Pletier Cooled Conicals - Anyone Used One?

[koongara]

G'day all,

With summer comming on and the need to cool rather than heat a fermenting batch I've been looking at all the options. I think I'll be going for the son of a fermentation chiller option but am interested in the idea of the peltier style cooling setup. I've seen the tempreature controlled conicals on morebeer.com that look as though they are cooled by peltier's. Reading the various posts it seems that home built coolers with peltiers arnt that good.
My thoughts are would a stainless pot with a side hammered flat and a peltier attached be a workable option? (insulated of course)
So has anyone treied anything similar or got one of the fancy climate controlled conicals?

 

[matho]

i tried to cool an insulated box with th 50w version from jaycar. it cooled down the box by about 5 deg but then leveled off. i think that the heatsink on the outside could not dispate the heat fast enough and should of had a fan on it. Anyway i havn't got back to playing around with it.They require a fairly large power supply (6 amps at 15v), i built one from a transformer from jaycar that cost about $40 but you are proberly better of using an atx power supply from a computer you can buy a 400w for $40. get the largest heatsink you can find and put a fan on it.

 

[mesa]

Hi Dazzla,
If you haven't purchased the pot you you might want to consider ally rather than SS to give better heat conduction, but it shouldn't really matter.

A couple of things come to mind. You'll want to bolt the peltier on pretty tight to the pot (i.e. clamp it between the pot and the heatsink). The tighter is is the better the thermal conductivity. You'll also want a bit of heat sink paste (use as little as possible to fill in any slight imperfections in the two surfaces) I don't know if your planing on drilling holes in the pot to pass bolts through or welding some bolts on. If you drill holes, be aware of cleaning the seal each time you sanatise.

If it were at all possible I'd run water cooling to cool the hot side of the peltier.i.e. water bucket radiator pump. Don't know what size peltier your attaching, but if you get one like Matho's your talking about 60W of power disipation. This is similar to what a computer CPU does. A computer heatsink can disipate 60W if the air is like 30C and the heatsink is like 60C. Your asking the peltiers heatsink to disipate 60W when the air is like 30C and the heatsink is like 40C. Its going to need to be a fair bit bigger than a CPU heatsink, and I think water cooling would be appropriate.

Essentially what I'm saying is its hard to make a peltier work but they do work. An alternative cooling option (assuming you can't get another fridge) is perhaps running a cold water loop through your fermenter. Couple of holes in the lid and a length of vinyl tube dumped into the fermenting beer, connect up to a pump and a bucket with lots of ice and water and a temperature probe in the wort. (I've never actually tried this)

Good luck,
--
mesa.

 

[koongara]

All sounds a bit tricky, I think ice blocks are sounding a whole lot better

 

[Hutch]

Hi Dazzla,

mesa and matho have both made some very good points.

Just to add to the discussion, I made such a cooler box over a year ago.
When you do it properly, it works REALLY well - much better control than a fridge, and allows heating AND cooling (reverse-cycle).

...But, there are a few things I should point-out:

You will struggle to get down and hold lager temps in summer (10-12deg), unless your box is REALLY well insulated, and you have very effective radiation on the waste-heat side of the peltier.

Just as an example, my box was made to about half the height of a family fridge, with 70mm construction polystyrene, plus ABS plastic lining the outside and the inside. I used 4 x 40W peltiers in parallel (to maximise thermal efficiency), PWM control, and an ATX-equivalent PSU (with a high-current 12V supply). For the hot-side heat-exchange, I used a large (12x12cm) copper water-block that I salvaged from a metal recycler (VERY lucky find!), through which I pump glycol/water coolant to a small car radiator, with 4 cheap PC fans to dump the heat.
As I said this works very well indead, maintaining +-0.2deg control, although it tends to run close to flat-out in the warmer weather just maintaining 18deg Ale fermentation temps (although it does sit outside my back door in the warm air).

I keep meaning to post a pick - I'll try to remember to do it tonight.

Hope this helps Dazzla.
Hutch.

 

[koongara]

Thanks Hutch, look forward to seeing the photos.

