Author Topic: Immersion cooler thermal dynamics  (Read 11019 times)

Offline SleepySamSlim

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Immersion cooler thermal dynamics
« on: January 21, 2009, 06:31:03 PM »
Or How to get my wort to the right temperature ...

I just finished making an immersion cooler and will brew this weekend. I'm doing a partial boil with extract and specialty grains. I start with 3.5G and have about 3G after the boil and the whole leaf hops soak up water.

So the question is how far down do I cool my hot wort (still in the steel pot) before pouring it into the plastic fermenter AND topping off with 2 Gal of clean room temp water ?  With the goal of hitting that magic range of 79-75 degrees so I can quickly pitch the yeast.

Water has a high thermal capacity (ability to hold its temperature stable) --- so I'm thinking the wort in the kettle should be between 90 - 85 degrees --- pour & filter -- add 2 gallons of say 65 degree water and hit the magic range ??

Certainly you don't want to overshoot and hit 65 degrees.

Comments from the enlightened appreciated ... I'm just looking forward to reducing the whole brewing process down to a few hours and getting better beer for it.

Thanks
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #1 on: January 21, 2009, 06:39:36 PM »
Maybe this is a new function for BeerSmith  ;D

Of course wort is not water (different properties) this equation may get it close

http://dbhs.wvusd.k12.ca.us/webdocs/Thermochem/MixingWater.html

Thankfully my wife is a "math geek"  ... I'll get my calculator out
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #2 on: January 21, 2009, 07:01:05 PM »
Still looking

this may be better
http://74.125.113.132/search?q=cache:fDqzJ6ccKjQJ:www.olemiss.edu/projects/eisenhower/activities/docs/Heat/Thermal%2520Energy%2520Lab%25202.doc+water+thermal+mixing+calculator&hl=en&ct=clnk&cd=7&gl=us&client=firefox-a

   7. The relationship between temperature and volumes of a mixture of water can  be expressed as

   T1*V1 + T2V2= TfVf.  Describe this equation in words, if 1 is hot water and 2 is cold water.
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #3 on: January 21, 2009, 09:06:46 PM »
Ok - finished dinner - watched the news

using   T1*V1 + T2V2= TfVf    and solving for Tf

  Tf = (T1*V1 + T2*V2)/Vf
So assuming wort = 85deg    added water = 65deg

Tf = (85*3G + 65*2G)/5G
Tf=  (255 + 130)/5 =  385/5 = 77deg

Also checks out in metric ---- so thats really cool (sorry for the pun). Certainly the SG of wort will most likely make it retain more heat and be less influenced by water ... so the above result might be around 79 - 80-ish degrees

I would have done better in physics if we were solving critical problems like these ....
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #4 on: January 21, 2009, 09:08:06 PM »
Later I'll post opposing views to my thread for more balance .... :o
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SOGOAK

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Re: Immersion cooler thermal dynamics
« Reply #5 on: January 22, 2009, 06:28:11 AM »
I stick to KISS.  My floating brewers thermo moves slower than the wort temp so when I get to sub 90, I cut the water.  Then with 2 Gallons of top up, I get in the mid to upper 70s.  This will be subject to change soon when I hit all grain.

I DID over cool the first time-kid with a new toy.  That and pokey wyeast1214 had me in a panic.

Use science, also use touch, use the force...

OK sorry-not enough coffee :)
Good Recipe, Good Ingredients, Good Procedure, Good Sanitation = Good Brew.

Offline MaltLicker

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Re: Immersion cooler thermal dynamics
« Reply #6 on: January 22, 2009, 07:26:08 AM »
Looking at it from a different angle, many "experts" recommend cooling the wort to below 80F before pouring/splashing it IOT prevent any aeration while it is hot.  Aeration at this stage is believed by some to lead to oxidation issues later. 

And absolutely true is that the faster, colder you chill the wort, the better the "cold break" will be, maximizing the proteins and other junk you drop out, enhancing clarity, flavor, and preventing chill haze later. 

If I had to add top-off water myself, I would probably chill the wort colder for those benefits, and then use room-temp water to bring the entire batch to the desired pitch temp. 

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #7 on: January 22, 2009, 01:53:05 PM »
As a science junky and semi-retired engineer, I can't help but look at processes or the world in mathematical terms. Which also means doing a lot of experiments to prove or disprove your ideas/assumptions.

And as an engineer my approach always was KISS. So my gut assumption with what I know about liquids told me mid-80 degrees.

