Cooling in vacuum needs some attention

[abud]

1 hour ago, blash365 said:

How do you keep your battery bank from overheating?

There is 1 tile of wallpaper behind those batteries. Small amount of liquid on that tiles make fast heat transfer between batteries and metal where they sit on. Behind that metal tile, there is a pipe with 20C PW.

[psusi]

3 hours ago, heckubis said:

look up the composition of asteroids and comets. notice how boiling water isn't one of the components. although they do melt fast under direct sunlight. on a table in a vacuum the water is still receiving loads of thermal radiation modifying state change conditions. Even without direct sunlight all things emit thermal radiation known as infrared. this constant leak of thermal energy is why things in space freeze so long as they have the mass to stay together

I'm not sure you understood me.  In a vacuum, even at very cold temperatures, ice will sublimate into gas.  So if you pump water into the vacuum, it should turn to cold steam.

[heckubis]

no i understood perfectly that under no circumstances does ice sublimate without thermal energy and cold steam is only found in labs not in nature the closest you get is under direct sunlight causing the vapor trail behind comets and that's mostly ice

[shanemadden]

7 minutes ago, psusi said:

I'm not sure you understood me.  In a vacuum, even at very cold temperatures, ice will sublimate into gas.  So if you pump water into the vacuum, it should turn to cold steam.

Yeah, definitely no concept of varying evaporation points depending on environmental pressure. It'd be nice to be able to be able to prevent evaporation with added pressure, too..

[psusi]

11 minutes ago, heckubis said:

no i understood perfectly that under no circumstances does ice sublimate without thermal energy and cold steam is only found in labs not in nature the closest you get is under direct sunlight causing the vapor trail behind comets and that's mostly ice

No, ice under only one or two pascals of pressure will sublimate even at -50 C.  The lower the pressure, the lower the temperature needed  https://en.wikipedia.org/wiki/Triple_point

 

[heckubis]

14 minutes ago, psusi said:

No, ice under only one or two pascals of pressure will sublimate even at -50 C.  The lower the pressure, the lower the temperature needed  https://en.wikipedia.org/wiki/Triple_point

 

notice all the floating water in our solar system ? what is a comet made of? lab results are in reference to a lab setting you cant stop the thermal activity with an artificial vacuum it just changes its radiation type entropy will always prevail.

ever wonder why giant chunks of cold steam leave giant craters on the moon and mars wow steam sure has a lot of physical mass that completely blows your bs out of the conversation next you going to tell me that all that is from some older planet that blew up billions of years ago and that the sublimation took some time off just because it was  doing other things you know it had a date or something so it couldent get to the rest of the ice in our solarsystem

[psusi]

13 minutes ago, heckubis said:

notice all the floating water in our solar system ? what is a comet made of?

Ice that is much colder than -50 C.

13 minutes ago, heckubis said:

ever wonder why giant chunks of cold steam leave giant craters on the moon and mars wow steam sure has a lot of physical mass that completely blows your bs out of the conversation

Yea.. because it heats up to -50 C.  That was also kind of my point: that the water will boil to steam, not sit there as liquid.  What does mass have to do with it?  And there's no BS here.  Go read the triple point diagram I linked.

[heckubis]

if sublimation happens in that environment there should not be any ice left in the first place to talk about for comets and asteroids they should just be floating piles of steam gently wifting through the cosmos.like space clouds

[psusi]

1 minute ago, heckubis said:

if sublimation happens in that environment there should not be any ice left in the first place to talk about for comets and asteroids they should just be floating piles of steam gently wifting through the cosmos

Please read the page I linked, which you can also find in many science textbooks.  In a vacuum, liquid ice does not exist, period.  It is either cold enough to stay solid ( less than -50 C ), or above that, it is a gas.

 

[heckubis]

sorry i find no comparison to a lab vacuum to a real vacuum and can fathom no correlation considering the radiation part of heat transfer a terrestrial experiment cant do it we cant as humans actually remove the excess thermal radiation from the experiment making it invalid given proofs in the cosmos

[shanemadden]

18 minutes ago, heckubis said:

sorry i find no comparison to a lab vacuum to a real vacuum and can fathom no correlation considering the radiation part of heat transfer a terrestrial experiment cant do it we cant as humans actually remove the excess thermal radiation from the experiment making it invalid given proofs in the cosmos

https://www.popularmechanics.com/science/a15834856/vacuum-chamber-snow/

[heckubis]

12 minutes ago, shanemadden said:

https://www.popularmechanics.com/science/a15834856/vacuum-chamber-snow/

lab results on earth contain thermal energy not put into the test but from you know light for this example its a vacuum sure but prevents no thermal energy from a visual range of light infra red for example has no problem passing through a glass jar and infra red is thermal energy.

at most your cooling the area around the jar

[shanemadden]

5 minutes ago, heckubis said:

lab results on earth contain thermal energy not put into the test but from you know light for this example its a vacuum sure but prevents no thermal energy from a visual range of light infra red for example has no problem passing through a glass jar

There's plenty of thermal energy in the ice itself to evaporate, assuming it's warmer than absolute zero.  The lower pressure in the vacuum causes some of the ice to sublimate, which drops the overall temperature of the mixture due to the extra energy cost to phase change to a gas (but maintains the same total thermal potential energy).

