Fermentation Fridge Concept

[calumscott]

Mark that looks spot on!

So you can have the 3 brewing chambers each plumbed to the cooling circuit. The solenoid valves for each controlled by the arduino. I guess in an "all closed" event you could even shut down the pump from the arduino too!

Then, if tube heaters were your preference, you could have one of those in each chamber through SSRs again, controlled by the arduino.

And so using a fridge-freezer with a split freezer compartment, half for the coolant tank and half for hops, you then have the fridge for chilling your beer, or you could cool a chamber to act as a kegerator - or if you were "having it large" you could turn more than one chamber into a kegerator/bottlerator leaving the fridge free for the salads and sides for the barbecue...

...Let me run this past my big bruv who is an industrial insulation guru to figure out what U-values you'd need between the chambers.

What are the temperature ranges we're talking about here?

Min 0C - Max 24Cish??

 

[markpeace]

Any industrial advice gratefully received. I've just realised I could mirror this plumbing at the bottom with a mini hot water tank for warming. This might also drift into trademark markpeace overcomplicating!

0 to 24 would be a brilliant temperature range. I suspect I'll not get it down to 0, though. Low enough to crash cool would be great...

 

[calumscott]

Yeah, I'm thinking 2-3C for lagering and cold crashing. 24C for crazy belgian things where you want banana esters and whatnot...

...I'll speak to him tonight. I know he'll recommend aerogel cos he likes selling it, very thin and awesome U-value to thickness, just be interesting to know just how much is sensible.

 

[Northern Brewer]

I was thinking of getting a raspberry pi and blowing the dust of my coding skills, I was thinking of using something like this to speed up development. Its got all the I/O you need and a snazzy interface.

 

[calumscott]

Right then...

Based on this

And our musings...

...and my very limited knowledge of electronics I've come up with...

this

I think it might be about right...

 

[calumscott]

Spoke to big bruv last night and his off the cuff take on it is that:

a) Don't make one big chamber and subdivide. Make three individual ones with about an inch airspace between.
b) The cheapest and easiest way to get enough insulation will be 4" styrofoam, 6" if you can spare the space. He's pointed me at the relevant equations but says that the various values are lab-conditions values and so will give a theoretical maximum performance.

So I'm off to get those equations and plug them into a spreadsheet and see what comes out!

 

[markpeace]

That's good advice. On a practical level, the airspace in between could also serve as a cavity for the various bits of plumbing so that it's accessible (although, of course, I'd have to then insulate that plumbing itself so that I don't lose heat/cool in transit).

I've rummage out the circuit diagram for my current fridge at some point, you may find it helpful.

 

[calumscott]

Right here goes!!!

Based on 100mm styrofoam...

Thermal resistance of styrofoam: 2.90 m2K/W
Internal dimensions of chamber: 0.60 x 0.60 x 1.50m
Max temp differential: 26 K
Interal area of chamber: 4.3 Sq m
Thermal transmission potential: 38.73103448 Watts
Energy transfer per hour: 139431.7241 Joules
Assume a 23l brew and that it is actually 100% water because I can't be bothered looking up the specific heat of beer! Specific heat of water is 4181.3 J/kgK
Temp change over the hour: 1.45K

That's your worst case: e.g maintaining 19C with an external temp of -7C.

More normally you're probably looking at overnight temps around 8C, differential of 11K which gives a temp change of 0.61 K/H requiring c. 16W to maintain.

So even in the dead of winter a 60W tube heater is nearly double the capacity you'd need - that's probably more than enough to cover the "real world" errors you can expect.

Howsat?

 

[calumscott]

...and if you want to play around and find the right R-value for your own brew cupboards...

...here's a handy calculatorey thingy I've knocked together.

 

[markpeace]

So I've sourced a cheap freezer and the next step would be to drill a hole in each side... any tips from anyone on doing this without the doomful hiss...?

 

[calumscott]

Yup! Electronic cable/stud finder! Should do the trick - you'll need to seriously tinker with the setting to get it to accurately pick up the pipes though.

