compact peltier cooled carboy setup

[Gruel]

I think this is a downside of buying cheap TECs from Amazon. You are right that thermal cycling is not good for them, but lately they have been running full out, not quite reaching the set point temperature, so it's not the cycling that kills them. I think they are just crap TECs, not quite meeting their specs, and having a short lifetime. They are under a bit of compression preload.

As I had mentioned earlier, colleagues at work just kept replacing the TECs when they died.
(For the latest iteration of a similar system (module testing for a silicon tracking detector) the engineer in charge moved away from peltiers altogether, and just went for a more powerful glycol unit.)
Unfortunately my TECs are glued to the water cooling bodies. For now I will try to simply bypass dead ones, but eventually I should either get a small compressor (mechanical refrigerator) unit, or switch to a setup where the peltiers are clamped and replaceable.
Actually, eventually the plan is to move into a bigger place with a garage and a basement...; still, it would be nice to build a robust apartment/condo system.

 

[Argyll Gargoyle]

One idea I was thinking about for fermenter insulation was to put your carboy or bucket into a 10 gallon igloo water cooler. It looks like a 6 gallon bucket would fit inside and even allow the lid to be put on—but you’d likely need to cut a hole in the lid for your airlock. However, you gotta do that anyway to get the water hoses out. Bonus insulation if you wrap the fermenter in aluminum foil to reflect radiative heat transfer...

 

[Gruel]

Yeah, but build a few of those enclosures, and soon you'll be at the size of a small chest freezer. Actually, today I thought about getting one, but space wise I'm telling myself I'm a bit better off building a custom enclosure that just fits my three vessels. Plus, I get to build something!
On the other hand, keeping it modular and only hooking up what you need to the cooling system is what I like about my current setup. So, that's an argument in favor of your igloo water cooler approach. But I still need to store the rest of the vessels even when I'm not using them. Hence the idea of building an enclosure just for the three vessels; they would keep their individual insulation, since I want to run them at different temperatures.

I think aluminized mylar works better than aluminum foil. That's what they make cryogenic super insulation (radiative multilayer insulation) from. I think it also works ok if not in a vacuum, due to the many separate trapped air layers. You can buy it pre-crinkled.

 

[Argyll Gargoyle]

Nice to know about the super insulation - how long before my fermenter gets mistaken for a lunar lander? Just need a dish now...

 

[Saunassa]

I knew them as TEDs -thermo electric diodes and played around and used them in a tester in the 1980s. We used a number of them and the cheaper ones would have the substrate crack from thermal cycling. Best long term was using springs to clamp them between the heatsink and the plate to be cooled.

 

[dtashmore547]

a great article, helps me a lot as I had ideas of using Peltiers to chill a fermentation box but after reading your article I realise it will be too inefficient for our 30 plus summer temperatures (South Africa) if it is of interest to you I made something of a similar size to chill my keg beer for serving using a 1/4 hp compressor, works out a lot cheaper power wise cost a lot less to build and can get my ales down to 5 degrees

 

[Gruel]

That looks pretty compact! Where did you get the chiller from? The Peltiers are about a factor 10 less efficient than a mechanical refrigerator.

 

[Gruel]

I finally decided to build a small enclosure for the carboy and the two kegs. I bought two sheets of 1" polyisocyanurate foam with aluminum facing on both sides at Menards (thickest they had in stock), and was able to cut all the parts for a box with internal dimensions 36" long by 28" tall by 14" wide, with very little left over. Outer surface area is about 33 sq.ft, the R value (US units, not metric!) of 2" polyiso is 13 (see table in picture), so 30W or 100 BTU/hr should get me 40F below ambient (40F*33sq.ft/(13 hr sq.ft. F/BTU) is about 100 BTU/hr); 40W should get me close to freezing, except the Peltiers become less and less efficient. We'll see. Hopefully it will help with condensation.

Apropos condensation: what killed one of the peltiers was corrosion; foam pieces I had put between the old independent 40mm heat exchanger and peltier stacks had become wet, and one of the wires touching the foam corroded right off the peltier. I did a shoddy job at soldering (due to too good a job at heat-sinking the peltier ...), but for now it seems to work, and the short circuited cooling loop went right down to 6C/43F, which is pretty much the minimum temperature the peltiers can reach given the current ambient of close to 80F.

