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 Cajun_Tiger33 09-01-2012 04:12 AM

Counterflow wort chiller

I live in south Louisiana and our water here is around 75-80 degrees. I'm planning on building a CFC and I was wondering how long I should build it? Should I go with 25' or 30'?

 ChuckO 09-01-2012 11:53 AM

Because of the warmth of your water supply I would go with as large a one as you can. There is an inverse relationship between cooling ability and water flow rate while chilling. Therefore at any given cooling water flow rate the longer time the water and wort are in the chiller the greater the cooling effect. Since we are trying to cool as fast as possible, not cool with minimum water usage, a longer chiller will reduce cooling time.

I would look at the cost and decide based on that. Im going to start by saying I havent done any testing of this but based on my knowledge of thermodynamics (I have a degree in Engineering) I would say its not going to matter to much. While length does allow for more contact and thus more cooling, there is a limit to the effectiveness. There is an equation, which without getting to into detail, there are 3 variables which effect the heat transfer, the heat coefficient (how well the heat is transfered), the area of contact, and the difference in temp. This gives the transfer of heat per time. So difference in temp is set depending on water, so is the heat coefficient. The only variable which adding more length will change is the Area.

The problem with adding more length is the more length you have the less effective the length is. The first 5 feet is the most effective as the temp difference is the greatest, as you move through the chiller its gets less and less effective. So by the last 5 feet you arent getting much change. It gets a lot more complicated based on the method of heat transfer and time in contact, etc. But the based idea stays constant

Based on my experience the wort reaches an equilibrium temperature fairly quick in the chiller, slowing down the flow will help maximize the effectiveness of the length to make sure that the output of the water is as close to the temp of the wort as possible and adjusting as needed. There has been many discussion on this forum about the flow rate and length.

I would recommend just going with the 25', but thats just me and knowing that the extra 5' isnt adding much. If someone with more hands on experience has something different feel free to add to what I have said. Again I havent tested the difference but from my experience with my chiller thats what I would recommend,

Now to get the full bang for you buck on those 25' running the water through a pre-chiller submerged in ice water to lower the temp will give a greater cooling efficiency.

 Cajun_Tiger33 09-02-2012 01:53 AM

Quote:
 Originally Posted by Adeering Now to get the full bang for you buck on those 25' running the water through a pre-chiller submerged in ice water to lower the temp will give a greater cooling efficiency.
When you say pre chiller you mean basically coiling the garden hose up in a bucket of ice water before It enters the chiller?

Sorry I'm still a noob, I'm just trying to get all my stuff straight before I jump into this..

 RiverCityBrewer 09-02-2012 01:32 PM

The hose wouldn't get very good cooling transfer... a prechiller is basically just a small immersion chiller that sits in an ice bath that you run your hose water through on the way to the counter flow or plate chiller.

 eanmcnulty 09-02-2012 01:37 PM

Quote:
 Originally Posted by Cajun_Tiger33 When you say pre chiller you mean basically coiling the garden hose up in a bucket of ice water before It enters the chiller? Sorry I'm still a noob, I'm just trying to get all my stuff straight before I jump into this..
You would make the immersion pre-chiller out of a copper coil. That woulb be submerged in an ice bath.
Water hose to immersion pre-chiller to another hose to cfc.

 Misplaced_Canuck 09-02-2012 01:43 PM

Not that I've ever experimented that much with it, but I'd say that a POST-Reverse immersion chiller would be more efficient. In other words, when the wort comes out of the CFC, say at 80-85F, run that through another coil of copper inside a bucket with ice water. It seems silly to me [again, un-tested] to run a large amount of water through ice water instead of running the wort through it.

I use a therminator plate chiller that gets me from 200F+ down to 72F using 68F well water. I would venture to say that a CFC would get me to about 78-80F using the same water source.

I've done twin CFC's back to back, both with water in series and in parallel; the water in series, oddly enough, worked better by a few degrees.

MC

 E-Mursed 09-02-2012 03:17 PM

Quote:
 Originally Posted by RiverCityBrewer The hose wouldn't get very good cooling transfer... a prechiller is basically just a small immersion chiller that sits in an ice bath that you run your hose water through on the way to the counter flow or plate chiller.
This is what I do and it works like a charm.

I take my old IC and put it in a homer bucket with ice from the frig along with enough water to make an ice bath, then run that water to my CFWC. It gets my wort down to 60 degrees every time.

 eanmcnulty 09-02-2012 09:02 PM

Quote:
 Originally Posted by Misplaced_Canuck ...the wort comes out of the CFC, say at 80-85F, run that through another coil of copper inside a bucket with ice water. MC
This sounds like a great idea. The beer is only 80F at this point. Might work. I might try it.

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