 

[graysalchemy]

Just found this that may be of help

clicky

 

[calumscott]

:ugeek:

Like that! Nowhere near enough insulation in those boxes for my taste, those paint can heaters would be on pretty much 8 months of the year here!

But that's where I want to get to, minus the fans, plus the chilling circuit.

Love the idea of a web interface to keep an eye on the beer and control the system... You could keep an eye on your fermentation and switch to a cold crash ready for you to rack and bottle on your return from a fortnight on the beach... :thumb:

 

[markpeace]

Nice. Thanks. I'm going to try to hold myself back from going as far as built in webcams, though. I say *try*, of course.

 

[calumscott]

What about mike'ing it up to record airlock bloops per minute...? :lol:

 

[markpeace]

Ok, I'm going to run with this as a little experiment. First component to play with is the freezer itself. Here's my first plan (the freezer is a half height one)...

So it's the coolant recirculation method. I've moved away from a internal reservoir to a coil (as per grays link).

Conundrum #1: More surface area = more heat exchange, but also less volume in the freezer at any one time. I'm assuming this is still best, but I'm guessing balancing recirculation speed is going to be key here. The author of that link uses 6m rubber tubing, but I'm wondering whether a square copper coil might be better in terms of exchange efficiency.

By the time this is finished, it'll probably be winter. So I can make good use of the cooling functionality :eyebrow:

 

[markpeace]

So I've managed to drill an entry and exit holes in the fridge with no disasters, and have knocked up the first two (of three) layers of heat exchange coil ...

Have run out of beer spends now. boo. Next pump, little crappy pump and tubing to run a first experiment recirculating coolant.

 

[EskiBrew]

Glad to see people putting the RaspberryPi to good use

I've got my eye on the Raspberry Pi, though - cleverer people than I are having a play with the IO Bus it comes fitted with. Once that develops a bit, it can replace the arduino all together and become the unit for inputting/outputting to electronics components. Its not quite there yet, though, and I'm not skilled enough to bodge around the problems.

The Gertboard is now available - not looked at the spec myself as I'm happy to work with the RPi header directly but it might be of use :geek:

Will watch with interest :thumb:

 

[tknice]

:ugeek:

Like that! Nowhere near enough insulation in those boxes for my taste, those paint can heaters would be on pretty much 8 months of the year here!

But that's where I want to get to, minus the fans, plus the chilling circuit.

Love the idea of a web interface to keep an eye on the beer and control the system... You could keep an eye on your fermentation and switch to a cold crash ready for you to rack and bottle on your return from a fortnight on the beach... :thumb:

I went a little crazy with it, I admit! :grin:

Wife is yelling at me because we are suppose to be leaving for the beach. I'll give a few more details of the different decisions I made when I can get on next. My buddy went with insulation twice as thick as mine on his chamber.

 

[tknice]

Bloops per minute (bpm)... I love it.

Okay, on the road now. To the OP, I'm very excited to see what you decided on. I think moving air into the chambers will work well but if you decided on circulating water or glycol like I did, there is definitely a transfer of heat that takes place and you will want to make sure he freezer you use is powerful enough to balance the temps.

I was limited on space and the freezer I have is not as powerful as I'd like. With all 4 chambers enabled (I can turn off water flow to use only the top two or all 4), the freezer temp is around 25F and the chambers sit at 63-65F. If only two chambers are active the temps drops a little lower. Once beer is actively fermenting, the chamber temps rise slightly to around 66-67 and the beer probes are always about 5 degrees higher during active fermentation. This usually lasts 2-3 days. During this time, the freezer is fighting to keep the chamber temps at 66F so it rises to around 30F. Every system is going to be a bit different in terms of the strength of the freezer and cubic space of the chambers.

Bear in mind that I have not completely sealed my chambers where the tubes enter in the back. I expect that they will perform a little better once I spray expanding foam in those areas. Before this project, I wasn't sure how it would all pan out and was hoping to get lower temps-- low enough to lager. Obviously this didn't happen (at least not yet), so I do all of my lagering in another temp controlled freezer.

Hope these details help with your decision and sorry for the Fahrenheit temps. :)

TK