Keeping the ice chest cold
Keeping the ice chest cold
(OP)
Not a terribly important subject but I thought it would be a fun one.
To keep the ice chest cold on extended camping trips do you want to empty the water from the melting ice or keep it in there?
My thoughts are to keep the cold water in the ice chest because the sun has to heat up the mass of the water and the ice. But the flip side is that water is a better conductor of the heat so it ends up melting the remaining ice faster.
To keep the ice chest cold on extended camping trips do you want to empty the water from the melting ice or keep it in there?
My thoughts are to keep the cold water in the ice chest because the sun has to heat up the mass of the water and the ice. But the flip side is that water is a better conductor of the heat so it ends up melting the remaining ice faster.





RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
Same reason a bottle of beer will cool much faster in a bucket of ice water than in the freezer.
RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
TTFN
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RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
keep a wet towel covering the cooler.... keep it wet.
magicme
------------------------------------
there's no place like gnome.
RE: Keeping the ice chest cold
Better designs? Thicker foam at the bottom and partly up the sides to compensate for the water contact. An internal ice container, made of aluminum, to keep meltwater from contacting the foam. Of course, "better" depends on whether the purpose of the cooler is to cool things placed into the cooler or to keep cool things already prechilled before placement into the cooler. But the OP did specify "camping trip."
RE: Keeping the ice chest cold
Drink all beer before ice melts...use a funnel if needed. have fun.
RE: Keeping the ice chest cold
It would seem that the conductivity of the water would only be an issue if there were significant mixing of the ice-water-beer.
There are many variables to consider imo this would be an interesting science fair project for a young student.
RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
Only true if delta T is constant. Air and water result in different delta T, since air, being less conductive, sucks up more of the delta T, leaving less delta T across the insulation. This is the reason that double pane windows are more efficient at insulating.
TTFN
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RE: Keeping the ice chest cold
True if your boundary is the interior surface of the wall.
If we are considering the heat transfer out of the beer to the ambient air, then you have to consider the convective film coefficient. Water's will be much higher than air.
RE: Keeping the ice chest cold
MintJulep I assumed at the intial state the contents of the cooler were at a uniform temperature and the ambient air is the higher temperature. Hence heat would travel from the outside and eventually to the beer.
All of the energy reaching the contents must pass through the wall. Granted the contents will eventually warm and the delta T will shrink but it will be slow (if the cooler is any good). So which can absorb more energy and increase in temperature the least?
RE: Keeping the ice chest cold
Heat enters the cooler's exterior skin via combined convection, radiation and conduction if in contact with some solid such as the ground or a picnic table.
Passes through the exterior skin via conduction.
Passes to the insulation. If we assume bonded closed cell insulation we can simplify to conduction.
Passes to inner skin, same simplified assumption.
From the inner skin:
Convection to the air.
Lets start with 100% ice, 0% water. Conduction where the ice is touching the inner skin.
Conduction to any beer containers that may be in contact with the skin.
Radiation to ice and beer containers.
Ice begins to melt.
Add convection from skin to water, water to ice and water to beer containers.
Add radiation between water and inner skin, water and any ice that remains "high and dry", and between water and beer containers.
As the ice melts, the volume occupied by H2O decreases, leading to infiltration of warm outside air.
Obviously the initial conditions will affect all of this as well.
On thing is clear however, in summer conditions, by the time the system reaches a steady-state condition the beer will be too warm to drink (unless you are British).
RE: Keeping the ice chest cold
magicme
------------------------------------
there's no place like gnome.
RE: Keeping the ice chest cold
Using some typical, yet arbitrarily chosen, numbers, water results in 28 W/m^2 transferred through the insulation, while air results in 17 W/m^2 transferred through the insulation. A difference in 10ÂșC in the delta T across the insulation between water and air on the inside.
TTFN
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RE: Keeping the ice chest cold
it seems you are disregarding the masses (water versus air). it takes a lot longer time to change the temperature of a cooler filled with cold water than a cooler filled with cold air ... i did not run any numbers but i think that would offset the differences in conduction (water vs air).
i think mass is a big factor in this problem.
magicme
------------------------------------
there's no place like gnome.
