Son/Mother of Fermentation Ice Bottle Recipes? Does it Scientifically matter?

[Zachkary525]

So one of the amazing things my mother has shown me back in the day was to mix isopropyl/ethanol alcohol, whatever you've got, into water placed into ziplock bags for ice packs. The result was this incredibly cold and squishy ice pack (obviously should be a hard container for the fermentation chamber). It transferred so much cold to the products I used with it that it would freeze anything it came into contact with (similar to dry ice; seeing as they both are lighter compounds than water they evaporate faster thus releasing heat faster[like CO2 releasing making a beer at 33 degrees freeze{so cool}]). I'm not certain on whether the alcohol/water solution or just plain ice lasts longer in the situation of the Son of Fermentation Chamber. What I do know is that it takes longer for the alcohol/water solution to completely solidify; seeming like it is retaining more "coldness" from the freezer.

I have two questions pertaining this matter.

Would the alcohol/water solution that gives off cold at a faster rate benefit someones situation, such as lagering or living in areas of extreme heat?

And..

Does anyone know about thermal dynamics and could you inform me on whether I would be wasting my time performing the experiment on which water solution actually stays cold longer, given the same time in the freezer?

I'm expecting the answer for the second question might be, " Since your freezer only gets down to a certain temperature, whatever solution you use will only get down to that certain temperature. Especially in the enclosed and insulated environment of the SoFC the properties of the different solutions don't make much of a difference." While the answer for the first one should be a little more open ended.

Any comments would be awesome on this topic. Thanks Folks!

 

[DurtyChemist]

How long they will stay cold won't depend on how cold you get them. If you get them to 0F or 34F they're both the same starting temperature and regardless of where they start they'll lose their cold at the same rate. The only difference would be how long it would take them to get to room temp.


I'd just put them in a freezer overnight them out them on a counter and check the temperature every 5 minutes and write it down. You'll know exactly how many degrees they lose per minute when you're done and can find out the answer.

 

[TxBigHops]

Curiously following this. I currently use frozen 20 oz bottles in my swamp cooler. Would be happy to add some alcohol if it would help the swamp cooler to stay cool longer. You say it freezes anything it touches - does that mean they need to be handled with gloves on?

 

[pricelessbrewing]

How long they will stay cold won't depend on how cold you get them. If you get them to 0F or 34F they're both the same starting temperature and regardless of where they start they'll lose their cold at the same rate. The only difference would be how long it would take them to get to room temp.


I'd just put them in a freezer overnight them out them on a counter and check the temperature every 5 minutes and write it down. You'll know exactly how many degrees they lose per minute when you're done and can find out the answer.

It's been a few years sine my heat and thermo classes but I'm pretty sure the temperature difference matters for heat flow.

 

[doug293cz]

Ok boys and girls, buckle up for the thermodynamics lecture...

First, things do not "give off cold." The only thing that ever happens is heat flows from warmer matter to cooler matter. When this happens the warmer matter cools down and the cooler matter heats up (or goes thru a phase change which requires the absorption of energy.)

The cooling capacity of frozen matter comes not so much from its actual temperature, but the fact that it must absorb heat (often a lot) to change from a solid material to a liquid material. The frozen material can absorb heat from anything that is warmer than the freezing point of the frozen material.

For example: the heat capacity of water is 1 BTU/lb-˚F. That means it takes one BTU of heat energy to raise the temperature of 1 lb of water by 1˚F. Ice has a heat a capacity about half that of liquid water, meaning that it takes about 0.5 BTU to raise the temperature of 1 lb of ice by 1˚F. So, raising the temperature of ice from 0˚ to 32˚F takes about 16 BTU/lb. In order to turn the ice at 32˚F into water at 32˚F takes 144 BTU/lb. So, taking 1 lb of ice from 0˚ to 32˚F takes 16 BTU, but then raising the temp to 33˚F (and melting the ice) takes an additional 145 BTU. It's the phase change that gives you most of the benefit. So, ice at 32˚F gives you a lot more cooling capacity than water at 32˚F.

Now to the ice/alcohol mix. What happens here is the alcohol lowers the freezing point of the solution, but what freezes when it gets cold enough is the water (the alcohol doesn't freeze until much lower temps.) If the heat capacities of water and alcohol were the same (they're not but it doesn't matter for this discussion), it would take about 24 - 40 BTU's to raise the temp of 1 lb of solution from 0˚F to 40˚F plus the amount of heat required to melt the ice into water. But, with an alcohol water solution, you have less water going from ice to liquid, so it doesn't need to absorb as much heat. Thus the alcohol/water mix will have less cooling capacity than pure water ice.

There will be a test tomorrow. Class dismissed :cross:

Brew on