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 Home Brew Forums > Peltier Lagering
07-10-2008, 09:33 PM   #11
z987k
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This guy has a cool thing going on. I wonder how well it works and if he'd chime in here.

"Two carboys inside one side of the fermentation cooler. The top shows the inner side of the peltier cooler outfitted with a fan. The temperature sensor wire is seen running down to an insulated sleeve which detects the wort temperature more accurately than if it were just hanging inside the cooler."

Fermentation cooler dual controller and one of the two peltier units.

I wonder if he can get that thing down to lagering temps.

07-11-2008, 03:28 AM   #12
LayMeister
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Quote:
 Originally Posted by scoates Remember: 40A @ 12V is only 4A @ 120V. (480 watts) I tried to build a Peltier swamp bucket with some peltiers given to me by another guy in the club (from an old office water cooler), but they just weren't powerful enough to get the temp down more than a couple °C (uninsulated, but well cooled on the hot side (air cooled)). S
The problem here is simply the lack of insulation.

Lets do some basic calculations:

If we approximate a 5G carboy by a cylinder 46 cm high and 27 cm in diameter then the surface area is about .5 m^2 . A carboy weighs 5.5 Kg. The density of glass is 2.5 gm/cm^3. From this we find the average thickness of the glass is 0.44 cm (assume uniform thickness over entire surface).

Now lets assume the glass in the insulator between the beer and the outside world. The thermal resistance of glass is 1.1 W/(m-K). So the thermal resistance of the carboy is about 123 W/K or W/degree C.

If the beer in the carboy is 3 degrees C colder than the outside environment then there is a net flow of 3 * 123 = 369 Watts out of the carboy. This seems very consistent with the results obtained using the Swamp Bucket.

You can actually verify the thermal resistance by putting cold water into the carboy and monitoring the liquid and ambient temperatures over a period of a few hours, as the water warms up. I did and the actual resistance seems to be just a little higher than my simple calculation (remember the water is also an insulator of sorts).

I am now more sure than ever that Peltier Lagering will work. That it will cost me about \$75 by the time I'm finished and will be more energy efficient than a refrigerator. I guess the proof will be in the putting. I'm building the very well insulated box on the weekend and the Peltier device should arrive early next week.

I'll keep you posted.

Paul
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07-11-2008, 02:54 PM   #13
conpewter
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I do think this may work well with an insulated box (Son of fermentation chiller type) because insulation from the outside world will be so much more important. I also think that if insulated well enough this could be used out in a garage (maybe with more than one peltier device) then in the winter you can use it in reverse to keep it warm enough for fermentation.

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07-12-2008, 03:24 PM   #14
scoates
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FWIW, I was measuring the temperature of the chill water in my tests, not the temperature inside the cooler. Yeah, I do think insulation would have helped, but I'm sure that the main problem was underpowered peltiers/supply.

S

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07-12-2008, 04:56 PM   #15
david_42
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I tried using one (had R-40 insulation in the box). Keeping the hot-side cooled is very difficult. Between the power supply and the heat-sink's output, it was like having an electric heater in the room. A 2L bottle of ice changed out every day works much better.

