Pentcho Valev
2017-02-12 22:50:16 UTC
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http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.205.5763&rep=rep1&type=pdf
I. BREVIK, EXPERIMENTS IN PHENOMENOLOGICAL ELECTRODYNAMICS AND THE ELECTROMAGNETIC ENERGY-MOMENTUM TENSOR, pp. 143-144: "We shall first give some supplementary comments on the well known situation shown in fig. 1, where two parallel condenser plates are partially immersed in a dielectric liquid. When a horizontal electric field E is applied between the plates, the liquid will rise within the condenser to some equilibrium height h. [...] What makes the liquid rise between the plates? Certainly not the electrostriction force."

But the rising dielectric liquid can do useful work, e.g. by lifting some floating weight, and the crucial question is: At the expense of what energy is the work done? Since, by switching the field on and off, we do no work on the system, the energy supplier can only be the ambient heat. That is, the system can cyclically lift floating weights at the expense of heat absorbed from the surroundings, in violation of the second law of thermodynamics.

More illustrations:


Rise in Liquid Level Between Plates of a Capacitor


Liquid Dielectric Capacitor


Chapter 11.6.2: Force on a liquid dielectric

Pentcho Valev
Pentcho Valev
2017-02-14 19:47:55 UTC
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"Recently, its scientists, working with European Thermodynamics Ltd, created low-cost thermoelectric materials that could be used to capture heat from automobiles and convert it into electricity. That electricity can then be used to recharge the batteries in hybrid, plug-in hybrid, and electric cars to give them more range. The team - led by Prof Ian Kinloch, Prof Robert Freer, and Yue Lin - added a small amount of graphene to strontium titanium oxide. The resulting composite was able to convert heat that would otherwise be wasted into an electric current over a broad temperature range, beginning at room temperature. Previously, thermoelectric materials only functioned at extremely high temperatures around 700 degrees Celsius." http://gas2.org/2015/08/24/graphene-converts-heat-electricity/

"Beginning at room temperature" means that the device can convert heat into electricity isothermally, in violation of the second law of thermodynamics. Here are similar reports:

http://scitation.aip.org/content/aip/journal/apl/103/16/10.1063/1.4825269
Electricity generated from ambient heat across a silicon surface, Guoan Tai, Zihan Xu, and Jinsong Liu, Appl. Phys. Lett. 103, 163902 (2013): "We report generation of electricity from the limitless thermal motion of ions across a two-dimensional (2D) silicon (Si) surface at room temperature. [...] ...limitless ambient heat, which is universally present in the form of kinetic energy from molecular, particle, and ion sources, has not yet been reported to generate electricity. [...] This study provides insights into the development of self-charging technologies to harvest energy from ambient heat, and the power output is comparable to several environmental energy harvesting techniques such as ZnO nanogenerator, liquid and gas flow-induced electricity generation across carbon nanotube thin films and graphene, although this remains a challenge to the second law of thermodynamics..."

http://arxiv.org/abs/1203.0161
Self-Charged Graphene Battery Harvests Electricity from Thermal Energy of the Environment, Zihan Xu et al: "Moreover, the thermal velocity of ions can be maintained by the external environment, which means it is unlimited. However, little study has been reported on converting the ionic thermal energy into electricity. Here we present a graphene device with asymmetric electrodes configuration to capture such ionic thermal energy and convert it into electricity. [...] To exclude the possibility of chemical reaction, we performed control experiments... [...] In conclusion, we could not find any evidences that support the opinion that the induced voltage came from chemical reaction. The mechanism for electricity generation by graphene in solution is a pure physical process..."


"The Super Supercapacitor"

Pentcho Valev
Pentcho Valev
2017-02-16 14:47:42 UTC
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Violations of the second law of thermodynamics would be commonplace if it were not for misleading education of this kind:

http://physics.bu.edu/~duffy/py105/Heatengines.html
"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."

This is simply not true. There are heat engines functioning in isothermal conditions - e.g. the work-producing force is activated by some chemical agent, not by heating. I have already described macroscopic contractile polymers which, on adding acid (H+) to the system, develop a huge work-producing force, contract and light a weight:

Loading Image...

All isothermal heat engines, except for those which do not differ essentially from ideal gas systems, can violate the second law of thermodynamics. However, under isothermal conditions, the heat that is to be converted into work is supplied extremely slowly - a major hurdle that prevents not only technological applications but also convincing demonstrations of the violation.

Pentcho Valev

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