coolers and physics

Didn’t want to sidetrack the cooler discussion, this is related but a bit different. Coolers are basically an insulated box, but what about what is put into that cooler?

Some one mentioned sawdust, someone else mentioned a plant oil based product that freezes at 0 degrees. Does it matter what temp the cooling component “freezes” at? If a block of water is cooled to zero degrees and a block of plant oil cooled to zero degrees, is one to expect the same results? How about a rock which is cooled to zero degrees?

Seems like the most dense substance (whatever substance) would maintain the same temp it started out at for the longest period of time.

A friend of mine has electric heat in his home. His system is designed to draw power at “off peak” times of the day yet will provide heat to the home at anytime during the day. It does this by heating a large man made “rock” with in the furnace during the off peak hours. The “rock” stores the actual heat and when the blower moves air over it, the heated air is sent though out the house.

Are we not expecting the same thing in reverse when using a cooler? We put a cold object into an insulated box and hope it stays cold until we can replenish or re-cool the original object. All the while expecting that object to keep other objects (our food) cool in the process.

So, going back to water as ice or a variation of it as ice. If they both are brought down to the same temp, should one expect the same or very nearly the same results?

Well, I’m not a physicist, but it boils (pun intended) down to thermal conductivity and how well the media stores it’s energy (or lack thereof thermal energy).

Every media or substance has different thermal properties therefore it will take a different amount of energy to heat (or cool). Water for instance is a poor conductor of thermal energy making it a better insulator. It will heat or cool very slowly. A metal like aluminum is a great conductor making it a very poor insulator.

So, if you put an ice block and an aluminum block of the same mass and temperature in separate coolers of the same kind, the ice will give up (or absorb) thermal energy much slower than the aluminum block, this lasting longer.

Now if you start adding things to water you are changing it’s thermal properties. If you add sawdust for example, I suspect the ice will not heat as quickly as a normal ice block because it is insulated internally. The one thing it will give up is it’s abili to cool things around it. That may not be a big deal because a 34 degree beer isn’t much different than a 35 degree beer.

When it comes to coolers, there are countless factors that will change their efficiency. These are only a couple.

Yes it matters. Dump warm soda, say 85 degrees with a bag of ice in a cooler and the ice melts sure fast. Pre-chill your soda to 40 degrees and you ice lasts much longer.

Got through Dave’s post alright, then biggill had to come hard with the thermal conductivity and lost me

im just a guy that enjoys a cold beer while I jig…… you guys lost me. and by jig yes I mean this

Randy Wieland wrote:

Yes it matters. Dump warm soda, say 85 degrees with a bag of ice in a cooler and the ice melts sure fast. Pre-chill your soda to 40 degrees and you ice lasts much longer.

Randy, you are missing the point of this discussion.

I did specify the temps were the same for both cooling agents, water or a variation of water or even a rock, all cooled to zero degrees.

Not figuring in any other variables such as temp of any added food.

crappie55369 wrote:

im just a guy that enjoys a cold beer while I jig…… you guys lost me. and by jig yes I mean this

The jig on the right looks like it is working harder. Must have had a little saw dust on her.

What we’re really discussing here is the “specific heat” of different materials. This refers to the amount of energy needed to increase the temperature of the material one degree. If you look up a table showing this you will see that it takes more energy to heat up water than almost any other material.

Now, a block of aluminum at zero degrees and a block of ice at zero degrees are the same temperature to start. It takes more energy (for example from an external heat source, like the warm air around the cooler) to raise the temperature of the ice than it does for the aluminum.

I’ll be very interested to see the results of the ice versus water/sawdust mixture test. Right now my money is on the water.

S.R.

biggill wrote:

Well, I’m not a physicist, but it boils (pun intended) down to thermal conductivity and how well the media stores it’s energy (or lack thereof thermal energy).

Every media or substance has different thermal properties therefore it will take a different amount of energy to heat (or cool). Water for instance is a poor conductor of thermal energy making it a better insulator. It will heat or cool very slowly. A metal like aluminum is a great conductor making it a very poor insulator.

So, if you put an ice block and an aluminum block of the same mass and temperature in separate coolers of the same kind, the ice will give up (or absorb) thermal energy much slower than the aluminum block, this lasting longer.

Now if you start adding things to water you are changing it’s thermal properties. If you add sawdust for example, I suspect the ice will not heat as quickly as a normal ice block because it is insulated internally. The one thing it will give up is it’s abili to cool things around it. That may not be a big deal because a 34 degree beer isn’t much different than a 35 degree beer.

When it comes to coolers, there are countless factors that will change their efficiency. These are only a couple.

Biggill,

Totally agree with what you are saying and it does indeed become a balancing act. If the object being used as a cooling agent starts out at zero degrees and it’s temp never raises, then it’s not doing its job of absorbing the heat from the item(s) we wish to keep cool.

The idea is for the ice to absorb the heat energy from another object. The question becomes: at what rate? Do we want it colder for less time or a bit warmer but for a longer period?

Depends if you are trying to keep ice frozen or drinks and food 35°. The closer the 2 temperatures are, longer it will last, once your source for cooling starts to heat up rapidly. It will make itself warm even faster.

Steve Root wrote:

What we’re really discussing here is the “specific heat” of different materials. This refers to the amount of energy needed to increase the temperature of the material one degree. If you look up a table showing this you will see that it takes more energy to heat up water than almost any other material.

Now, a block of aluminum at zero degrees and a block of ice at zero degrees are the same temperature to start. It takes more energy (for example from an external heat source, like the warm air around the cooler) to raise the temperature of the ice than it does for the aluminum.

