At 11:11 PM 11/27/4, Harry Veeder wrote:
>Hi,
>
>This is my first post.
>
>I was wondering if anyone in CF community has looked for evidence of a
>correlation between the orientation of a CF cell and the amount of excess
>heat produced.
>
>Perhaps the performance of a CF cell would change if the cell or some of its
>parts were rotated 90 degrees or even spun.
>
>This questions are based on the speculation that the direction of gravity
>(rather than the magnitude of gravity) may effect the performance of CF
>cells.
>
>Harry Veeder
In replying to your query earlier I should have noted that centrifugal
force can be used to improve electrolysis in general. For example, the
following is a post of mine from 2003:
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
ELECTROLYSER DESIGN
The following is a proposed design and some design considerations for a
high efficiency electrolyser, especially one where the cathode and anode
gasses can be provided as a mixed product, or gas only evolves from one
plate. Further, a means is provided to place ordinary hydrogen
electrolysis in these categories by extracting the hydrogen directly
through the cathode.
It is well known that reducing plate separation, in order to reduce cell
resistance, is required to increase existing cell efficiency. It is also
known that slow bubble evolution limits the closeness of plates due to the
reduction of plate area and effective current path area. Electrolysers
currently rely on gravity to remove their bubbles using displacement
forces, but reduce the bubble formation rate by operating at high pressure.
One method suggested here to solve the bubble problem is to place the
plates in a rotatable centrifugal tank as shown in Fig. 1. (Fixed
proportion font like "courier" is required for viewing Fig. 1) The plates
are thus in annular coaxial form with central circular holes with radial
spokes connected to a central shaft, with insulating spacers and/or axial
bolts included to hold the plate array together. This use of a centrifugal
force on the rotating plates permits the effectiveness of removing bubbles
to be increased by two or more orders of magnitude over the use of gravity.
The process is made continuous by replenishing the electrolyte and
retrieving the evolved gas through a central open space in the centrifuge
and/or through piping in a hollow central rotor shaft. During rotation,
the electrolyte is pinned to the outer walls of the cylindrical tank by
centrifugal force.
--------- I --------- KEY:
| <- . I . -> |
| ===== . I . ===== | -| - rotating electrolyser tank
| ===== . I . ===== | .. - rotating electrolyte level
| ===== . I . ===== | == - rotating electrolytic plates
| ===== . I . ===== | I - central rotor shaft
| ===== . I . ===== | -> - direction of electrolyte flow
| ===== . I . ===== |
| ===== . I . ===== |
| <- . I . -> |
-----------I-----------
Fig. 1 - Centrifugal Electrolysis Device
By placing the entire apparatus inside a pressure vessel, with appropriate
plumbing and electrical connections, and temperature control, operation can
occur at high temperatures and pressures currently in use with high
efficiency electrolysers.
The use of bubble scrubbing dielectric particles in the electrolyte is
feasible in this configuration due the pumping action of the electrolyte
through the plates due to the displacement force of the bubbles. The
electrolyte flow between the plates is thus toward the central shaft, and
the flow outside the plate region is axially away from the central rotor
shaft as shown by arrows in Fig. 1. The largest dimension of such
particles should be about one fourth the plate separation distance.
Using the methods described here, plate separation can be made almost
arbitrarily close, but plate thickness itself is increased due to the need
for plate structural strength and diffusion requirements.
When electrolysing hydrogen, use can be made of a diffuse or porous
(essentially transparent to hydrogen) but structurally strong material as
a supporting structure for a Pd surfaced cathode in the centrifuge. Such a
material can be made by sintering metal or ceramic granules of the size
required for the support of the Pd. A gradation of granularity can be made
to occur, with the finest granularity located at the cathode surface, just
below the palladium surface. The Pd coated cathode's interior would then
either be hollow or very porous, so as to conduct the H2 gas away from the
electrolyser directly through the plate interior and then through a hollow
supporting structure (e.g. spokes) for the plate, and to a hollow central
rotor. In this manner, only O2 would evolve between the plates. The
hydrogen principally is driven into the cathode interior by the high
operating pressure, but also by the electrolytic potential.
The electrolytic plates in the suggested use act as cathode on one side and
anode on the other. Therefore a sandwich style construction is suggested.
The anode side might be stainless steal, possibly with an exterior platinum
plating for longer anode life. A space between the anode side and cathode
side of the electrode can be made by using conductive spacers that permit
free flow of hydrogen through the electrode to the central shaft. A seal
zone around the perimeter of the electrode, and between the anode and
cathode portion, can seal out electrolyte and seal in the hydrogen. Bolts
parallel to the main shaft that hold the electrode array together have to
be insulated and their entry and exit points sealed from the interior
hydrogen space.
