New and More Efficient Wort Chilling Method?

[BrewerB]

Has anyone ever tried an alternate method of wort chilling by which you pump your hot wort through an immersion chiller that is sitting in a bucket of cold or ice cold water? This seems more efficient to me than the typical method of pumping hose water through an immersion chiller sitting in the hot wort.

I'm considering switching to this method but was wondering:

A) Has anyone tried this yet and if so, does it work?
B) Are there things I should be concerned with in implementing this method of chilling?

It goes without saying that I'd need to properly, thoroughly clean and sanitize my chiller prior to each use for this method.

Why am I considering this?

The standard immersion chilling method involves exposing a large volume of hot wort to a much smaller volume of colder copper coils. In the other scenario, we're reversing the tables and pumping a small volume of hot wort through a potentially much larger volume of cold (or ice cold) water. It seems to me that exposing a smaller portion of hot wort to a much larger volume of cold water would be far more efficient at cooling down the hot wort.

One of the issues I've always had with my immersion chillers is the amount of water it takes to cool things down to pitching temp. Typically, I'm running 15+ gallons of water through the chiller to cool down my 6 or so gallons of hot wort. If I'm using a pre-chiller, this can easily take over 20 gallons. Even so, I usually don't get the wort down to ale pitching temps (under 70F) without using far more than 20 gallons and spending a lot of time in the process. On my last ale batch, I stopped the cooling with the wort at around 80F and let the fridge finish the rest of the job (which took another 5 hours).

While I can find ways to use some of this extra water (plants, doing dishes, flushing toilets, etc), it has always felt rather wasteful and I always end up dumping 5+ gallons down the drain. I think that with just 5 gallons of ice cold water I could easily cool down an entire carboy of hot wort but would like to hear what the fellow BN Army thinks.

[Buttwidget]

I've been a user of the Jamil whirlpool chiller for almost a year and love the thing. The one upgrade I've thought of is to add a plate chiller in the pumped wort loop. I bet that would really do a great job of dropping the temp in no time.

Otherwise I wouldn't change anything. Whirpool chiller rocks.

~widget

[spiderwrangler]

Do you reduce your flow rate on your chiller as the temp of your wort drops? This can reduce waste water as well. The rate at which the heat is exchanged is related to the temperature difference between the two (sure AJ can provide formulas for you if you'd like). What you are describing is basically a counterflow chiller without the counterflow part. As the water in your chilling bucket heats up, you will get less and less exchange, and would need to slow your flow rate of your wort to allow more time for heat to transfer, as well as agitate your chilling water (or move the chiller around). One of the issues I foresee is that it may be hard to dial in your final temp, as the exchange rate will be changing as you chill. For a straight up immersion chiller, you just go till you're where you want to be, and for counterflow, you can fiddle with wort and water flow rates to get exactly the temp you want.

[MachineShopBrewing]

You have to have flow to remove the heat from the contact point. If you run it into a chiller in a bucket of ice water, you will just heat up the water around the coils. Also, if you have 5-6 gallons of wort at 212F, a 5 gallon pail of ~35F water is not going to chill all the wort down to ~70F without heating up too much as you remove the heat from the wort. Sounds like you may just want to run a counterflow chiller with a pre-chiller in an ice water bath. That would cut down some on the water you use. Or, set up some kind of glycol system with an old chest freezer and a pump. That would be interesting to see. You wouldn't use any water then.

[siwelwerd]

The rate at which the heat is exchanged is related to the temperature difference between the two

Newton's law of heating and cooling states that the rate of temperature change is directly proportional to the temperature difference, i.e. dT/dt=k(T-A) where k is a constant based on physical properties and A is the "ambient" temp. Note that if the ambient medium itself is not constant in temperature, this amounts to a critically damped second order ODE.

As to the OP's concerns, I'd be concerned with cleanliness of the inside of that chiller since you are pumping wort through it.

[CRBrewHound]

I have done this with a counterflow chiller and and it makes a big difference in the cooling times. Never done it with an Immersion chiller, but I would think it would work as well. Big problem would be melting the ice before reaching ideal temp.

[dstar26t]

I pump out of the kettle, through a 40 plate chiller hooked to hose water. After the plate chiller, the wort goes through a 50' SS coil immersed in 40 lbs of ice in water in a rubbermaid 10 gallon cooler. A pond pump in the cooler agitates the water so there aren't any hot spots. This system chills 12 gallons of wort from boiling to 48F in 20 minutes in the summer, even cooler in the winter. When the kettle is empty, I hook up CO2 to the hot end to blow the chillers and hoses clear into the fermenter so very little wort is wasted. The system gets back flushed with hot water and then a hot caustic recirc (real caustic, not PBW) so it stays clean.
The following pictures also have a hopback plumbed in...gravity drain from the kettle to the hopback.
http://s86.photobucket.com/albums/k98/d ... hoto14.jpg
http://s86.photobucket.com/albums/k98/d ... oto5-2.jpg
http://s86.photobucket.com/albums/k98/d ... oto4-1.jpg

[foomench]

As others have alluded to, an equal amount of ice water isn't going to get your boiling wort down to pitching temperature. You will need to add more ice as it heats up. When you use 15-20 gallons of water now, that "waste" water has done its job. If you absolutely want to conserve water with an immersion chiller, you should set your flow rate so the temp of the waste water pretty much matches the temp of your wort at that time. If the water comes out colder, you've wasted water that could have absorbed more heat. It won't come out hotter, but if it is at the temperature of the wort before reaching the end of the coil, you're just wasting time. That last foot of coil isn't doing anything for you.

My typical regimen to minimize water, time, and energy use is to run tap water through my chiller for the first 15 minutes or so. This lowers the wort from 205 F (5000') to something around 90-110 F, depending on the tap water temperature. Then I switch to using a pre-chiller in icewater to finish the job, usually in another 15 minutes or less. Typically I am brewing 10+ gallon batches.