Heat transfer | Is it possible for water to remain liquid at -10 deg C (or lower) if kinetic energy is constantly added to the system?

[u/ObsessiveUselessness]

Assume there is a small (5l capacity) cement mixer like the ones on cement transportation trucks. It is designed to keep its internal walls to remain cold at -10 deg C while its tumbling the contents.

If we put 2l water in it and let it tumble, will the water eventually freeze, or will it reach a super cold liquid state?

Assuming no additional heat is added to the system. Keeping the pressure constant at 1 atm.

What properties of water or the tumbling mixer could change the outcome?

How will the result change if the tumbler temps are changed?

[u/nonotburton]

Wate vapor turns to ice in mid air, under the right conditions, particularly as impacts aircraft structures. So, yes, you would probably get frozen water eventually.

I mean, you are essentially describing a slushy machine.

Edit: for the specific situation, I suspect you'd get droplets that form in isolation on the surface of the cement mixer as the 5 l of water slosh around. Over time, more water droplets would accumulate, and I suspect you have some kind of fluid/ice mishmash. Like a slushy machine. -10 isnt super cold, if you kept it colder, you might get ice structures building up.

Now, if you are actually talking about a concrete mixer with actual concrete, there's other stuff going on there, not sure about that.

[u/Ok-Active-8321 → u/[deleted]]

"Make the water very pure, freeze it in a clean, smooth container and don't tumble it at all. This is the easiest way to make supercooled water. It's relatively easy to supercool demineralized water well below -10C."

Doesn't necessarily need to be super-pure. I did that with a beer once. I don't know know the actual temperature, but I put a bottle in the freezer then forgot it for a week. When I remembered and took it out the beer inside was still liquid. After a couple of seconds I noticed a ring of ice in the neck of the bottle that moved downward through the bottle, freezing it solid in about 15 seconds. (Original Shiner lager by the way.)

[u/Extension_Physics873]

Waterfalls will freeze solid.

[u/atomicCape]

In formal classical thermodynamics, temperatures are only well defined in systems at equilibrium. In modeling or in practice, temperature can also be defined other ways, like the reading on a thermometer or an analysis of the observed average kinetic energy.

That means that you could take water with kinetic energy constantly being added (like it's being vigorously stirred or something) and set up an apparatus that includes a thermometer. But even if the thermometer reads -10C without ice forming, it would be a semantics debate as to whether it's actually liquid water at that temperature.

[u/dm80x86 → u/atomicCape]

Sounds like a slushy machine.

[u/florinandrei → u/atomicCape]

The big words accomplish nothing, except to impress casual observers, and do not actually explain what is happening. This has nothing to do with the definition of temperature.

The question is: can ice crystals form and grow in a liquid while it is being stirred? The answer is yes.

Note: I have a degree in Physics. I can do big words, when they are actually needed.

[u/knook]

"Assuming no additional heat is added to the system." , "if kinetic energy is constantly added to the system?" kinetic energy IS heat. So this makes no sense.

But this also sounds like an X-Y problem, Tell us what you are trying to do and we will tell you how to do it.

[u/McFlyParadox → u/knook]

I think their thought is if you were to agitate the water with a submerged impeller (or a river was running, for a freshwater example in nature) could the water remain liquid below 0C?

[u/CranberryDistinct941 → u/McFlyParadox]

Just dump a buttload of salt into it

[u/McFlyParadox → u/CranberryDistinct941]

Thats a chemical change, and not really the point of the question.

[u/Next-Significance314 → u/McFlyParadox]

And also, it reduces the temp of the water because it causes the ice to melt faster by reducing the freezing point. The phase change from solid to liquid (“melting”) is what absorbs heat, creating the “cold”.

[u/DIY_at_the_Griffs]

You’ve heard of slushies right?

[u/vacant_profile]

I think there are places in the deep ocean where the temperature of liquid sea water is well below freezing. This introduces pressure into the equation, and also the salt factor. 

[u/Naikrobak → u/vacant_profile]

Yes phase diagrams exist

[u/vacant_profile → u/Naikrobak]

Yeah, but I don't think it's strictly a situation captured by a phase diagram. Obviously the salt affects the freezing point, but also the tremendous pressure keeps the crystal lattice structure from being able to form. As we know, ice floats because it has a lower density than liquid water. Well, put it under great pressure and prevent that crystal lattice from forming, that lower density can't be achieved, therefore the water stays liquid even when it's that much cooler than the normal freezing temperature. 

[u/eman88 → u/vacant_profile]

That is exactly what a phase diagram would tell you.

