Author Topic: ISS water recycle efficiency discussion  (Read 11071 times)

Online Herb Schaltegger

ISS water recycle efficiency discussion
« on: 03/01/2015 01:41 PM »
As there will be no external payload in the Dragon trunk on this flight, will this Dragon carry a greater mass of internal payload?
Or is the mass of the internal payload (largely) independent of the mass of the external payload?

Zubenelgenubi

As I understand it, internal mass is more volume limited. Could be different if they start shipping water or other more dense materiel.

Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.
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Online gongora

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Re: ISS water recycle efficiency discussion
« Reply #1 on: 03/01/2015 01:53 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

Online Herb Schaltegger

Re: ISS water recycle efficiency discussion
« Reply #2 on: 03/01/2015 01:56 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;) 
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Offline Robotbeat

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Re: ISS water recycle efficiency discussion
« Reply #3 on: 03/01/2015 01:59 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.
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Online Herb Schaltegger

Re: ISS water recycle efficiency discussion
« Reply #4 on: 03/01/2015 02:03 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.

I was there when it was being designed in 1990. It most certainly was.

In fact, under certain crew-load circumstances and with all hardware operating nominally and to specification, there are (or were, anyway) situations when the entire closed-loop ECLSS would be operating at water-positive in the mass-balance. I was part of the design working group at Boeing around 1992 that set specifications and requirements for ECLSS system vents for carbon dioxide from the CDRA, cabin atmosphere in case of catastrophic fire or contamination, and - yes - water.

« Last Edit: 03/01/2015 02:11 PM by Herb Schaltegger »
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Online meekGee

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Re: ISS water recycle efficiency discussion
« Reply #5 on: 03/01/2015 03:33 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.
The ECLSS does not have to recycle 100% on a "single pass".

The only way water can leave the system is through waste, astronaut weight gain, and atmospheric humidity in departing vehicles.

However, water gets added as a natural byproduct of metabolism (burning hydrocarbons), as residual content in food, astronaut weight loss, and atmospheric humidity in incoming vehicles.

Some of these are negligible of course, but the point is that A) the water balance can be positive, B) the ECLSS can be only partly efficient "per pass", but since the water can hide, but can't run away, the ECLSS will get it anyway.
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Offline MP99

Re: ISS water recycle efficiency discussion
« Reply #6 on: 03/01/2015 05:43 PM »


Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.

I was there when it was being designed in 1990. It most certainly was.

In fact, under certain crew-load circumstances and with all hardware operating nominally and to specification, there are (or were, anyway) situations when the entire closed-loop ECLSS would be operating at water-positive in the mass-balance. I was part of the design working group at Boeing around 1992 that set specifications and requirements for ECLSS system vents for carbon dioxide from the CDRA, cabin atmosphere in case of catastrophic fire or contamination, and - yes - water.

You guys are talking past each other. "Recover every last drop". "Recover enough for all crew needs".

Cheers, Martin

Offline Llian Rhydderch

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Re: ISS water recycle efficiency discussion
« Reply #7 on: 03/01/2015 06:25 PM »
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.

I was there when it was being designed in 1990. It most certainly was.

In fact, under certain crew-load circumstances and with all hardware operating nominally and to specification, there are (or were, anyway) situations when the entire closed-loop ECLSS would be operating at water-positive in the mass-balance. I was part of the design working group at Boeing around 1992 that set specifications and requirements for ECLSS system vents for carbon dioxide from the CDRA, cabin atmosphere in case of catastrophic fire or contamination, and - yes - water.

Herb, do you happen to have a source for that?

Sounds like it might have been a political specification, or perhaps a high-level "requirement" statement (which are often just "desirements"). 

Was there really a group of engineers that designed the ISS ECLSS system for 100.0000% recycling? ... with no additional water to be added from outside the system indefinitely?  Sounds very difficult to believe to my ears with some years of system development behind me.

Or perhaps were "engineering" specs unduly influenced by the inherently political process of "getting funded" or "being selected", in which case--just like schedules and costs are typically underestimated in these sorts of projects--may have been, ummm, a tad overstated.
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Offline Comga

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Re: ISS water recycle efficiency discussion
« Reply #8 on: 03/01/2015 08:32 PM »
This  water discussion belongs elsewhere, where you can continue to talk past each other.  Water recycling and the definition, desirability, and necessity of "100%" is not specific to the SpX-6 launch.

The fact is that the CRS-6 Dragon was modified and is certified to carry water to the ISS.  Was it Gerst who stated that it was thought sufficient to have one vehicle able to carry water to the station but that bet was lost with the Antares launch failure?

Also, while there was a statement that the SpX-6 launch would be delayed into mid-April there is at least one recent official planning document in L2 that still has the April 8 date.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Herb Schaltegger

Re: ISS water recycle efficiency discussion
« Reply #9 on: 03/01/2015 11:22 PM »
Herb, do you happen to have a source for that?

