Double-thermoelectric ferm chamber

turkeydinner · Nov 9, 2014

In Estonia the tempereatures are rarely suitable for fermentation. In summer it is usually to hot and in winter times the heating systems cause it to be too hot. So I decided to build my own fermentation chamber. I read many threads and articles and blog posts about them, and I decided I was going to make an automated system(with temp control). First I tried to find a fridge to suit me, but it seems even old fridges here are very overpriced. Also most of them are too big for my apartment. Even went to check one out, but it was too big to fit into my car, so i disbanded that idea. Instead I decided to build one with peltier elements. I know many people have had unsatisfactory results, but hey, I had to try.

For the peltier, I went with this two-element version:
http://www.aliexpress.com/item/1-se...em-Kit-Cooler-fan-DIY-JSK8299/2032977627.html

1-set-new-Thermoelectric-Peltier-Refrigeration-Cooling-System-Kit-Cooler-fan-DIY-JSK8299.jpg

And over a couple of weeks constructed the chamber[attached pictures].

Specs:

It has 5cm EPS, 2cm XPS and 6mm plywood. Imperial R value of around 11-12 for walls and bottom, 8 for top(4cm XPS). The R-values are not bad, but the top has two holes in the inner XPS plate for the chiller radiators and fans so it will weaken my insulation factor a bit.

The container outer dimensions are height: 72cm(23.3inches), width and length 60cm(23.6 inches).
Inner height: 56cm(22 inches), width and depth 45cm(17.7 inches).

Experiment:

I finished most of it yesterday. And I put it through a rough insulation test WITHOUT the cooler just to test the insulation. When I get my PSU for the peltiers (hopefully in a few days) I will test that too.

I took it outside where it was about 7C(44.6F) and left it there to cool it down. Then put the lid on and the temperature controller thermometer in and brought it inside where the ambient temperature was 22-23C (71.7-73.4F). I took notes how the temperature changed over time.

Temperature change in C over minutes, from 7.9C-19.5C during 210 minutes with ambient 22-23C:

Sample points:
0 - 7.9
30 - 10
59 - 12.9
100 - 16.0

Temperature change in F over minutes, from 46.2-67.1F during 210 minutes with ambient 71.7-73.4F:

Sample points:
0 - 46.2
30 - 50
59 - 55.2
100 - 60.8

But most importantly I also have a question/problem. I have tried to find methods/equations that would help we determine how many watts is thermal conduction moving into my chamber. I would appreciate If someone would help me find this out. Thanks in advance to you.

Further updates are sure to come.

Thank you for reading!

agrazela · Nov 9, 2014

I wish you all the best with this, I really hope those peltiers can draw the heat out of 20L of wort in a reasonable amount of time, and can keep up with the heat of fermentation.

turkeydinner · Nov 9, 2014

Thanks. I am also finishing up my wort-chiller, so I can chill the wort to the correct temperature to begin with, so the peltiers wouldn't have a hard time in the beginning. They should be able to deal with fermentation waste heat easily.

turkeydinner · Nov 10, 2014

I got my own results verified by a third party. The box lets in about 0.16Watts by conduction. By glancing around HBT/web it seems that it would basically be a miracle if the yeast would produce anything close to or over a single Watt at their peak.

1.005 is heat capacity of air around fermentation temps
0.1134 is the volume in m^3

1.005 * 0.1134 * 5 = 0.569835kJ = circa 0.16W/h to keep it 5C below ambient in sub-fermentation temperatures. So it is even less when the temperature is closer to ambient temps.

I should have about 40-60W of cooling power with the two peltiers. So it seems they are on roughly a couple of minutes per hour.

Disclaimer: I may be very wrong about all of this...but it seems to be in the right ballpark.

Will update with real-life results when I get my PSU.

cutigerusa · Jan 8, 2015

I'm looking to do a son of a fermentation chamber and looking at using the ice versus the thermoelectric (peltier) for cooling. I'd love to know how this turns out. Good luck!

turkeydinner · Jan 10, 2015

I have now used this for three fermentations.

Empirical data for me is as follows:

With my specific container, 2*5A(12V) peltiers, and about 20L(5.5 gallons) of wort.

During high krausen (most heat generated) I can keep the wort ~3C(~5F) below ambient. During this the cooler is on for almost the whole day (up to 24h). On all other times, I can keep it about 13C below ambient - with full throttle. So there isn't much load on it when not in high krausen and keeping ale temps.

The delta ambient might seem low, but usually wort temperatures reach several degress above ambient if not cooled. So the effect is noticeable. I insulate and tape the STC-1000 controller thermometer to the plastic bucket I use so the temperature measurements should be pretty exact.

So for me, this works well for ales. Before and after krausen it turns on for 10-15 minutes every 1-2 hours - it tries to keep the temp +-0.3C(0.5F).
As soon as you start to raise your fermentation temp you give the cooler a nice break and it will turn on rarely.

So for me, It is definitely worth it. Maybe a fridge would be cheaper and more effective, but I live in an apartment and don't have the room, so my custom build box sits by the front door looking nice.

