Minimalist kegerator - Peltier cooling?

If there was ever a topic for the "Brewery"...

I've been homebrewing beer for decades, and just this evening finally dipped my toe in the sea of kegging.  Long story short I'm brewing a batch or two for a party, will borrow the real CO2 stuff for that, but otherwise now have a keg to think about.  And it would be nice to put my beer into kegs instead of bottles, except that I currently live in a 700 Ft^2 apartment and have no space for a second fridge.

So here's the idea... a minimalist kegerator.  Heavy insulation (3-5" of rigid polystyrene foam?) around one or two Cornelius (aka "soda fountain) 5 gallon kegs.  A Peltier effect cooler of the sort used in RV/boat coolers to keep the temperature some 20-30 degrees Farenheit below ambient.  I don't care about "ice cold", I much prefer "cellar temp" for my beer.

Plausible? 

Should work... good insulation will help.

I bottled up a batch of home brew tonight..

Beer good...

JR

JohnRoberts said:

Beer good...

Click to expand...

Beer good indeed my friend, beer good indeed

> a minimalist kegerator.

I went to Sears for a bar-fridge, expecting a Freon machine. All they had in-stock was a very low-price Peltier box. I understood it didn't make or keep ice; that was acceptable. In my once-a-day use (hold my lunch), it works very fine. It is very slow about chilling things; when I buy drinks I get them from the quickie-mart cooler, not from the shelf.

http://www.sears.com/shc/s/p_10153_12605_04691772000P?mv=rr
White Galaxy 1.7 cu. ft. Compact Refrigerator $74.99
Sears item# 04691772000 Mfr. model# 91772
This Thermoelectric refrigerator chills your food without noise and vibration.
No Harmful Refrigerants
Height: 19-15/16 in. 
Width: 16-5/16 in. 
Depth: 18-15/16 in. 

VERY poor reviews.... maybe mine is an exception? 

The contraption is ready-made. The box/door is real cheap. You probably could not buy Peltier, power supply, and fans for less than the whole box. It is roughly keg size. A keg won't fit inside, but if you sliced off the top it may drop-in; heck, I suppose it will work fine laying on its back with the door off, as long as the heat-reject fan can breathe. Throw a packing-blanket over the keg to trap the cool. Or if a keg will not fit, pull the fan/Peltier unit and build a foam box.

One party? You can buy a LOT of ice for the cost of a large Peltier, but I suppose the melt is a problem. Make a deal to use neighbor's shower for pre-party freshness, then fill your bathtub with ice and kegs? Worked for us back in the old days.

i used to be up to date on computer overclocking, and peltiers were what the guys used that had the best results.

they work great, but all the ones i saw were processor size ( >3"sq) and required A LOT of energy to work. i couldnt imagine using those to cool any large amount of a substance.
gotta be an easier way.

ale or lager? guessing peltier will be inefficient and expensive compared to a converted fridge. plus you need an insulated volume to minimize temp fluctuations, why reinvent the wheel?--I have wondered how a peltier may work for a wort cooler.
here a guy is controling fermentation temp w/pelt cooler:
http://hbd.org/discus/messages/26895/29631.html

still bigger than the carboy--why not a cheep mini fridge?

I did a little research, and Peltier is definitely less efficient than conventional refrigeration.  And the other half of the problem is waste heat in the summer, though by then I'll probably not have any kegs sitting around.  The idea right now is to brew more in the winter when it's easier and cooler, leaving bottles for the summer when I can stuff my fridge with them.

Oh, and we're using ice for the party, no problem there.  It's more about having the beer on tap here at home.

But on the upside this year I'll be looking into buying a house, ideally with a basement.

I like PRR's suggestion. Or even a conventional small refer.

Maybe make a cubic keg from some oversized tupperware or storage containers. Perhaps line with some food grade tubing/bags if the container is nasty. For serious use, consider cutting a hole in the door for a spigot. Constantly opening the door will lose the cool.

With the Peltier element, if you DIY maybe make the heat sink a food warmer or heat water for some use. 

JR

> is waste heat in the summer

Any way you cool, there's "waste" heat.

> computer overclocking...  required A LOT of energy to work.