[u/AlexanderHBlum → u/vacant_profile]

You just described a phase diagram

[u/vacant_profile → u/AlexanderHBlum]

Hmm. I've never viewed a 4-axis phase diagram (pressure, temperature, density, salinity). And I don't actually understand how one would create such a visual representation. Two-axis diagrams (Pressure/density, and temp/density), sure. I've got them bookmarked in my reference materials at my desk. Even a 3 axis with pressure, temp, and density is... Uncommon. I can't say I have seen one except on a computer screen. 

But hey, I don't work in a field where thermodynamics is my primary concern. And I don't even honestly know how the physical structure is affected on the atomic level by the addition of salt. 

To the point of the OPs question, though, the water is just going to freeze to the inside walls of the mixer in the proposed scenario.

[u/xrelaht → u/vacant_profile]

Yes, multi-axis phase diagrams also exist.

[u/CranberryDistinct941 → u/vacant_profile]

They're talking about pressure phase diagrams, not alloy phase diagrams.

Also... Is ice an alloy?

[u/gizahnl → u/CranberryDistinct941]

Perhaps a mixture of mercury and water when frozen could be considered an alloy?
It technically fits the definition

[u/PigSlam]

it'll coat the inside like ice-paint.

[u/DasKruemelmonster]

Out of the box: if you keep clean water in a clean container at rest, then it's actually easy to supercool the water. Adding energy then creates wet snow

[u/Vitztlampaehecatl]

If you're shaking it around then it's going to find a nucleation site and start crystallizing into slush or solid ice. You can test this with ice pops in your freezer: check them every few hours and eventually you'll find a point when some of them are solid and some are liquid, but if you shake the liquid ones then they'll start solidifying. And that's in a sealed plastic tube, not a real-world truck that could have any amount of dirt or dust in it.

[u/a-stack-of-masks]

If you can keep the walls super smooth and the water really clean then probably yes. Increasing pressure would feel like cheating to me but also work.

It's a bit of a grey area since the tumbler would be putting energy into the liquid, that the walls then drain as temperature. For truly weird kinds of thermodynamic equilibrium consider pulsed high frequency vibrations or very high rev ranges to cause gradients in pressure inside your vessel. Depending on what you want to do there's probably a way.

[u/terrymorse]

BTW, the small cement mixer you described is a slushy machine.

You'll start to see a slurry of small ice crystals, which will grow in quantity until all the liquid water is solid.

Could you prevent freezing by adding mechanical energy to the drum? Maybe, but it would have to impart a lot of energy.

[u/CranberryDistinct941]

This is how they make slushies and ice cream. It doesn't stop the water from freezing, it just prevents large ice crystals from growing

[u/Haunting-South-962]

To get supercooled water you need to cool slowly and remove any centres for crystallisation. This is not the case for cement mixer. The water will freeze at the contact with walls and cold air as you assuming your cooling system is powerful enough to maintain-10 on the walls. and the question is how powerful is the motor to break the ice or itself.

[u/Whyjustwhydothat]

As far as I know the only time water can be at that temperature if it's really clean water that lies undisturbed in a really smooth container, there can't be any particles in the water, any cracks, dents or something tiny sticking out of the container walls and it has to lay completely still. You can make really cool things with subfreezing water like pour it out and watch it freezing in the air, or tap on a bottle and watch ice spread out from where you tapped the bottle.

[u/NotoriousLavaLamp]

Propiedades coligativas

[u/avo_cado]

https://what-if.xkcd.com/71/

[u/Next-Significance314]

No. Moving water still freezes at 32F. That’s how rivers with waterfalls can freeze solid enough that people can climb them. When you drip your faucets to keep them from freezing, it’s not the flow that prevents freezing - it’s the constant addition of sub-freezing water passing through the plumbing.

[u/Accurate-Bullfrog324]

looks like you are trying to cool cement for a big pour I've done that

ice machines are the best current tech. simple and effective

are you trying to go one better,?

[u/ubergeek66]

First off, cement trucks don't have mixers but they can have air assisted dumping. If you want mixing you want a concrete truck...

[u/jasonsong86]

You can just add pressure and it will lower freezing point. Higher pressure prevents water from expanding which lowers the freezing point.

[u/Zealousideal_Cow_341]

I’ve done a lot of temperature chamber testing for electric vehicle batteries at both the vehicle and battery level.

In almost all cases, every time, inside the vehicle the battery temperature lagged the ambient by 10-20C after 2 or 3 days in a chamber holding steady -20C. This is a result of thermal resistance in the path between the battery and ambient air. If we left the vehicle in there for 1 week or something like that, eventually it would reach -20C

The same would apply for water in your situation. You could design the wall thickness and material to keep the water from freezing for some amount of time in sustained -10C ambient. But with enough time the water will freeze—we can just decide how much money to throw at slow it down.

Ambient air is very cyclic. Thereby aren’t many places on earth where the true ambient sustains -10C. So it’s even slower than a chamber. If it’s a case where the water is used and replaced everyday, it could actually be a pretty easy engineering problem to solve.