Given an ice chest containing ice and water (the water being ice that has melted), is it better to empty the water (in the ice chest) before adding more ice? Or just add the ice without emptying?
This issue has been hotly debated around our campsite. My friends say, “the water is 32 degrees, don’t throw it out”. But I am thinking if it is 32 degrees then why isn’t it frozen? Please help settle this.
The water is chilled. But nowhere near 32 degrees. Otherwise the ice wouldn’t be melting in it.
WAG I’d guess the ice chest water is in the mid 40’s. A thermometer would quickly settle the argument.
An ice and water bath will cover more square inches of surface area of anything that is soaking in it. Ice alone will have gaps of air between cubes.
the water is in contact with the walls of the cooler and provides a transfer path for heat out of the cooler.
if you want to transfer lots of heat from an object you are better off immersing it in an ice water bath than putting it in ice only. placing cold stuff in a cooler doesn’t demand cooling it just maintaining its coldness.
As long as there is some ice left, the water will remain at 32 degrees; you can see this for yourself with a simple experiment:
However, there is still a big difference between 32 degree ice and 32 degree water; the latter will quickly warm up as it absorbs heat while ice requires a lot of energy to melt. On the other hand, keeping the water, as long as it isn’t a problem, will increase the thermal mass and prolong the time before it gets too warm if for some reason you can’t replace the ice and it all melts.
Define “better”.
If you add ice without dumping the water, it will melt faster, because water conducts heat away from the cubes to the sides of the cooler (which are warmed by the sun/outside air) better than air between the cubes conducts heat away from the cubes.
If you want to make your stuff cool off faster, then add the ice without dumping the water, because the water will pull the heat away from the warmer Stuff faster than air will.
So it depends on what you’re trying to do. If you’re trying to keep cool stuff cool, then dump the water first, as long as you have plenty of ice to replace it with. If you’re trying to cool down warm stuff as quickly as possible, keep the water. If you’re on your last bag of ice and want your stuff to stay cool as long as possible, keep the water.
My source: 15 years of camping with coolers.
Thermal mass = colder beer.
:o
what a dolt, make your sentences match your thoughts.
the water is in contact with the walls of the cooler and provides a transfer path for heat into the cooler.
There’s a reason that they build coolers with those drain plugs in the bottom.
That’s the part you came back to clarify? I understood what you meant by that, but not this:
If the stuff in the cooler (you don’t say what it is) is equal to or warmer than the water then you are better off leaving the water in.
Let’s say you have a case of room-temperature beer in the cooler, and you ice it down. The beer gets colder and the ice melts. The heat transfer continues until the melted ice (i.e., water) and the beer are the same temperature. However, you may be talking about adding ice before that equilibrium is reached. In that case, the water still has heat capacity that you want to take advantage of, and you don’t want to drain it out. Only if the beer and water have come to equilibrium does it make sense to drain the water.
As mentioned by others, it also depends on whether you are trying to cool something down fast, get to the coolest possible temperature, or keep something cold that’s already cold.
if the food you put in the cooler that is already at refrigerator temperature then you want to maintain that temperature (or close to it). ice in an otherwise dry cooler will do that best.
People are still missing the relevant point (which was stated by Michael63129): a mixture of ice and water will remain at 32 F until nearly all the ice is melted. That’s just basic physics: the energy that would heat the water goes into melting the ice first.
So if you add ice to the slurry, it will continue to remain at 32 F.
If you put a can of beer on ice, it will cool down to 32 F. The ice around it will be at 32 F. The water that results as the ice melts in the chilling process remains as 32F until the ice is nearly gone.
If you drain the water and add ice, it would be no different than keeping the water there. The water is at 32F and so is the ice. The main advantage is that water doesn’t have the air spaces, so it will make better contact with the can of beer, cooling it more efficiently.
If you want to cool things down further, add salt to the mix.
I’d say stuff it as full of ice as possible with your beer, etc. in it and let the water flow out, but keep all the water that fills the air spaces between the ice.
It appears that the original question was nebulous. The objective, for long term camping in remote areas (no ice store), is to maintain the ice as long as possible. Because when the ice is gone, the party is over! With this objective in mind, toss the water? or keep the water? Thanks for the input.
What about the “heat of fusion”, the water has already undergone the phase change.
Depends what you are trying to do. To collect the info above…
If you are cooling or keeping cool your beer or other tasty beverage - ice and water mix is ideal. The water, which is at 32F, makes full contact with the can or bottle, thus cooling it faster since water has a high heat latency and conduction. Immersion in an ice-water mix is the fastest way to cool beer. (Technically, in an ice-saltwater mix, since it will be even colder).
However, that same water makes good contact with the side of the cooler, thus transferring heat in from the outside faster. Your ice melts faster.
Air is a poorer conductor of heat. Ice, but no water, will last longer in the cooler, thus preventing the defrost and spoilage of food. The air will not convey the heat to the contents of the cooler as fast as water. However, food in contact with the cooler walls may get warmer.
Ice as it is heated reaches 32F or 0C - 1 cal per 1 degree C per 10ml of water, IIRC. Then it starts to melt. It takes 80 cal to melt that 10ml of water from ice at 0C to water at 0C. Hence, this is why ice is a good source of cold - that’s a fairly high heat sink value. Once the ice is gone, the water starts to heat over 0C/32F.
(Technically it’s a bit more complex, water is densest at 4C, so the ice and cold water floats on the top and water at 4C accumulates along the bottom - which is why it’s hard to freeze a pond deeper than a foot or 3 no matter how cold the winter is. Convetion stops rotating the warm water up at 4C.)
If the goal is to keep thngs cool longer
Then you should wrap your cooler in blankets and bury it in the ground.
But if you wish to use that ice to cool certain things, the story becomes more complicated. This is the situation that many posters have addressed.
the ground (earth) is a massive heat source/sink. if you put something into it then it will go to that earth temperature; i.e. it will warm up your cooler.
better to wrap in blankets (insulate all sides) and isolate it from the earth.
As is the earth’s atmosphere.
The advantage of burying it is that the below-ground temperature will be lower than the above-ground temperature at the times of year when ice-filled coolers are in use. And a buried cooler will see much lower air circulation, and thus lower rates of heat transfer.