If momentary reverse emf pulses are used in order to disrupt the
electrolyte interface, then a high enough pressure will have to be used to
avoid significant out gassing of the hydrogen from the cathode during those
brief periods. It is not known if this specific out gassing prevention
method is workable. However, any out gassing at all can be expected to
momentarily disrupt the interface, so may assist in providing the intended
effect. Operating at high temperatures and nearly boiling conditions
further places the interface under disruptive stresses, thus reducing the
electrical energy required to achieve electrolysis. It is not known what
percentage of the hydrogen can be adsorbed, because a film of water between
the hydrogen bubble and the electrode could prevent adsorption. Even
though full adsorption may not take place, it would be very useful if
enough could be adsorbed that the remaining mixed gas is difficult to
ignite or explode.
H2 flows easily through thin Pd foil at a moderate pressure and the high g
force of a centrifuge certainly provides sufficient pressure.
It may be that a porous cathode surface provides the best alternative for
removing hydrogen directly at the cathode surface, or a combination of
adsorption and porous extraction can be used. In this mode, a negative
pressure must be applied to the interior of the cathode via the spokes via
the central shaft. This negative pressure then sucks both hydrogen and to
some degree electrolyte and water vapor or steam through the pores and out
the spokes and out the central shaft. Appropriate bearings and fittings are
then needed on the shaft to send the hydrogen-electrolyte mixture sucked
through the cathode interior to an external separator. Alternatively,
separation can occur centrifugally in a separator included on a segment of
the shaft, and the electrolyte returned to the main electrolyte level via
siphoning. In any event, appropriate bearings and fillings are required to
continually deliver hydrogen from the shaft to atmospheric pressure. The
negative pressure applied to the interior of the shaft can be simply the
ambient pressure of one atmosphere, thus the negative pressure inside the
electrodes is really supplied by operation of the centrifuge at high
pressure. This technique limits the centrifugal force that can be
obtained, because the negative pressure must be sufficient to extract the
hydrogen against the centrifugal force. It may be that gas-electrolyte
separation can be achieved in the interior of the cathode if there is a
break in the seal provided on the outermost tip of the electrode for the
electrolyte to escape. Operation is then dependent upon a good balance of
centrifugal force and operating pressure.
A similar technique of sucking the evolved oxygen into the interior of the
anode might be used as well. A barrier between the O2 and H sides of the
interior them must be supplied as well as separate paths and liquid-gas
separators within or upon the central shaft, and delivery means from the
rotating shaft to ambient conditions. If gasses are directly extracted by
both cathode and anode surfaces, then no scrubber particles are necessary,
and very limited centrifugal force is useful for the gas-liquid separation.
Perhaps a useful version requiring no centrifugal force at the plates at
all can be implemented!
One way to get power to the electrolytic plates for the electrolysis is to
make a segment, or a segment of the interior, of the central shaft of the
centrifuge a (rotating) transformer core, with linkage to it being magnetic
from an external stationary "C" core that has a primary coil on it. The
linkage between core segments can be achieved by utilizing a small gap
between the core containing segment of the shaft and holes in the C core of
a size to accept the shaft. A secondary coil can then be wrapped about the
segment of the core that rotates, i.e. about the outside of the segment of
the central centrifuge shaft containing the rotating piece of core. The
secondary coil output can then be fed to rectifiers and then to the plates.
As an example, assume a stack of 50 plates and a secondary voltage of 100
V, which gives about 2 V per plate for electrolysis current. There need be
no wiring to the individual plates, only to the outermost two. If it is
desired to superimpose a HF signal on the high current electrolytic
current, then a circuit to do so can be powered by the secondary coil or by
another secondary coil in the same location. The rectifiers, circuitry and
wiring can all be located inside the rotating centrifuge shaft. Thus no
brushes are necessary. It may, however, be cheaper and easier to simply
use brushes. Such brushes would not be located in the electrolyte, but
would be located within an outer pressure vessel, so should work in a
normal fashion. If an explodable hydrogen/oxygen mixture evolves from the
plates, then brushes are highly undesirable.
If it is desired to create hydrogen from rotational kinetic energy, as from
a windmill, then it may be preferable to make a portion of the shaft into a
generator armature. No transformer is then required. No brushes are
required to or from the armature as the energy is delivered to the shaft
itself, though rectification is still required.
A good electrolyte for hydrogen evolution is easily made by making a
saturated lye solution and then diluting 1 part of that with two parts
distilled water.
If the hollow or porous cathode technique described here proves viable in
practice, as combined with high g electrolysis or not, it could have some
significance on worldwide energy supplies and the building of a hydrogen
infrastructure in particular by providing a low technology means of
converting sporadic kinetic energy sources, like wind power, into storable
form.
Regards,
Horace Heffner
