Hot/cold fermentation cabinet with TEC (peltier) module

Ciao

Hi I’m an Italian Homebrewer and I got lot of my inspiration for my DIY project from the forum pages…In Italy the hombrewer community is far away from certain incredible realization but nevertheless I would like to share my experience in building a thermostatic fermentation chamber using TEC (peltier) module

The reason for such an approach are well known..

-No mechanical part with maintenance like normal compressor
-No hysteresis in switching on and off the engine
-Both cooling and heating capability
-Low Noise, compact size implementation

There are also many disadvantages starting from efficency…

The most attractive feature for me is the capability to drive the TEC module with a programmable electronic circuit that is capable to revert the polarity (h bridge circuit) and to modulate via PWM the power with a fine PID control. With this solution I’m able to cool or heat the chamber in a very effective way and try to have a constant range of temperature regardless external temperature (my cellar is very cool in winter and to hot in summer)

The TEC module was based on 4 x120W cells driven by 24V source PWM modulated. It has been assembled by myself adding 2 heat sink and 2 fan on both side.



The electronic circuit to drive the TEC module is passed on TeTech TC-36-25-RS232 that uses solid-state MOSFET devices in an electrical "H" bridge configuration to automatically control the direction of current simply based on the temperature set point. The controller can be communicated with and programmed directly through a personal computer’s RS232 serial communication port



Here you can find all the picture of the fermentation cabinet and the assembling

https://picasaweb.google.com/mysobr...icaACelleDiPeltier?authuser=0&feat=directlink

The cabinet is based on IKEA trolley …it’s stainless steal, robust, light and perfect for 50L fermentation bucket





For insulating I have used some polyurethane panel 2CM thick inserted in the cabinet frame connect with hot glue.





Than I have applied an external and internal thin plastic panel in order to further insulate and have an internal clean surface.



On the bottom I have inserted the TEC module opening a proper hole in the insulating panel





Finally I have sealed all the split with a specific foam



The top cover can be removed as well the front door kept on it’s own place with super magnet



I’m in the final stage and I have to insert in a proper enclosure the power supply and the control circuit as well a thermometer
I’ts not and AAA+ refrigerator but it looks nice ..isn’t it?





When everything is completed I will start to tune PID and software parameter and I will share the result in term of performance and stability
Any comment is off course appreciated.. sorry for my English !


Stay tuned
Davide

 

Cool project!

I have also thought about a peltier fermentation chamber but haven't ever done it. Your project looks very nicely constructed, and I look forward to hearing how it works!

 

Some more pics and update of the final assembly with the electronic part.

Control panel wit 24V switching power supply, PID controller with H-bridge power circuit, digital potentiometer


Inside details with fan mounting



Back panel mounting



Final result , rear, front, top






Enjoy

Davide

 

Great post! Have you fermented in it yet? How well does it keep temps?

 

not really yet...just tried with plain water...would like to tune PID parameter, sensor probe positioning, digital potentiometer mapping etc..

With 15L of water the system is stable and I have reached 8C (celsius) as lower temperature with 20-22 c external temp

will update with a real beer batch that produces hot during fermentation

regards
Davide

 

Ahhhh peltier coolers. I did 3-4 science projects back in the day with them - really fun stuff if you can dissipate the heat on the backside fast enough.

Awesome build and thanks for the write up!

 

Hi
Some more tests in order to monitor power consumption and avoid surprise in the electricity bill!

I have inserted on the power supply a basic device that allow to measure current and power (istant and max)
In the above example I have a set point of 16.1 and a measured temperature of 17.3 so the PID control uses all the fridge power (-100%) to drive the TEC module.
As result the consumption is 153W






Around the set point of course the PID reduces the power…in a range of +- 20% (it depends on many factor ..external temperature…set point…heat produced by fermentation..)…in my experiment I have measured a power around 50W for in a stable standard situation.





Anyway the worst case is 150W that is not so much also for a long period…maybe I can switch off a light in one room..but I don’t want to give up drinking a good beer !

Davide

 

Very cool!

 

This is an awesome project. I really like the use of the cart and the reversable nature of the peltier devices to both heat and cool based on DC current direction. Do you have any schematics that you can share for the circuitry to build the control system?

A couple of thoughts came to me while reading your posts. One, that cart may not really be stainless steel because most magnets won't stick to most stainless. So, it may not be a corrosion resistant as you think. Two, that thin foam insulation just placed between the frame members many not prove to be very good insulation because the frame members themselves will thermally bridge the inside to the outside. I'd consider continuous layer of insulation on the outside to break up the thermal bridge and make the cabinet far more efficient because it's already efficiency challenged by the peltier devices.

 

I have no a circuit design and details, I hva bought the controller ready made from a US manufacturer..there are few suppliers of this type of circuits.

http://www.tetech.com/Temperature-Controllers.html
The PID control is not a big issue..it's quite common in this type of applications..the power circuit is more complex..it includes PWM modulator and H-bridge power section. Than there is the control software that drives via RS232 the board and allow you to set the parameter.
In order to configure the set point I have selected the "potentiometer" option and I have used a "digital" 10Khom potentiometer from Bourns 3680 family

http://www.bourns.com/data/global/pdfs/3680.pdf

The frame is not stainless steel...I don't see any problem since you shouldn't have liquid in direct contact.

please consider that inside the thin plastic foil (internal and external) you have 2cm insulating layer that perfectly insert into the frame.