Some pics:

 

[dtashmore547]

That looks pretty compact! Where did you get the chiller from? The Peltiers are about a factor 10 less efficient than a mechanical refrigerator.

totally home made, purchased the components from my local Reco outlet except the steel for the box and 18mm ply for the base, and the gassing up via a friend in the business. at current exchange it totaled up around $150. uses the same controller you have used, 1/4 hp compressor, 6 pack cooler box for the glycol bath, 1/2 in copper pipe, 1/4in copper pipe 0.7mm capillary tube (calculated the length with app from Dancap), 2 lt glycol (for safe from a vape company), best condenser I could pick up for my buck, 1/2 of a 1200 x 2400mm x 1.5mm galvanised steel sheet for the box, for flow and silver solder rods, plus a few odds and sods to complete the job.
used far too much 1/4 in tube for the beer chilling, works but rather a slow flow, I plan to change that part. the 1/2 in copper coiled tube works as the evaporator in the glycol mixture with a 1/4 in copper coiled tube inside that for chilling my ale. this could be an option for you if you have the tools to construct it.

 

[Gruel]

That's amazing! I never thought about that, but that is a good solution. I guess the only tricky part is the dimensioning of the capillary? How do you determine how much refrigerant to put in? Do you have to calculate the volume of your plumbing, or is it just filling to some pressure at a given temperature?

 

[Argyll Gargoyle]

I suppose a compressor and fill valve could be scavenged from any old, defunct junker fridge? What’s the lowest coolant volume you can get away with? Presumably that’s a function of your coil size, which in this case is much smaller than a full fridge.

 

[dtashmore547]

you can calculate the capillary length with an app from Dancap, the layout of the refrigeration components are readily available on the internet, it is preferable to get a professional to gas up as it needs the correct pressure and some oil but mainly needs vacuuming prior to gassing, this also makes sure that there are no leaks.

That's amazing! I never thought about that, but that is a good solution. I guess the only tricky part is the dimensioning of the capillary? How do you determine how much refrigerant to put in? Do you have to calculate the volume of your plumbing, or is it just filling to some pressure at a given temperature?

 

[dtashmore547]

I suppose a compressor and fill valve could be scavenged from any old, defunct junker fridge? What’s the lowest coolant volume you can get away with? Presumably that’s a function of your coil size, which in this case is much smaller than a full fridge.

you can use an old compressor but make sure you use the correct refrigerant, I used a plastic cooler box for a six pack something like 6 lts coolant with 2 of glycol, personally I preferred to go the brew way with the components, nothing more annoying to get it working and a free months down the line have it fail.
my coil was 2 meters long 1/2 inch pipe, coiled around a wooden former, filled the pipe with salt and duck taped the ends before winding. othe 1/4 inch pipe was easy to wind up but I used too much, some 4 meters and it offers too much impatience to

 

[Gruel]

Wouldn't the compressor be pretty much the only thing that can break on a fridge/freezer? I'd pick one from a working fridge, or find out why exactly your donor fridge/freezer was dumped.

 

[Gruel]

Here is the assembled and taped fermenter&keg enclosure:

Two inches of polyisocyanurate, which adds up to an R (F * square feet / (BTU/hour)) of 13. Long term this stuff degrades a bit, by about 10%, it seems (compare LTTR = long term thermal resistance and metric R column in the earlier picture). The box fits my 7.5 gallon carboy and my two 5 gallon kegs. Hopefully this will cut down on condensation (dew point indoors is currently about 14C), and allow the peltier system to run colder.

Edit: corrected; thanks, garzlok! Also, the polyiso (safer to abbreviate...) might only be R 11 at beer temperatures.

