Author Topic: electric field screening  (Read 15836 times)

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Re: electric field screening
« Reply #32 on: July 15, 2013, 12:41:29 pm »
Hydrogen Fuel Cell

Hydrogen and oxygen can be combined in a fuel cell to produce electrical energy. A fuel cell uses a chemical reaction to provide an external voltage, as does a battery, but differs from a battery in that the fuel is continually supplied in the form of hydrogen and oxygen gas. It can produce electrical energy at a higher efficiency than just burning the hydrogen to produce heat to drive a generator because it is not subject to the thermal bottleneck from the second law of thermodynamics. It's only product is water, so it is pollution-free. All these features have led to periodic great excitement about its potential, but we are still in the process of developing that potential as a pollution-free, efficient energy source (see Kartha and Grimes).

(http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/fuelcell.gif)
Combining a mole of hydrogen gas and a half-mole of oxygen gas from their normal diatomic forms produces a mole of water. A detailed analysis of the process makes use of the thermodynamic potentials. This process is presumed to be at 298K and one atmosphere pressure, and the relevant values are taken from a table of thermodynamic properties.

Quantity   
H2
0.5 O2
H2O
Change
Enthalpy   
0
0
-285.83 kJ
ΔH = -285.83 kJ
Entropy   
130.68 J/K
0.5 x 205.14 J/K
69.91 J/K
TΔS = -48.7 kJ
Energy is provided by the combining of the atoms and from the decrease of the volume of the gases. Both of those are included in the change in enthalpy included in the table above. At temperature 298K and one atmosphere pressure, the system work is

W = PΔV = (101.3 x 103 Pa)(1.5 moles)(-22.4 x 10-3 m3/mol)(298K/273K) = -3715 J
Since the enthalpy H= U+PV, the change in internal energy U is then

ΔU = ΔH - PΔV = -285.83 kJ - 3.72 kJ = -282.1 kJ
The entropy of the gases decreases by 48.7 kJ in the process of combination since the number of water molecules is less than the number of hydrogen and oxygen molecules combining. Since the total entropy will not decrease in the reaction, the excess entropy in the amount TΔS must be expelled to the environment as heat at temperature T. The amount of energy per mole of hydrogen which can be provided as electrical energy is the change in the Gibbs free energy:

ΔG = ΔH - TΔS = -285.83 kJ + 48.7 kJ = -237.1 kJ
For this ideal case, the fuel energy is converted to electrical energy at an efficiency of 237.1/285.8 x100% = 83%! This is far greater than the ideal efficiency of a generating facility which burned the hydrogen and used the heat to power a generator! Although real fuel cells do not approach that ideal efficiency, they are still much more efficient than any electric power plant which burns a fuel.

Comparison of electrolysis and the fuel cell process
In comparing the fuel cell process to its reverse reaction, electrolysis of water, it is useful treat the enthalpy change as the overall energy change. The Gibbs free energy is that which you actually have to supply if you want to drive a reaction, or the amount that you can actually get out if the reaction is working for you. So in the electrolysis/fuel cell pair where the enthalpy change is 285.8 kJ, you have to put in 237 kJ of energy to drive electrolysis and the heat from the environment will contribute TΔS=48.7 kJ to help you. Going the other way in the fuel cell, you can get out the 237 kJ as electric energy, but have to dump TΔS = 48.7 kJ to the environment.

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Re: electric field screening
« Reply #33 on: July 15, 2013, 12:46:30 pm »
Electrolysis of Water

By providing energy from a battery, water (H2O) can be dissociated into the diatomic molecules of hydrogen (H2) and oxygen (O2). This process is a good example of the the application of the four thermodynamic potentials.

(http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/imgheat/electrol.gif)
The electrolysis of one mole of water produces a mole of hydrogen gas and a half-mole of oxygen gas in their normal diatomic forms. A detailed analysis of the process makes use of the thermodyamic potentials and the first law of thermodynamics. This process is presumed to be at 298K and one atmosphere pressure, and the relevant values are taken from a table of thermodynamic properties.

