ISS question

On Thu, 08 Apr 2010 11:55:26 -0800, Pat Flannery
wrote:

I note that tomorrow they will be EVAing to replace a ammonia tank on
the ISS which is supposed to be "depleted".
This is the second or third time this has been done on the station.
I know the ISS uses the ammonia for its cooling system radiators, but
how exactly is the ammonia getting depleted?
Does the cooling system leak, or does the ammonia deteriorate with use
and need to be replaced? I can see adding more as new modules are added,
but when this happens they say the old tank is empty.

I believe new things getting connected and more ammonia is needed to
fill the volume added is the real usage. These was a problem with one
of the radiator panels, but that was valved off. These may help.

http://www.boeing.com/defense-space/...l%20System.pdf

http://en.wikipedia.org/wiki/Major_i..._damaged_panel

On 4/9/2010 12:42 PM, me wrote:


I believe new things getting connected and more ammonia is needed to
fill the volume added is the real usage. These was a problem with one
of the radiator panels, but that was valved off. These may help.

http://www.boeing.com/defense-space/...l%20System.pdf

http://en.wikipedia.org/wiki/Major_i..._damaged_panel

Thanks, I'll go over those.
Mir used glycol in its cooling system, and they had real problems with
deterioration of the aluminum coolant pipes inside the station, leading
to leaks. IIRC this was due to electrolytic effects where the pipes came
into contact with other type metals in the moist environment.
Does the Shuttle use glycol or ammonia in its cargo bay radiators?

Pat

Pat Flannery drukte met precisie uit :
On 4/9/2010 12:42 PM, me wrote:


I believe new things getting connected and more ammonia is needed to
fill the volume added is the real usage. These was a problem with one
of the radiator panels, but that was valved off. These may help.

http://www.boeing.com/defense-space/...l%20System.pdf

http://en.wikipedia.org/wiki/Major_i..._damaged_panel

Thanks, I'll go over those.
Mir used glycol in its cooling system, and they had real problems with
deterioration of the aluminum coolant pipes inside the station, leading to
leaks. IIRC this was due to electrolytic effects where the pipes came into
contact with other type metals in the moist environment.
Does the Shuttle use glycol or ammonia in its cargo bay radiators?

Pat

A.F.A.I.K.: The coolant liquid in the Shuttle cargo bay radiators is
ammonia

André wrote:
Pat Flannery drukte met precisie uit :
On 4/9/2010 12:42 PM, me wrote:


I believe new things getting connected and more ammonia is needed to
fill the volume added is the real usage. These was a problem with one
of the radiator panels, but that was valved off. These may help.

http://www.boeing.com/defense-space/...l%20System.pdf


http://en.wikipedia.org/wiki/Major_i..._damaged_panel


Thanks, I'll go over those.
Mir used glycol in its cooling system, and they had real problems with
deterioration of the aluminum coolant pipes inside the station,
leading to leaks. IIRC this was due to electrolytic effects where the
pipes came into contact with other type metals in the moist environment.
Does the Shuttle use glycol or ammonia in its cargo bay radiators?

Pat

A.F.A.I.K.: The coolant liquid in the Shuttle cargo bay radiators is
ammonia



Incorrect. It is Freon.

Jorge R. Frank had uiteengezet :
André wrote:
Pat Flannery drukte met precisie uit :
On 4/9/2010 12:42 PM, me wrote:


I believe new things getting connected and more ammonia is needed to
fill the volume added is the real usage. These was a problem with one
of the radiator panels, but that was valved off. These may help.

http://www.boeing.com/defense-space/...l%20System.pdf

http://en.wikipedia.org/wiki/Major_i..._damaged_panel


Thanks, I'll go over those.
Mir used glycol in its cooling system, and they had real problems with
deterioration of the aluminum coolant pipes inside the station, leading to
leaks. IIRC this was due to electrolytic effects where the pipes came into
contact with other type metals in the moist environment.
Does the Shuttle use glycol or ammonia in its cargo bay radiators?

Pat

A.F.A.I.K.: The coolant liquid in the Shuttle cargo bay radiators is
ammonia

Incorrect. It is Freon.

Thanks for the info and correction.
(I should have known this...)

On 4/10/2010 11:59 AM, =?ISO-8859-15?Q?Andr=E9 wrote:

A.F.A.I.K.: The coolant liquid in the Shuttle cargo bay radiators is
ammonia

Incorrect. It is Freon.