 

[garzlok]

I’m sure you meant Polyisocyanurate Foam Boards....nobody wants anything to do with an isocyanate. (Nice build, nice use of space/materials)

 

[Argyll Gargoyle]

Looks really good - I see that you have a lip on the lid - that ought to help with air infiltration and thus condensation. I had wondered about different ways to seal a lid. The magnetic rubber strips in fridge doors are pretty nice, but I wonder if some sort of a drape over the lid, secured by magnets, would be an idea? Some kind of plastic or rubber skirt?
I’d be tempted to fill all the empty space between kegs with foam packing peanuts.

 

[Gruel]

I think best would be a dry purge. But for some reason they are running neither dry air nor nitrogen lines in our condo...

 

[Argyll Gargoyle]

So this build has got me reconsidering.. I like the ability to reconfigure your fermenter for just the cost of some sheet insulation. Recently, I bought about 8x 1gal jugs from uline with the idea of doing splits. I’m wondering how hard it would be to build a multi chamber fermenter capable of independent temp control of, say, 4 jugs. The scheme would probably be to use a common cooling loop with 4 independent heaters. Do you think this could work? What would a good cooling loop geometry look like?

 

[JAReeves]

This is a fascinating idea. So, I am not an engineer, but I DIY a lot of stuff using plans from people much more technically-educated than I.

I use the Anvil Cooling system for my fermenter. The last brew I had to put about 10# of ice in the 20+Gallon cooler 1-2x/day, with ice cream salt and H2O as the coolant to keep my brew in the 65-67F range for a week. That was a lot of ice to buy and because of the salt to lower the temp more, I couldn't just reuse it to water the garden.

1: Looking at what has been posted on this thread, would a Peltier like this work to keep a 6-pack cooler with glycol cold enough to lower the beer temp 20-30F below ambient for fermentation (assuming that is enough coolant to cool the beer, this idea did not work with just ice water and I haven't tried glycol yet):

Semiconductor Chilling Plate: TEC1-12706

• Size: 40 * 40 * 3.75mm
• Internal Resistance: 2.1~2.4Ω
• Max. Temperature Difference: 67°C Above
• Rated Voltage: 12V(Vmax. 15V, Starting Current 5.8A)
• Working Current: Imax.=4~4.6A(Rated 12V)
• Refrigeration Power: Max. 50~60W
• Working Environment: -55~83°C

2: Assuming it works to cool well enough, should the Peltier fluid exchanger be in series with the tubing and aquarium pump of the anvil cooling system, or as a separate system?

3: The refrigerator pump pictured a few posts above also looks like a good idea. Would that be more energy efficient in a 6-pack cooler with glycol than the Peltier?

I am also not in a position to set up a fermentation chamber using an A/C unit or mini fridge at this time, though I have looked at plans and designs to build them.

Keep posting cool stuff!

Reevesie

 

[Gruel]

So, while I like and run my system, I must say it is marginal and not robust. I am using nine (9) of those TEC1-12706 peltiers (or whatever it is you actually get when you order them from the cheapest supplier on Amazon), several of them are already broken, and it seems with the fermenter (empty) and both kegs in the box, I can run the almost full Weissbier keg at 8-9C, while the Pilsner keg (still fermenting) is not hooked up to the cooling loop and just tagging along at 18C, finishing the fermentation from 1.03 further down, which is good enough for me, but I shouldn't have to use nine (seven or eight working) 12706 peltiers and 270W to do that.

This is with 270W electrical power when on, and just a little bit of cycling off, i.e. the 8C setpoint is pretty close to the lowest temperature this system can reach. (I'm running 4 of the 9 at 6V, hence the lower power.)

Maybe there are TEC peltiers that meet their specs, the ones I bought certainly don't. At 12V they draw about 3A.

Condensation (running the cold side below the dew point of your house/apartment) can take away an essentially unlimited amount of cooling power.

What I would do if I started over:
-keep the copper cooling loops wound around the kegs, attached with stretched aluminum tape
-do the same type of external cooling loop for the fermenter, or use an off-the-shelf stainless steel cooling insert, or switch to fermenting in a keg (which is what I'm doing with the Pils right now)
-keep the box: it is a bit of work, but quite a bit cheaper and lighter than a freezer
-keep the cheap pumps, temperature controllers and hot side radiator (the radiator only unless using a mechanical compressor, option c below); self priming pumps would be nice, but venting the loops every few disconnect cycles is not that bad
-maybe try push-to-connect fittings instead of the somewhat expensive quick disconnects?