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07-12-2008, 07:12 PM   #16
z987k
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Quote:
 Originally Posted by david_42 I tried using one (had R-40 insulation in the box). Keeping the hot-side cooled is very difficult. Between the power supply and the heat-sink's output, it was like having an electric heater in the room. A 2L bottle of ice changed out every day works much better.
but can you get lager temps with that?
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01-31-2009, 01:19 PM   #17
JoeyB
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Quote:
 Originally Posted by LayMeister The problem here is simply the lack of insulation. Lets do some basic calculations: If we approximate a 5G carboy by a cylinder 46 cm high and 27 cm in diameter then the surface area is about .5 m^2 . A carboy weighs 5.5 Kg. The density of glass is 2.5 gm/cm^3. From this we find the average thickness of the glass is 0.44 cm (assume uniform thickness over entire surface). Now lets assume the glass in the insulator between the beer and the outside world. The thermal resistance of glass is 1.1 W/(m-K). So the thermal resistance of the carboy is about 123 W/K or W/degree C. If the beer in the carboy is 3 degrees C colder than the outside environment then there is a net flow of 3 * 123 = 369 Watts out of the carboy. This seems very consistent with the results obtained using the Swamp Bucket. You can actually verify the thermal resistance by putting cold water into the carboy and monitoring the liquid and ambient temperatures over a period of a few hours, as the water warms up. I did and the actual resistance seems to be just a little higher than my simple calculation (remember the water is also an insulator of sorts). I am now more sure than ever that Peltier Lagering will work. That it will cost me about \$75 by the time I'm finished and will be more energy efficient than a refrigerator. I guess the proof will be in the putting. I'm building the very well insulated box on the weekend and the Peltier device should arrive early next week. I'll keep you posted. Paul
I'm thinking about welding up a aluminum box just big enough for two carboys side by side. I'd fix the TECs to the outside of the box. Put the carboys in the box, fill the box with water. For the hot side of the TECs, heat sinks sitting in plastic ductwork with a blower fan forcing the air. Insulation on the outside of the metal box. What do you think?
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08-10-2009, 08:49 AM   #18
cell
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I had the same idea and was already planning circuit design. Basically, I was planning a manual PWM control over the cell, with an automatic "too-cold" ON/OFF circuit (like powering off the peltier cell below 8°C and then back on at 12°C). Your thread caught my attention. I'm impressed with your calculations. I was planning to put the peltier cell on top of the insulated box and the carboy slightly higher than the bottom to put ice packs. Keep us updated!

Quote:
 Originally Posted by LayMeister The problem here is simply the lack of insulation. Lets do some basic calculations: If we approximate a 5G carboy by a cylinder 46 cm high and 27 cm in diameter then the surface area is about .5 m^2 . A carboy weighs 5.5 Kg. The density of glass is 2.5 gm/cm^3. From this we find the average thickness of the glass is 0.44 cm (assume uniform thickness over entire surface). Now lets assume the glass in the insulator between the beer and the outside world. The thermal resistance of glass is 1.1 W/(m-K). So the thermal resistance of the carboy is about 123 W/K or W/degree C. If the beer in the carboy is 3 degrees C colder than the outside environment then there is a net flow of 3 * 123 = 369 Watts out of the carboy. This seems very consistent with the results obtained using the Swamp Bucket. You can actually verify the thermal resistance by putting cold water into the carboy and monitoring the liquid and ambient temperatures over a period of a few hours, as the water warms up. I did and the actual resistance seems to be just a little higher than my simple calculation (remember the water is also an insulator of sorts). I am now more sure than ever that Peltier Lagering will work. That it will cost me about \$75 by the time I'm finished and will be more energy efficient than a refrigerator. I guess the proof will be in the putting. I'm building the very well insulated box on the weekend and the Peltier device should arrive early next week. I'll keep you posted. Paul
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09-07-2009, 01:28 AM   #19
cell
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After googleing a bit, I found this and decided to build it:
Wort-O-Matic: 38DD Mother of a Fermentation Chiller

Today I bought the insulation; one 48"x96"x2" thick foam. I also ordered a 136W peltier and one LCD module off ebay. Also, I'm coding a PIC to control safely the temperature of the fermentation box. Maybe I'll post a DIY after...

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09-07-2009, 09:44 PM   #20
walther
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Just a quick reply, I only read most of the posts loosely,...

Peltiers are rocket science !
They sound very attractive, but you need to read a lot about them. I have read quite a bit, and gave up my project.
There are different types of peltiers with very different specs, they do not cope very well with moisture, you need _lots_ of cooling on the hot side, you need a high quality powersupply,... these are just some of the things I remember,...

But do by all means share any experience, I would love to use one !

cheers,
walther

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