It seems the simplicity of the peltier dissapears with the need for radiators, glycol and other cooling mechanisms. It seems the commercial ones work without the need for the coolant system, just a heat sink and a fan.

If I could keep it under 20 dec C in Melbourne I'd be a happy man - and my kegs will be better supplied!

 

[Hutch]

Thanks Hutch, look forward to seeing the photos.


It seems the simplicity of the peltier dissapears with the need for radiators, glycol and other cooling mechanisms. It seems the commercial ones work without the need for the coolant system, just a heat sink and a fan.

If I could keep it under 20 dec C in Melbourne I'd be a happy man - and my kegs will be better supplied!

Those mini-fridges that use peltiers don't need sophisticated cooling systems because they really don't have much work to do.
A brewing fridge on the other hand needs to deal with a fairly large-size fermenter, and the energy/heat released by fermentation.

FWIW, I use my Peltier machine for Ales during autumn/winter/spring, where it's not having to work very hard (heating mode is much more efficient). I also use a normal fridge for lagers year-round, and also for ales during summer. All bases covered.


...been meaning to post those pics for quite a while now
I'll take a pic of the APA I've got brewing in the fridge ATM.

 

[rwmingis]

Thanks Hutch, look forward to seeing the photos.

It seems the simplicity of the peltier dissapears with the need for radiators, glycol and other cooling mechanisms. It seems the commercial ones work without the need for the coolant system, just a heat sink and a fan.

If I could keep it under 20 dec C in Melbourne I'd be a happy man - and my kegs will be better supplied!

One option to consider as well is that water is a better conductor than air. Since these peltier effect modules run on about 12V, you might investigate a way of submerging the heat sink only in a tray of water but keep the peltier module above the surface of the water. You'd also have to consider where the heat goes once it goes through the water and into the tray, maybe through the walls of the pan and into a room temperature floor? If you can keep the shallow water at room temperature, the heat sink should be darn near room temp too. You definately need to have good pressure between the peltier module and heatsink and equipment to be chilled, and use the heat sink compound. Don't forget to allow for the fact that all the water may evaporate if unattended for a while, meaning it could overheat. You might get good results. I haven't done this myself however. Depending on how you reduce your voltage from mains to 12V you also might have safety issues with water and electricity. Always be careful with this sort of thing, my old boss lost a mate to 240V.

Keep in mind that peltier effect modules are quite inefficient. In one of the cases above, 4 units at 40 watts uses 160 watt's continuosly. A small bar fridge is about 80 watts and only runs a fraction of the time. Something to think about in the current times.

Cheers,

Rob

 

[Hutch]

In one of the cases above, 4 units at 40 watts uses 160 watt's continuosly. A small bar fridge is about 80 watts and only runs a fraction of the time. Something to think about in the current times.

Cheers,

Rob

Brewing Bob is right about the Peltiers being inefficient little buggers - You can't beat an ordinary fridge for efficient cooling.
...although I should qualify that though I use 4 x peltiers, I've limited each of them to about 2A, to avoid excessive temperature differentials, and resulting inefficiency. So worst-case, they're running about 8Amps at 12V (~100W). Coolant liquid gets up around 40-50degrees in warm weather, so efficiency does suffer considerably.

This is certainly a "worst-case" power consumption. In winter, the thing chugs along at about 10-20W average, since heating is far more efficient than cooling. Very happy with it, though I certainly wouldn't be without my fridge(s)

 

[mesa]

Just though I should mention since we are all focusing on the hot side heat sink, having a decent cold side heat sink helps as well. Having a large area contacting the wort that is only slightly cool will be much more efficient than having a small area thats really cool. Might even be worth considering if an ally pot for the fermenter might be better than an SS pot because of the thermal conductivity.

 

[Hutch]

Finally took some pix of my DIY Peltier controlled fridge, complete with 20Ltrs of DrSmurto's Golden Ale bubbling away nicely ...






