HF AC
V1 o--- ---o V2
| |
OOO
======= T1
OOOOOOO
| | |
i--> | | | <--i
-----M1------- | -------M2-----
| | |
o----C1---------o---------C2----o
| | |
F1 F2 F3
| | |
o---(+)DC1(-)---o---(-)DC2(+)---o
Fig. 1 - Method of superimposing AC signal
on DC electrolysis current
A frequent objective of electrolysis cell designs is to overcome the
DC bias required to push current through the interface layer between
the electrolyte and the electrodes while driving the principle
electrolysis current from an AC source. Figure 1 shows a method of
adding an alternating electrolysis driving current on top of a DC
bias in such a way the principle electrolysis current is driven by
the AC source.
The electrolytic cells in Figure 1 are designated M1 and M2. These
cells can be implemented as series multi-plate cells, so that large
voltages can be applied. DC power supplies DC1 and DC2 provide DC
potential right at the critical voltage level, where cells M1 or M2
just begin to conduct current and thus perform electrolysis. DC1 and
DC2 can contain protection diodes that prevent back current through
them. Filters F1, F2 and F3 isolate the DC power supplies from the AC
while allowing DC to pass These can simply be large inductors. The
center tapped transformer T1 provides current through M1 on one half
phase, and M2 on the other half phase. The core of T1 is not biased
on average by any DC current because any DC currents through the two
secondary windings cancel magnetically. Capacitors C1 and C2 are
provided to complete the AC circuit through the cells.
If M1 is exchanged with C1, and M2 exchanged with C2, in Figure 1,
then it is easy to see that M1 and M2 can be implemented as a single
series multi-plate electrolysis cell with the center plate attached
to the center tap of T1, thus avoiding multiple electrolysis cell
containers, gas feeds, etc.
Note that the voltage applied in the secondaries of T1 are
*incremental* to the voltage supplied by the DC power supplies. Note
also that, except for electrolysis cell internal resistance, the
active AC elements of the circuit are inductances or capacitances,
providing as large a phase angle as possible.
The HF AC power supply is driven at the LC resonance frequency for
the AC portion of the circuit. A tuning capacitor or inductor in
either the M1 or M2 half of the circuit may be useful to match
resonant frequencies for both sides of the circuit.
Figure 2 shows a half circuit version of Figure 1, which lacks the
balance of the circuit in Figure 1, but which may be useful if the HF
AC power supply can handle the current imbalance and an air core
transformer is used for T1, or a transformer not operating near
saturation and thus not adversely affected by DC current through the
secondary.
HF AC
V1 o--- ---o V2
| |
OOO
OOOO T1
| |
i--> | |
-----M1------- |
| |
o----C1---------o
| |
F1 F2
| |
o---(+)DC1(-)---o
Fig. 2 - Method of superimposing AC signal
on DC electrolysis current - half circuit
Figure 3 shows the AC portion of the half circuit.
OOOO L1
| |
| |
-----M1------- |
| |
o----C1---------o
Fig. 3 - AC portion of electrolysis circuit
Part of the electrolysis efficiency provided by using superimposed AC
is provided by the fact the electrolytic cell conducts by two
parallel means: (1) ion current conduction and (2) AC capacitive
conduction. DC can not use the capacitive conduction path through
the cell. By using a superimposed AC current, the current to and
through the electrolyte-electrode interface layer is increased for a
given cell configuration by activating a second conduction pathway
through the electrolyte. The reactance X of a capacitor, the
equivalence to DC resistance, for capacitance C and frequency f is:
X = 1/(2 Pi f C)
When f is in Hz and C in farads then X is in ohms. Therefore, the
higher the frequency and the greater the capacitance the more the AC
current through the capacitive portion of the electrolyte at a given
voltage.
It is notable that all AC current is not Faradaic, i.e. resulting in
electrolysis. Though it passes through the electrolyte to the
interface more easily, some AC current can pass through the two
molecule thick interface without causing electrolysis. However,
since a DC bias is provided, it is expected a high Faradaic ratio can
be achieved.
SOME SAMPLE CALCULATIONS
Water has a dielectric constant of about 50, which is large. If Cm is
the capacitance of the cell M1, then the total capacitance Ct in the
AC portion of the circuit is given by:
Ct = 1/((1/C1) + (1/Cm)) = (C1 Cm)/(C1 + Cm)
For example, if C1 is made equal to Cm then Ct = 0.5 Cm.
The capacitance of a multi-plate electrolysis cell can be determined
by looking at the area Ai and separation Si of each electrolyte gap.
The capacitance Ci of gap i is then
Ci = 50 (8.854 F/m) Ai/Si
So, given plate size of 10 cm by 10 cm and plate separation of 0.1 cm
we have:
Ci = 50 (8.854x10^-12 F/m) (0.1 m)^2 / (0.001 m) = 4.427x10^-9 F
He capacitance Cm of n electrolyte gaps in series is:
Cm = 1/((1/C1) + (1/C2) + ... + (1/Cn))
Given 12 equal sized gaps like the above for Ci we have:
Cm = 1/(12/Ci) = Ci/12 = 3.689x10^-10 F
Using C1 = Cm we have:
Ct = 0.5 Cm = 1.845x10^-10 F
Now to consider a toroidal air core transformer. Assume the conductor
is made of tubing about 0.5 cm diameter. Small radius of the torus is
4 cm. Inner radius of torus is 15 cm. Major radius Mr is thus 19
cm. and outer radius is 23 cm. Total turns N = 45. Coil area A is
about 50 cm^2. Coil conductor length is about 11.3 m. Inductance is
approximated by:
L = u N^2 A (1/Mr) (1.26x10^-6 H)
L = (1) (45^2) (50) (1/(19)) (1.26x10^-6 H)
L = 6.71 mH
Resonant frequency f is
f = 1 / (2 Pi * (L C)^(1/2))
= 1 / (2 * 3.14159 * ((6.71x10^-3 H) * (1.845x10^-10 F))^(1/2))
= 1.43x10^5 Hz = 143 kHz
This frequency may be a bit high to be practical, and certainly
requires good shielding. It appears a ferrite core transformer is
most likely the best option. If the inductance is increased by a
factor of 100 the frequency drops by a factor of 10, so for a 0.671 H
transformer secondary:
f = 14.3 kHz
An alternative means to drop the frequency is to make the plates
larger and use fewer in sequence.
One good thing about using high frequencies is the filters Fi get
cheaper and smaller. Choice of frequency may be important.
Puharich , US Patent 4,394,230 (1983) used a rectified AM signal, and
found resonances in pure water at 3,980 Hz, and octaves 7,960,
15,920, 31840, and 63,690 Hz. It is notable that running all those
octave overtones gives a lazy (triangular half cycle) sawtooth wave.
It has been conjectured that is why Stanley Meyer operated at around
16,000 Hz. Frequencies between 9 kHz and 150 kHz work well.
Horace Heffner
http://www.mtaonline.net/~hheffner/
