Moreno

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  1. Thermoelectric effects in metals

    No, it is not.
  2. Thermoelectric effects in metals

    How can it be explained that Platinum has the smallest Seebeck coefficient among pure metals which is conditionally taken for zero? https://en.wikipedia.org/wiki/Seebeck_coefficient#Definition
  3. Thermoelectric effects in metals

    Well, obviously I meant: "all the valence electrons are free". Though this is a rude approximation.
  4. It seems that some thermoelectric effects (such as Seebeck and Peltier effects) can be associated with carriers (electrons and holes) generation and recombination. But thermoelectric effects can be observed in many metals as well, not only in semiconductors. Can there be such effects as carrier generation and recombination in metals? It doesn't seem to be possible as all electrons in metals are typically free electrons even at 0 K, at elevated temperatures all the more so. How then could there be an electron-hole recombination in metals? For example in Bismuth, Antimony, etc.?
  5. Fermi energy and batteries

    Why there exist a large discrepancy between electrochemical potentials (Fermi levels) and standard electrode potentials? For example difference of Fermi energies between Sodium (3.24 eV) and Aluminum (11.7 eV) is larger than between Sodium and Copper (7 eV). http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/fermi.html#c1 However if we look at standard electrode potentials we will see that potential difference between Sodium (-2.71 V) and Copper (+0.33 V) is much larger than between Sodium (-2.7 V) and Aluminum (-1.6). https://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page) So, if we take in account difference between electrochemical potentials (Fermi levels) we would expect that reaction between Sodium and Aluminum will give us much more energy than reaction between Sodium and Copper. But if we look at standard electrode potentials we would expect otherwise. How can we explain it?
  6. Some solvation reactions are quite energetic (either endothermic or exothermic). Does it allow us to create an energy storage (similar to battery) in which energy would be generated when metal atoms pass to a solution through an ion-conducting membrane? If yes, how much energy may we expect to obtain and what about reverse-ability?
  7. I think that a fundamental physical laws similar to "energy conservation law" can be perceived on intuitive level only, no any algebra can be attempted to prove or disprove them. This is just a completely wrong approach. The laws of that kind as majority of other fundamental physical notions are rather philosophical than mathematical categories. And therefore belong to the realm of philosophy (and metaphysics).
  8. Do you routinely stop participating in threads when you've been handed your ass? When may I expect a proper response to my repeated queries in the thread on planetary energy? Too frightened to continue discussion?

    1. StringJunky

      StringJunky

      What do you want him to do, capitulate and preen your ego? :P 

    2. hypervalent_iodine

      hypervalent_iodine

      Area54, I hardly think this is appropriate. Please use your better judgement when engaging with members here, and refrain from acting so hostile.

  9. Fast breeder reactors

    FLiBe is a molten salt made from a mixture of lithium fluoride (LiF) and beryllium fluoride (BeF2). It is both a nuclear reactor coolant and solvent for fertile or fissile material. It served both purposes in the Molten-Salt Reactor Experiment (MSRE). https://en.wikipedia.org/wiki/FLiBe During reactor operation Beryllium and Lithium are converted to other chemical elements by process of nuclear mutation, it seems.
  10. Fast breeder reactors

    Sure, you can discuss them. Or any other kind of nuclear reactors. If I no make mistake LFTR's use thermal neutron spectrum rather than fast neutrons? What is bad about LFTR, I think, is they waste Lithium and Beryllium - a valuable metals. And other expenses are huge. I think accelerator driven reactors look more attractive.
  11. Fast breeder reactors

    Not necessarily. For example this article describes a method of solid state refrigeration which doesn't involve a semiconductors. Word "solid state" in technics typically means there are no gases, liquids, or mechanicaly moving parts involved. http://journals.sagepub.com/doi/abs/10.1243/0954406042369062?journalCode=picb Direct charging generators[edit] In the first type, the primary generator consists of a capacitor which is charged by the current of charged particles from a radioactive layer deposited on one of the electrodes. Spacing can be either vacuum or dielectric. Negatively charged beta particles or positively charged alpha particles, positrons or fission fragments may be utilized. Although this form of nuclear-electric generator dates back to 1913, few applications have been found in the past for the extremely low currents and inconveniently high voltages provided by direct charging generators. Oscillator/transformer systems are employed to reduce the voltages, then rectifiers are used to transform the AC power back to direct current. English physicist H.G.J. Moseley constructed the first of these. Moseley’s apparatus consisted of a glass globe silvered on the inside with a radium emitter mounted on the tip of a wire at the center. The charged particles from the radium created a flow of electricity as they moved quickly from the radium to the inside surface of the sphere. As late as 1945 the Moseley model guided other efforts to build experimental batteries generating electricity from the emissions of radioactive elements. https://en.wikipedia.org/wiki/Atomic_battery#Direct_charging_generators
  12. Fast breeder reactors

    No macroscopic quantities of liquid or gas inside of reactor is needed.
  13. Fast breeder reactors

    I've already mentioned how. Some substances, such as boron-10 are capable to capture neutrons, convert to Lithium and radiate protons. Proton radiation subsequently can be easily converted to electricity with help of electrostatic converter. In this way no liquid or gaseous heat carrier is needed, potentially.
  14. Fast breeder reactors

    I suggested a possibility that fast neutron reactors can be made solid state. For now no such reactor exist.
  15. Fast breeder reactors

    I think that at the present and near future level of technology solar and wind power can be regarded only as a supplemental type of power generation only. First of all, Sun and wind are intermittent and if more than 50% of power will be generated in this way, this intermittence may lead to an unpredictable, possibly even catastrophic consequences. Secondly, it requires too much expensive and sometimes rare materials. A typical nuclear power plant has 1 GWt output. Usually it includes a few nuclear reactors. And here is the size of a wind turbine which allows to generate just 10 MW of energy. And you will need to build at least 100 of those monsters to provide 1 GWt. But wind practically never blows all the time with the same strength, so this number will unavoidably grow to at least 200. Possibly even more. And each of this monsters requires tons of copper and neodymium for electric motors, hundreds of tons of aluminum and high grade stainless steel, etc. Some of this materials aren't particularly common. The price of this enterprise will unavoidably start to grow exponentially when all the World will start to build them on mass scale.