I also calculated the worst-case amount of time they would be on, for example If I fermented two batches in a month. The power bill would only be a couple of €.

TODO:
Even better insulation(fill all the cracks)
Probably getting two 10A elements
The cooler element sits on top of the lid, and thus when the coolers are off, they transfer heat in(through the heatsink and also the large holes). Maybe I will turn my setup into liquid cooling with peltiers.

Attached image show my box containing an IPA in the cleanup stage.

johnodonovan · Jan 14, 2015

Using 5 or 10 amp peltier for the plots above?

Sent from my iPad using Home Brew

kiteD · Jan 14, 2015

I'm thinking about using the Peltiers as well. I've done the math on their website FAQs that describes the efficiency, (COD). I got for Ale temperatures inside a house as hot as 27 degC, running a TEC1-12706 should get you about 50W of cooling and for lagering down to 2 degC, 33W. I can't imagine that not being enough, and you're probably buying two of those.

I've lost my thread, but I saw a molar heat calculation that figured total heat produced by a fermentation in kJ, and then divided it by only a 24 hour fermentation to find an average 18W generated. Then they commented lower temperature will be slower fermentation, therefore, the heat produced by the beer should be easily managed...providing I calculated correctly and trusted the right internet chemist.

So, yes, I see you're trying to figure heat loss for a fermentation chamber. That would be the next piece of the puzzle. Correct me if I'm wrong, but your plots are simply the temperature increase inside your fermentation chamber without a TEC? I think you can calculate it out from your experiment.

It will take you a little googling, but should be able take how much air volume you have in your chamber. Through some basic molar chemistry that should give you the number of grams of air. You then can figure how many joules it took to heat the chamber on average (see specific heat equations.) Then you divide by the amount of time in seconds to give you the number of Watts. Sorry, broad strokes, but if no one hands you the answer, I'm pretty sure that would be how it's done.

Further, the Peltier website has a calculator based on how thick your insulation, operating conditions etc that suggests a specific device. The biggest issue w/ your box, though is not the insulation thickness, it's the construction leaks.

https://tetech.com/peltier-thermoelectric-cooler-modules/?gclid=CIzTmdmslMMCFZMkgQod-XgAgw

These guys pretty well prove a single Peltier is enough, but they are using direct heat transfer instead of a fan:

https://www.kickstarter.com/projects/433436998/brewjacket-immersion-lager-beer-without-a-refriger

One question I have though, is how do you plan on controlling your TECs? The Peltier website FAQs pretty clearly indicate you do not want to just cycle them on and off like a refrigerator condenser. You'll kill the lifespan. how quickly is up for debate, but...

TECs are meant to be PID controlled with a PWM device. I've looked into retooling the BrewPi for the purpose, but it may be a lot to reverse/re-engineer and I hate everything web server, scripting etc.

My first thought is I just want to brew in a cooler. I've seen one big enough and the right shape to fit either a 6.5 Gallon bucket or a carboy, airlocks included. Still, why not just use the cooler to ferment?

Research suggests they're food grade plastic, and they're made to steady a temperature. I think you could find one and maybe add a bit of a gasket in order to make it air tight enough. Seems like a dream solution, but I'm waiting for the gotcha...

Oh, this guy is trying an Arduino TEC solution, but he hasn't posted code or results.

http://makezine.com/2014/03/28/arduino-controlled-tec-coolingheating-system-for-beer-fermentation/

cutigerusa · Jan 19, 2015

Looking to repurpose a wood cabinet lined with rigid insulation and a peltier setup mounted in to keep it cooled for a ferm chamber. I'm not an electrical engineer, but have some basic electronics experience, and was curious about using a kit like the following to put a peltier in for the cooling and heating exchange portion.

http://www.amazon.com/dp/B00IEO8H22/?tag=skimlinks_replacement-20

turkeydinner · Jan 21, 2015

johnodonovan said:
Using 5 or 10 amp peltier for the plots above?

These are done using two 5 Amp peltiers.

turkeydinner · Jan 21, 2015

cutigerusa said:
Looking to repurpose a wood cabinet lined with rigid insulation and a peltier setup mounted in to keep it cooled for a ferm chamber. I'm not an electrical engineer, but have some basic electronics experience, and was curious about using a kit like the following to put a peltier in for the cooling and heating exchange portion.

http://www.amazon.com/dp/B00IEO8H22/?tag=skimlinks_replacement-20

If I was to upgrade my current air-cooling situation I would probably use something like that. The chinese one with my kit is rather sucky, but it works. So anything with a bit more quality is probaby an upgrade.

turkeydinner · Jan 21, 2015

kiteD said:
I'm thinking about using the Peltiers as well. I've done the math on their website FAQs that describes the efficiency, (COD). I got for Ale temperatures inside a house as hot as 27 degC, running a TEC1-12706 should get you about 50W of cooling and for lagering down to 2 degC, 33W. I can't imagine that not being enough, and you're probably buying two of those.

