Peltier plate fermentation control

Im working on building a Fermentation temp controller from a Peltier plate.

http://en.wikipedia.org/wiki/Thermoelectric_cooling

Ive got a pretty simple design thought up to place the plate between a heat-sink and fan on the hot side, and a water plate on the cold side, and a small dc pump to circulate a coolant liquid submersed in a plastic fermenter. Has anyone ever tried something like this? I bought all the materials for less than $150 from various websites and it just seems like a good concept for space saving, it should all fut on top of the fermenter lid( too much brew equipment in the garage to fit a second freezer) and its power consumption will be roughly 1 Amp at 120Volts AC. so power consumption will be much better than any other option Ive found.
Let me know what yalls thoughts are.

 

It has been done, like this one for example.
While it can be done, it is not a great idea in most cases. TEC efficiency is pretty bad, so you might be able to maintain fermentation temperature, but lowering temperature might not be feasible. You really need to do your homework when it comes to these devices. They can only achieve so much temperature difference, so you really need very good cooling for hot side. I also think you should consider a decent size, well insulated, reservoir for cold size and keep TEC running continuously and only turn pump on/off depending on fermentation temperature.

 

Thanks for the advice, I kind of figured that if not that many people are doing it, theirs a reason why, but being an Electrician and having a good deal of experience in process controls and design build, I thought it would be a fun experiment. The water block I ordered can hold up to 4 of the TEC's on it, so I'll have room to expand if I decide to head down that path. My main goal is space saving and cost efficiency, so if I can get it to maintain an ale temperature for less than 1Kwh a day ill be happy.

 

I'd love to know if theres any progress you've made on this. Been thinking about doing it myself. Apparently, MoreBeer's jacketed conicals are peltier cooled, so its not like no one is doing it. I just don't think its as popular as the whole tap-into-refrigerant-lines cooling system (something I want to avoid for space reasons).

 

I would actually suggest the other way, have a minimal resevour and a decent cold plate. Then turn on the pump peltiers when required. This way you are not having to constantly cool a mass that is trying to absorb ambient heat when not needed. The peltiers might not be able to get the coolant down to temp in 1 pass but should get it there on the 2nd or 3rd try.

The way I view peltiers is they are a space saving device. It is much more effieicnet and cost effective to use a standard refrigeration cycle fridge/freezer. But from your first post I see this as the main goal anyway so good luck

 

Basically, what it comes down to is making the trade off's you are willing to make.
TEC's can operate with acceptable efficiency, but you will need to be very careful in design. More TEC's operating at lower voltage are more efficient than fewer on higher voltage. Generally, more compact gives worse efficiency. Simple regulation scheme (PWM or on/off) will give worse efficiency and shortens the lifespan of the TEC's.

Adding a decent sized, well insulated reservoir is a simple and effective way to reduce a number of issues.
You could pre cool the reservoir, so that you could actually lower the temperature of the wort/beer to correct fermentation temp quickly. You could avoid the complex task of designing a good control scheme for the TEC's. The TEC's can operate at constant voltage, minimizing thermal-mechanical stress, which is what kills them, prolonging lifetime.
The actual system could still be fairly compact when disassembled and tucked away, you would just need to have something that could be used as the reservoir when in use.

You could of course design a system without a reservoir, but it will be a greater challenge.

 

I'm using a peltier without the water circulation just straight air to air and been having great results. Its not as complicated and I'd imagine allot cheaper. All I need use is a simple 60W peltier with a heat/cold sink on either end through a couple pieces of foam insulation and cheap temp controller.

 

Where is the fermenter? Are you fermenting in the cooler?

 

Yep, It fits a 6 gallon carboy with about 0.25 inches between the carboy and the cooler wall. In the first picture you can just make out the top of the air lock.

 

Interesting! What do you mean by great results? How much lower than ambient can you go and how long does it take you to reach there on a 5 gallon batch?
60W does not seem like a lot to me, and only a fraction of that would actually be effective as cooling.

 

My great results have been maintaining brew fermentation temps stable at a exact temp of my choosing without changing out ice. I have thought about adding a light bulb on the inside to generate heat for brews that like to ferment warm. I can achieve a 35 degree difference below ambient and since I brew in an apt it stays very close to a 70 year round. It does take a while to get there about 36 hrs but with the help of added ice through the little hatch I can cut that down to around 10, but once it gets there it has no trouble maintaining.

 

Thanks for all the advice, and ideas. the project has been a little bit of a learning experience. I burnt up a TEC trying it with the heatsink and fan. the aluminum heatsink just didnt cut it. so i bought another micro pump and a small radiator. and now it is a water-to-water heat-pump. Obviously not as efficient as refrigeration, but again, I'm going for space saving. I set the now (3) TEC's between two water plates, and now one is a hot side to the radiator, and the other is to the coil in the wort. It was going great, until i dripped a little water on the DC power supply, and it fried 2 diodes and a SCR. I have a new one on order, so ill have to wait a few weeks for it to get here from China. The project is quite ridiculous, but fun to play with none the less. Im still holding out for it to be a good space saving device, since the footprint is about the size of the Power supply.

 

I got the new DC power supply in and installed. I tested it, and it ran on down to 63 Degrees pretty quick, but started forming condensation so i shut it down due to it being attached to the power supply, and not wanting to fry a second one. Ill get back working on it this week, Been working on building an outdoor kitchen/ Brewery and trying to get it finished by July 4th. So this fermnter project got put on hold for a little bit.

 

Looking good! I think the water/water approach is good if you're aiming for a compact setup.
I would seriously consider keeping the PSU as far away from anything that might leak or form condensation though. Maybe seal 'er up with silicone when you feel comfortable? Condensation can kill the TEC's as well.
Thumbs up! I'd like to hear more on your progress.