For the actual cooling, I see three options:
a) Combine hot and cold loop, put the radiator directly in front of a window A/C unit outlet, and see how low that gets (no Peltiers).
b) Higher nominal wattage peltiers, possibly running at lower voltage: this would be another experiment, using 12710 or 12715. If using peltiers, I would definitely recommend the Meanwell power supply.
c) Converted window A/C unit or home made setup (see dtashmore's posts above) using a commercial compressor to provide the cold liquid (in a cooler, with the pumps sitting in the bath, which solves the self priming/loop venting issue).

I don't want to sound too pessimistic, I guess it all depends how much experimentation and fiddling you are prepared to deal with. After all, we are not running a life support system, it's just beer...

Argyll, regarding the one loop/several heaters idea: I'm afraid a peltier based system will never have cooling capacity to spare. The pumps are pretty cheap, so maybe run several independent loops against the same hot side heat exchanger? (separate peltiers and cold side heat exchangers).

 

[Gruel]

Forgot to answer JAreeves' questions 2 and 3:
2: in series, I'd think, i.e. the cold side directly plumbed into the anvil loop. One pump only, obviously. Putting a reservoir and two heat exchangers in between (or just a reservoir, used by two separately pumped loops) just introduces more heat.
3: a factor ten (10) more efficient. (A mechanical system produces about a factor three more cooling power than the electricity it consumes: 3500 BTU/hr = 1kW, but you typically get at least 12 SEER = BTU/hr per W; a peltier system is maybe 30% efficient - very dependent on the temperature difference it is trying to produce).

 

[Argyll Gargoyle]

How much heat load do you estimate you are dealing with from heat leak through your insulation, and from the actual fermentation? I’ve seen estimates that active fermentation can generate 10-50W.
I imagine that peltiers are the preferred solution below a certain cooling power level where there aren’t many options for compressor systems

 

[Gruel]

I think it's all heat leak and condensation (on the lines outside the enclosure), except for 5-10W.

I'm more and more convinced that motor bike electrics and home brewing heat gain do not follow the normal laws of physics.

 

[Argyll Gargoyle]

I hadn’t considered the heat load of condensation before. I can see how that could be substantial.

 

[dtashmore547]

So, while I like and run my system, I must say it is marginal and not robust. I am using nine (9) of those TEC1-12706 peltiers (or whatever it is you actually get when you order them from the cheapest supplier on Amazon), several of them are already broken, and it seems with the fermenter (empty) and both kegs in the box, I can run the almost full Weissbier keg at 8-9C, while the Pilsner keg (still fermenting) is not hooked up to the cooling loop and just tagging along at 18C, finishing the fermentation from 1.03 further down, which is good enough for me, but I shouldn't have to use nine (seven or eight working) 12706 peltiers and 270W to do that.

This is with 270W electrical power when on, and just a little bit of cycling off, i.e. the 8C setpoint is pretty close to the lowest temperature this system can reach. (I'm running 4 of the 9 at 6V, hence the lower power.)

Maybe there are TEC peltiers that meet their specs, the ones I bought certainly don't. At 12V they draw about 3A.

Condensation (running the cold side below the dew point of your house/apartment) can take away an essentially unlimited amount of cooling power.

What I would do if I started over:
-keep the copper cooling loops wound around the kegs, attached with stretched aluminum tape
-do the same type of external cooling loop for the fermenter, or use an off-the-shelf stainless steel cooling insert, or switch to fermenting in a keg (which is what I'm doing with the Pils right now)
-keep the box: it is a bit of work, but quite a bit cheaper and lighter than a freezer
-keep the cheap pumps, temperature controllers and hot side radiator (the radiator only unless using a mechanical compressor, option c below); self priming pumps would be nice, but venting the loops every few disconnect cycles is not that bad
-maybe try push-to-connect fittings instead of the somewhat expensive quick disconnects?

