Thermal mass in a freezer

[Frank S]

My wife decided the side by side freezer in our 31 Cubic foot fridge was not sufficient for our longer term storage needs. I agreed since much of the freezer section is wasted with an ice maker that we never use so I removed the auger from the compartment to allow for things to be stored in there.
 The other day we bought a chest freezer but currently don't have enough to properly fill it
 I am wondering what would be the best thermal mass to put in it.
 To me water unless it were brine or have a heavy saline content to lower its freezing point.
 I was thinking about linseed oil because it freezes at -4°f another thought would be blocks of aluminum
 Any ideas? I would like to have something in it to fill possibly 1/4 to 1/3 of the space unless otherwise required for frozen food stuffs

[Frank S]

I also want this to slow the flywheel  effect of freeze thaw to help prevent crystallization or freezer burn which can be caused by food warming slightly but not thawing even though vacuum sealed

[MagnetJuice]

99.99 % pure gold would be my first choice. About 600 Lbs. depending on the size of the freezer. I know Texas has a lot of gold. If not golden in color, they have black gold. 

My second choice would be something cheaper like wood. Oak or maple is dense enough to do a good job. Put it in heavy plastic bags and place it vertically in the freezer so it can be removed quickly if necessary.

Ed

[bigrockcandymountain]

I would do water.  It has extremely high specific heat capacity and the latent heat for melting is also very high, so if your freezer dies, you'll be ok for a long time. 

[Frank S]

99.99 % pure gold would be my first choice. About 600 Lbs. depending on the size of the freezer. I know Texas has a lot of gold. If not golden in color, they have black gold. 

My second choice would be something cheaper like wood. Oak or maple is dense enough to do a good job. Put it in heavy plastic bags and place it vertically in the freezer so it can be removed quickly if necessary.

Ed

I don't have any gold, yellow black or otherwise. but I have something that may become even more valuable
 About 1500lbs of raw lead, but due to the extreme high density of lead even if I were to place the entire 1500 lbs in the freezer the amount of surface area available to aid in temperature stabilization would be limited.
 Water is a PCM (phase change material) but it changes at 32°f  (0°c)Not the best for keeping things frozen in the event of a longer power outage. Making brine by boiling the water and dissolving salt to the highest saturation level then freezing it will lower the PC° to about 25/26°f (-4°c) linseed/ flaxseed oil has a PC of around -4°f (-26°c) that is why I am thinking about using it 

[mab]

Water stores 4200J/'C/kg (or litre)
Ice stores 1200J/'C/kg.

I use storage heater blocks (magnetite) in my freezer; they store only 935J/'C/kg but are quite dense:- 5.2kg/litre so store more than ice. Iron would also be better than ice (only 450J/'C/kg but 7.8kg/litre).

Linseed oil has a heat capacity of 1800J/'C/kg, density 0.942kg/litre - so is better than ice even without the phase change - assuming it stays constant - heat capacity of oils can be a bit variable.

I can't seem to find the specific latent heat of freezing for it though.

[Mary B]

I just use gallon jugs of water when ti isn't full of meat(right now it is pushing max...). When I process a hog I render the fat for lard and that goes in jars in the freezer, no clue what pork fats specs are but it keeps it fresh for a year LOL

[MattM]

I store a few jugs of canola oil in the chest freezer.  I just figured it would take longer to thaw than the jugs of water we used to keep for the same reason.  Lost power for four days and the stuff in the chest all stayed frozen.  It probably helps the lid insulation got swapped out about ten years ago after the wife dented it.  I couldn't believe how flimsy it was when it was new.  But I had no idea how ridiculously cheap it was built until it suddenly became floppy from the center edges getting bent/crushed.  It had a cheap fiberglass mat - not even filling the entire lid area - where I was expecting at least a styrofoam chunk.  It got replaced by a piece of phenolic roof insulation and the result was a rigid top that doesn't get cold.  Taking the sides apart proved too much work but it looked like rockwool in them.  When we run low on oil I can always thaw out a jug and use it.  It turns cloudy from the phase change but cooks fine.

[Bruce S]

Frank S;
I use two items that I have access to so YMMV;
180 Proof Alky ( doesn't freeze, get more like syrup & chills the outside of the container during thaw), Tallow , Beef Tallow will keep pretty much like Lard will, but I have access to FREE beef fat (family down home raises "fancy" cows).

Hunting season here, so freezer is like Mary B's at near capacity due to friends' needing a place to off-load last year's dear meat (YUM).

MattM;
Ditto, on the lids' insulation, mine wasn't dented but rusting. Removed it to outside for scrubbing, rust removal and painting.
Ended up replacing entire lid insulation with wool insulation ( was a recommendation from a commercial freezer repair crew). Never looked back.
 
