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-   -   Counterflow/immersion wort chiller (http://www.homebrewtalk.com/f51/counterflow-immersion-wort-chiller-35816/)

SenorWanderer 08-08-2007 12:45 AM

Counterflow/immersion wort chiller
 
hello everyone,

I've been trolling around for a bit and I have a question that I can't seem to find an answer for.

After a few batches of very basic all extract brews, I can no longer fight the pull of my DIY nature. my first project is a wort chiller. a counterflow design seems easy enough and I've seen many versions all over the internet. every design I've seen so far has the wort flowing through the inner pipe, and the coolant flowing in the outer pipe. am i wrong in presuming that the wort would cool faster if it was flowing through the outer pipe, so that it's spread thinner and is being cooled by two different surfaces, the inside pipe with the coolant as well as the air temperature on the outside. is there a design flaw here that i'm missing?

Secondly, if this design is viable, why not incorporate an immersion along with the counterflow. The design I'm envisioning is an all copper counterflow chiller that is built into a 5 gal bucket. coolant and hot wort go in the top as usual, and exit on the side of the bucket at the bottom. the bucket is filled with ice water. in the end you have a thin spiral cylinder of hot wort being cooled on both sides.

please explain why this will or will not work!!

kladue 08-08-2007 03:43 AM

Without trying to get too technical here are the main points for heat exchange

Surface area of tubing
Wall thickness
Thermal conductivity of tubing material
Flow rate
Turbulence of flow
Difference in temperatures
Thermal conductivity of coolant

Most of the counterflow chillers use 3/8"-1/2" tubing to keep the flow turbulent enough to enable efficient heat transfer through the tubing. Water as a coolant is able to conduct the heat away from the outside surface of the tubing much more efficiently than air. Passing the wort through the inside of the tubing is much easier to clean and sanitize as the inside is relatively smooth and not likely to trap particles which would provide a home for bacteria. Copper tubing counducts heat much better than the 300 series stainless alloys, so copper chillers can be made with as little as 10' of tubing and still work well with 55 degree cooling water.

bradsul 08-08-2007 04:07 AM

I think sanitation would be the biggest reason not to flow wort through the outer pipe rather than the inner one. My outer pipe always has water left in it when I'm done. Just because of the way the junction of the pipes are designed it's impossible to get it all out. I'm not sure that the large risk of infection would be worth the savings in minutes you may get.

fifelee 08-08-2007 08:07 AM

Very interesting ideas. Your design would cool very well, but there are things to consider other than just cooling rate. With a garden hose counterflow I wouldn't want my wort touching the rubber hose. Rubber flavored beer just doesn't sound that good. B3 sells an all copper counter flow chiller, but you would still have the infection issue Bradsul mentioned. That issue could be solved if you bake it in an oven to sanitize, but then you have added a big hassle to your brew day. Plus with all that copper they are pricey. That is why I love immersion chillers. You don't even have to really clean them if you don't want. Just drop them into the boil and go.

FSR402 08-08-2007 11:17 AM

What I have for a CFC I did not build and have yet to use so I can't really say if it's good or not. But the guy I bought it from (along with all his other brew gear) said that it dropped his temp from boil to 70* in one pass thru.
All it is made of is a 4" PVC pipe about 2 feet long with end caps glued on. The inside has a 3/8 id copper tubing that is coiled the whole length of the pipe and sticking out each end. There is also one water port glued into the end caps (both ends). Tap water is run thru the pvc pipe and wort thru the copper tubing. He said that he gravity feed it and it worked great.
I'll let you know how well it works this weekend. I will need to use it, my IC is not big enough for a 10 gallon batch. :rockin:

SenorWanderer 08-09-2007 01:13 AM

Thanks for the replies everyone. The thought of wort getting stuck everywhere the two pipes meet inside the coil did cross my mind, but i figured running boiling water through behind the wort would clean that up well. do you think it's not to safe sanitation-wise to think that?

FSR402, i have seen pictures of the chiller you're describing somewhere along the way. one thought i had along those lines is a single coil integrated into a 5 gal bucket. if that design can achieve pitching temps or colder in one pass through then why get complicated! I'm looking forward to hearing how well your chiller works this weekend.

FSR402 08-09-2007 02:21 AM

Quote:

Originally Posted by SenorWanderer
Thanks for the replies everyone. The thought of wort getting stuck everywhere the two pipes meet inside the coil did cross my mind, but i figured running boiling water through behind the wort would clean that up well. do you think it's not to safe sanitation-wise to think that?

FSR402, i have seen pictures of the chiller you're describing somewhere along the way. one thought i had along those lines is a single coil integrated into a 5 gal bucket. if that design can achieve pitching temps or colder in one pass through then why get complicated! I'm looking forward to hearing how well your chiller works this weekend.

I will let you know tomorrow night. I got all my stuff together tonight to be able to use it. Then I built an "arm" off my brew tower to hold it with it hooked up to my brew pot and the other end dumping right into a 6.5 gal carboy.
it got late so tomorrow night I'm going to boil up 5 gallons and send it on tru to see what the temps do. It's not going to be exactly the same as wort but close..

Oh and a lot of people bitch about how much water they use with an IC, well what I have done was put garden hose fitings on bothe ends. The hose going in will feed the chiller, the hose going out will feed a sprinkler. God knows my grass needs the water. :D

FSR402 08-10-2007 02:17 AM

Well it did not work out as well as I hoped it would.
I boiled up 5 gallons of water, I actually shut the flame off at 218*, turned on the water and and opened the ball valve. I had to have it as slow as it would go and still flow. At the end of 30 minutes it had drained out about 4 gallons and was at 90*. Yeah you "can" pitch at that but I don't like to. I want it down to 70*.

The guy had the right idea but he just did not build it right.
I popped one of the caps off to have a look at how it was built and no wonder why it was not getting low enough. He had only about 6 feet of copper tubing in there. It went in and to the other end, turned and back to the start, turned again and out the other end.
I think had he taken at least 12 - 15 feet of the tubing and coiled it tru the pvc it would have worked slick.

Looks like I will be using my IC this weekend and just taking longer to get the temp down. I will rebuild this CFC the right way or I will just build a new one later.

FSR402 08-11-2007 02:48 PM

Ok first I have to say.... "I'm an idiot".....

I was on my way into work this morning and thinking about my brew day today and tomorrow. I got to thinking about this chiller that I tried and found it not to work well enough. This is where I figured out that I'm an idiot.
I had my garden hose hooked up to the same end as the beer "in" side. Thus, my coldest water was hitting my hotest brew. :drunk: Dumb, Dumb, Dumb.... I think this thing will work great if I hooked it up the other way.. But now I don't have time to "test" it for today's brew, plus clean it and sanitize it. I just have to much other stuff to do..
Maybe I can test it after I'm done brewing, if I have time.

killian 08-11-2007 03:07 PM

fsr402 are you using your immersion chiller at the same time?


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