RE: Keeping the ice chest cold
I do considerable deep sea fishing in the Gulf of Mexico with numerous extended trips of 2 to 4 days where the ice has to last. I drain the water off all coolers both large and small and use a wooden grid in the bottom of all coolers to insure they drain.
On the larger boat we go to great lengths to insure the coolers drain and that they are air tight and are only opened when it is required. On one of the boats we have a box that holds about 1500 pounds of ice and we can stay 4 days and still arrive with fresh fish. On the larger boat we can carry about 60,000 pounds of ice and can stay about 20 days.
Anecdotal:
Several years ago I had an acquaintance that believed in keeping water in his cooler. While in a fishing tournament he caught a 22+ pound red snapper. He put the fish in his cooler and started for home. He broke down and had to be towed to the dock. While checking the fish at the scales the weigh master deemed that the fish had soured therefore it must have been caught before the start. All his ice had melted and and the warm fish soured in the 5 hrs it took to get to the dock. A 11 pound Red Snapper won the tournament and the $1,000 prize.
RE: Keeping the ice chest cold
The reason to drain the water off the ice in a boat iw weight and room (for the fish).
You drain water you are loosing energy unless the water is warmer than outside the box.
RE: Keeping the ice chest cold
I remember a thermo quiz problem on the cooling of a champagne bottle. You kept the water and ice mixture, slush and the problem was determine the optimum speed to turn the bottle for fastest cooling and a certain end point and how long would it take to achieve the same end point without turning.
With fish you let the cold water run over the fish while minimizing the heat transfer through the walls.
RE: Keeping the ice chest cold
as a Hemingway fan, i hate to disagree with a deep sea fisherman, but i have to stand by what i said earlier .... keep the water until it's warmer than you want the beer (or fish) to be ..... as long as the water colder than that temperature, it is keeping the beer (fish) cool.
i'd like to prove that but i usually finish the beer before the ice melts ;>)
magicme
------------------------------------
there's no place like gnome.
RE: Keeping the ice chest cold
Air 1000 kJK/kg
Liquid H2O 4000 kJK/kg
Solid H2o 2000 kJK/kg
(approximate values)
RE: Keeping the ice chest cold
OTOH, if the goal is to rapidly cool warm beer, leave the water in (to keep the convection/conduction to the bottle high)(note also that no drinkable beer comes in a can) until the beer is cold enough to drink, then drain the water out.
Heat capacity: the heat (cold) capacity of water is 1/80 the heat capacity of ice, due to the heat of fusion (80 cal/g ice vs. 1 cal/g water). Until the ice melts, the temp. of the ice/water bath remains at 32 F/0 C, and the water contributes nothing from its heat capacity, since its temperature never changes.
Fish: keeping the fish out of water is best, but the more important reason (besides keeping ice icy longer) is that melting ice yields fresh, pure water. Fishies, even fresh-water fishies, have a saline fluid in their bodies. Soaking a cleaned (dead) fish in fresh water causes its internal, um, juices, to continually leach out of its tissues due to osmotic pressure (note that living fish have cellular mechanisms to resist this effect), the result is the fish's flesh gets soggy and limp, and its eyeballs sink, two signs that most people use to say whether a fish is "fresh" or not. Secondly, the leaching fish fluids make a lovely protein-rich bath for microbes to multiply in, resulting in your fish smelling fishy (the third way people determine fish freshness).
Say this 3 times fast: "leaching fish fluid makes fish smell fishy".
Grant proposal: I believe on the whole, the order of magnitude of drained vs. undrained ice retention time differences would be small, for an average-sized cooler on an average summer day. I further submit that everyone reading this post should pony up $1 US, and I will gladly conduct a side-by-side comparison test, with temperature-instrumented coolers and two cases of bottled microbrew; test protocol would involve removing one bottle from each cooler per 30 minute elapsed time interval, and recording temperatures of the fluids prior to their, ahem, disposal. The test would probably need to be repeated on a second day, swapping coolers, to avoid having a defective cooler skew the results, therefore make it $2 US.
RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
I would also be willing to assist with the disposal of the waste test fluid.
