Células De Alta Eficiencias

High-efficiency series-cell electrolyzer
tero.ranta@bigfoot.com
Ver 1.2 2nd June 2006

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Electrolyzer
The electrolyzer shown in Figure 1 is based on the common-duct series-cell electrolyzer concept
originally developed and patented by William Rhodes, Ernest Spirig, Yull Brown and later refined
by Bob Boyce, George Wiseman, etc… It uses an alkaline (NaOH, KOH) electrolyte to splitdistilled
water into hydrogen and oxygen components very efficiently.
The produced hydrogen and oxygen gasses are not separated to separate containers, but kept
mixed. The produced oxyhydrogen gas is a stoichiometric mixture of hydrogen (2 parts vol.) and
oxygen (1 part vol.) and can be combusted in vacuum.
The combination of series-cell topology is very efficient, because it allows the cellsto operate as
close to their optimal cell voltage (1.47V) as possible. The electrolyzer runs fairly cool, at about 3050 C depending on the current and electrolyte.
The electrolyzer shown in this report has about 80-90% total efficiency when all things are
considered (ambient temperature, ambient pressure, accurate measurement of gas volume and
current) when powered by straight DC. Pulsing(PWM) or modulation of the input voltage waveform
could increase the performance further, as it is known that in the beginning of each pulse larger
current flows than in the steady state condition, thus lowering the cell voltage needed to push thru
a certain amount of current and increasing the efficiency slightly. There are also claims of various
resonance phenomena (Boyce, Meyer, etc.) thatsupposedly dramatically increase the gas
production rate vs. input current when the electrolyzer is driven with a certain type of PWM rich in
harmonics. However, this author has not been able to replicate any resonance modes in any sort
of electrolyzer.
The electrolyzer has 7 cells with a target input voltage of about 12.9-14.1Vdc depending on
temperature. This makes the cell voltage about1.85-2.0V.

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+12..14Vdc @
5-10A

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Plate spacing 3mm, active plate
area ~170cm^2 per side
Gas vent hole
in each plate
Gas output, water
input valve
Electrolyte level ~20mm
below gas vent hole
PVC end plate
Stainless steel
electrodes

Electrolyte in each compartment is practically
isolated from other compartments, but there
are 3mm diameter electrolyte level
equalization holesdrilled in the bottom
corner of each plate (staggered)

Soft transparent
PVC spacers rings

Figure 1. Series cell electrolyzer cross-section

Electrolyzer construction
The eight electrolyzer plates (Figure 2) are about 0.8mm thick 160mm x 200 mm stainless steel
(304 grade). A 10mm gas vent hole is drilled in each plate. The electrolyte level is always about
25mm below the gas venthole. There are 3mm diameter liquid level equalization holes drilled in
the bottom corner of each plate (not shown) in such a way that adjacent plates have holes in
opposite corners. Staggering and using small holes minimizes any efficiency loss due to current
leakage between cells, but makes electrolyte refilling and level equalization significantly easier.
The two end plates have a small SSpiece welded for electrical contact. After taking the picture the
plates were sanded with an orbital sander to expose clear metal and then cross-hatch pattern was
“engraved” on the plates with a rough file attached to a wooden block. This is to increase the active
surface area of the plates and seems necessary for ultra high efficiency. Other methods to
increase plate area exist as well.Figure 2. Stainless steel electrolyzer plates (8 total)

Nine spacers (Figure 3) were cut out of 3mm thick soft and transparent PVC sheet with a knife.
The wall thickness is 12mm. The PVC sheet is originally designed for door material for large roomsize refrigerators. The small square PVC blocks were meant to keep proper distance between SS
plate centers, but they turned out to be unnecessary and...