Eutectic Solution Solution

[jeffnick]

Had a pleasurable experience with the small chest freezer on my aft deck. The challenge was to keep my beer cold without freezing my wife's lettuce and use no power and buy no ice for a minimum of 5 days.

I filled a 5 gallon flexible/portable water container with brine. I set the freezer at minimum temperature and froze the container into a solid brick before we left. I didn't put anything in the freezer for the 3 hr tow to the lake.

Once settled at anchor for the night, I moved the contents of the cooler to the unplugged freezer and added 18 bottles of room temp beer. I could have done this before we hit the road, but I wanted the freezer to normalize so the beer and lettuce didn't freeze. I have 2 remote bulb thermometers mounted on the side of the freezer...one reads the temp 1/2 way down the brick (about 4" off the freezer bottom) and the other at the bottom of the freezer basket -- about 8" from the top of the freezer. The temps at this time were 34 on top and 28 below. My bottled beer was placed directly on the brick.

The next morning the readings were 36/28 and my breakfast beer was perfect. There was a plastic food bag with a little water in it from the cooler above my beer, and that water froze solid. At the end of the day, we were at 40/28.

The next day the basket probe was showing 45. The brick probe was 29+. Worried at the climb of the basket temp, I powered the freezer for about an hour and saw 36/28. On day 4 I powered the freezer for 1/2 hr with similar results. Looking back, I'll bet most coolers have areas of 45 or higher regularly.

So now the big question. If/when I 'recharge' the freezer by applying power, will I be adding recharge time by setting the freezer thermostat at 28 versus having it at -20? The intent being that I wouldn't have to worry about over recharging and freezing my brew - screw the lettuce.

Blog entry about the trip here:
One More Time Around: Merlin - Just Like Me

 

[Keith]

Cool! What was the composition of your brine?

 

[ben2go]

I have seen this done with much success.I plan to do it when we finish remodeling our other house and move into it.

Hack Your Own Super Fridge - The Daily Green

 

[FF]

Ice is an insulator , so a thin eutetic plate will be frozen faster than a BBL.

Adler & Barbour built a special eutetic plate that had a huge flat plate inside , with the freon paths pressed in , like a home fridge evaporator.

Freeze time of under 45 min on the 4000BTU plate.

Co$t to mfg killed the deal. Saving cold could be more effective than saving batt power , but not many are willing to spring the bucks.Everyone has an alternator , and an extra bunch of batterys is cheap.

Even with China slave labor and a $5.00 eutetic plate , the hassle of hanging a compressor (8- 10hp) on the engine or noisemaker takes bucks.

Seems only sailors are willing to pay for the Sound of Silence!

 

[jeffnick]

My brine was roughly 1 carton of salt for 5 gallons of water.

I boiled a couple of gallons of water to disolve the salt, let it cool, put the brine in the container and filled it up to almost full. It takes over 24 hrs to 'brick in the freezer'.

The little chest freezer from Walmart online was $160 (delivered to store).

This is day 5 with only the gen time shown in the original post.

Ambient has hovered around 100 during the day.

The thermometers were $1.85 each (includes shipping) from eBay/China but had to be modified to read fahrenheit and took a couple weeks to arrive.

 

[skipperdude]

You can also use ammonium nitrate.

Takes a little longer to freeze as most home freezers don't want to go low enough to freeze it quickly.

SD

 

[RickB]

You can also use ammonium nitrate.

You could do that. Mix it with a bit of diesel fuel and really chill.

 

[skipperdude]

:lol:Hardy har har. You are so funny Rick.:lol:

SD

 

[FF]

Its the WATER , changing from frozen to liquid (latent heat of crystilazation) that does the cooling.

Not the salt , which just changes the temperature melting happens.

SALT takes up space too , so the less salt the more BTU of work in a fixed volume.

 

[jeffnick]

The brine brick didn't last as long as the water brick and the brine took longer to get solid. However, we're asking the brine to maintain a greater difference from ambient.

But no one has helped me with my question.
Will there be a difference in the time it takes the brine brick to solidify (or recover) if I set the freezer thermostat to 28 vs zero? It appears that until the solution is solid, the temperature in the freezer never gets much below the melting point of the solution...in which case there would be little benefit to setting the thermostat to anything below that temp. The intent being to insure that the beer doesn't get below 28 even after the brine is solid.

Interesting to note that the freezer wiil quickly show -40 at minimum thermostat when empty, but has yet to approach that with contents.

 

[FF]

The problem is that ice is an insulator so a really low box temperature is little help in freezing the remaining internal water.

A different shape E solution holder , with less distance for the cold to need to go thru the insulating ice is required.

 

[skipperdude]

Amonimum nitrate 42% by weight.
Water 58% by weight.

Freezes and thaws at 2 deg F

Salt freezes and thaws at -6 deg F

Salt 23% by weight.
Water 77% by weight

This formula could take a few days to freeze in your home freezer.
freeze it in beer cans. The aluminum really transfers the heat and a great new use for them.

You can freeze your fish in a cooler before they even get home.

SD