On Sat, 01 Jul 2006 04:29:08 GMT, cavelamb
wrote:


Anyone out there use dry ice for refrigeration?

I want to keep the cooler cooler longer.


A couple pounds of dry ice seems like a good idea,
but how to use it?

Mix with wet ice?

Or keep separate?

Richard

The CO2 evolved from dry ice is too cold for chilling food and drinks
directly, but it can keep the water ice from melting so quickly.
This suggests a cooler within a cooler - the inner cooler giving
off CO2 gas which bubbles through a water ice mixture, which chills
the food container.

Dry ice provides a tidy explosion if its vapor has nowhere to go, and
it is not a good breathing gas - but at least it gives plenty of
warning - we are designed to pant if the CO2 proportion rises
(unlike low O2 which induces unconsciousness with no warning at all.)

You might take a look at the electric cooler boxes. Either way,
expanded polystyrene is an excellent insulation.

Brian Whatcott Altus OK

I have routinely taken a half gallon of ice cream on our Kayak
excursions. It is inside a smaller lunchbox size cooler with about 5
lbs of dryice on top, and that cooler placed inside another cooler.
Works great. The only problem has been that the ice cream was sometimes
still frozen (after 3 days) too rock hard to dispense. It hat to sit
out for thirty minutes to get a scoop in it.

I doubt it's advantageous to use dry ice for a longer cooler duration.
Three days seems to be the maximum. But if you want to keep things
frozen, it's perfect. It's available around here in any local grocery
store, from a special "Dry Ice" freezer by the entrance.

Brian Whatcott wrote:

On Sat, 01 Jul 2006 04:29:08 GMT, cavelamb
wrote:


Anyone out there use dry ice for refrigeration?

I want to keep the cooler cooler longer.


A couple pounds of dry ice seems like a good idea,
but how to use it?

Mix with wet ice?

Or keep separate?

Richard


The CO2 evolved from dry ice is too cold for chilling food and drinks
directly, but it can keep the water ice from melting so quickly.
This suggests a cooler within a cooler - the inner cooler giving
off CO2 gas which bubbles through a water ice mixture, which chills
the food container.

Dry ice provides a tidy explosion if its vapor has nowhere to go, and
it is not a good breathing gas - but at least it gives plenty of
warning - we are designed to pant if the CO2 proportion rises
(unlike low O2 which induces unconsciousness with no warning at all.)

You might take a look at the electric cooler boxes. Either way,
expanded polystyrene is an excellent insulation.

Brian Whatcott Altus OK

Well, I asked, didn't I.

Thanks to all for the information.

As it worked out a couple or three pounds of dry ice in one corner of the
ice chest kept the rest of the wet ice well frozen for three days. (!)

I think the wet ice is acting as insulation to protect the food stuff from
the dry ice - depending on how close stuff is to the dry stuff.

My boat is an 18 foot Capri (Catalina) so we don't have a lot of room to
play with. But with the companionway open at all there doesn't seem to be
much danger from CO2. There is just not enough dry ice in the box to make
much CO2 very rapidly (as was pointed out several times).

BUT! It really does keep the cooler cooler longer...

Thanks folks,

Richard

On Thu, 06 Jul 2006 16:41:41 GMT, cavelamb
wrote:

I think the wet ice is acting as insulation to protect the food stuff from
the dry ice - depending on how close stuff is to the dry stuff.

That is exactly the right way to use dry ice in a cooler box.
Otherwise there are problems with things that come in direct contact
such as beverage cans which will quick freeze and rupture.

The one exception is carboard juice boxes which don't seem to mind
being frozen, and actually make an excellent ice substitute if frozen
in advance.

Wayne.B wrote:
On Thu, 06 Jul 2006 16:41:41 GMT, cavelamb
wrote:


I think the wet ice is acting as insulation to protect the food stuff from
the dry ice - depending on how close stuff is to the dry stuff.


That is exactly the right way to use dry ice in a cooler box.
Otherwise there are problems with things that come in direct contact
such as beverage cans which will quick freeze and rupture.

The one exception is carboard juice boxes which don't seem to mind
being frozen, and actually make an excellent ice substitute if frozen
in advance.


doh!