Module utilizes static water-feed electrolysis system and air-cooled fins to remove heat generated by cell inefficiencies. Module generates 0.15 pounds of oxygen and 0.0188 pounds of hydrogen at current density of 100 amps per square foot. Generator operates in aircraft, spacecraft, or submarine cabins

Schubert, F. H.

English

NASA Technical Reports Server

June 1971	 Brief 71-10203 
NASA TECH BRIEF 
Ames Research Center
	
_4V 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield; Virginia 22151. Requests for individual copies or questions relating to the. Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Water Electrolysis Module 
Power 
Supply 
e- 
H2 
=	
!—[I
02 
Anode (+) 
Cathode	
—= 
—:	 Electrolyte 
supported 
in Matrix 
Water Feed 
Membrane	
—: 
-	 Case 
[I-Ed 
—:—:—:—:—:—:—:—:--E—:—:—I—i(-'-- H20 
The problem: 
To supply the oxygen requirements of crews by an 
on-site generator which can operate in aircraft, space-
craft, or submarine cabins. 
The solution: 
A module which utilizes a static water-feed electrol-
ysis system and has air-cooled fins to remove the heat 
generated by cell inefficiencies; the module generates 
0.15 pounds of oxygen and 0.0188 pounds of hydro-
gen at a current density of 100 amps/ft2.
How it's done: 
The electrolysis module consists of 10 electrochem-
ical cells; a single cell of the static-feed water electrol-
ysis module is shown in the figure. Each cell is divided 
into 3 compartments, viz., water, hydrogen, and ox-
ygen. The oxygen and hydrogen compartments are 
separated by a porous matrix sandwiched between 
two catalytically active electrodes; the electrolyte-
impregnated matrix is held between these electrodes. 
A water-feed membrane separates the feed-water 
cavity from the gaseous hydrogen compartment. Dur-
ing electrolysis, i.e., when electrical power is applied 
to the electrodes, water vapor diffuses from the feed 
membrane to the porous cell matrix. 
The feed-water manifolds, ports, and compart-
ments, are electrically insulated from current-carry-
ing components, and the method of construction 
eliminates intercell electrolysis, a direct cause of gas 
generation inside feed-water passages. 
The primary structural material selected for the 
electrolysis cells is polysulf one plastic, but polypropy-
lene spacers and support screen are used in the water 
cavities. All metallic parts (except electrodes) exposed 
to electrolyte are manufactured entirely of nickel or 
from other metals that are subsequently plated with 
nickel. The latter method of manufacture was used 
to obtain thin parts with corrosion resistance and 
high thermal conductivity. 
The water-feed cavity is filled initially with potas-
sium hydroxide electrolyte at the same concentration 
at that in the cell matrix. As water in the cell matrix 
is consumed by electrolysis; the vapor pressure of the 
water in the electrolyte decreases as the KOH con-
centration increases. The vapor pressure of the water 
(continued overleaf) 
This documet was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000202 2020-03-17T02:19:27+00:00Z
in the water-feed cavity is not affected by electrolysis 
and, therefore, is higher than that of the cell electro-
lyte. As a result, water vapor diffuses through the 
feed membrane during electrolysis, through the hy-
drogen cavity and the pores in the hydrogen elec-
trode, and into the cell electrolyte. The transport of 
water continues as long as the vapor pressure of the 
cell electrolyte is lower than that of the water-feed 
electrolyte. Makeup water is forced into the water-
feed cavity from a feed reservoir that is divided into 
two parts by a flexible diaphragm; the pressure on 
the gaseous side of the diaphragm is adjusted to 
maintain the water-feed cavity at a pressure of 1-1.5 
psi below the pressure in the hydrogen cavity so as 
to prevent flooding of the hydrogen cavity. 
Notes: 
1. The following documentation is available from: 
National Technical Information Service 
Operations Division 
Springfield, Virginia 22151
Single document price $3.00 
(or microfiche $0.95) 
Reference: 
NASA CR-73394, Aircrew Oxygen System 
Development: Water Electrolysis Subsystem 
Report. 
2. Requests for further information may be directed 
to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B71-10203 
Patent status: 
No patent action is contemplated by NASA. 
Source: Franz H. Schubert 
TRW, Inc. 
under contract to 
Ames Research Center 
(ARC-10246) 
Brief 71-10203	 Category 03


Water electrolysis module

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