Space Suit Cooling

On 7/18/2013 9:43 AM, Jeff Findley wrote: In article , says...

On 4/10/2013 8:37 AM, Jeff Findley wrote:

Can't even test spacesuits. Specifically, Apollo (and shuttle, and US-
ISS) spacesuits all use water (for cooling. This works because it is
essentially vented to vacuum where it freezes and sublimates. This
won't work well, or at all, on Mars due to the thin atmosphere.

Water vented to a vacuum will boil, not freeze.

Nope. Look here for "ice" and "sublimates".

Liquid Cooling and Ventilation Garment
http://en.wikipedia.org/wiki/Liquid_...lation_Garment

Jeff



Forking a new thread from an old one. From the article it looks like the
LCVG heat exchanger back in the PLSS exchanges the closed loop LCVG
coolant heat with an open-loop ice sheet that is vented into space and
sublimates.

Jeff I'm curious tho', how is that ice sheet formed in the PLSS?

Dave

In article , nospam@
127.0.0.1 says...

Forking a new thread from an old one. From the article it looks like
the
LCVG heat exchanger back in the PLSS exchanges the closed loop LCVG
coolant heat with an open-loop ice sheet that is vented into space and
sublimates.

Jeff I'm curious tho', how is that ice sheet formed in the PLSS?

Essentially a plate with holes in it. Water on one side seeps out
through the holes in the plate (on the vacuum side) where it freezes,
then sublimates. When enough of the ice sublimates to open up a hole,
more water flows out, freezes, and etc.

http://www.hq.nasa.gov/alsj/LM15_Por...tem_ppP1-5.pdf

It's my understanding that Apollo suits and EMUs (both shuttle and ISS
era) use this same mechanism for cooling.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer

On 7/18/2013 11:32 AM, Jeff Findley wrote:
In article , nospam@
127.0.0.1 says...
Jeff I'm curious tho', how is that ice sheet formed in the PLSS?

Essentially a plate with holes in it. Water on one side seeps out
through the holes in the plate (on the vacuum side) where it freezes,
then sublimates. When enough of the ice sublimates to open up a hole,
more water flows out, freezes, and etc.

http://www.hq.nasa.gov/alsj/LM15_Por...tem_ppP1-5.pdf

It's my understanding that Apollo suits and EMUs (both shuttle and ISS
era) use this same mechanism for cooling.

Thanks I also got this from the Wikipedia article:

/quote
Heat exchanger

For portable earth bound applications, the heat exchanger for cooling
the liquid can be very low-tech, consisting simply of a container for
holding ice, and an electric pump to circulate water from the container
through the tubing. The return water is cooled by the melting ice, and
again pumped through the tubes. Regulation of flow is done by varying
pump speed or using an adjustable flow valve. Ice storage can be
achieved using a belt-pack, a backpack, or a duffel bag, depending on
the length of time needed for the cooling system to operate between
refilling the ice storage.

In situations where the wearer must stay in place inside a vehicle,
heavy but long-term-operation heat exchangers can be used, such as a
[refrigeration] system to cool the liquid.

When the user's movement is partially hindered through the use of a
life-support umbilical, cooling liquid can also be supplied via the
umbilical.

/end-quote

I didn't know that suits had to be packed with ice before an EVA!
For Apollo was there a refrigerator or ice chest as part of the
equipment in the LM? (Question off top of head, if answered in the
reference I will read it later today.)

Thanks for that link...

Dave

On Thursday, July 18, 2013 2:02:34 PM UTC-4, Jeff Findley wrote:


See those big, gray, suitcase like things they're carrying which are

attached to their suits? They're not used in space, but on the ground.


Those aren't heat exchangers, but liquid oxygen for breathing and cooling