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-   -   Hot/cold fermentation cabinet with TEC (peltier) module (http://www.homebrewtalk.com/f51/hot-cold-fermentation-cabinet-tec-peltier-module-307438/)

mysobry 02-24-2012 04:06 PM

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.

https://lh4.googleusercontent.com/-n...0/P1080309.JPG

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

http://www.tetech.com/images/product...6-25-RS232.jpg

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

https://picasaweb.google.com/mysobry.picasa/CameraTermostaticaACelleDiPeltier?authuser=0&feat= directlink

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

http://www.ikea.com/it/it/images/pro...E190638_S4.jpg

https://lh5.googleusercontent.com/-f...0/P1080301.JPG

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

https://lh6.googleusercontent.com/-A...0/P1080335.JPG

https://lh3.googleusercontent.com/-2...0/P1080344.JPG

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

https://lh3.googleusercontent.com/-0...0/P1080349.JPG

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

https://lh4.googleusercontent.com/-o...121_155356.jpg

https://lh6.googleusercontent.com/-w...121_155345.jpg

Finally I have sealed all the split with a specific foam

https://lh4.googleusercontent.com/-v...0/P1080485.JPG

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

https://lh4.googleusercontent.com/-B...0/P1080331.JPG

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?

https://lh3.googleusercontent.com/-V...0/P1080488.JPG

https://lh4.googleusercontent.com/-6...0/P1080492.JPG

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

thepartsmancometh 02-24-2012 04:57 PM

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!

mysobry 02-27-2012 08:52 AM

some more pics
 
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
https://lh6.googleusercontent.com/-e...0/P1080499.JPG

Inside details with fan mounting
https://lh3.googleusercontent.com/-Y...0/P1080504.JPG


Back panel mounting
https://lh5.googleusercontent.com/-o...0/P1080507.JPG


Final result , rear, front, top
https://lh6.googleusercontent.com/-e...0/P1080510.JPG

https://lh5.googleusercontent.com/-V...0/P1080511.JPG

https://lh3.googleusercontent.com/-h...0/P1080513.JPG

Enjoy

Davide

thelorax121 02-27-2012 02:30 PM

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

mysobry 02-27-2012 02:53 PM

Quote:

Originally Posted by thelorax121 (Post 3834183)
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

rhamilton 02-27-2012 03:02 PM

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!

mysobry 03-01-2012 09:11 AM

power compsumption
 
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

https://lh4.googleusercontent.com/-t...%2520teemp.jpg

https://lh6.googleusercontent.com/-w...0/P1080515.JPG


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.

https://lh3.googleusercontent.com/-i...temp%25202.jpg

https://lh6.googleusercontent.com/-i...0/P1080519.JPG

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

wyzazz 03-01-2012 02:08 PM

Very cool!

starsailor 03-01-2012 02:48 PM

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.

mysobry 03-01-2012 08:10 PM

Quote:

Originally Posted by starsailor (Post 3846390)
Do you have any schematics that you can share for the circuitry to build the control system?

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


Quote:

Originally Posted by starsailor (Post 3846390)
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.

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

Quote:

Originally Posted by starsailor (Post 3846390)
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.

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


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