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Frozen Olive Oil compared to frozen water

  1. Mar 15, 2019 #1
    Would frozen Olive oil stay as cold for as long as frozen water.
    I am making a small Stainless Steel tank that I will put in freezer and freeze to aprox -10 c . I don’t want to use water because it expands when frozen and will push my tank out of shape. I read that vegetable oil doesn’t expand, so am thinking to use this. The purpose of the tank is to keep bait cold for as long as possible when traveling out in the boat.
    Is there some other liquid that would stay cold longer that doesn’t expand?
    Is there a correlation between liquid density and staying cold longer?
    Thanks
     
  2. jcsd
  3. Mar 15, 2019 #2
    Get a well-insulated 'picnic' tub and a bunch of standard ice-packs, the plastic 'hip-flask' things you shove into a freezer.
    Safer, simpler, cheaper...
    IMHO, YMMV...
     
  4. Mar 15, 2019 #3

    anorlunda

    Staff: Mentor

    Do you mean like that "blue ice" stuff they sell in the stores? That stuff is ammonium nitrate plus water in a waterproof package that prevents your food from getting contaminated by the ammonium nitrate.

    The specific heat of water is 4.19 (kJ/(kg K)), for olive oil it is 1.97. So water is roughly twice as good as olive oil.
     
  5. Mar 15, 2019 #4

    russ_watters

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    Staff: Mentor

    Everything about it performs worse than water:
    -Less dense.
    -Higher freezing point
    -Lower specific heat
    -Lower heat of fusion
    Specific heat and heat of fusion are expressed per unit mass, so yes; denser means more heat capacity.
     
  6. Mar 15, 2019 #5
    Not suitable, must be a frozen tank
     
  7. Mar 15, 2019 #6
    The Blue Ice stuff expands when frozen, so it's not suitable for what I want
     
  8. Mar 15, 2019 #7
    Thanks for the info. I found a liquid density chart but all the liquids denser than water sounded dangerous ie acids. Glucose looked ok but it expands more than water.
    Glycol is denser, can't find anything on expansion though and not sure of cost as I require 7 litres.
    Will keep searching
     
  9. Mar 16, 2019 #8
    Then just don't fill it up completely with water and then it'll not deform (noticeably).
     
  10. Mar 16, 2019 #9

    Tom.G

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    Science Advisor

    Be very careful with glycols, some attack the nervous system, heart, and kidneys; even the fumes can be lethal. Others are used in food and medicines and are considerd 'safe' up to a dosage of 25mg for every kilogram of body weight, or 1.75grams if you weigh 70kg (or 1/16 of an ounce if you weigh 150pounds.)

    @Rive has a good idea there. Water expands just under 10% when freezing. If you can be careful about how the freezing progresses, that could work well. For instance underfill the tank by 15% and freeze from the largest side of the tank while leaving an air vent open. You could try the approach using a plastic jug (1 gallon, 4 litres).

    Cheers,
    Tom
     
  11. Mar 16, 2019 #10

    256bits

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    Gold Member

    Why is that a must criteria?
    A 'must' in design limits the choices, some of them fairly obvious and more practical.

    The ice will turn into liquid water over time anyways, so the suggestion from @Nik_2213 does have some merit.
    As the very least, one can more easily remove the bait from movable unis than from one soild chunk.
    You gain more from good insulation of the container than you probably expect.

    Perhaps tweek it a bit.
    If you find that you need X amount of ice to keep the contents frozen for a set amount of time, then make the tank of a volume X+x, where X is the amount of ice cubes, and x is an amount of liquid water. You will thus have an interior temperature of 0 C for as long as the ice cubes continue melting - an ice bath, which is what you end up with anyways as the journey progresses.

    The heat of fusion of water ( ie soild/liquid ) is 334 kJ/kg (144 BTU/lbm . ie as X turns into liquid.
    The specific heat of ice is 2.0 kJ/kg/K - subcooling a kg ice to -10C and you gain only 20 kJ cooling capacity
    The specific heat capacity of water is 4.19 kJ/kg/K - for a temperature increase to 10 C, one gains only 41.9 cooling capacity after all the ice has melted.

    You are correct that you want ice.
    Subcooled, though, doesn't matter all that much.
    Heat of fusion does.

    here is a list of heat of fusion ( enthalpy of fusion ) of some common materials.
    https://www.engineeringtoolbox.com/latent-heat-melting-solids-d_96.html
    Not too many substance top water.
    Aluminium comes close, but that's no good for you as the melting temperature is quite high.
    Ammonia is a little bit better, but really nasty.. In addition ammonia's melting temperature is -77 C - quite low, lower than the average freezer.
     
  12. Mar 16, 2019 #11
    Thanks everyone. Will stay away from glycol.
    Tank fits inside another insulated box. Size can not be varied. Ice packs wear thru. Tank will be fully sealed via welding after filling with liquid, no vents.
    Have trialled a few plastic containers with ice and blue ice and find that expansion happens at end of freezing process in a very small area, this causes a larger deformity to a small area.
    Could build a slightly concave tank and hope the tank strength will spread the expansion evenly.
    Will search for any water additives that reduce the expansion of water when it freezes
    Thanks again.
    Dave
     
  13. Mar 16, 2019 #12

    rbelli1

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    Can you slightly taper the tank so it is larger at the top? This would only need to be a small amount so the ice plug at the top moves up with the freezing of the lower portion of water. You will need to leave an air gap at the top as Rive and Tom.G said.

