Thermodynamics Question

[TromboneAl]

One problem with coolers, on a long trip, is that if you buy a bag of ice, and put it in the cooler, it will melt, and leak, and you'll find yourself fishing around in the water for soggy butter, etc.

My solution is to put the ice in a "dry bag," that is, a waterproof container, like this:

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This solves the water problem, but the cooler doesn't seem to get as cold. I figure that the dry bag is essentially insulating the ice from the rest of the cooler compartment, so it doesn't transfer heat as quickly, and the equilibrium temperature of the cooler is higher.

Sound right to you?

Suggestions to have a colder, dry cooler?

BTW, one trick I find useful is to make a "supercooler" by packing sleeping bags, sweatshirts, etc. around the cooler in the trunk of the car.

 

[happy2bretired]

Freeze some bottled water for both cooling and drinking.

 

[Sam]

Freeze some bottled water for both cooling and drinking.

I was going to suggest the same thing.

 

[TromboneAl]

That will work fine for the first few days, but after that I don't have access to a freezer (I'll be gone for a few weeks).

 

[happy2bretired]

Get some wide mouth plastic containers so that you can scoop ice into them. I would imagine that the plastic freezer containers would have less insulating properties than the thermal bag.

 

[FIRE'd@51]

You need a cooler with better insulation. Your "trick" proved this.

 

[BOBOT]

Use dry ice. And check out the coolers (COleman?) that purport to be good for a week at least.

 

[TromboneAl]

The cooler I have (pictured above) is a Coleman. The walls are pretty thick, so I wouldn't think that I could improve much on the insulation.

I like the container idea, thanks.

Dry ice is a good idea, but I'd rather not deal with some of the handling hassles.

 

[HFWR]

Why not do a 180, and store the food in a waterproof container...

 

[cute fuzzy bunny]

Fill old clean gallon milk jugs with water. Freeze. Put one or more in the cooler. Then you also have clean cold water to drink.

If the gallon is too big, use a half gallon.

Milk jug walls are non insulating.

 

[greg]

T-Al:

What I've done for an extended trip in the past is buy 10 pound blocks of ice while on the road. It has less surface area than cubes and subsequently lasts longer. Some of these blocks come with little holes in them, so you should have one or two larger size baggie products (twenty gallon yard waste bags?) to wrap the already wrapped ice (that very well may leak). Drain bag and refresh the single cube as needed. These things always need regular attention though.

Or buy a motor home with a fridge-freezer, but this gets a bit expensive just for cold food.

 

[packrat44]

Al,

Place your waterproof bag of ice on top the goods to be chilled rather than underneath. Warm air is less dense and will rise; cool air is more dense and will drop.

The other idea of additional insulation on the outside of the cooler is right on target. Make sure you elimate/reduce as much solar gain as possible.

 

[Sam]

A little off topic: I wish car manufacturers offer a small freezer that only run when the engine is running. That way we can freeze a few water bottles and use them in the cooler instead of buying ice on long road trips.

 

[Goonie]

I've used the one-gallon Ziplocs with good success. Fill them with ice cubes, and stuff them in the cooler, and like packrat says, lay them on top of whatever you have in the cooler. When the ice is melted all you have to do is dump out the water and refill with ice cubes. BTW, I always refilled my water jug with the water from the Ziplocs.

 

[ERD50]

Will the cooler be in the car, or do you have access to 12VDC?

They make coolers with a solid state peltier cooler in them that runs from 12VDC. I don't think they get down to freezing, but I'd bet that supplemented with the ice in a bag or in jugs it would keep things cold a long long time.

-ERD50

 

[Joss]

Water is better for thermal conduction than air. Immersing the things to be kept really cold (or to get cold quickly) is more efficient than keeping it above or out of the water.

The problem you describe is basically taste and convenience (fishing stuff our of the cold water and not liking some things to get soaked).

Butter (real butter) will last quite some time if just cool. It ultimately goes rancid but it doesn't really spoil (though that might not seem very different).

Find a tray that will float on top of the ice water in the chest and keep the things you prefer to keep dry in it. If it has a cover even better.

Minimize the goods that have to kept COLD - fresh meat, chicken, etc.

Substitute cans or preserved goods. It is a camping trip after all.

If you just have to do that special dinner, make a trip to the store that day and get fresh stuff.

 

[CyclingInvestor]

I use a bunch of "blue ice" containers, each the size of a hip flask. No leakage, seem
to stay cold for many hours, stack well in the freezer, have used some of them for
20 years now.

I also have one of the small electric coolers the ERD50 mentioned. It is not really
powerful enough to cool down a bunch of warm sodas, but it will keep pre-cooled
ones nice and cold as long as it is plugged in.

 

[Sandy]

You can start with some of your food already frozen (steak, chicken). It saves space, since the food doubles as ice and once it thaws you cook it. so there is not as much "ice" needed and less cold melted water in the bottom.

 

[maddythebeagle]

How about save all of those ziplock bags that you wash out and fill them with ice cubes... Ok...Goonie said the same thing with ziplock bags...

 

[mathjak107]

keeing ice even in the plastic super market bag seems to make it inefficiant in sucking up heat from the cooler

 

[samclem]

There's a good chance you'll end up with a lot of water in the cooler over a long trip even if the ice is in a perfectly waterproof bag, especially if the cooler is not airtight or you open it frequently. If the ice bag external surface temp is below the dew point of the air in the cooler, then there will be condensation on the bag. The water will drip off and collect in the bottom of the cooler. The water won't evaporate very quickly or at all since the RH in the cooler will be close to 100%. Your use of a slightly insulating dry bag for the ice might overcome this problem since the surface of the ice bag might not get below the dewpoint of the air in the cooler.

 

[TromboneAl]

Why not do a 180, and store the food in a waterproof container...

This is what I've been doing, thanks HFWR. I just tilt/dump out the water in the grocery store parking lot and throw the new ice in. All the ice melts after 1-2 days, but today I bought a 9 pound block -- we'll see how that goes.

Sure gets hot around here (I'm in San Clemente right now).

 

[me_no_boss]

Let me guess.
Air leaks in cooler?
Now I know you are extremely scientific in your measurements since you are a musician.

When you have flooded the cooler with melted ice water, the air volume is much reduced so heat conduction by air leakage is reduced.
But with a nice tidy plastic baggy there is alot more air in the box, a different environment all together.
You may even be peaking in there more to check how your snazzy idea is working and made it worse.

That's how your AC work.