Most of my stuff from those days is packed away and I've never found it. I do have the 1993 PDR design description document for the regenerable ECLSS. I've thought about scanning it and posting, but it's got a big, blunt ITAR warning on the cover page and I'm not inclined to go chasing down that rabbit hole to see if ITAR restrictions are even applicable anymore after nearly a quarter century. And was stated above, this is off-topic for this particular thread.

That said, this thread is suffering the worst examples of "smartest people on the internet" syndrome where semi-informed people with high post counts, with far too many "LIKES" from others equally-uninformed or moreseo, are telling people who designed the hardware how it's supposed to work. If there's any wonder my most people active in the biz post under pseudonyms if they post at all, you're looking at the explanation writ large.
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Offline Robotbeat

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Re: ISS water recycle efficiency discussion
« Reply #10 on: 03/02/2015 12:20 AM »
Here is a continuation of the discussion that started here: http://forum.nasaspaceflight.com/index.php?topic=36892.0
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Offline Robotbeat

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Re: ISS water recycle efficiency discussion
« Reply #11 on: 03/02/2015 12:22 AM »
...

That said, this thread is suffering the worst examples of "smartest people on the internet" syndrome where semi-informed people with high post counts, with far too many "LIKES" from others equally-uninformed or moreseo, are telling people who designed the hardware how it's supposed to work. If there's any wonder my most people active in the biz post under pseudonyms if they post at all, you're looking at the explanation writ large.
In my defense, I will joyously admit I was wrong given sufficient evidence. (And I am "active in the biz" although not on ISS and I also am posting under a pseudonym... although I /definitely/ spend too much time on here! guilty as charged!)

And how is someone supposed to know you helped design the hardware in question (although it sounds like you worked on /related/ hardware, not the exact hardware...) unless they challenge you to back up your claim? :) As far as I knew, you were also a "smartest person on the internet." :)

Anyway, here's a new thread to carry on the discussion. I really am interested in comparing designed-for recycling efficiency with achieved efficiency:
http://forum.nasaspaceflight.com/index.php?topic=36926.0

(Mods, can you perhaps move the previous posts there?)
« Last Edit: 03/02/2015 12:51 AM by Robotbeat »
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Online meekGee

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Re: ISS water recycle efficiency discussion
« Reply #12 on: 03/02/2015 12:33 AM »
Herb, do you happen to have a source for that?

Most of my stuff from those days is packed away and I've never found it. I do have the 1993 PDR design description document for the regenerable ECLSS. I've thought about scanning it and posting, but it's got a big, blunt ITAR warning on the cover page and I'm not inclined to go chasing down that rabbit hole to see if ITAR restrictions are even applicable anymore after nearly a quarter century. And was stated above, this is off-topic for this particular thread.

That said, this thread is suffering the worst examples of "smartest people on the internet" syndrome where semi-informed people with high post counts, with far too many "LIKES" from others equally-uninformed or moreseo, are telling people who designed the hardware how it's supposed to work. If there's any wonder my most people active in the biz post under pseudonyms if they post at all, you're looking at the explanation writ large.

As a semi-informed person with a high post count and far too many "LIKES", I have three questions:
- Where did I ever tell you how it's supposed to work?
- Is it correct (based on your knowledge) that in order to maintain 100% closed ECLSS, the filtering system does not necessarily have to be able to 100% separate (for example) water from urine in a single pass?
- Can you clarify whether "100% closed ECLSS" takes into account water produced by natural operating conditions (e.g. produced by people) or is it "100% closed" in the sense that it actually prevents any water leaving the closed environment?

Thanks.
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Offline Robotbeat

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Re: ISS water recycle efficiency discussion
« Reply #13 on: 03/02/2015 12:34 AM »
To get started, from this document:
"In the baseline ISS ECLSS, CO2 and H2 are vented overboard from the resulting carbon dioxide removal and
oxygen generation processes. "
http://www.nasa.gov/externalflash/iss-lessons-learned/docs/design_ECLSS_Tech_Evolution.pdf
(and attached)

Since oxygen for crew consumption is produced via electrolysis of water, this is one avenue of water loss from ISS. So, even if no other sources of loss were present, there would be significant water loss (equivalent in mass roughly to the amount of carbon dioxide exhauled, minus the carbon) in the baseline ISS design.

As far as I'm aware, the newer Sabatier reactor, which was added later on, was not designed to process /all/ CO2 on ISS. So even with the addition of the Sabatier process, full recycling efficiency is not achieved. EDIT: Yup, only a portion of the CO2 is processed by the Sabatier unit on-board ISS: "Because there is not enough stoichiometric hydrogen to reduce all the metabolic carbon dioxide with the Sabatier reaction, the Sabatier CRA alone cannot completely close the oxygen loop."