We have a pretty good understanding of the energy impacts of light in a vacuum, too..

https://en.wikipedia.org/wiki/Radiometer

This is all pretty well understood and studied chemistry, which you're trying to disprove with a pretty obscure counterpoint: the conditions on the surface of a comet, which you've never directly observed.

[heckubis]

no i dont but science does and comets have ice not pockets of cold steam

[psusi]

2 hours ago, heckubis said:

sorry i find no comparison to a lab vacuum to a real vacuum and can fathom no correlation considering the radiation part of heat transfer a terrestrial experiment cant do it we cant as humans actually remove the excess thermal radiation from the experiment making it invalid given proofs in the cosmos

Are you a flat earther retard or something?  This is basic physics.  Under low enough pressure, water does not exist in the liquid phase.  Either it has enough energy to sublimate into gas, or it remains a solid.  There is no liquid in between at low enough pressures.  A lab vacuum *is* a real vacuum.

1 hour ago, heckubis said:

no i dont but science does and comets have ice not pockets of cold steam

Again, commets have ice because they are cold enough.  What the do not have is liquid water.

[storm6436]

And where does the comet tail come from?  Ice sublimating off the comet into a gas trail as a function of photon flux (ie incoming light).    This is why tails are longer the closer to the sun a comet it.

 

You don't need a physics undergrad to understand that... but evidently it helps. 

[heckubis]

did you read what i said about comets being subject to radiant thermal energy under direct sunlight? apparently not i do under stand that ice trail off the comets """ICE""" TRAILS OFF THE COMETS " not cold steam. an objuect shattering under a pressure change weather or not its thermally induced is shattering from a pressure standpoint powdered iced chunks my act like but are not in fact steam

[KittenIsAGeek]

I thought that in 2017 they passed through the tail of a comet with a satellite and found that the tail was not sublimating ice.  Besides, if comets lose mass every time they pass the sun, wouldn't it alter their trajectories and change their orbits?  AFAIK, the only time comets change orbits is when passing through the OORT cloud, due to the dynamic mass in that region.

[Sevio]

3 hours ago, KittenIsAGeek said:

Besides, if comets lose mass every time they pass the sun, wouldn't it alter their trajectories and change their orbits?

I couldn't easily find anything on google about how sublimation affects their orbits.

My educated guess: The escape velocity of the gas would be rather low so it wouldn't do much. (which doesn't stop scientists from investigating even the smallest phenomena) Also, comets aren't rocket engines with nozzles created specifically for thrust, so part of the forces generated would cancel each other out. Furthermore, the sublimation would happen on the day side of the comet so if there is a significant enough direct force it would generally be away from the sun. (slowing it down as it approaches the sun, pushing it out radially near perihelion and speeding it back up as it leaves the sun)

[Christophlette]

I always thought comets were made of refined iron or regolith 

[Steve Raptor]

(First forum reply!) I think I found a reliable solution to cool auto sweepers in a vacuum.

At first I was trying water dripping but it didn't seem to work.

However when I manually dropped a bigger chunk of water on top of it, the sweeper was momentarily covered in liquid and could exchange heat.

I therefor came up with this simplistic design, and it works well in my automated solar farm.

From there you can easily cool the water using worts (replacing the floor of the water chamber with metal tiles and building a hydrogen+wort room below), or any other method.

 

 

 

 

 

 

[psusi]

9 hours ago, heckubis said:

did you read what i said about comets being subject to radiant thermal energy under direct sunlight? apparently not i do under stand that ice trail off the comets """ICE""" TRAILS OFF THE COMETS " not cold steam. an objuect shattering under a pressure change weather or not its thermally induced is shattering from a pressure standpoint powdered iced chunks my act like but are not in fact steam

It doesn't shatter; it sublimates.  What pressure change would cause it to shatter?  Even if it did, it wouldn't leave the surface of the comet.  It's the change to gas phase that causes it to blow off of the comet.  In any case, this has nothing to do with the fact that if you expose even near freezing water to a vacuum, it boils.  Some may get cold enough to freeze in the process, but you don't have liquid water left.

[Sasza22]

2 hours ago, Christophlette said:

I always thought comets were made of refined iron or regolith 

Asteroids are made of metalic iron and rock. Comets are made of dirty ice and and rock. They are so far away from the sun for most of the time that the ice stays on their surface.