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Freezing moving water

ChrisJ
ChrisJ Member Posts: 13,557
I figured I'd throw this one up on the pole and see who salutes it. :D

Does circulating or moving water lower the freezing point? If so, how much?
Does simply circulating water with a pump warm the water at all? Theoretically?

Would the water's freezing point be higher at the suction side of the pump, or leaving the pump? Let's assume slight vacuum on the suction side and 5 PSI on the outlet.

What about if the pump is intentionally run into slight cavitation, how would this effect temperature and freezing points? Does cavitation cool or warm the water?
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

Comments

  • fentonc
    fentonc Member Posts: 165


    I think the affect of pressure changes on freezing temperature is pretty negligible for water. There might be some actual effect from the mechanical movement of water that prevents/delays freezing, but it seems like the energy from running the pump either gets dissipated into the room around the pump or into the water/pipes (because where else would it go?). If the circulator is running without an external heat source like a boiler, and the water is cooler than room temperature in the house, the dominant effect will be the radiators acting in reverse - heating up the water and cooling down the room (and thus preventing water from freezing by warming it up).
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,658
    just a guess. Pump will warm the water, cavitation will really warm it but just at the pump because it's not moving. Resistance to flow causes pipe friction and warms the water but wouldn't change water freeze point
  • ChrisJ
    ChrisJ Member Posts: 13,557

    just a guess. Pump will warm the water, cavitation will really warm it but just at the pump because it's not moving. Resistance to flow causes pipe friction and warms the water but wouldn't change water freeze point

    I'm lost as to what you mean "it's not moving".
    Do you mean the actual cavitation it self isn't moving?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 10,044
    Standing water in lakes and ponds will freeze before running/moving water in rivers and streams.

    No math used or needed.
  • mattmia2
    mattmia2 Member Posts: 6,670
    Is that because it is moving or because it is mixing with warmer water below?
  • ChrisJ
    ChrisJ Member Posts: 13,557
    mattmia2 said:

    Is that because it is moving or because it is mixing with warmer water below?

    I believe simply because it's being mixed with warmer water.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    DJD775
  • JUGHNE
    JUGHNE Member Posts: 10,044
    I think because it is moving.

    Where would the warmer water be coming from?

    Sources could be some underground springs, but many miles away.

    It will eventually freeze over but later than ponds.
  • ChrisJ
    ChrisJ Member Posts: 13,557
    edited November 22
    JUGHNE said:

    I think because it is moving.

    Where would the warmer water be coming from?

    Sources could be some underground springs, but many miles away.

    It will eventually freeze over but later than ponds.


    Most if not all streams are fed by lakes or springs.
    The lakes freeze over which insulates the water from the air.

    The springs are insulated by soil.

    Everything I've looked up claims water moving or not freezes at the same temperature.
    That's why I started this thread. I'm curious how true it is, and what other things effect it.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 4,280
    I think that @fentonc covered it perfectly, even using charts and graphs that on one understands. Of course @JUGHNE is spot on with his highly technical observations. What else do you need to know?

    IMHO just leave leave the tap dripping and the circulator operating if the burner goes out during freezing weather conditions. You can't be any worse off.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org

  • ChrisJ
    ChrisJ Member Posts: 13,557

    I think that @fentonc covered it perfectly, even using charts and graphs that on one understands. Of course @JUGHNE is spot on with his highly technical observations. What else do you need to know?

    IMHO just leave leave the tap dripping and the circulator operating if the burner goes out during freezing weather conditions. You can't be any worse off.


    This question has nothing to do with HW heat or any heating system.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • GGross
    GGross Member Posts: 334
    ChrisJ said:

    JUGHNE said:

    I think because it is moving.

    Where would the warmer water be coming from?

    Sources could be some underground springs, but many miles away.

    It will eventually freeze over but later than ponds.


    Most if not all streams are fed by lakes or springs.
    The lakes freeze over which insulates the water from the air.

    The springs are insulated by soil.

    Everything I've looked up claims water moving or not freezes at the same temperature.
    That's why I started this thread. I'm curious how true it is, and what other things effect it.


    I think this is correct. When you look this up online remember they are talking about the water temperature freeze point being the same. So in my understanding the freeze point remains the same, but it would require a lower ambient temperature to get the water to freeze point when it is moving, instead of standing still

  • JUGHNE
    JUGHNE Member Posts: 10,044
    I recall a lab experiment where a beaker of water was cooled down to right at freezing or maybe a little below. The water did not freeze until you bumped the beaker and then it all instantly froze.

    Maybe nothing to do with this conversation but just testing my memory. ;)
    STEVEusaPA
  • Matt_67
    Matt_67 Member Posts: 231
    I agree with the moving water picking up heat from the ground. Typical commercial ice machines have a pump that moves water over the evaporator, i doubt they'd do that if it took more energy. Water is unique in that its most dense at around 34 degrees and then gets less dense as it actually freezes so that might play a role here too.
  • PC7060
    PC7060 Member Posts: 838
    Yes, standing water freezes faster.  Moving water inhibits the chain reaction between molecules that occurs during crystallizing process.    
    CLamb
  • Jamie Hall
    Jamie Hall Member Posts: 19,960
    Water is funny stuff. One of the most often overlooked characteristics of it is that it is densest at 4 C, unlike almost any other liquid, which would be densest at its freezing point. Furthermore, normal ice is considerably less dense than water at any temperature.