...so it seems I AM vindicated! ISS was not designed for 100% recycling. :)
« Last Edit: 03/02/2015 12:58 AM by Robotbeat »
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Offline Norm Hartnett

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Re: ISS water recycle efficiency discussion
« Reply #14 on: 03/02/2015 01:55 AM »

...so it seems I AM vindicated! ISS was not designed for 100% recycling. :)

Not exactly Robotbeat, Herb's statement was that the system was designed for 100% water recycling. Since there is very little, if any, solid waste recycling the ISS has a long, long ways to go for 100% recycling. ;)

Could anyone point me towards any more recent data on the ECLSS efficiency and hardware updates? I'd like to see  know how many filter, chemicals, and etc. are being consumed. I'd also like pointers toward any advanced ECLSS systems being developed for the future.
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Offline Robotbeat

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Re: ISS water recycle efficiency discussion
« Reply #15 on: 03/02/2015 02:19 AM »

...so it seems I AM vindicated! ISS was not designed for 100% recycling. :)

Not exactly Robotbeat, Herb's statement was that the system was designed for 100% water recycling. ...
However, he wasn't referring narrowly to water recycling, but that the recycling would be sufficient that water shipments wouldn't be necessary! ("Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. " --Herb)

But my statement (which he objected to) was about overall recycling. See here for context:
Well, hopefully they'll never have to ship water. Unless the ECLSS water recovery hardware fails or goes drastically out of spec due to contamination they should never have to ship water, or not much of it. Water is a metabolic byproduct and is recovered from both breathing air as part of the ECLSS temperature and humidity control systems, as well as from urine.

They do need to ship water, and the Progress cargo ship that just went up there carried some.  They don't recycle 100%.

That's the reality that everyone pushing so hard for Mars needs to pay close attention to, now isn't it? The hardware we designed should have obviated the need. The hardware the contractors built and installed doesn't work as well as it was spec'd. ;)
False. It was never spec'd for 100% recycling.
The ECLSS does not have to recycle 100% on a "single pass".

The only way water can leave the system is through waste, astronaut weight gain, and atmospheric humidity in departing vehicles.

However, water gets added as a natural byproduct of metabolism (burning hydrocarbons), as residual content in food, astronaut weight loss, and atmospheric humidity in incoming vehicles.

Some of these are negligible of course, but the point is that A) the water balance can be positive, B) the ECLSS can be only partly efficient "per pass", but since the water can hide, but can't run away, the ECLSS will get it anyway.


But it doesn't matter either way who was "right," as we now have learned more about how ISS's whole ECLSS works, now, haven't we? To arrive at a better understanding of the truth is the goal.
« Last Edit: 03/02/2015 02:23 AM by Robotbeat »
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Offline Fuji

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Re: ISS water recycle efficiency discussion
« Reply #16 on: 03/03/2015 08:31 PM »
JAXA is developing new water recycle system technology demonstration system.
Compare with current U.S. WRS, size is 1/4 (95 x 98 x 101 cm), power consumption is 1/2.
90% recycling is targeted better than U.S WRS.
Ion-exchange membrane is recycled by washing (by acid and alkali water which are reuse of wastewater electrodialytic treatment).  Goal is maintenance free system !

JFY 2016, this technology demonstration model will be launched to the ISS.

Offline Rik ISS-fan

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Re: ISS water recycle efficiency discussion
« Reply #17 on: 03/03/2015 09:01 PM »
While I read through this topic, I remembered reading about an ISPR rack ESA is developing.
Instead of building two more ATV's ESA made the deal with NASA to develop a CO2 recycling system and the propulsion module for Orion.
After searching I discovered I read about it in ESABulletin 143
The dubbel ISPR rack is called (ACLS) Advanced Closed Loop System. It will be a larger version of the Sabatier-reactor, and it will recycle the CO2 emited by three crewmembers.
The latest information I found was from August 2014, the rack will be launched with HTV7 planned for 2017.
I've added three hyperlinks to documents about the ACLS.
1) Design Status ACLS 2011
2) Envihab Symposium 2011
3) Design Status ACLS 8-2014
« Last Edit: 03/03/2015 09:04 PM by Rik ISS-fan »

Offline Norm Hartnett

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Re: ISS water recycle efficiency discussion
« Reply #18 on: 03/10/2015 10:18 PM »
With at least four separate and different systems processing water and/or air maintaining atmosphere and water quality are going to be interesting. This is the type of baseline research that the ISS is so necessary for.
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Re: ISS water recycle efficiency discussion
« Reply #19 on: 03/11/2015 12:22 PM »
I have a question, actually two related questions.

1. Food sent to the ISS is usually not dehydrated, correct? MRE contain a lot of water, it should be enough to replace any losses.

2. Feces contain a lot of water. Is that water recycled by drying and storing only the dry mass for disposal? I suspect it is not dried so there is the loss of water that prevents a closed loop for water. Correct?

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