Bar Fridge As A Heat Exchanger?

[sijani]

As the title suggests. I was bored at work and my mind wandered towards beer :icon_drool2: .

I've been thinking of how to build a really efficient heat exchanger for cooling. I won't get into my ideas for HE in a HERMS... :blink:

One of the ideas I've come up with is to put a coil of elliptical 3/8 tubing with copper wire brazed in a spiral inside an aluminium pot inflow at the bottom outflow at the top, fill it with water, seal it and bung it in a 120L bar fridge with a thermocouple at the outflow controlling the thermostat. Drill a couple of holes in the door and add some insulation to the inflow and outflow pipes.

What I want to use it for is wort chilling and then to slowly pump water around a HE inside(s/s coil) or outside(copper coil) an insulated conical fermenter.

I know everyone will say buy a fridge and bung the fermentor(s) in there.

But what I'm trying to do is combine my chiller with my fermentation temp in a small and portable unit. And besides, I only want one fermentor and don't have the space for a second fridge.

I've seen 120L (new) going for $220 and I'm sure I can get one cheaper on ebay.

Do ya reckon it will work or am I getting obsessed with reinventing the wheel :huh:

 

[LethalCorpse]

I like the way you're thinking, but I'm afraid it's a really inefficient heat exchanger. The fridge won't be able to cool the water in the aluminium vessel quickly enough to deal with the heat from the kettle. When you're using it to drive a fermentation chiller, you've got the normal losses from the fridge to atmosphere, plus the losses from the conical to ambient, which won't be insulated (at least not as well as the fridge). It would probably work to some extent, but not very well, and certainly not efficiently. In terms of how quickly it would cool your wort, you might as well have just put the wort in the fridge. (which isn't a terrible idea, but I assume you've considered it)

I've got a few ideas about wort cooling using refridgeration, though. How about a fridge or aircon modified for a die-contact area instead of a cold side heat exchanger, as used in extreme CPU cooling, bolted directly onto the kettle? Or, if the boiling temps would cause the fridge loop to explode, a cascade system (which is basically a glycol cooling loop with a standard immersion chiller, reservoir, pump and waterblock mounted to the above-mentioned die interface).

 

[sijani]

Wouldn't a pot filled with about 60L of water at (pre chilled, not on the fly) 4C be able to easily cool 40L of wort down to pitching temps? Could chuck in some ice at the beginning of the chill...

I've also considered a 3/8" inner core for wort with a 1/2" glycol jacket inside a frozen vessel. Just refreeze before use. But it's only going to work for a chiller, not a steady 4 week ferment.

I'm not clear on what you mean with the die. Like a cpu or gpu heat exchanger?

Edit: pre-chill addition

 

[T.D.]

I agree with LC about the heat exchanger idea. a bar fridge will be effectively useless keeping chilling water cool long enough. In no time the water in the stock pot would warm to greater than a reasonable pitching temp and the chilling from that point onwards would not be very effective. The fridge part of this plan is kind of a moot point. Just think, how long does it take to cool a 600ml bottle of coke in a bar fridge from room temp? I would say a couple of hours. So how long do you thing it would take to cool 60L of warm water that is being further warmed by pumping hot liquid through it constantly?

On the other hand i think the plan to use it for cooling a conical is much more plausible. But you'll have to factor in some temp losses between the fridge and the conical. ie if your temp controller in the bar fridge is set at 18, the temp that the conical is being held at will be a little higher.

 

[warrenlw63]

Couple of ideas in the Brewing Network Gadget Library that may be of help. Though they could deviate a little from what you're looking for.

Here
Here

Though I tend to think that the expense you'd go through for the second idea is a little akin to robbing peter to pay Paul. :blink:

Warren -

 

[chappo1970]

Not to hijack this thread but I have a simular thought as you sijani but for my plate chiller. Running glycol from the freezer not the fridge but in a simuliar fashion as described but having both 20lt resorvior and a 20lt HE in the freezer. The promblem I see is what others have been saying the heat on the outflow side over powering the fridges capacity and rendering the whole exercise useless. The plate chiller is very effective in bringing the wort down to tap temp 27C ATM but it seems to take another 5-6 hours to drop to 18C pitching temp. As for lager pitching it imagine it would take longer.

EDIT: BTW Warren you were right about my digital thermometer is kaputt 2 brews in... Useless hunk of junk!

 

[Batz]

I don't chill very often anymore,but when I do I have an old refrigerated water drinking fountain. The cool water from the fountain runs through my convoluted counterflow chiller cooling the wort quicker,this was necessary when I lived in the northwest as my tap water often reached in excess of 38c.


Batz

 

[Offline]

Wouldn't a pot filled with about 60L of water at (pre chilled, not on the fly) 4C be able to easily cool 40L of wort down to pitching temps? Could chuck in some ice at the beginning of the chill...

Should work fine, but efficiency wise you would be better of using tap water first to drop the wort temp to say 60 degrees (i just guessed a number) then use your pot, with or with out the ice.

This should not effect the cooling time too much but would allow for a smaller pot, using less electricity to cool initaly.