I've lost my thread, but I saw a molar heat calculation that figured total heat produced by a fermentation in kJ, and then divided it by only a 24 hour fermentation to find an average 18W generated. Then they commented lower temperature will be slower fermentation, therefore, the heat produced by the beer should be easily managed...providing I calculated correctly and trusted the right internet chemist.

So, yes, I see you're trying to figure heat loss for a fermentation chamber. That would be the next piece of the puzzle. Correct me if I'm wrong, but your plots are simply the temperature increase inside your fermentation chamber without a TEC? I think you can calculate it out from your experiment.

It will take you a little googling, but should be able take how much air volume you have in your chamber. Through some basic molar chemistry that should give you the number of grams of air. You then can figure how many joules it took to heat the chamber on average (see specific heat equations.) Then you divide by the amount of time in seconds to give you the number of Watts. Sorry, broad strokes, but if no one hands you the answer, I'm pretty sure that would be how it's done.

Further, the Peltier website has a calculator based on how thick your insulation, operating conditions etc that suggests a specific device. The biggest issue w/ your box, though is not the insulation thickness, it's the construction leaks.

https://tetech.com/peltier-thermoelectric-cooler-modules/?gclid=CIzTmdmslMMCFZMkgQod-XgAgw

These guys pretty well prove a single Peltier is enough, but they are using direct heat transfer instead of a fan:

https://www.kickstarter.com/projects/433436998/brewjacket-immersion-lager-beer-without-a-refriger

One question I have though, is how do you plan on controlling your TECs? The Peltier website FAQs pretty clearly indicate you do not want to just cycle them on and off like a refrigerator condenser. You'll kill the lifespan. how quickly is up for debate, but...

TECs are meant to be PID controlled with a PWM device. I've looked into retooling the BrewPi for the purpose, but it may be a lot to reverse/re-engineer and I hate everything web server, scripting etc.

My first thought is I just want to brew in a cooler. I've seen one big enough and the right shape to fit either a 6.5 Gallon bucket or a carboy, airlocks included. Still, why not just use the cooler to ferment?

Research suggests they're food grade plastic, and they're made to steady a temperature. I think you could find one and maybe add a bit of a gasket in order to make it air tight enough. Seems like a dream solution, but I'm waiting for the gotcha...

Oh, this guy is trying an Arduino TEC solution, but he hasn't posted code or results.

http://makezine.com/2014/03/28/arduino-controlled-tec-coolingheating-system-for-beer-fermentation/

After ordering and before receiveing my cooler I googled for days on topics like efficiency, insulation, thermal leakage, etc. I am an IT engineer, so physics topics may get over my head.
But I did the math using suggestions from smarter people and I got nothing useful out of it in the end. But I can promise to you that a single 12706 TEC will not provide you with pure 50W of cooling, and you won't get a fermeting beer to ridiculously low temperatures. The problem with calculations was that they are theoretical - there are endless variables you can not take into consideration, so while things may look good in paper, real life is a whole other thing, as I experienced first hand with these. Basically, everything leaks (energy) and you don't reach expected efficiencies with the electronics or insulation.

I am controlling my TEC`s currently with hard power cycling using a STC-1000. This may not be the best for them, but I am not trying to get 10+ years of usage out of them - so I don't think it really matters that much in a home environment. Also, if by some miracle you are able to wear them out in a short time, then buying a couple of new ones shouldn't be a problem. But I do acknowledge that using PWM should make them better insulators when powered down.

Maybe I'll do some new calculations now that I have used my box 4 times(a new one is fermenting there since yesterday) and have a bit more data to do useful calculations. The problem before was that I had no real world data to compare the calculations to. In the end I found two seemingly correct calculation methods, but the final numbers differed by a magnitude, so I couldn't expect them to be correct until I was able to compare them to real world data.

Also, an update!
I previously reported that the TECs are having a hard time keeping 18C. It seems I overpitched on previous batches and the yeast was super active. Currently (during peak fermentation) I am holding 17.5C(wort temp) in 22-23C ambient with the TEC being on for 1/2-1/3 of the time. As fermentation winds down the run times will go down as well. I must say that I am relatively happy with this. While it may not be the best, it is much better than I feared it could turn out.

kiteD · Jan 22, 2015

Cool. I'll post if I have any results. Project is all speculation now.

Been chatting w/ alphaomega about this. He's got me convinced the stc-1000 is probably the way to go. On the other hand I just kinda want to do the spark mcu and PWM PID, but it would require work.

Here's the efficiency on a Pelt, but I suspect this is a better brand than that 12706. Got me thinking you don't want to use the lower currents, either. Probably best to soft start it, but hover around the beneficial points of the curves. Other cooling devices get better than 100% efficiency, but to just stabilize temp a few degrees under ambient shouldn't be too much of an issue. 50W cooling for an ale *should* be possible by this. Problem is how much are you losing. I think thermo coupling might be another issue. I'm going to try to fab up a direct cooling conductor that submerses.

https://tetech.com/faqs/#5

Double-thermoelectric ferm chamber

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