For the actual cooling, I see three options:
a) Combine hot and cold loop, put the radiator directly in front of a window A/C unit outlet, and see how low that gets (no Peltiers).
b) Higher nominal wattage peltiers, possibly running at lower voltage: this would be another experiment, using 12710 or 12715. If using peltiers, I would definitely recommend the Meanwell power supply.
c) Converted window A/C unit or home made setup (see dtashmore's posts above) using a commercial compressor to provide the cold liquid (in a cooler, with the pumps sitting in the bath, which solves the self priming/loop venting issue).

I don't want to sound too pessimistic, I guess it all depends how much experimentation and fiddling you are prepared to deal with. After all, we are not running a life support system, it's just beer...

Argyll, regarding the one loop/several heaters idea: I'm afraid a peltier based system will never have cooling capacity to spare. The pumps are pretty cheap, so maybe run several independent loops against the same hot side heat exchanger? (separate peltiers and cold side heat exchangers).

hi just a small update from my side which may help, I am not too interested in making calculations, so my first effort into cooling was only a minor success, I made a keggerator from a broken fridge which had morning but the condenser left working, I used the cheapest compressor I could get, 1/10hp, it produces just 70w of cooling power and uses 100w of 230v ac power, this is cooling a

 

[dtashmore547]

sorry accidental posting.
it is cooling a 30lt keg, it still manages to get it down to 8 degrees C with 35 degrees of indoor ambient. it is running continuous at this. the other chiller unit is 2.5 times this size and can easily get down to 5 degrees with about 50 percent utility.

 

[Gruel]

dtashmore, stupid question: these horse power ratings, they are in 745.7 Watt= 1 hp horse powers, and they are what the compressor draws electrically, not its cooling output, right?
But you are probably right: too much calculation can spoil the fun.
Autocorrect garbled your post a bit; what was the 'morning' actually supposed to be?

I'm now thinking of simplifying my setup, removing the old individual 40mmx40mm heat exchangers completely, and replacing the TEC1-12706's with three TEC1-12715 running at 8V each, mounted between the two 120mmx40mm heat exchangers. This would simplify the plumbing a lot. Assuming those guys draw 8A at 8V, this should yield the same cooling power as eight 12706's drawing 3A each at 12V, but with only 2/3 the waste heat produced. Well, let's not jinx it with numbers.

 

[dtashmore547]

dtashmore, stupid question: these horse power ratings, they are in 745.7 Watt= 1 hp horse powers, and they are what the compressor draws electrically, not its cooling output, right?
But you are probably right: too much calculation can spoil the fun.
Autocorrect garbled your post a bit; what was the 'morning' actually supposed to be?

I'm now thinking of simplifying my setup, removing the old individual 40mmx40mm heat exchangers completely, and replacing the TEC1-12706's with three TEC1-12715 running at 8V each, mounted between the two 120mmx40mm heat exchangers. This would simplify the plumbing a lot. Assuming those guys draw 8A at 8V, this should yield the same cooling power as eight 12706's drawing 3A each at 12V, but with only 2/3 the waste heat produced. Well, let's not jinx it with numbers.

yes that is the convertion factor. sorry about the error couldn't go back and correct the error after accidentally hitting the post reply button, the output power is around 75 to 80 percent of the input power so for a 1/10 hp compressor the input power will be 100 watts for 75 watts output. the word morning should have read "nothing"

 

[Gruel]

Pretty exciting: the three TEC1-12715 in series connected to 24V (seeing 8V each) are indeed drawing 8A. With a short-circuited cooling loop and the hot side radiator drawing in 78F/25C room air, the system now reaches 32F/0C!
That's with about 220W electrical power - still need to measure the actual AC side draw. With the old 12706 setup, under the same conditions the system would reach 43F/6C drawing 270W.

With the radiator mounted in front of the 63F/17C A/C outlet, the new setup reaches 26F/-3C with the short-circuited cooling loop.
It's now again hooked up to my Weissbier keg inside the polyiso box, with the set point at 6C.

In anticipation that this might work I had also ordered some food grade propylene glycol; I'm running a 1:3 glycol:water mix that should be good to 10F/-10C.

I should post some pics later. The plumbing is a lot simpler now.