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Old 09-24-2009, 12:28 PM   #1
mattd2
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Default Peltier fermenter cooler using water heat exchangers

I have read a lot of post about these peltiers, but most seem to be cooling a cabinet sort of arangment. Has anyone investigated using a cooling coil inside their fermenter and running chilled water through that. Another HX would be needed to provide the chilling for the water, this would use the peltiers. The peltier heat exchanger I have in mind would be made out of 2 heatsinks welded together to form a tunnel with the fins on the inside and headers either end, the peltiers would be placed either side (or all 4 sides if this helps at all). My thoughts would be this would provide more uniformed cooling compared with just straping the peltier to the side of the fermenter.
Just sounding out the idea now (got a wife and 2 young girls so I will not have the money to prototype anytime soon!)
Would be keen for your guys thoughts/previous experiences
Cheers,
Matt

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Old 09-24-2009, 01:24 PM   #2
lamarguy
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Liquid peltier cooling devices are commercially available for fish tanks that are capable of dropping the temperature 5 - 10F below ambient. The idea works for small batches (e.g., up to 5 gallons), except most people wrap the coil around the outside of the fermenter for sanitation and ease of cleaning purposes.

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Old 09-24-2009, 09:37 PM   #3
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Thanks, yeah I have seen some commercial peltier water coolers, they looked a bit more industrial than for just fish tanks but were of a cold plate design, the water ran through holes drilled in the plate. the idea of using heat sinks to form a tunnel was to increase the surface area and therefore the heat transfer. Another question is just how much heat would be needed to be removed from the fermenter. I don't know how correct I am, but some article (http://www.nysaes.cornell.edu/fst/fa...rmentation.pdf) I read state that 1 mole (180g) of sugar fermentered released 24 kCal of energy. For a normal 6 gal batch this works out to about 15 watts if fermentation was completed in 24 hours (conservative assumption)
If the batch is to be kept at 10 deg C, and the ambiant temp is 25 deg C. I am assuming the major heat loss will be by radiation (correct me if I am wrong but this should be much larger that heat loss due to only natural air convection, right?) which for a 6 gal SS conical with a surface area of 0.5 m^2 gives about 35 watts.
So total heat loss is 15 + 35 = 50 watts (170 BTU/hr). Not that much heat to be removed really, increasing the batch size will increase this but the % increase should be less than the % volumen increase due to surface area to volume being less.
I could also insulated the fermenter but then it wouldn't look as cool!
Sound right/thoughts? (by the way I am a mechanical engineer so that is why I want the theory to be there before I spend money, i don't have, on building the thing)

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Old 09-25-2009, 02:53 AM   #4
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So I tried out the peltier scheme this summer, with every intention of running chilled water through a stainless coil in my fermenter as it sounds like you're thinking. It seemed like a great plan in that it really wouldn't take much room at all outside of the fermenter, and would be portable and collapsible for storage.

The peltiers themselves are often rated to something like 67 degrees temp difference in Celsius - I thought that with proper heat management on the peltier I should easily be able to get to 0 f. In practice I was able to get roughly 25 degrees f cooler than ambient in a small test loop.

I tried with 2 different types of peltiers - the smaller 80 watt ones, and a big honkin 245 watt. I cannibalized a few different computer power supplies to provide plenty of 12v juice. My initial plan was to attach computer cpu heatsinks and fans to the hot side and computer liquid cooling water blocks on the cold side. The heatsinks would do their best to dissipate 80+ (or 245+) watts of heat, and bring that side as close to ambient as possible. The cold side would then presumably be 67 degrees C colder than the hot side, and the water block on that side would allow me to pump glycol through a copper heat exchanger designed specifically to tranfser heat to/from a liquid. I suggest browsing the liquid cooling section at www.frozencpu.com .

I got copper blocks to put between the various parts, and lapped those pretty damn smooth. I used heat sink compound sparingly, then in quantity. I tried without the copper blocks. I verified that the cold side would generate frost in my garage (Houston) in the summer. The water temp never got as low as I would have expected. The heat sinks were definitely blowing hot air, but my IR temp guage (cheap, likely very inaccurate, or at least not able to get into position to properly measure the temp through the fan and fins of the heatsink) never read terribly high. Based on that temp - even accounting for what I thought of as gross miscalculations on my part - I expected lower water temps.

SO I went to the next level and bought a computer liquid cooling radiator, presuming I wasn't keeping the hot side close enough to ambient. This at least tripled the surface area for cooling the hot side. I sandwiched the peltier between two water blocks - one circulating cold glycol (to the fermenter obstensibly), the other side hot (to the radiator). The radiator and fans (3 now) worked like a charm and kept the temps reasonable - it got warm but not hot by any stretch (and I know the hot side of the peltiers can cook). Cold side still generated frost, but the water temp stayed moderate.

I suppose getting into the 57-58 degree range isn't too bad, but I was hoping for a lot more. As well, this was a low volume test loop - I presumed 5 gallons would be a much tougher job to keep that cool. In fairness, I had no insulation, but my hoses were silicone. I put a temp probe in the cold side reservoir and let it run for 30+ minutes - temp was more or less stabilized at that point.

My plan was to have N units in series (peltiers sandwiched by water blocks) to increase cooling power. Given my lack of success with such a small volume (< 2 liters) I couldn't imagine much improvement when stepping up to 5 gallons with 2 or even 3 units, so I halted my experiment.

Nifty gizmos, definitely. Not feasible for (south Texas at least) garage fermenting. Not to rain on your parade, and it's entirely possible that my experiment was flawed. I feel like the number of configurations I tried was pretty comprehensive though. I say buy a mini-fridge or 3 instead for cost efficiency.

