the ground has high heat capacity and fast heat transfer. to slow down the heat transfer rate you would need thick dense solid insulation.
in the air you could slow down heat transfer with stagnant air. put a plastic bag with air inside and loosely over the cooler, put another bag over that. you will have stopped air circulation from direct contact with the cooler and have an air blanket in between. even better with the cooler wrapped in blankets.
And better still if this is done in a hole in the ground, where the ambient temperature is lower and there is close to zero air circulation.
Use dry ice. Pack the cooler with the dry ice on one side, water ice next to that, then the beverages and food. There should be enough ice and dry ice to take up about half the cooler space. The food and drinks should be cold going in, and any frozen items (bacon, butter, etc.) are a plus. And of course it’s best if the cooler is full (no big air space), opened as little as possible, and kept shaded.
I usually use 20-25 lbs. dry ice in a medium size cooler (~50 qt.). Last month I still had a remnant of dry ice – and water ice and cold drinks – at the end of 5 day trip on a western river with daytime temps around 100ºF. Earlier this month I had the same after a week with temps around 90º.
Toss the water. Ice without water lasts longer.
On the assumption that the cooler will be opened and closed repeatedly throughout the day to retrieve drinks and stuff, I say keep the water.
When you open the cooler, warm air will exchange with the cold air in the cooler. More water means less air which means less warm air replacing cool air when the cooler is opened.
Also, 32 degrees is usually not refrigerator temperature. 40 degrees is usually sufficient. Once the ice has melted, a bunch of water at 32 degrees will take longer to get to 40 degrees than a cooler full of air at 32 degrees.
this is just begging for an experiment.
best is two identical coolers with drains. remote temperature sensing (wireless outdoor thermometer would be great).
next best is a single cooler with drain and a very stable (multiday) temperature environment (e.g. basement).
i don’t travel with coolers, any i have are battered (broken latches, hinges, drains); not good experimental subjects.
How cold is the ice?
This is one key question.
The other point is that it takes energy to convert 32 degree F ice to 32 degree F water(if I remember my chemistry correctly). So 32 degree water has less cooling capacity than 32 degree ice. So if you can replace the water with finely chopped ice, you’ll keep stuff cooler.
Not any more. At least in some cases. I just bought two new ones from WalMart (different brands) and neither had drains. Didn’t notice until I got them home.
Drain plugs are a good idea even if it turns out keeping the water in is better - it makes the thing easier to clean.
I think it depends what you are trying to accomplish. If I have warm drinks I drop them in ice water, when the remainder of ice melts I drain the water and add ice. Ice is much colder than 32 degrees, but 32 degrees is also much colder than what you need to bring your supplies down to. Water will more effectively remove the heat from your supplies than ice will but it is also gaining temperature as it removes heat, once all the ice is gone the water temp starts rising.
One more question: Where is the additional ice being stored?
If you’ve got a insulated cooler, and a bag of ice sitting out in the sun, you should be trying to get as much of that bag of ice into your cooler as possible, removing 32F water as necessary to get more of the ice in. (the ice has more ‘cold’ capacity than the water, even if they’re the same temp).
you take coolers with nothing but dry ice and water ice to replenish your food cooler.
I’m assuming a semi-regular trip to the store to get more ice.
When we are at the cottage, it is reasonably remote, but an hour’s boat trip to the store about halfway through a week-long trip to get more ice makes sense.
We have also used the garbage can buried in the ground and covered trick (keeps stuff cool-ish even without ice - the problem is convenience) and the lowering sealed bottles into the lake trick to get 'em cool (gotta be careful with this one, or you can lose your bottles - we once, on a remote lake, fished up someone’s bucket they lost when fishing!)
This is getting rather complex. How about these 2 situations:
In favour of 1: poorer heat conduction to the walls of the chest.
2: more thermal mass, requires more heat to increase temperature.
I think which is better will depend on the exact conditions and amounts of ice and water, or is there a clear winner?
Right: case 2 has more thermal inertia, but increased conduction to the sides of the cooler. The question is, which factor is more significant, and does that depend on other factors?
The “other factors” that come to mind are the conductivity of the insulation and the difference in temperature between inside and outside the cooler. As I see it, these shouldn’t matter, because heat transfer is linear with respect to both. That is, the answer to the OP’s question doesn’t depend on these variables.
Another variable might be the temperature of the ice in the water, but Aaron factored that out by positing 0-degree ice. That’s a pretty close approximation in the case where there’s lots of water. In the case where there’s a lot of ice and a little water, it might be a factor.
I like the idea of testing this. Unfortunately, it’s not going to happen this week.