Electrolytic cells regenerate oxygen from the water vapor in the air of closed-loop life-support system and remove water vapor from air circulated through them. Water is converted into oxygen and hydrogen; the oxygen is returned to the air, the hydrogen is vented or used elsewhere

Celino, V. A.

Roebelen, G.

English

NASA Technical Reports Server

1972	 Brief 72-10166 
NASA TECH BRIEF 
Ames Research Center	
-4:v 
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. 
Cell for Electrolysis of Water Vapor 
Current Distributor Bus Microporous–j 1—Hydrogen 
Membrane / I Cavity 
Cabin I —O-Ring	 Anode	 Cabin 
Air	 I -..JI Seals	 'Air
(+) 
H2 
Cabin Air–F' 
/ L Microporous 
Current- — Membrane 
Carrying 
Spacer
The problem: 
To regenerate oxygen from the water vapor that 
is in the air of a closed-loop life-support system. 
The solution: 
Electrolytic cells which remove water vapor from 
air circulated through them; the water is converted 
into oxygen and hydrogen, and the oxygen is re-
turned to the air. The hydrogen is vented or used 
elsewhere. 
How it's done: 
The electrolytic cells are packaged in pairs, as 
indicated in the diagram. The cathodes of the two
Cabin Air 
"— Cathode 
Anode 
cells are metal screens which form the sides of a com-
mon hydrogen cavity. A thin corrugated metal spacer 
in contact with the cathodes serves as a current-
carrying element. Each anode is also made of metal 
mesh or screen, one side of which is in contact with 
the electrolyte; the other side is exposed to a flow 
of air from the life-support circulating system. 
The cathode electrolyte compartment of each cell 
is separated from the anode electrolyte compartment 
by a microporous membrane. The ionized species in 
the compartments are derived from sulfuric acid, and 
since the cells must operate in any position and in 
gravity-free space, the electrolyte is immobilized by 
(continued overléaf) 
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absorption in a matrix of fumed silica (the combi-
nation forms a thick gel). Concentrated solutions of 
sulfuric acid are hygroscopic; thus, when moist air 
is passed over the immobilized electrolyte, the water 
content of the air is largely taken up by the acid 
and made available for electrolytic action. Oxygen 
formed by electrolysis at the anode mixes with the 
flow of air; as a result, air rich with moisture flows 
into one end of the cell and comes out reduced in 
moisture and enriched in oxygen. Hydrogen formed 
in the central core of the cell combination is led out 
to be used for power in the spacecraft or vented. 
The moisture present in cabin atmospheres is de-
rived from the metabolic processes of the crew as 
well as from other processes; a suitable number of 
pairs of cells of the type shown can be used to pro-
vide a large part of the oxygen required by the crew 
and to maintain the cabin atmosphere at comfortable 
humidity levels.
Note: 
Requests for further information may be di-
rected to: 
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: B72-10166 
Patent status: 
No patent action is contemplated by NASA. 
Source: Vincent A. Ceilno and 
George Roebelen of

United Aircraft/Hamilton Standard 
under contract to
Ames Research Center 
(ARC-10521) 
Brief 72-10166	 Category 03


Cell for electrolysis of water vapor

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