Thanks for the info and correction.
(I should have known this...)

I asked this once before but never got a reply - after the Shuttle
lands, they apparently hook it up to some sort of system that circulates
fluid through pipes mounted inside of its belly to take up the heat of
reentry before it can migrate all the way through the belly tiles and
damage the structure of the underbelly and wing.
Does anyone know any details about how that all works, what the piping
layout is like, and what sort of fluid gets circulated through it?

Pat

On Apr 10, 9:01*pm, Pat Flannery wrote:
On 4/10/2010 11:59 AM, =?ISO-8859-15?Q?Andr=E9 wrote:

I asked this once before but never got a reply - after the Shuttle
lands, they apparently hook it up to some sort of system that circulates
fluid through pipes mounted inside of its belly to take up the heat of
reentry before it can migrate all the way through the belly tiles and
damage the structure of the underbelly and wing.
Does anyone know any details about how that all works, what the piping
layout is like, and what sort of fluid gets circulated through it?

Pat

It isn't a separate cooling loop, it is the same as the one used on
orbit and the same as used prelaunch. There are just multiple ways
of removing heat from this loop.

Prelaunch: a GSE heat exchanger in the cooling loop is removing the
heat through the tail service mast umbilical.
Ascent: The vehicle relies on thermal mass until around 100k ft where
flash evaporators are used.
Orbit: The familiar payload door radiators are used with the flash
evaporators for peak loads
Descent: The flash evaporators are employed from payload door closure
to 100kft, after which ammonia boilers are used.
Post landing: The ammonia boilers are used until the ground cooling
vehicle is used. It is hooked up to the same interfaces as used
prelaunch . The other vehicle provides cooling via conditioned air.



http://spaceflight1.nasa.gov/shuttle...clss/atcs.html

On 4/12/2010 8:57 AM, Me wrote:
On Apr 10, 9:01 pm, Pat wrote:
On 4/10/2010 11:59 AM, =?ISO-8859-15?Q?Andr=E9 wrote:

I asked this once before but never got a reply - after the Shuttle
lands, they apparently hook it up to some sort of system that circulates
fluid through pipes mounted inside of its belly to take up the heat of
reentry before it can migrate all the way through the belly tiles and
damage the structure of the underbelly and wing.
Does anyone know any details about how that all works, what the piping
layout is like, and what sort of fluid gets circulated through it?

Pat

It isn't a separate cooling loop, it is the same as the one used on
orbit and the same as used prelaunch. There are just multiple ways
of removing heat from this loop.

Prelaunch: a GSE heat exchanger in the cooling loop is removing the
heat through the tail service mast umbilical.
Ascent: The vehicle relies on thermal mass until around 100k ft where
flash evaporators are used.
Orbit: The familiar payload door radiators are used with the flash
evaporators for peak loads
Descent: The flash evaporators are employed from payload door closure
to 100kft, after which ammonia boilers are used.
Post landing: The ammonia boilers are used until the ground cooling
vehicle is used. It is hooked up to the same interfaces as used
prelaunch . The other vehicle provides cooling via conditioned air.



http://spaceflight1.nasa.gov/shuttle...clss/atcs.html

Thanks, that was a interesting read.

Pat

What was the reasoning behind having Node2 and Node3 have their own
ammonia exchangers instead of using CBM based water loops to dump heat
to Destiny ?

The boeing document states that there are to be 10 ammonia/water
exchangers. Couldn't they have been all located on Destiny to give
sufficient water cooling capacity for the whole station ? (this would
gave rediced the need to run ammonia lines across modules and requiring
"dangerous" EVAs to connect and/or maintain those lines.)

They could have piped Destiny's forwards CBM to have the water
connections go directly to ammonia/water exchangers dedicated to that
portion of the station, or they could have pooled all hot water together
and had them run through 10 ammonia exchangers which would give more
redundancy and better load balancing of heat loads).

On Apr 14, 11:07*pm, John Doe wrote:
What was the reasoning behind having Node2 and Node3 have their own
ammonia exchangers instead of using CBM based water loops to dump heat
to Destiny ?

It would use up too much space in Destiny. more avionics were placed
in the nodes than the original plane, Also Node 3 is not connected to
Destiny.