Peltier Cooler

[cantgetaround]

hi all,

i love my homebrew and here in sunny brisbane is a nice very hot summer at around 34c, i was looking into making a fridge cooler from my waceo cooler which is a 30w peltier consits of... outside to inside are the fan,heatsink,peltier,alloy block,botls the the cooler being alloy basket inside, hope you understand that, now i have taken the fridge motor off and all parts too ( motor fried ), and made a hole in the angle part where crisper goes ( i have turned fridge upside down aswell ), i got hold of a heatsink and fan for the cold side and put it all together and it work fine, the fridge compartment is 347L, inside is 600 wide, 1000 high, 550 deep, with a wall of 60mm thick, it does work in the fridge but only get 2/4 degc below outside temp, is the 30w unit too small, i have been googling this for a few days now and see other ppl using 60w and higher, i know because of the fridge size it wont get really cool but if i can get it to aleast 20c would be good, i have noticed that at night it reads 14c due to outside temp is low too, so at night i would not run it and only during the day and also through a temp controller i already have ( turns on hot and cold ), would i need bigger peltier to do what i would like.....
any help would be great thanks...

[Tom Mix]

Please don't waste your time with peltier effect devices- they are f#$%&*N useless!!! The amount of power from 12v batt for next to no cooling!!- fergit em!! I have!!! Anyone can pick up a "beer- fridge" for a few $- till then a wet chaff bag or even wet newspaper will cool the precious drop/s! (yes, I love beer too & drink - in moderation of course-about 8 kings a day- & don't get even moderately tipsy! And have done so for about 45 years!.

[Downunder35m]

1. writing a request in a readable form is much nicer than dropping a bandworm like that....
2. a peltier can only work with sufficient cooling/heating
It does not matter how big your peltier is or much amp you pump into it, only if the generated heat is dealt with properly it will cool.
A peltier can only create a limited temperatur difference, meaning if the outside is already over 30° by theory you can still get down to -30° on the other side.
But and it's a huge but: This theoretical max can't be accomplished!
a) the cold side has to have a big heat sink, best with fan
b) the hot side needs even more fan power and a bigger cooler
In most coolers the 12V part is meant to keep the temp down while driving, after that gas or 240V take over.
Fridge freezers can go lower on 12V but unless you pay top $ they won't make it from warm to freeze just on 12V alone...

If you want to cool your beer in style get an old bar fridge and cut all the housing and all away, so you are left with the compressor and the inside/outside of the cooling system.
Make a nice housing to hold a barrel of beer and fit the cooling part between barrel and wall, hide the rest in a suitable box (use your phantasy...)

[cantgetaround]

thanks for replys.... Tom Mix - i know what your saying as i have read heaps and heaps of websites with people saying the same, but i do read the one with the good use with them,,, Downunder35m - i have read heaps of website saying the same but EVERYONE has videos or tells you of the temp it can get at the pelteir itself, mine can get below 0c at the pelteir but the is not what im after, today was 26.5c inside the fridge and when turned on it only came down to 24.9c which for beer is an ok temp, for the out side of the fridge the unit has a D90SL-12 90mm 0.14A fan bolted to a 120x120x(30 fin height) heatsink (alloy), and the inside is CHA8012CS 80mm 0.17A fan bolted to a 80x75x(45 fin height) heatsink (alloy), the 90mm fan can with the cooler unit and i have added the 80mm fan to it..
the unit will be run via the temp controller so it will come on .5 to 1.0 above my preset temp and my heater comes on at .5 to 1.0 below my preset is 22c but do some beers at 24c...

i have attached some pics, i hope they work as first time adding...

[Downunder35m]

Well that is pretty tiny for such a big fridge...
That size is in my portable cooler...

[cantgetaround]

yer that is what it came out of, i was thinking of getting a 60w peltier to see if it gets cooler or i might need a 100w to do the job, jaycar have abit of a range there...

[Downunder35m]

Your best option would be several smallone with a proper heat sink on both sides, hot side with fans.
But putting it all together, plus parts cost and a bar fridge is much cheaper, especially while cooling in the summer

[Uncle Fester]

I am thinking you would be running 100W 24/7 to get a 23litre batch cooled only a few degrees below ambient.
That is 2.4kW/h a day and you will never get it anywhere near 20C from ambient 34C that way.