Quantity   
H2O
H2
0.5 O2
Change
Enthalpy   
-285.83 kJ
0
0
ΔH = 285.83 kJ
Entropy   
69.91 J/K
130.68 J/K
0.5 x 205.14 J/K
TΔS = 48.7 kJ
The process must provide the energy for the dissociation plus the energy to expand the produced gases. Both of those are included in the change in enthalpy included in the table above. At temperature 298K and one atmosphere pressure, the system work is

W = PΔV = (101.3 x 103 Pa)(1.5 moles)(22.4 x 10-3 m3/mol)(298K/273K) = 3715 J
Since the enthalpy H= U+PV, the change in internal energy U is then

ΔU = ΔH - PΔV = 285.83 kJ - 3.72 kJ = 282.1 kJ
This change in internal energy must be accompanied by the expansion of the gases produced, so the change in enthalpy represents the necessary energy to accomplish the electrolysis. However, it is not necessary to put in this whole amount in the form of electrical energy. Since the entropy increases in the process of dissociation, the amount TΔS can be provided from the environment at temperature T. The amount which must be supplied by the battery is actually the change in the Gibbs free energy:

ΔG = ΔH - TΔS = 285.83 kJ - 48.7 kJ = 237.1 kJ
Since the electrolysis process results in an increase in entropy, the environment "helps" the process by contributing the amount TΔS. The utility of the Gibbs free energy is that it tells you what amount of energy in other forms must be supplied to get the process to proceed.

Reverse process: Hydrogen fuel cell

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Re: electric field screening
« Reply #34 on: July 16, 2013, 06:07:01 am »
I just made a calculation based on this numbers

237,1Kj = 65,89W If you divide this by 2 mols of electrons (+-53,6 Amps)  than you get the voltage 1,23v would be required to give this electrical energy

now

285Kj = 79,16W    divided by 53,6 Amps the voltage is 1,48V 

« Last Edit: July 16, 2013, 17:37:54 pm by sebosfato »

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Re: electric field screening
« Reply #35 on: July 16, 2013, 14:16:42 pm »
has anybody ever used 100kV pulses to dissociate water ??

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Re: electric field screening
« Reply #36 on: July 16, 2013, 17:45:12 pm »
The only chance i got to place high voltage on water was when i:

Used ultra high purity water   (up to 2kv straight to the water cell)

Used mylar foils rolled around the electrode     (here vapor was generated applying 40kv at certain frequency) the vapor came out from the inter mylar layers)

Used corona dope coating on the electrodes.    No result at all

Used wax   No   results at all

Using deionized water i think i could get up to at least 800V

Using resonance i could make two cells get up to 20 amps thru where there was 600v at the resonant tank at 16khz    the coils was big thick wire, about 1mH

 


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Re: electric field screening
« Reply #37 on: July 16, 2013, 20:34:15 pm »
I think with 55kV water vapor will explode according to the "theory" I told you can you verify using the formula I gave 3 pages back because my calculations gave a weird result?  post #24
« Last Edit: July 16, 2013, 20:49:26 pm by geon »

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Re: electric field screening
« Reply #38 on: July 16, 2013, 22:23:24 pm »
Geon:

...with regards to voltages across the cell, currently I'm getting higher voltages across the plates by smearing dielectric sparkplug grease on the plates and using RO water with 100,000uf of caps connected in parallel.

believe it or not the grease even with a 1/8 inch layer makes gas at below 100ma...

the stuff is supposed to stop electrical shorts when covering automobile electrical components yet it appears to work somehow on the plates for more gas at higher voltages...

kb

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Re: electric field screening
« Reply #39 on: July 18, 2013, 02:24:38 am »
what if tay he han was a collaborator of meyer responsible to patent the restriction of the amps only technology? just to fool everyone ?

Look at the year the patents came out!

Or maybe meyer copied tay he han ideas and improved them?

Meyer circuits seems to be exactly the needed equipment for making the thing happens in terms of system operability!