And so now pray tell just what the hell is this mysterious 'substance' youve
added ( to the case in point)
Given a vacuum with some small amount of frozen water in it........will it
( eventually ) sublime or no ???
Dessicants, lubricants, contaminants. They will not release water of
hydration just because you apply a vacuum at ambient temperatures.
Neither will slugs of free water trapped in lines, without either a lot
of time or an external heating source.
Only in proportion to the heat added. It *will not* sublime at all if
there is no heat added, even in a perfect vacuum.
The universe is full of solid water in the near-perfect vacuum of space.
Comets are an example.
Commercial food freeze-drying apparatus provide a circulating heat
medium on the trays. You can't just shove hunks of wet food in a vacuum
chamber and pump it down to freeze-dry it, practically speaking.
Neither can you dry out a wet HVAC system by leaving it on a vacuum. I
know this is an article of faith in the HVAC trade, but it is a myth
beacuse the tradesmen only learn a shallow smattering of chemistry and
thermodynamics. And they just want to believe it.
Ignore the entire concept of latent heat if its convenient to you then....
Point being is the heat was already added or subtrcated from the sytstem
before or after the phase change took place........still, its pressure
causing the actual change to occur.
Im done, your a fuckwit and my opinion still stands.
And I've heard that it's fucking hotter than hell out there, too...
Haven't ignored anything.
(Regardless, I suspect you mean sensible heat.)
The heat initially present in the water itself, or something intimately
in contact with it, will vaporize very little water, and in practice the
ambient heat will not flow in quickly (the vacuum being an insulator).
And this only applies to free water. Ordinary vacuum dessication does
not work for water bound in something like a silica gel dessicant, or
entrained in the oil, or hydrating contaminants.
A lot of people have been taught the pseudo-scientific myth that "water
boils in a vacuum" in some magic sense that it doesn't in the
atmosphere. The truth is that water vaporizes in a vacuum or in the
atmosphere the same way: *only* because you add heat. In the same
sense, water doesn't boil at 212 deg F, it boils because you add more
heat after it is at 212 deg F.
Another related myth is that if *you* were put into a vacuum, your body
would explode or your "blood would boil". Pure bunk.
Another popular (and yes, even in the HVAC trade) myth is "saturation"
of air with humidity, that the moisture is carried or dissolved in the
air, and that it "saturates" like a solution of salt in water.
On 22 Aug 2005 08:46:05 -0400, email@example.com wrote:
If that air, nitrogen and oxygen is anything but 0 degrees Kelvin it
has heat. That is why we have "AIR" conditionoing in the first place.
For the purposes of this silly argument, water in the system will
actually be touching the metal or in the oil, both excellent
conductors of ambient heat. If the water is trapped in the dessicants
of the dryer, who cares?, That should be in the trash by now and a new
dryer in the system. If you are not replacing your dryers you are
certainly a hack.
I think Dido is talking about when you have a evap coil exposed to other
cold temps within a running freezer.. a common occurence in the
This is what the man meant, I believe.
Doesn't matter--next time it snows, watch your outside temp real close, and
take note of any period over several days, or perhaps up to a week where the
temp stays constantly below freezing....notice that the snow 'just kinda
dissapears'....given enough time, it will eventually dissapear altogether,
without ever reaching a temp above freezing, and without rain falling on it,
etc.....now note that this process speeds up considerably at pressures below
OK, I buy that! The info in your article also said "If you've got a
week" or something similar. I don't think a tech in the field has that
kind of time, so perhaps that's what Dido is addressing.
I've seen ice develop in commercial Vacuum systems, and it does not
dissipate easily... it takes a long and slow pull. (NO one please make a
inference from this given my comments below)...
I *do* understand the pressure relationship, believe it or not....
BTW, I think I was either drunk or high in 9th grade science class...or
perhaps making passes at the lovely 'Tracey' that sat next to me, as I
recall. Tracey ended up on crack or welfare, or both, I think...
Oh, I got an A in Science... maybe it was Math, or English... or
ahhhh... the '70's. DON'T TRY THIS NOW, KIDS!
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