Finding the equation was interesting as it validated (more or less) my assumption. And SOGOAK's information on what he sees wraps all this up with a nice bow.

Of course, prior experience tells me the first time I use the chiller it will be a total comedy of errors. And life goes on ....
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline SOGOAK

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Re: Immersion cooler thermal dynamics
« Reply #8 on: January 22, 2009, 05:38:25 PM »
My 3rd or 4th time was interesting-my water in tube got into the flame, luckily it was too long anyway
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Offline UselessBrewing

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Re: Immersion cooler thermal dynamics
« Reply #9 on: January 23, 2009, 08:07:57 AM »
How did I miss this post!

SSS puts a whole new level on KISS.  Funny thing, I got out my old college books then dug through the internet to see if he was right. Guess What...

Besides my brain hurting, I still did not understand  :-[  LOL

Glad to have you SleepySamSlim. Beer Drinkers and Big Thinkers! Patent pending...

Cheers
Preston
The woodpecker pecks, Not to annoy, But to survive!

Offline MaltLicker

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Re: Immersion cooler thermal dynamics
« Reply #10 on: January 23, 2009, 08:38:37 AM »
SSS - when you do break in the wort chiller, it speeds cooling immensely to gently move the chiller in the wort.  I brewed twice in three days recently, so outside and water temps were fairly similar, and on the first batch agitation was zero then on the second batch agitation was nearly continuous.  It was about a 55F difference (140F versus 85F) with the agitation, both after 20 gallons of cold tap water thru the chiller. 

Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #11 on: January 23, 2009, 10:22:56 PM »
Maltlicker - Thats good to hear ! I love the brewing process --- but waiting for the wort to cool was a drag. Cold water baths - ice cubes in the sink -- repeat as needed.  Very much looking to better beer and better brewing.
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

Offline WaynesWorld

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Re: Immersion cooler thermal dynamics
« Reply #12 on: January 25, 2009, 06:46:05 AM »
This reminds me of the ol'  (Heat Lost = Heat Gained) .... :D

SSS - As a newbie I do not as yet use liquid yeast but rehydrate
my dried yeast.  Rather than just boiling a cup of water and letting it cool
to the rehydration temp for the yeast, I preboil a quantity of water so
that it is available for a myriad of uses, one being to elevate the wort temp if necessary (replaces the
evaporated and hop absorption volumes). I also start my fermentation pail out with 1.5 gallons of
refrigerated water which is stirred vigorously for aeration before wort is added to it helping to give the
little beasties their required O2 needs.
My question is this:  with the temp and volume formula you gave us above, would I
need to make two passes with it?  The first being for the cold and preboiled
temps and volumes, and the second being for this then adjusted temp&volume and the
actual wort temp&volume prior to adding to the fermentor?

Or do I add a T3 and a V3 making it
(T1*V1) + (T2*V2) + (T3*V3) = (Tf*Vf)

After reading John Palmer's book, "How to Brew", I do understand the need for
getting the wort to cold break under the 80F.  Like was mentioned also in
this thread, I too sat on pins and needles because I believe my first batches
were way too cool for the yeast to begin the fermentation process.
thank you for breaking this process down to a formula which assists myself in having
control instead of the process controlling me.
« Last Edit: January 25, 2009, 07:03:30 AM by WaynesWorld »

Offline SOGOAK

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Re: Immersion cooler thermal dynamics
« Reply #13 on: January 25, 2009, 07:15:42 PM »
I don't agitate-I'm clumsey!

I stir inside the coil which pushes the wort through the coil.  Same effect.

But as SSS will learn, the IC is one more "How did I live without THAT?" tool. 
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Offline SleepySamSlim

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Re: Immersion cooler thermal dynamics
« Reply #14 on: January 26, 2009, 11:45:32 PM »
WaynesWorld -- I don't know if you can just tag in a third liquid volume into that equation -- but if you have a thermometer and four containers you can do the experiment  ;D   As a note, on our first use of the IM cooler we were blown away at going from boiling to 85deg in 10 minutes. Then pour + strain into the primary added room temp filtered spring water and hit 76deg. Pretty much what the equation indicated. Its all good.

SOGOAK --- Tried the IM agitation ... too much work. Like you we just ran a sanitized spoon around inside the IM coils
Some people tell you the old walkin' blues ain't bad
Worst old feelin' that I've ever had ...
-Robert Johnson

 

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