    This is helpful. In still water, the water cooled by the air, if it's below freezing, will stay at the surface -- and may freeze, but it won't sink, and the ice will happily float on the surface. Leaving warmer liquid water underneath. Now if there is a spring, or currents in the body of water, that will bring that warmer (denser) water to the surface or near it, and may keep it from freezing -- or just thin the layer of ice (as countless people have discovered to their dismay...).

    So in a body of water it's not so much the moving itself which keeps it from freezing, but the mixing with warmer, more dense water. If there isn't a source of that slightly warmer water, though, a stream will freeze eventually.

    Even in a very cold long winter, a lake will rarely freeze more than a couple of feet thick because of this. Good for fish...

    If you're looking at a pipe, though, it won't freeze provided two things: the water is kept flowing, and there has to be at some point in that flow path where it has a chance to warm up again. Where I've seen heating systems get in trouble is where there are several paths for the water to take, and one of them is really cold -- then ice will start to form in that path, and that reduces the flow, so it gets colder, so more ice forms, and eventually (it may not take long) a plug of ice forms -- and then you have a frozen pipe. It's much worse with domestic water, as it can take a fair amount of flow to keep things warm enough. The proverbial dripping faucet is not enough sometimes.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    PC7060ChrisJ
  • ChrisJ
    ChrisJ Member Posts: 13,557
    One thing I have experience with is water not freezing at a higher pressure.

    Specifically a 2 liter bottle of soda I forgot in the freezer at my parent's old house when I was around 20 years old. I took it out, thought "Oh, it didn't freeze, good!" and as I was unscrewing the cap I paused thinking "Maybe this is a bad idea" and before I could tighten it, it blew off and dented the kitchen ceiling.

    It made some mess, but not near as bad as you'd expect as the slush / ice plugged the bottle.

    Now, it's been over 20 years since that happened so maybe I'm remembering wrong, but I do know it dented the ceiling. Not much, but enough to see a slight outline from the cap.

    Makes you wonder.....
    If letting a faucet run under the wrong conditions could actually cause it to freeze.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • hot_rod
    hot_rod Member Posts: 17,537
    Some bottled water has a lower freezing point also. Is it because it is super purified, or that they added sodium or other ingredients? Or both I suspect.

    Be interesting to know when water in tube moving 3 fps freezes. DI water would be a lower freeze point?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jamie Hall
    Jamie Hall Member Posts: 19,960
    DI water has a higher freeze point -- anything in the way of dissolved solids will lower the freezing point.

    I love @ChrisJ 's experience with the soda bottle! Not so much, perhaps, depression of the freezing point with pressure (it does drop, but not that much!) but supercooled. If there are no nuclei for the crystals to form, they may not -- until a shock (did you shake that bottle even a little??) comes along and then whang the whole thing starts to freeze up.

    It's a pilot's nightmare, by the way -- supercooled water is not that uncommon in some weather conditions, but when an airplane comes along and disturbs it it does the same thing -- and ice cubes don't fly very well.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ChrisJ
    ChrisJ Member Posts: 13,557
    DI water has a higher freeze point -- anything in the way of dissolved solids will lower the freezing point. I love @ChrisJ 's experience with the soda bottle! Not so much, perhaps, depression of the freezing point with pressure (it does drop, but not that much!) but supercooled. If there are no nuclei for the crystals to form, they may not -- until a shock (did you shake that bottle even a little??) comes along and then whang the whole thing starts to freeze up. It's a pilot's nightmare, by the way -- supercooled water is not that uncommon in some weather conditions, but when an airplane comes along and disturbs it it does the same thing -- and ice cubes don't fly very well.

    Not on purpose or that I remember.

    But something upset it.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • JUGHNE
    JUGHNE Member Posts: 10,044
    If a soda machine loses power in the winter, the heaters quit working and the diet soda (no sugar) freezes first. FWIW

    Did you get in trouble or not get caught putting the dent in the ceiling?
  • mattmia2
    mattmia2 Member Posts: 6,670
    edited November 23
    ChrisJ said:

    One thing I have experience with is water not freezing at a higher pressure.

    Specifically a 2 liter bottle of soda I forgot in the freezer at my parent's old house when I was around 20 years old. I took it out, thought "Oh, it didn't freeze, good!" and as I was unscrewing the cap I paused thinking "Maybe this is a bad idea" and before I could tighten it, it blew off and dented the kitchen ceiling.

    It made some mess, but not near as bad as you'd expect as the slush / ice plugged the bottle.

    Now, it's been over 20 years since that happened so maybe I'm remembering wrong, but I do know it dented the ceiling. Not much, but enough to see a slight outline from the cap.

    Makes you wonder.....
    If letting a faucet run under the wrong conditions could actually cause it to freeze.

    That isn't because the pressure changes the freezing point but because as soon as you let the pressure off of it some of the carbon dioxide comes out of solution, the carbonic acid was depressing the freezing point. I think as soon as a little bit of carbon dioxide comes out of solution the liquid is now below its freezing point and most of the carbon dioxide comes out of solution as it turns to ice.
    ChrisJratio