> Peltier is definitely less efficient than conventional refrigeration

At what load??

The Peltier will run wide-open most of the time.

The Freon, even if the box is well insulated, and left closed, will start/stop many times a day.

The bar-fridge I had when young ate as much electricity as an older full-size reefer; we unplugged it. This Galaxy simply can't use that much juice even 24/7.

I do think the Galaxy is unsuited for cooling. It might run for 2 weeks chilling 5 gallons. It is exceptionally well insulated, so once chilled it holds the cool.

Contrary to the posted reviews, mine eventually gets so cold that tomato-slices get frost-bit, I had to back-off the thermostat to keep them chilled but not crunch/soggy.

The "cheapest" plan may be to run tap water over the keg inside a foam box. Tap water approximates the temperature you want. It is very cheap. An "icemaker kit" will tap a cold-water pipe and valve water to tubing wrapped around the keg. Run wide-open until brew comes down to desired temp, then shut-back to a trickle to hold temp without waste water. There's zero heat-pump loss inside your domain, and you can run the warm output water to drain if you don't want that heat. In summer the exhaust should be held until it warms to room temp (free cooling). In any season it can be used for plants, wash-up, even drinking if you keep the tubing sanitary.

PRR said:

> a minimalist kegerator.

I went to Sears for a bar-fridge, expecting a Freon machine. All they had in-stock was a very low-price Peltier box. I understood it didn't make or keep ice; that was acceptable. In my once-a-day use (hold my lunch), it works very fine. It is very slow about chilling things; when I buy drinks I get them from the quickie-mart cooler, not from the shelf.

Click to expand...

The trick with the TEC-based fridges is that you need to "pre-cool" the insides. I have one, and the manual said to put ice packs in it and then start the cooler. A small fan to circulate the air inside the fridge would help.

The coolers work a lot better in a vacuum, too, but that's rather inconvenient.

TECs work quite well if you need to keep a relatively small area, like say an image sensor, cold.

-a

how about a closed loop of liquid circulated through your freezer...a small volume pump, 100' or so of vinyl (or metal for better temp.transfer) maybe a heat exchanger in the freezer, an insulated enclosure for the cornys, and a few fittings to get i/o da freezer.

Scodiddly said:

But on the upside this year I'll be looking into buying a house, ideally with a basement.

Click to expand...

That's what I thought, but we get fixer-uppers.  We finished "Lucky #7 Pils", my seventh batch, bottled in champagne bottles, at the housewarming of our first house.  "Now I have a basement and a utility sink!"  I said.  "No more sterilization in the bathtub!"  
Two houses and 7 years later, batch #8 is still a dream.  There is always something to do- paint x, patch y, pull weeds in quadrant z.  My cooking has been more feeding the family than brewing beer.  But the whole house part is worth it.  When I have more time, #8 will be waiting for me.
Keep your powder dry, and go for the house.
Mike

shabtek said:

how about a closed loop of liquid circulated through your freezer...a small volume pump, 100' or so of vinyl (or metal for better temp.transfer) maybe a heat exchanger in the freezer, an insulated enclosure for the cornys, and a few fittings to get i/o da freezer.

Click to expand...

That certainly has crossed my mind.  But it's an apartment, I don't think I'll get away with drilling holes in the fridge. 

PRR said:

VERY poor reviews.... maybe mine is an exception? 

Click to expand...

Well it's obvious from the picture why they got the poor reviews.  The door didn't close with all that stuff inside the compartment.

> with the TEC-based fridges is that you need to "pre-cool" the insides. ...the manual said to put ice packs in it and then start the cooler. A small fan to circulate the air inside the fridge would help.

Mine did not say to do that (but I do not disagree with you). Mine does have two fans, heat and cool.

> The coolers work a lot better in a vacuum, too, but that's rather inconvenient.

Don't see why.

> TECs work quite well if you need to keep a relatively small area, like say an image sensor, cold.

Well, "cool", "cold" may be stretching it?

It IS a small-area very-thin device. The load should be small area. You want a serious heat-shield between the hot and cold sides. Otherwise the heat tends to get to the cold-side "short-circuiting" the heat-pump action.

