Water Freeze/Thaw Question

[MattC]

If this is off-topic, please delete, but it is hiking related, since it involves setting up a water cache for a long hike.

Gallon jugs of water will be left in a car trunk from 5 AM until about 1 PM. It will be a white car, in the shade for part of the time, and by 1, the temps should be about 80. Morning temps will probably be in the 60s. We would like the water to be cold when we arrive. Should the gallons be frozen solid beforehand, partially frozen, or just chilled? How long will it take to chill or freeze each gallon beforehand?

This might be a good one for Doug Paul, or any of our other sciencey types.

Matt

 

[Peakbagr]

Matt,

Put the water container in a large cooler with lots of ice. The trunk is way better than the car interior.

 

[bikehikeskifish]

In my bike racing days (and fishing days) I just started with cold tap water, put the jugs in the smallest cooler that will contain them, and fill the void with ice. I know from fishing that a cooler in the trunk of the car filled with ice will still be 75% ice after 12 hours or more.

If you can find a stream near the parking area, you can stash them in the water out of the sun too.

Tim

 

[teejay]

I'll let

Doug do the math of the thermodynamics, the radiant solar heat, heat transfer properties of the car's trunk and the water bottles, and all the other trivialities that will undoubtedly answer your question beyond a shadow of a doubt. What I'd do, techie, sciency type that I am, would be to take three bottles of water. One frozen, one partially frozen and the third chilled. When you get back to the car, you'll have your answer.

teejay

 

[Viewseeker]

ice

I agree...fill them,pack'em in ice and shade'em...if frozen then packed in ice im sure they will remain frozen...depends on end use...

 

[peakbagger]

Dry Ice is the solution. I left a cooler full of beer in a trunk of a car at Roaring Brook for three days in August many years ago with a small block of dry ice and the beer was still cold when I got back. Unfortunately not all the bottles survived the deep freeze so cans might have to be preferred.

 

[DougPaul]

Dry ice "freezes" at -109F. Great for keeping ice cream, too cold for keeping water without freezing it solid.

You don't state clearly what form you want the water to be in when you arrive--liquid or solid. I'll presume that you want cool liquid.

One way to do this would be to put bottles of pre-chilled (not frozen) water in a cooler and surround them with ice. The water in the bottles should not freeze and if there is any ice left, should be cool to cold. How long it will last depends on how much ice is used, how good the cooler is, the car temps, etc.

This is basically bikehikeskifish's suggestion and his experience is probably the best indicator of how long it will last.

If you put water bottles in a stream, any contamination from the stream will get on the bottles. (Yes, people have have developed intestinal problems from this even though the contents were safe.)

Doug

 

[Tom Rankin]

Matt, (I'm going on this hike), do you need a cooler? We have 2. We'd better start freezing extra ice!

 

[rhihn]

I'm also going and I'll bring a cooler along.

 

[MattC]

Thanks for the responses guys. The point was how much to chill or freeze the water in the bottles, so as to not have to use a cooler at all, since I don't have a large cooler. Sorry, I didn't make that as clear as I could have.

Tom and Dick, I just sent our group an e-mail about the cache. I wasn't sure who was bringing coolers, etc. So we can continue the discussion there

Hey, it's too bad our Kanadian friend won't be along. Then we'd have Tom, Dick and Harry on this hike!

Matt

 

[Tom Rankin]

Thanks for the responses guys. The point was how much to chill or freeze the water in the bottles, so as to not have to use a cooler at all, since I don't have a large cooler. Sorry, I didn't make that as clear as I could have.

No problem. I think a cooler is the safe way to go. Coxing has plenty of water either way, and Spring Farm must have a Spring right?

 

[imarchant]

Another option

Freeze one (or more) gallon(s) solid, I estimate it would take two days in the freezer. Bring other gallon containers not cooled at all. When you get to the cache some of the ice will be melted. Pour this water off and drink it. Replace that volume with the warm water. It will melt the ice and cool the warm water, repeat the process until all the ice is melted or you are rehydrated.

 

[Grumpy]

No-Cooler Method ...