I prefer this multilayer solution in order to keep the assembling clean and compact...in any case you will never reach AAA+ insultaion grade..

ciao
Davide

 

Hi

Dont know if I missed something, but how many peltiers did u use? And how is the attachment? I plan to build a small fridge to fit 2 corny kegs and I can think its stupid to invent the wheel twice.
How big are those cooler elements, and did you make some calculations of how big they had to be?

Not only I find it hard to find big cooler elements, they are expensive too. But in your build, shouldnt it be better to use the bigger cooler on the out side to get more heat away from the peltier?

But I really like your build.

 

Hi
sorry for the delay in my reply...

about the cooler I was quite lucky...I found an ebay surplus with 4 cells , heatsink and fan already assembled...I think the producer was supercool (http://www.supercool.se) .
It was a air/water exchanger that I have adapted air-to-air.
I don't perform specific calculation...just make the assembly and see the results...doing my best in insulating the carry on

About inner and outer heatsink again I have used what I was able to source budget price...and also trying to fulfil some mechanical constrains..

So not so much help...very empirical approach...hope you succeed to source your devices and got same results !

ciao
Davide

 

That's pretty slick...

 

I've been working on a peltier cooler but it's a much simpler and less costly design.

My biggest issue is, like someone else mentioned, dissipating heat. You have to dissipate the heat pulled out of the cabinet plus you have to dissipate the heat the unit generates. And between the two, the heat the unit generates can be greater.

Once the heat issue is solved and the design is done I will have a peltier cooler module you can just fasten to the side of your fermentation chamber, plug into the wall and dial in the temperature.

 

thats the problem with peltier junctions; none are more efficient than 60-70% at best... most cheap ones are in the range 30-50%. meaning for every 100w of cooling power, you need to feed them with 200w or more of electricity. the differential in power is converted into heat that has to be removed.

so a 50% efficient TEC with 100w of cooling power will consume 200w of electricity, remove 100 (or slightly less, just because its not exactly 1:1) watts of heat from the cold side, but will produce around 200w of heat on the hot side. so your heatsink has to be double the size you would normally need to cool 100w.

cool project though. im suprised you arent using more than ~150w to cool that chamber.

 

Maybe my english is not so good... but I don't understand the point related to heat generated by the unit...unless you are talking about the heat generated by power supply and TEC controller with h-bridge circuit (that have to be dissipated)
Peltier cells as far as I understad works like a heat pump..generating a delta T between hot and cold face...so you have to dissipate heat from let's say the hot face (it can be reverted) ..the more heat you dissipate the cooler is the other face. Of course there is a concept of "efficency" like all thermal sistems.

If you are saying that "heat that unit generates" menas that peltier cells are low efficency you are right...!! this is the main disadvantatge of this solid state approach ...but the advantages are on other points...

hope to have understood
ciao
Davide

 

totally agree...peltier cells = low efficency

but...in homebrewing efficency is not the main target...

moreover the capabilty to reverse the hot/cold surface, the capability to drive continuosly the power (PWM modulation) , the compact and no mechanical part assembly...should be considered vs some more wat

Davide

 

They work like a heat pump plus they generate their own heat when working. Thie is because all of the PN junctions have resistance and they get hot. The end result is for every BTU you pull out like a heat pump the unit itself generates up to one BTU. This also means that the hot side heat sink must be much larger than the cold side heat sink.

 

Here is the issue that halted my plans. Large heatsinks are hard to find. If I find , they are very very expensive.
I plan to use 4 millimeter aluminum for backside of my small corny fridge. Like 500 mm wide and 700 mm high. That will do as a heatsink for the cold side. Then.... The hot side.... Uh! Need to fill the entire back with expensive heatsinks and fans. The plan is to controll the cooler from a PID with PT100 sensor.

 

Just buy what you need by the foot here.
http://heatsinkusa.com/

 

I think it's a pretty cool project, nice work.

That being said, I fooled around with the idea of doing the same thing with Peltiers, but once I started playing around with them I realized how many I would need and the amount of power it would take to cool any significant amount of fermenting wort was going to be ridiculous. You've kind of found the same thing, I see. Getting the chamber down to 8C with a carboy full of water is a much easier task than keeping a vigorously fermenting beer at 18C.

As a comparison, my ferment chamber is about twice the size of yours and it is cooled with a 5,000BTU air conditioner. The chamber gets down below -15C within a few minutes when the AC is running.

Have fun with the project, I hope it works out for you, but I just don't think Peltiers are well suited for this task.

 

different way to say that peltier cells have low efficency...!

 

In my implementation there is no a side that is hot or cold…they revert themselves according to external temperature and set point
Ie when external temperature is to low the cabinet works like a oven…when the temperature is too high like a fridge..
This is one of the advantage of the peltier approach…off course you need a proper control board !