 Hope this helps

Bruce S

[Frank S]

For now I have just placed a few 3 ltr bottles of brine in the freezer and allowed them to freeze
 My whole reasoning for wanting the thermal mass is I doubt it we will fill it to near capacity with food stuffs so the mass will help to improve the efficiency plus in the event of power outage (Rare around here but has happened),the food will have a better chance of remaining safe for longer.
 The last outage here lasted for 12 hours our fridge freezer remained frozen but the fridge did warm up enough that a half gallon of milk almost turned. If I had had the freezer at that time I could have stolen a couple bottles of the brine and placed them in the fridge.
 Ultimately though I have a 6000 watt UPS that dumps all incoming energy into the batteries then the output is from the converter I want to connect it into a dedicated circuit which will be for a few essentials of the house and connect my 1.1KW worth of solar to the house with the proper grid tie and switch gear that will not feed the grid if there is no incoming power   

[Frank S]

last week the electric company had been doing lots of line and pole replacements in the area plus a major refit to our substation. they emailed called and visited everyone on our substation the power would be off between certain hours while transferring temporary power from another line then a couple days later after all of the upgrades would be completed it would go off again for a couple of hours. No big deal right? Well on the 2nd time the power was cut off when it didn't come back on in 3 hours a supervisor's truck pulls into our driveway and said that the feeder line I was on could not be reconnected for a while because some of the new transformers had shorted once energized and our power could be off for an extended period of time.
 I knew our freezer would be safe as I had it well over 2/3rds full by now so I pulled 3 of the 3 ltr bottles of frozen brine and placed 2 them in the fridge and 1 in the freezer section of the fridge. several hours later possibly 15 or so total, when the power was restored I opened the fridge to find that the digital temperatures showed the freezer to be 10°f and the fridge to be 43°f . Those bottles of frozen brine had done their job nothing had thawed and not even the milk warmed enough to spoil. So the bottles were returned to the chest freezer for another time.
 I'm a believer in thermal mass and the next time if we have a bad storm and the power goes out the first thing I will do it toss some in the fridge

[SparWeb]

Didn't think you would be proven so soon, eh?

[tanner0441]

Hi

A few years ago I had a couple of blocks of Dry Ice solid Co2 for use in a stage smoke machine.  I used most of one of them so the remainder and the full block I put in our domestic freezer. For the 3 days it was in there the compressor didn't run once. The blocks are about a foot across and 3ins thick.

It doesnt thaw as such but sublimates at around -78.5C (-109.2F)

Brian

[OperaHouse]

Old thread, but I have a chest fridge that only runs in the day since I have a minimal battery system. I've run for months at a time in summer for years without problem, stored cold in large quantities of liquids.  The modern freezers have all the chiller coils on the bottom now because higher up they put the hot exchangers.  I run a fan inside to limit stratification.  The bottom always freezes and you can't put cans there.

[Frank S]

Well, it has been a year now since we got the freezer. the electric has gone off only a couple of times and then only for a few hours but once this past summer the wife let out the Majic smoke on a vacuum cleaner I didn't think much about it at the time but the next day I noticed there was no little red light on the freezer. then discovered the breaker had been tripped everything in the freezer was still frozen even the ice cream, Flipped the breaker back on and only then did I remember that I had a second outlet on the same circuit as the freezer which I had thought I had removed and placed on the circuit the washer is on. Now the freezer is the only outlet on that breaker. Thanks to the 12 liters of frozen brine water and the freezer being 2/3rds full nothing was lost. this has gotten me to think about a micro-UPS with a Piezo alarm to be plugged into the same outlet as the freezer it will not have anything connected to it but will sound the alarm if the power is off on that circuit

[tanner0441]

Hi

I will second the dry ice comment a few years ago I had 3 bags of dry ice pellets to shrink some dowels prior to fitting them into a large press die. I put them in an under counter upright freezer, for the time they were in there the compressor didn't run, the thermometer was pinned to the stop and every thing in the freezer was solid, anything like chops or sliced meat took ages to defrost enough to separate them. It sublimates as well so no spillage of liquid as it thaws out.

What we saved on electricity not running the freezer we spent on the microwave defrosting things.

Brian

[Arctic Taco]

I tend to use passive means whenever possible in my cabin in Ak.
At home in the fall, I just use a few 2 quart jugs of water. Leave them in a cooler out on the porch-stuff will stay frozen for about a week before things get thawed on their own
I live off grid and use a Dometic 12v fridge during the summer which with 4 jugs and otherwise filled with food and just plug the fridge in during the day- my battery bank is pretty old- and it rarely gets up to 46 by morning when I plug it in.
Winter is a different story altogether, leave it outside and it stays frozen(but check frequently as winters aren’t as cold as they used to be) refrigerated items sit on the floor near the door.
Long story short, thermal mass is always a good idea, save energy as well as short term outrage insurance.

[Mary B]

Living in MN I have debated putting a glycol loop in the fridges freezer and one outside. Use it to move cold inside during the winter, would need to come up with a fan control to turn the fan on between the freezer and fridge to move cold air...

[machinemaker]

beef, chicken broilers, turkeys, or pork is what we use.
Kent