I’ll be very interested to see the results of the ice versus water/sawdust mixture test. Right now my money is on the water.

S.R.

Steve,
Thanks for jogging my memory a bit. Seems I may have heard that sometime before, in between chasing young women.

Dusty Gesinger wrote:

Depends if you are trying to keep ice frozen or drinks and food 35°. The closer the 2 temperatures are, longer it will last, once your source for cooling starts to heat up rapidly. It will make itself warm even faster.

What? If the food starts out at 35 degrees and the ice is 32 degrees, the ice will last longer than, if the food starts out at 35 degrees and the ice is cooled to zero degrees?

Steve above mentioned “specific heat” which is part of the equation. Something else missing from this discussion is the heat required to physically melt the ice, turning an ounce of ice at 32 degrees into an ounce of water at 32 degrees, called the “heat of fusion”. The heat of fusion is a pretty significant portion of the heat absorption capability of a bag or block of ice. If you had another substance that required more heat of fusion than water it would work better in a cooler.

Ron F wrote:

Steve above mentioned “specific heat” which is part of the equation. Something else missing from this discussion is the heat required to physically melt the ice, turning an ounce of ice at 32 degrees into an ounce of water at 32 degrees, called the “heat of fusion”. The heat of fusion is a pretty significant portion of the heat absorption capability of a bag or block of ice. If you had another substance that required more heat of fusion than water it would work better in a cooler.

Interesting, thanks for adding to the discussion. I will venture a guess that this has been discussed in depth by those in the cooler industry and also many other industries and applications. I suspect we will be, for the most part, be using plain old frozen water due to the cost/benefit ratio of alternative materials, if nothing else.

Ice can not be frozen below waters freeze point of 32 degrees.

1hl&sinker wrote:

Ice can not be frozen below waters freeze point of 32 degrees.

That is incorrect:
Inna Vishik, P.h.D. Applied Physics & Physics, Stanford University (2013)
Updated Apr 17 2015 · Author has 970 answers and 6.7m answer views
Frozen water will eventually equilibrate with the temperature of its environment which may well be below 0ºC.

edit; A prime naturally occurring example would be the earths polar caps where the ice temperature is commonly -15 to -20 Celsius. (5 to -4 degrees Fahrenheit)

The key to ice is the phase change. One lb of water or ice will rise in temp when 1 degree when 1 btu is added. That same 1 lb of ice will require 144 btus to change from 32 degree ice to 32 degree water. Find a substance that requires more btus to change phase from solid to liquid and your going to keep your cooler cold longer.

Dave maze wrote:

The key to ice is the phase change. One lb of water or ice will rise in temp when 1 degree when 1 btu is added. That same 1 lb of ice will require 144 btus to change from 32 degree ice to 32 degree water. Find a substance that requires more btus to change phase from solid to liquid and your going to keep your cooler cold longer.

Ahhh yes, I vaguely remember this chapter also. Must have been between the red head and the blond twins.

I read about this once and it got to the point someone put out that you need to prechill the cooler the day before or it holds heat IN! I quit reading after that.

I’ll fill my cooler with cold hose water for a half hour or so before loading it up for the weekend.
And in the winter I will fill my thermos with hot water prior to putting coffee in it.

Interesting…and here I’ve just been going to the store when I need more ice.

ClownColor wrote:

Interesting…and here I’ve just been going to the store when I need more ice.

Interesting….and here I didn’t know people didn’t go to places without stores….

Some of my funnest and memorable trips are they ones where there isn’t a store….or a road….or cell service.

Having cold beer and fresh fish are top priorities

Now to start another debate. What works better? Drain the water off the ice or leave the water?

Red Eye wrote:

Now to start another debate. What works better? Drain the water off the ice or leave the water?

Depends on if you want soggy sandwiches.
If its just beverages in there I leave the water.

Red Eye wrote:

Now to start another debate. What works better? Drain the water off the ice or leave the water?

That would always tick me off! Dad always drained the water from the cooler. We didn’t have anything to get soggy. I kept telling him he’s just tossing out the cold!!

Stubborn old man!!

Red Eye wrote:

Now to start another debate. What works better? Drain the water off the ice or leave the water?

That one is easy.
Leaving the water equals the items being colder.
Draining the water equals the ice lasting longer.
Fresh fish in packages sitting in the cold water, are always colder than the ones sitting above the water.

Huntindave wrote:

Now to start another debate. What works better? Drain the water off the ice or leave the water?

That one is easy.
Leaving the water equals the items being colder.
Draining the water equals the ice lasting longer.
Fresh fish in packages sitting in the cold water, are always colder than the ones sitting above the water.

This test has been done many many times. If you drain the water, the ice stays longer, but in the end you are left with no ice and no water in about the same exact amount of time.

In the end the only real way to keep ice solid for the longest period of time is to prechill the cooler before adding anything. I pack 1 cooler 100% full with only ice or freezer packs. For long trips, 7 days (including vehicle travel) I will pack an 8# block of dry ice in there. It must be a solid 8# block and not 2 4# blocks because dry ice sublimates around 4# per day. If you start with 2 individual 4# blocks they will BOTH be gone after day one.
About any cooler can keep ice for 2 days, so after the dry ice is gone, then I can take ice from that cooler to feed the other coolers.
The interesting thing about the Arctic Ice Tundra packs is while they freeze at 5 degrees that means they melt there too, well they still remained very cold for days (not sure exact temp) while they were thawed. A regular freezer pack once thawed is essentially useless.

I think the bigger question is why someone would leave beer in a cooler so long it got warm.