Pamela wrote:
Amazon/Morrison's deliver frozen food with ice packs containing some
fluid which doesn't stay frozen in my freezer.

What liquid are they using and do ice packs have any use once the frozen
food has been delivered? Seems a shame to throw them away.

You recharge freezer packs in the "chest freezer".

The regular refrigerator has to be set to a too aggressive
setting, to do freezer packs.

Only a "new" fridge makes rock hard ice cream, with
authority. When fridges get older, the chest freezer
is a good place to store the ice cream instead. Or, to charge
up a freezer pack.

You can store more energy in a freezer pack, if it
goes through a phase change. The phase change of your
particular freezer pack, is 3X better than water. The
"flat section" of the diagram for your freezer pack,
is three times wider than the plain-water diagram in
this article. That means the freezer pack might
"last twice as long" for some purpose.

https://chem.libretexts.org/Bookshel...Vapori zation

Paul