The fermenter sits on a large Aluminium cold-plate (heat-sink), under-which are the 4 x peltier modules (not visible).
This heat-sink is great when heating (heat rises), though pretty lousy in cooling, relying on thermal contact with the HDPE fermenter sitting on top.
The peltiers are sandwitched by a large copper water-block heat exchange using 4 stainless bolts.
A rather crude home-made sealed aquarium pump moves glycol around the loop, through a small car radiator, and the whole thing runs pretty close to silent.

In terms of construction, all walls (plus door) are 70mm polystyrene, giving pretty good thermal insulation. The frame was constructed with Al. brackets and pop-rivets, and the odd bit of ply-wood in the base to house the electronics.

Inside, the digital thermometer probe is affixed to the side of the fermenter to give an accurate measure of the brew temp (give or take).
I also put a mains socket in there to power the stir-plate on occasions.


Electronics...
There's a small touch-screen panel at the bottom that provides simple power-ON/OFF, and temperature control in 0.5deg steps. As you can see, it's holds constant temp pretty accurately (currently 13deg outside). The touch screen was overkill, but somewhat appropriate given it lives out in the elements.
The peltiers are fead by an H-bridge mosfet power circuit, using PWM control. This allows for reverse-cycle operation (heating & cooling).
...and there's also a Bluetooth module not shown - it connects to my computer to give a live display of temp VS time. :blink: overkill? :huh:

Needless to say that it took quite a while to make, and not nearly as efficient as a fridge, but it does what it was designed to do very well.

Hutch.

 

[Cocko]

Hutch, I love you man....

Its beautiful, just beautiful.

'wipes tear from eye'

:super:

 

[rwmingis]

Well done hutch, bluetooth and all! :icon_cheers:

Where'd you get that control panel by the way?

 

[Goofinder]

That is truly awesome.

:blink: overkill? :huh:

There's no such thing when it comes to beer!

 

[koongara]

Nice setup Hutch, after looking at that my planned concotion of plywood foam and liquid nails will be a real poor cousin effort.
where did you get the insulation foam - bunnings seems not to stock it

 

[Hutch]

Well done hutch, bluetooth and all! :icon_cheers:

Where'd you get that control panel by the way?

I made it by gutting a standard household light-switch panel, with some LED backlighting, and a QPROX touch sensor chip with copper touch-sensors behind dark transparent plastic, and a standard 16x2 backlit LCD.

Nice setup Hutch, after looking at that my planned concotion of plywood foam and liquid nails will be a real poor cousin effort.
where did you get the insulation foam - bunnings seems not to stock it

I managed to scrounge the foam from a dump skip just near work. There were all sorts of lengths, and it was a right pain in the ar$e cutting it all to size (actually made a hot-wire cutter to do the job properly).

I would advise you either buy it from a construction supply company, or I've also seen it at Clarke rubber (probably more expensive, but easier than trady suppliers). It glues together well with liquid nails, although areldite is a better (and more $$$ option).
I covered the lot in 3mm white ABS (same as fridge panels) to give it some strength, and protect the poly. This was probably the most time-consuming part, fitting all the panels, and sealing it up properly. Ah. the wonders of silicon sealant!

 

[koongara]

again very nice work

 

[Mearesy]

Wow! Thats an awesome idea! Top job

 

[Doogiechap]

Hey Dazzla,
I scored an awesome peltier from a mate which has an integral pump for liquid cooling/ heating. (A superseeded unit from Hydrocool)I controlled it with an older version of one of these Oatley kits. I added an external thermostat to enable heating cooling based on external ambient temps. Like Hutch getting things below 18 was a challenge particularly on hot Perth summer days and with more vigorous ferments. When those extremes weren't present then ferment temps were very stable. All said and done I ended up loaning it to a mate who has started out brewing and I have gone down the path of the Freezer/ Fridgemate which is more resilient on the hotter days
Some piccy's :-




Some other threads covering this are here and here.
I would love to try applying a peltier to a conical (my brew money allocation will never stretch there), I think if you can get a good heat junction between the unit and the vessel and some decent liquid heat transfer on the other side it would be a neat way of doing things.
Good luck !
It's fun fiddling with this stuff
Cheers
Doug