Newsgroups: sci.space.tech
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Recycling in Life Support
Date: Tue, 14 Nov 2000 19:41:53 GMT

In article <8u2m0m$g4h$1@nnrp1.deja.com>,  <cray74@hotmail.com> wrote:
>By what methods can carbon dioxide be scavenged from the
>air? I'm familiar with the basic chemical scrubber that binds
>the CO2, but are there any means to scrub out carbon dioxide
>from the air that are regenerateable? (i.e. the filters aren't
>used up permanently after capturing the CO2...besides plants).

Yes, molecular-sieve systems, as used on Skylab and now on ISS.  They
absorb CO2 (also moisture, so in general you've got to dehumidify the air
first), which can then be released by exposing them to vacuum and heating
them.  This means having more than one molecular-sieve bed, of course, so
one can be venting while another is processing air.

Apart from a certain amount of weight and complexity, the one real
disadvantage is that they can't hold the CO2 percentage down as low as
chemical absorbers can.

A number of other regenerable-CO2-scrubber ideas have been explored, but
none has made it to flight hardware.
--
When failure is not an option, success  |  Henry Spencer   henry@spsystems.net
can get expensive.   -- Peter Stibrany  |      (aka henry@zoo.toronto.edu)

Newsgroups: sci.space.tech
From: henry@spsystems.net (Henry Spencer)
Subject: Re: Recycling in Life Support
Date: Sat, 18 Nov 2000 23:14:26 GMT

In article <8uvhvu$chs$1@nnrp1.deja.com>,  <jakemcguire@my-deja.com> wrote:
>> Yes, molecular-sieve systems, as used on Skylab and now on ISS
>> A number of other regenerable-CO2-scrubber ideas have been explored,
>> but none has made it to flight hardware.
>
>  A solid-amine based system is a part of the EDO kit, and has flown
>multiple times.  At a minimum, STS-50, 69, 77, 83, 85, 87, and 90.

Hmm, I thought that was a molecular-sieve system, but on reflection I don't
know exactly where I got that impression...
--
When failure is not an option, success  |  Henry Spencer   henry@spsystems.net
can get expensive.   -- Peter Stibrany  |      (aka henry@zoo.toronto.edu)