I routinely fill 16 and 32 oz Nalgene polyethylene bottles with cold tap water, and wrap the filled bottles in a heavy blanket or heavy winter coat, to be left in a vehicle all day long during hot weather. I try to stash everything in a shaded nook inside the van. A car trunk probably would keep things cooler.

The stashed water is not exactly cold at the end of the day. But usually it certainly is not what you would call hot, or even lukewarm or tepid, either. It is quite drinkable, in fact. Sometimes, it even remains respectably cool. Of course, I am not an ice water fan, and never have been.

I do like my post-hike frothy adult beverages served adequately chilled, tough.

G.

 

[DougPaul]

I routinely fill 16 and 32 oz Nalgene polyethylene bottles with cold tap water, and wrap the filled bottles in a heavy blanket or heavy winter coat, to be left in a vehicle all day long during hot weather.

If you have bottle parkas/insulators for winter hiking, I suspect that they would work well here too.

Doug

 

[Grumpy]

If you have bottle parkas/insulators for winter hiking, I suspect that they would work well here too.

Doug

The secret seems to lie in keeping the bottles shielded from the sun. Wrapping them in blankets or a cushy winter coat serves that purpose, as well as providing insulation. It is best, also, if the bundle is stashed in a shaded nook of the vehicle (under a seat, for example).

G.

 

[Kevin Rooney]

I think there's a lot to be said in preventing/slowing airflow over a cold service as a way of keeping things cold. For example, if I want a couple of cold ones to really stay cold after a long hike, I wrap the blue-ice container itself in a towel, and place it in a small cooler, with the cans on top of that. Seems to work better to keep the cold source itself cool, and that keeps everything else in its proximity cool. If I don't do this towel trick, then everything in the cooler will be tepid.

I have NO idea why this works better. My English major brain says that by reducing airflow over the source it works. Need someone with a Math major brain to explain the whys and wherefores.

 

[DougPaul]

I think there's a lot to be said in preventing/slowing airflow over a cold service as a way of keeping things cold. For example, if I want a couple of cold ones to really stay cold after a long hike, I wrap the blue-ice container itself in a towel, and place it in a small cooler, with the cans on top of that. Seems to work better to keep the cold source itself cool, and that keeps everything else in its proximity cool. If I don't do this towel trick, then everything in the cooler will be tepid.

I suspect that if you plot drink temp vs time, you will find that without the towel, the drink will be colder at the start. However this will increase the heat flow (conductive heat flow per unit area is proportional to temp difference), so the blue ice will melt faster. Thus, the drink temp when you come back from the hike depends on how long you were away--short hike -> colder drink without the towel, medium hike -> colder with the towel, epic hike -> warm drink either way.

Ice boxes on boats exhibt a similar phenomenon--the ice will last longer if you drain the meltwater rather than keep it.

I have NO idea why this works better. My English major brain says that by reducing airflow over the source it works. Need someone with a Math major brain to explain the whys and wherefores.

Nope--don't want a math major either. You want a physics major.

Doug

 

[TCD]

An "ordinary" system like a cooler with ice and water bottles in it, in a trunk, in the sun, can generate a tremendous amount of Physics instruction in a small package! Great stuff!

I think your water will be fine. My experience is that even a very cheap, disposable styrofoam cooler, with a bag of convenience store ice will keep water and other beverages cold for a day in even extreme conditions. That's the system we use in Red Rocks. We pick up a cheap cooler, put our water, soda, gatorade, etc. in it (chilled, as purchased), cover with a bag of ice, and put the lid on tightly. This assembly sits from 9 AM to 5 PM in the back of an SUV (not the trunk), in worst case conditions of 105F and direct sun. When we get back at 5, there is still a little ice left, and the drinks are cold. And BOY, do they taste good!

 

[brianW]

My rule of thumb is to never freeze anything I plan to drink that day. Will add ice cubes to it though if possible.

About ten years ago I went on the eighth grade hike up Monadnock. One of the teachers told the students to freeze their water bottles. Sad to say the students that listened didn't have much to drink.

 

[bikehikeskifish]

Speaking of airflow... on a day like today (current temp 98F), a frozen, 16 oz water bottle stuck in the bottle cage of my bicycle will reach ambient temperature in about 20 minutes. A long time ago, I gave up trying to keep water bottles cold (while riding.)

Tim