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Low Temperature Thermionic Energy Harvester

Thermionic Emission with nanofluids

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Energy scarcity is at the root of many of the problems humanity now faces. This project explores a bleeding-edge concept in energy harvesting involving thermionics and nanoparticles. Claims in the existing literature usually say this technology works as a standard thermionic device [1]. This project is largely to check that assertion.

It is intended as an affordable and simple-as-possible experiment so that almost anyone can test the concept. Files, instructions and component lists are included here and also on Github.

This work is licensed under a Creative Commons Attribution 4.0 International License.
https://creativecommons.org/licenses/by/4.0/

This project will investigate four possible means of avoiding the second law of thermodynamics:

  1. Room Temperature thermionic devices
  2. Bipolar membrane devices
  3. High Temperature thermionic devices
  4. Magnetic devices utilizing attractors in nonlinear phase space and/or the concept of "second sound"

We will also discuss mesoscopic devices like the Graphene Energy Harvester and an analogous system using a superparamagnetic particle and a micron-scale pickup coil, but they requre integrated circuit etching technology, so we will not be replicating them here. Some hackers have built IC etching equipment in their home labs and we encourage them to try these.

Note I say avoiding, not violating, the second law: this is done in a manner analogous to how complex numbers have different properties than real numbers: when you start with a different set of axioms, you arrive at different maths.

In mathematical physics, we try to build models with minimal sets of assumptions. This is because, historically speaking, assumptions and constants have typically been indications of some incomplete understanding of the underlying physics we are attempting to model. The way it is taught today, an introductory student of Thermodynamics could be forgiven for thinking that the laws of thermodynamics are a set of such assumptions, but the second law in particular is based on a set of more fundamental mathematical assumptions, which are in question here.

 Firstly, the second law has an implicit assumption that all states in an ensemble have roughly the same order of magnitude of probability of receiving energy from another state in the ensemble during a small time interval. This assumption is called ergodicity, and if a statistical ensemble is ergodic, energy concentrated in one state will always spread out until the system reaches a steady state, where entropy is maximized. This is why, with the second law, we say entropy tends to increase, or heat flows from hot to cold. Ensembles in thermodynamics have roughly the same mathematical structure as Markov chains, so to put this another way, in order to get the second law of thermodynamics, we have to assume that it is impossible to build an ensemble that behaves like an absorbing (or oscillating) Markov chain.

In standard statistical mechanics there is also the assumption of "weak coupling" undergirding the second law. Weakly coupled quantum systems will tend not to display any correlations between interacting particles or quanta of energy, and such systems lead naturally to ergodicity. But in biology it is known that various enzymes and receptors are specifically not weakly coupled, and in condensed matter physics, the study of "correlated electron matter", where weak coupling should not be assumed, is a sizeable and active field. So if we know of counterexamples here, why not look for counterexamples to ergodicity?

Such a counterexample in and of itself isn't particularly interesting, but let's imagine an ensemble where the absorbing state happens to be a capacitor, or other energy storage system which we know how to harness. Then that capacitor can be periodically tapped for energy, dissipated during work into a second system. If that second system is in thermal contact with the first system, then the energy will eventually get captured again in the absorbing state, where it can be tapped again. Assuming the energy to switch the capacitor behavior is stored upon each discharge in one of the two systems involved, then the combination of the two systems has been engineered to minimize the poincare recurrence time in a predictable and useful way. When one views the systems separately, it appears that work is made available periodically, but when one views these as a single system, I propose we define a new quantity, called "play". If ergodicity is violable, many other interesting possibilities arise

These days, there are an increasing number of apparent counterexamples to the assumption of ergodicity, like...