This is not just about a random temperature drop but the amount of thermal energy you need to pump from something with a high thermal capacity like a fermenter of beer and a peltier is extremely inefficient and totally unsuitable for something like that.


My beer fridge is an old chest freezer where I simply turned up the thermostat screw so it works in a 2-18C range. I like brewing, storing and drinking Lager but an Ale is best brewed at 18C too.
On average it uses 0.2kW/h a day!!
Chest freezers work much more efficiently that way than a normal fridge and hardly anybody knows that.
I bought it for $80 in a garage sale and it is not made in China because it is old and should last another 30 years due to the short time it only needs to run each day to maintain these temperatures.


An external thermostat works fine too as long as the hysteresis keeps the compressor off for at least 15 minutes. It will even work using a $5 electro mechanical timer with 15 minute interval settings and a bit of experimentation and monitoring. I mean who doesn't check their brew at least on a daily basis.

[cantgetaround]

i am considering these for hot and cold side..... Corsair Hydro H100i Extreme Performance Liquid CPU Cooler..... with 1 60w peltier, Does anyone know what the differance is between 30w,60w,100w and al the other watts in peltier, does it mean the higher the watt the colder it gets ?

i know a lot of ppl are reading this and prob thinking why is he doing this, why not buy a fridge and mod it, well where is the fun in the DIY, i dont have much 240v on hand but have loads of amps at hand as our place runs from 1200w solar with a battery bank of 840amps, the only 240v invertor i have is for my pc and tv as i havent got around to making them 12v yet... i love my diy projects that i do, everything i have in my house and shed but the pc and tv and nearly all diy...

after some searching and reading that this can be done with a happy inbetween of pros and cons, i have found some items on ebay and at local pc stores..... for the hot side as the more heat is taken away the better the peltier works im thinking of a triple or quad fan radiator with a pmp 450 pump to a alloy/copper water block.... as for the cold side i dont think it needs to be as big so i might be able to go for a single fan radiator like the corsair h80i...

[Uncle Fester]

As I mentioned above it is about the amount of energy (heat) that you are pumping not the temperature difference. It is pointless if the temperature difference is 60C, the cold plate -20 and the hot side 40C. If you want to pump energy efficiently the temperature difference should be as low as possible, almost zero in theory.
The more watts means the more heat you can pump.


You want to try a real DIY soultion (without buying any fancy stuff that still might not work well)?

I would use as many low watt peltiers as possible to achieve a large surface.
At least 4 x 30W. I would bolt them on an aluminium plate about as big as the whole back of the fridge (inside). I would make little water tight metal containers (soldering) that are bolted to the hot sides of the peltiers. Don't forget the thermo paste.
Cover the containers with some insulation material (rock wool) around the back as they will stay inside the fridge.
Plump them in series with garden hose or pvc tubing, so that one end goes goes in and one out of the fridge tightly through small holes.
You will need a small pump, like a DC brush-less fountain pump, from Ebay (20-30$).
I would get a 24V pump like this:

and run it on your 12V system so it will last longer (unless you can find something that is not made in China)
The flow should still be enough if you don't need to pump much higher than the source of water.
Pump the water from your pond or rain water tank and back. The pump is best submersed in the tank or pond. Make a filter in front of the pump. I cut the top off a soft drink bottle so it looks like a funnel and wrap a bit of fly screen around the wide open end secured with fishing line. The small opening usually fits snug on the pump inlet or add some tape to match the diameter.
If the flow is strong enough you should hardly feel the water any warmer than it's source and the petiers should be pumping heat with maximum efficiency, similar to a 120W absorption bar fridge.

Most of the stuff above should already available in a good DIY household, execpt the pump.

[Downunder35m]

I still say the cheapest and easiest coller for a keg or a can collection is a simple fridge with a standard compressor system
Peltier elements, if huge cooling volume is needed must be stacked.
The problem still remains that they need to give up heat at one end and can only cool down accordingly.
If you still insist in using peltiers you will need to be inventive and prepared to waste a lot of moeny:
A peltier heated heatbed for a 3D printer that only measures 15x15cm uses a stack of 5x5 elements and the plate is only heated to 80°
For your size you will need at least 40cm² for the cold side, best with a heat pipe, big cooling ribs and fan.
Similar for the outside unless you use a water cooling for the hot side.
Compare that to an efficient freezer and you will be better off bying ice to cool your beer