A small-area heat exchanger can be coupled to a large volume of air (and beer) with fins and fans. I had a car-box which was just fins which dominated the inside of the box. In this larger unit, there's no good way to pull coolth off the Peltier to the lunch faster than heat leaks around the Peltier... unless you blow the sink. While there must be a sheet of thermal insulation isolating the two sides, by conducting to fins and blowing air over fins, you move the coolth and warmth in different directions, and a simple air-tight box nearly eliminates short-pathing.

The box/door is quite tight and insulated considering that it must cost $4 at the dock in China. I guess unless you build a custom-shape keg, that's moot in this application.

PRR said:

> The coolers work a lot better in a vacuum, too, but that's rather inconvenient.

Don't see why.

> TECs work quite well if you need to keep a relatively small area, like say an image sensor, cold.

Well, "cool", "cold" may be stretching it?

Click to expand...

Is there a practical limit on how cold these things get? I thought they could get pretty cold.
-----

I'm having a little trouble wrapping my head around thermal flow in a vacuum (space?). With no air to conduct heat away, there will surely be no convection, and forget about forced air in a vacuum. Radiation would be the remaining mechanism (paint it black?). I guess for a small image sensor you could count on the relative mass of the sensor to the rest of the apparatus to use simple conduction and rearrange the heat within the closed system, then perhaps use radiation to slowly scrub off excess heat (in space on the dark side of the moon). 

JR

JohnRoberts said:

PRR said:

> The coolers work a lot better in a vacuum, too, but that's rather inconvenient.

Don't see why.

> TECs work quite well if you need to keep a relatively small area, like say an image sensor, cold.

Well, "cool", "cold" may be stretching it?

Click to expand...

Is there a practical limit on how cold these things get? I thought they could get pretty cold.

Click to expand...

The limit is basically set by how cool you can keep the hot side. If you don't eliminate the waste heat, the TEC can unsolder itself, which is pretty exciting.

I'm having a little trouble wrapping my head around thermal flow in a vacuum (space?). With no air to conduct heat away, there will surely be no convection, and forget about forced air in a vacuum. Radiation would be the remaining mechanism (paint it black?). I guess for a small image sensor you could count on the relative mass of the sensor to the rest of the apparatus to use simple conduction and rearrange the heat within the closed system, then perhaps use radiation to slowly scrub off excess heat (in space on the dark side of the moon). 

Click to expand...

Arrrgh, what I said made no sense, so lemme restate! 

In a vacuum, you clearly need real good conduction cooling to keep the hot side cool as of course there is no convection.  This means you need a refrigerator for your refrigerator.

The reason for the vacuum is that you don't have to worry about dew point and water condensing on everything, which is obviously bad for electronics and image sensors.

Anyways, we're cooling beer to 40 degrees F, not cooling image sensors to -40 degrees F (or C). And storing your six-packs in a vacuum chamber is really kinda inconvenient.

Anyways anyways, I have to cool a little tiny sensor and I don't have a thermal model of the system. Which means some experimentation and some Matlab.

-a

PS: ever wonder why the word "fridge" has a "d" in it when the word "refrigerator" does not? I didn't think so.

Andy Peters said:

-a

PS: ever wonder why the word "fridge" has a "d" in it when the word "refrigerator" does not? I didn't think so.

Click to expand...

Slang for Frigidaire ?


JR

Andy Peters said:

Anyways, we're cooling beer to 40 degrees F, not cooling image sensors to -40 degrees F (or C). And storing your six-packs in a vacuum chamber is really kinda inconvenient.

Click to expand...

Actually "we", by which I mean "me" are hoping to cool beer to some 55F.  Good beer, that is, not the typical mass-market swill that does need to be dragged down to "taste bud numbing" temperatures.

PS: ever wonder why the word "fridge" has a "d" in it when the word "refrigerator" does not? I didn't think so.

Click to expand...

Spelled vs. phonetic.  Phonetic generally wins.


Anyway, one of you kind folk emailed a link to a surplus place carrying some "counter top" units originally meant for something else, with the bottom line being some $50 shipped.  Sorely tempting.  If I do anything, it'll be that.

> Slang for Frigidaire ?

That's not a Frigidaire.



That's a Frigidaire.