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  • 2 × gold coated silicon wafer, 4 in. dia
  • 1 × Pepto bismol
  • 1 × silver nitrate
  • 1 × formic acid
  • 1 × acetic acid

View all 13 components

  • Room Temperature Thermionic Device: Assembly and Testing

    Michael Perrone04/06/2023 at 13:26 0 comments

    to be added

    -use coated silicon wafers or carefully sanded surfaces

    -add film with the nanofluid to help the film adhere

    -add 2 micron diamond powder to help prevent shorting

    -enclose device

    -seal with vacuum epoxy

    -assemble DC hotplate

    -test on hotplate, stay below 120C

  • Room Temperature Thermionic Device

    Michael Perrone04/06/2023 at 13:16 0 comments

    Nanoparticle Synthesis

    Thermionic devices are one

    Surfactants Used:

    1. Polysorbate 20
    2. Polysorbate 80
    3. Glycerol Monostearate
    4. Triton X-100
    5. Dodecanol
    6. Dodecanethiol
    7. Lauric Acid
    8. Diaminododecane
    9. Dodecylamine
    10. Brij-L4

    Solubility test in 50 mL water

    1. 0.0161g Dissolved easily
    2. 0.0192g Dissolved with heat
    3. 0.0180g Some dissolved, cloudy
    4. 0.0231g Dissolved with heat
    5. 0.0133g Did not dissolve easily
    6. 0.0163g Did not dissolve easily
    7. 0.0239g Did not dissolve easily
    8. 0.0183g Did not dissolve easily
    9. 0.0134g Some dissolved, cloudy
    10. 0.0155g Some dissolved, cloudy

    Silver Nanoparticle Synthesis:

    Surfactants F and I (Dodecanethiol and Dodecylamine) were eliminated from the proceedings due to air sensitivity.

    Surfactant

    Name

    Molar Mass

    Concentration

    Amount Added to 50 mL

    A

    Polysorbate 20

    1226 (g/mol)

    .0005 M

    30.65 mg

    B

    Polysorbate 80

    1310 (g/mol)

    .0005 M

    32.75 mg

    C

    Glycerol Monostearate

    358.563 (g/mol)

    .0005 M

    8.96 mg

    D

    Triton X-100

    647 (g/mol)

    .0005 M

    16.18 mg

    E

    Dodecanol

    186.34 (g/mol)

    .001 M

    9.32 mg

    F

    Dodecanethiol

    N/A

    N/A

    N/A

    G

    Lauric Acid

    202.3998 (g/mol)

    .001 M

    10.12 mg

    H

    Diaminododecane

    200.37 (g/mol)

    .001 M

    10.02 mg

    I

    Dodecylamine

    N/A

    N/A

    N/A

    J

    Brij-L4

    362.5 (g/mol)

    .0005 M

    9.06 mg

    Table 1: Names and amounts of surfactants used

    For the synthesis of silver nanoparticles, 100 mL of .00025 M silver nitrate solution was prepared. This is enough for each of the different surfactant solutions, as 12.5 mL is used for each of the 8 options.

    For each individual surfactant solution, 50 mL of a .0005 M solution (apart from E, G, and H, which were .001 M) of the surfactant was made with DI water (see table 1 for surfactant quantities). This solution was heated to 70 C to assist in dissolving the surfactant, stirring constantly. Once heated, the solution is put in an ice bath and chilled to 10 C. Upon reaching this temperature, 1.89 mg of sodium borohydride is added to make a solution with .001 M surfactant and .001 M sodium borohydride.

    figure 2: Silver nanoparticles showing the gold/yellow color

    Immediately after the sodium borohydride is added, 12.5 mL of the .00025 M silver nitrate solution is added dropwise at a rate of approx. 1 drop per second, stirring constantly. As the silver nitrate solution is added, the solution turns to a yellow/amber color. The resulting solution is removed from the ice bath and divided into vials. Red, green, and blue lasers were shined through the vials to see the effects of the nanoparticles on the light.

    Bismuth Nanoparticle Synthesis

    To produce bismuth nanoparticles, we first need to make the compounds used in the synthesis. We first obtained Bi powder using Pepto-Bismol. The Pepto-Bismol was evaporated in an oven set to 140 C for approximately 6-10 hours, until all the liquid is gone. Once all the liquid evaporated, the resulting solid was baked in a kiln at 600 C for 2 hours, loosely covered with a lid to prevent evaporation of the bismuth oxide.

    From there, we mixed 37% hydrochloric acid and potassium nitrate, both added in equal weight. To that we added the Bi powder in excess and mixed on hot plate set to 100 C. The container was capped loosely to discourage evaporation while not being put under pressure, in a “poor man’s aqua regia” setup. This is not an optimal mixture, but worked for our purposes.

    To the resulting bismuth nitrate/bismuth chloride, we added sodium hydroxide until the mixture was basic. Once...

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