RE: Keeping the ice chest cold
why don't you folks just move to alaska where keeping the "refreshments" above freezing is needed in order to enjoy them.
now to my answer, air has a lower coefficient of heat transfer than water does, yes, temp difference between the cooler inside and the atmosphere will be the driving force of heat transfer. a btu is a btu, so to keep cool items cool in a cooler, it is no different than the refrigerator. remove the water. to cool a warm object, cool in water and then place in cooler without water, but with ice.
enjoy!
-pmover
RE: Keeping the ice chest cold
Therefore, to re-iterate, the goal is to conserve the ice as long as possible.
I had access to a multi channel data logger at my previous job but not here. I think I'll run a test with two identical cups, some ice and a manual data logger (aka me).
RE: Keeping the ice chest cold
KEEP YOUR ICE DRY
RE: Keeping the ice chest cold
jt
RE: Keeping the ice chest cold
And it doesn't get wet like regular ice.
TTFN
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RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
If you combine dry ice and water ice I assume you'd have to keep them seperated? Otherwise the water will melt the dry ice really fast and you'd just have a fog machine on your hands.
RE: Keeping the ice chest cold
We use wet ice to keep stuff frozen on the larger fishing boats. We have pens where we stack frozen boxes of bait. We essentially use the wet ice for insulation of the frozen bait.
We do the same for food stuff but take the liberty to drop the temperature of the food to -40F prior to packing in ice.
This will keep stuff frozen for about 20 days if the pens are not opened but once a day.
After twenty days the bait gets salted and the crew eats can goods.
Before the advent of those little blue thingies we would ship fresh seafood with dry ice. There have been shipments to Japan using dry ice.
RE: Keeping the ice chest cold
RE: Keeping the ice chest cold
Now why is this possible? one thing that nobody has mentioned is the effect of ice and water sloshing around in the chest. What does this do? it causes the water to become colder than ice sitting still in water. Similar to adding salt to make the water colder than the ice.
When I used to leave the water in the chest, I would have to add an additional bag of ice daily to keep things cool. By draining the water, I was able to go 3 to 4 days before adding an additional bag. Without water, there is no movement, so there is a siginificant reduction in heat transfer.
RE: Keeping the ice chest cold
Some are in my cooler that has tabs on the feet to prevent wear and also as stated above keep the box off the deck.
It also has a wood grate in the bottom.
The other is a standard 48 quart cooler with no adornments.
Both will drain to dismay of the neighbor's cats. So I'll have a check in the morning a which is the best.
RE: Keeping the ice chest cold
don't use ice, frozen beer works great(efficient as well)
Take one ice chest for each day
Put frozen beer and food into chest and duct tape all seams
As long as no one takes a peep inside, and the cooler stays in the shade you can enjoy a cold beer and sitting in your lawn chair on the border a full week after departure
... Have fun
RE: Keeping the ice chest cold
You use ice to take advantage of the latent heat of melting. The temperature in the inside of the cooler should be zero C until all ice has melted.
Assumption: the R value of the insulation is >>> than the difference in convective heat transfer between the inside wall of the cooler & water and inside cooler & air or the convective heat tranfer between the ice and the water.
If my assumption is true, the heat transfer from the cooler is mostly insulated by the cooler insulation, not by the difference in convective heat transfer between water & cooler or air & cooler. If you leave the water in the cooler, once all the ice melts, you are left with zero C degree water that must be heated. Water has a very high heat capacity compared to almost any other substance (such as air). So I say you leave the water in.
RE: Keeping the ice chest cold
It depends on wether you want ICE for as long as possible or if you want it cold as long as possible (im even sure the last case will ever win out to favour keeping the water) - here is why:
As long as the ice is COLDER than freezing (0 deg C sorry SI) then the "cold" comes from HEATING the ice. Once the ice starts to melt the cold comes from MELTING the ice. Now as many has said - the water increases the heat transfer - and propably A LOT! So in order to keep ice for as long as possible you should drain the chest continiously (a drain hole would propably be justifiably even though heat loss here is higher.
On the other hand - once all the ice is melted you still have the heat capacity from 0 deg C to say 10 deg C - that also count for someting but i think in most cases draining would be the way to go - unless you have VERY good insulation on the box.
Best regards
Morten
RE: Keeping the ice chest cold
Morten
RE: Keeping the ice chest cold
RE: Keeping the ice chest cold