    BoB
     
  14. Mar 16, 2019 #13

    256bits

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    Ok. Now it is clear that the can holds the water/ ice and not the bait.:rolleyes:

    What's the matter with a metal can of this type?
    metal-fstyle-cans.jpg
    Water turning into ice will just bulge out the sides.
    It shouldn't burst the seams.
    When filling squeeze the sides slightly inwards to bring the water right to the fill point, and close.
    No air gap needed, and no pressure buildup from compressed gas, which does present a problem on its own, even if the chance of injury is slight.
     
  15. Mar 16, 2019 #14

    russ_watters

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    Staff: Mentor

    So the bait isn't going in this tank? Where is the bait? How much of it is there? What kind of container it in.

    These requirements you have seem oddly specific and don't seem to be all that necessary...
     
  16. Mar 16, 2019 #15
    OT: please take care to distinguish between 'glycol' often found in hydraulics and seriously toxic, and glycerol, which is neither...

    For several years, I shared a desk and phone with our Pharma complaints department.
    I still remember fielding a late Friday afternoon call from an irate customer who was unaware of the difference...
    Another time, there was a passionate Vegetarian who took a LOT of convincing that all our glycerol was synthetic...
     
  17. Mar 16, 2019 #16
    The holding box only fits in one spot. It is 500 mm long X 220 mm wide in a slight L shape, it is 165 mm deep. It is insulated. The Stainless tank will sit inside the holding box The stainless tank will be 499 X 219 L shape X 75 mm deep with sides continuing up to 165 mmm. So the stainless box sits inside the insulated holding box. The stainless box's lower 75 mm is a frozen tank and above that it is a box that holds the bait. The bait box is 90 mm deep and the bait is sitting directly on the frozen box.
    For various reasons I don't want plastic boxes/bags. So after considering all of above I am going to build a temporary test bait tank and 2 or 3 temp tanks out of expandable plastic and freeze both water and oil and put box in sun. Whilst Oil will heat up much faster it may last the 6 hours I need.?? (North Qld tropics) Would like to test some other liquids as well. Thanks again, at least I now know there's no magic liquid and I understand why everyone uses ice to keep things cold. If I have to use water I will build a tank with a concave bottom equal to 10% of water.
     
  18. Mar 17, 2019 at 12:18 AM #17

    Tom.G

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    Science Advisor

    Many of the plastic milk jugs sold here have panels that expand if the contents freeze or the jug is dropped. Note the circular depression on the left side, there is a matching one on the opposite surface.

    milkgallon-300x300.jpg

    Another design approach is a spring bottom oil can. Although I understand the detail design of the bottom is tricky!
    oil-can.jpg

    Cheers,
    Tom
     
  19. Mar 17, 2019 at 9:43 AM #18

    rbelli1

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    Gold Member

    The problem I see is that the frozen material is on the bottom and will come out of contact with the interfacing plate between the cooling and the cooled areas. You will send much of your cooing capacity into the bottom of the well.

    Can you design the insert so that one wall has the frozen substance sealed inside?

    BoB
     
  20. Mar 22, 2019 at 7:31 PM #19
    Umm.
    Booze.
    Windshield washer fluid is 50% methanol, 50% water and good down to -40ºC
    But methanol is nasty.
    So pick a cheap vodka, rum or rye and fill 'er up.

    Now, since you would like to get as much ICE as possible for that sweet 334 kJ/kg heat of fusion, without it freezing solid and expanding, you would experiment by putting your booze of choice in your freezer of choice and diluting until you get a mix that will fill up with a boatload of ice crystals, but not freeze solid and expand

    Now, really what you are asking is 'what is the biggest heat sink I can create in a given, constant, volume.
    Ice expands, so it breaks that constant constraint.
    Phrased another way, what non-expanding substance has the highest specific heat per LITRE?
    https://en.wikipedia.org/wiki/Volumetric_heat_capacity
    Water weighs a 1 kg/L with a specific heat of 4.19 kJ/(kg *K) --> 4.19 kJ/(L *K)
    Aluminum weighs 2.83 kg/L with a specific heat of 0.921 kJ/(kg *K) --> 2.6 kJ/(L *K) more weight but poor specific heat
    Lead weighs 11.34 kg/L with a specific heat of 0.125 kJ/(kg *K) --> 1.42 kJ/(L *K) way more weight but even poorer specific heat
    Iron is apparently best at 3.5 KJ/(L*K)

    The phase change heat for ice is ~100x larger than the specific heat -- so you'd like a phase change.
    Your winner might be Galistan -- $400/lb
    https://www.rotometals.com/low-melting-point-alloy-galinstan-68-5-ga-21-5-in-10-sn-50-grams/
    https://en.wikipedia.org/wiki/Galinstan
    Gallium has a molar weight of 69.72 g/mol, a density of 5.91 g/cm3 and a heat of fusion of 5.59 kJ/mol (Galistan I don't quite know)
    That's 473 kJ/L for the heat of fusion and a specific heat of 1.74 kJ/(L*K)

    Or play with booze.
     
  21. Mar 22, 2019 at 9:18 PM #20
    "So pick a cheap vodka, rum or rye and fill 'er up."

    Yeah, so a leak won't poison you. And, worse case, you may toast the one that got away...

    'Methylated Spirit', which is pure ethanol plus purple dye and 'barf bitters' is an inexpensive alternative to potable alcohol. Just don't drink it...
     
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