 

I've got a peltier based cooler very similar to the one being described here. I love it. It's not great at quickly dropping the temperature of large volumes of liquid, but for keeping fermenting beer at a steady temperature within 20ºF of ambient it has never let me down. I get precise control with a PID, very little noise, and a significantly smaller footprint than I would have with an equivalently compressor-based system. I don't mean to knock on your system, as I'm sure it works great for you. But, peltiers definitely can work and, for some, are far and away the best option.

 

It's a better option if you need something quiet and unassuming. Fortunately I don't have that constraint.

 

This is my first post, but not my first rodeo, not peltier project. That said, it is not finished yet. I thought I would let you all know my peltier based conical is silent and works like a dream and does not cost me that much to run. Anyway, I made a few different peltier projects, both are in progress, but I have brewing with them. I have attached some photos of my peltier cooled conical fermenter. It runs at about 146 watts and runs me about $50-100 a year a according to my "kill a watt." What do you all think? I would be happy to help others.

 

Very cool, I'd be interested to hear more about how you accomplished this. Maybe you could do a small write up in a separate thread and link to it here?

 

How often is it running to cost you that $50-100? That seems like an awful lot to me. My 13ft3 chest keezer only costs $25-$30/yr to run and that's going 24-7-365.

 

I would be happy to do so. I think the most important thing when using the peltier is removing the heat from the system, and the best way of doing that is to use liquid not air. So I have a dual loop, one hot and one cold, system. Basicly I have sandwiched the peltier between two watter blocks. The cold loop consist of a pump, a reservoir, water block, and a copper coil that wraps around the fermentation chamber. The hot side replaces the copper coil with radiators and fans. The cheapest and most efficient that I have found happens to be large heater cores from cars. If people want I will start another thread, I don't want to "hijack" this one. I have just been working with these things for a bit and after a lot of trial and error I have learned how to make the peltier work pretty dam well, or so I think. The best thing is how silent it is, the only thing I can hear is my refrigerator running and this thing is almost completely silent.

I have a photo of the conical after I made a custom stand for it and before I put all of the stuff on it. I think this photo makes it easier to understand.

 

Hi
what an incredible piece of HW...it seems more a nuclear reactor than a conical fermenter ..
Since I have implemented something similar (see my picasa photalbum) I don’t understand how it works yours



https://picasaweb.google.com/109693051818481428547/FermentatoreTroncoConicoControllatoInTemperatura?authuser=0&feat=directlink

Where is the fermenter chiller ? inside or outside ?
How do you perform heat exchange ? air-water ?
Could you explain the design and different hot/cold flows ?

Thank you
Regards

 

Im interested about those waterblocks. How does they look?

 

The water blocks that I use on my conical fermentor are from CPU water blocks and it holds one module. The ones I made are from aluminum square tubing, 3/4" with mitered ends to create a pathway for the glycol to run. I have some photos of the blocks next to an for scale. I hope to one day use the arduino to run it via a phone app so you can start laggering while on vacation.

I am not certain on my physics, but I think if I use this setup on a stainless conical it would be more efficient than the thick walled minibrew that I am using now. Also I was wondering about using stainless tubing to create an immersion/submerged cooler so it was a better transfer of the coldness to the beer without contacting it.

Oh, and yes it may use more power than a fridge, if you have the space for a freezer then go for it. As for me, I started off making this because my condo has only so much room and I could not manage to bring myself to have a third fridge for beer. I have a small one for bottles and a my kegerator, not to mention my main fridge. Little did I know the world that I was entering.

I have an idea of using the peltier along with ice jugs that would run at certain temp ranges. May be that idea would be even cheaper to run?

 

How cool can you get it? How many peltier coolers and what watts are they?

I have 4 and plan to run them at 12V. They are 136W at 15V. So I need to cool down 400W an Im gonna use fans through a transmission radiator with 120mm fans. Pic soon of the cooling section.

 

I’m starting the upgrade of the cooler of my conical fermenter.

I have sourced a surplus COOLIT freezone…that was made by a Canadian company in the past in order to watercool PC (overclocked CPU)




The basic principle is still the same…air-water heat exchanger and the cool water is recirculated inside the conical fermenter via a stainless steal coil



The new exchanger is a very nice piece of engineering…very compact, colplete with pump, peltier cells, reservoir, fan…and it comes with a controller board that can control the power applied to the 6 cells and the speed of fun/pump according to set point and current measured temperature. So I expect that once the worth has reached the target temp the power will be adjusted in order to compensate just the heat produced by fermentation and loss of the system



The unit can be controlled by software PC via USB but it can works also stand alone…it is possible also to log temperature and power during the whole time !

I need this week and to adapt some fittings and mechanical details and then I’m ready to test

stay tuned!
Davide

 

made some preliminary test and a partial assembly

installed the stainless steel coil…



connected the heat exchanger and the pump



insulated the fermenter



the water flows and the pump seems to have enough power..I just want to add a reservoir in order to make the circuit refill easier
Just waiting for a 10A power supply (the 5A that I have is not able to drive the cells) and then I can test with water the power and stability

enjoy
Davide