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Old 09-25-2009, 03:04 AM   #5
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I have been looking into them, too. I found a few suppliers on eBay for commercial units. Then I found these guys. http://www.supercool.se/default.asp?...07.asp?sida=82 (check the marine/automotive coolers)

I haven't found a retailer yet, but I found a few things similar on eBay. I'm doubt that they would be any cheaper to put together than a regular keezer/kegerator, but it would be interesting to be able to basically build any shape you wanted then just mount one of these deals on it.

(I just noticed you were looking for water heat exchangers, whoops).

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Old 09-25-2009, 03:13 AM   #6
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Quote:
Originally Posted by airving View Post
The peltiers themselves are often rated to something like 67 degrees temp difference in Celsius - I thought that with proper heat management on the peltier I should easily be able to get to 0 f. In practice I was able to get roughly 25 degrees f cooler than ambient in a small test loop.

I tried with 2 different types of peltiers - the smaller 80 watt ones, and a big honkin 245 watt.
Thanks Airving,
I don't know how much you have read up on the peltiers but one thing to point out is the rated power and delta T are maximums, i.e. you can get 67 degs temp difference over the hot - cold side if you are not actually cooling anything (no power (heat) going "through" the peltier), or you can move the rated power, say 80W through the peltier if the hot and cold side are the same temp. It takes a bit to get your head around and "sizing" the modules is a bit of a looping process. Taking a few assumptions I was thinking of using 70w peltiers with ambiant being 25 and my heat sink estimated to be 15 degs more (all thes degrees and in celcius by the way) so to cool to 0 degs I would need a delta T of 40 degrees. At this the peltier can transfer an estimated 33 or so watts of heat from the cold to hot side with an input of about 70 watts of electricity. so you would need about 6 peltiers to get 200 watts of cooling. Checking that the hot side would actually be at 15 degs above ambient, 1 forced cooled heat sink about 0.05 deg/w (is that about right, I know that natural convection allows for about 0.6 deg/w thermal resistance, so I took 10x more efficient?) 3 peltiers per side so total power = about 300w -> 300 x 0.05 = 15 degs tmp increase.

Some things to think about, these things seem to be a bit of an art to size correctly.
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Old 09-25-2009, 03:20 AM   #7
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Quote:
Originally Posted by gplutt View Post
I have been looking into them, too. I found a few suppliers on eBay for commercial units. Then I found these guys. http://www.supercool.se/default.asp?...07.asp?sida=82 (check the marine/automotive coolers)

I haven't found a retailer yet, but I found a few things similar on eBay. I'm doubt that they would be any cheaper to put together than a regular keezer/kegerator, but it would be interesting to be able to basically build any shape you wanted then just mount one of these deals on it.

(I just noticed you were looking for water heat exchangers, whoops).

I had check out their website before, some pretty cool stuff on there (sorry no pun intended)
They have some of the liquid coolers on there, but again it looks like a drilled block on the cold side. My plan would be to maximise the surface area exposed to the liquid to get the most cooling I can.

Tried to post this before but it would post;

Thanks, yeah I have seen some commercial peltier water coolers, they looked a bit more industrial than for just fish tanks but were of a cold plate design, the water ran through holes drilled in the plate. the idea of using heat sinks to form a tunnel was to increase the surface area and therefore the heat transfer. Another question is just how much heat would be needed to be removed from the fermenter. I don't know how correct I am, but some article (http://www.nysaes.cornell.edu/fst/fa...rmentation.pdf) I read state that 1 mole (180g) of sugar fermentered released 24 kCal of energy. For a normal 6 gal batch this works out to about 15 watts if fermentation was completed in 24 hours (conservative assumption)
If the batch is to be kept at 10 deg C, and the ambiant temp is 25 deg C. I am Assuming the major heat loss will be by radiation (correct me if I am wrong but this should be much larger that heat loss due to only natural convection, right?) which for a 6 gal SS conical with a surface area of 0.5 m^2 gives about 35 watts.
So total heat loss is 15 + 35 = 50 watts (170 BTU/hr)
I could also insulated the fermenter but then it wouldn't look as cool!
Sound right? Thoughts?
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Old 09-25-2009, 03:26 AM   #8
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Quote:
Originally Posted by airving View Post
Nifty gizmos, definitely. Not feasible for (south Texas at least) garage fermenting. Not to rain on your parade, and it's entirely possible that my experiment was flawed. I feel like the number of configurations I tried was pretty comprehensive though. I say buy a mini-fridge or 3 instead for cost efficiency.
I was looking into this to save space (like everyone else that hasn't converted a fridge yet) and also for the future prospects of scaling up to a big fermenter (one that can't fit in any fridge), and slightly for bragging rights if it ever did work!
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Old 09-25-2009, 04:07 AM   #9
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Originally Posted by mattd2 View Post
I was looking into this to save space (like everyone else that hasn't converted a fridge yet) and also for the future prospects of scaling up to a big fermenter (one that can't fit in any fridge), and slightly for bragging rights if it ever did work!
Ha, nice. They do make portable aquarium chillers with a compressor.

AquaEuroUSA Mighty Pro CL-150 Aquarium Chiller For Tanks Up To 24 Gallons


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Old 09-25-2009, 04:11 AM   #10
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Quote:
Originally Posted by mattd2 View Post
I was looking into this...for bragging rights if it ever did work!
You should talk to these guys - Haier NuCool for fermentation. I've experimented with peltier devices for fermentation cooling too, so I've attempted to keep their expectations realistic.

After being unsatisfied with the performance of peltier coolers a year ago, I went out and bought an upright freezer and installed a Love controller. I haven't looked back.
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Fermenting: 6 gals of 1.090 stout (Belgian) & 6 gals of 1.090 stout (English)
Tapped: Berliner Weisse, Black English IPA, German Pils, & Live Oak Primus
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