aluminum immersion chiller

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dantodd

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Any significant disadvantage to using aluminum for an immersion chiller? It is about 1/3 the cost of copper tubing at OSH.
 
That's sort of what I was thinking. Since my kettle is aluminum too I'm sure you can guess where the aluminazis stand on my list...
 
You won't get as good of a heat transfer with aluminium than you would with copper, but if I were in your situation, I'd go for the aluminium tubing too.
 
eviltwinofjoni said:
You won't get as good of a heat transfer with aluminium than you would with copper, but if I were in your situation, I'd go for the aluminium tubing too.
INCORRECT! Stainless would be less efficient as a heat conductor, but aluminum is at least as good a heat conductor as copper, if not better.
 
Man I love google!

Aluminum, 136 BTU/(hr - ft - dF)
Copper 231 BTU/(hr - ft - dF)

I can easily put twice the aluminum for less than copper. I'm not sure if I really want 2X the tubing for the same cooling though. I also don't know exactly how much faster copper of the same length would cool the wort or how much more aluminum it takes to get similar results.

lots to think about....
 
Nice find! I guess I was slightly incorrect about aluminum being as efficient as copper. Even so, there's a reason they make aluminum radiators... The heat transfer potential also depends on the thickness of the tubing.
 
Yuri_Rage said:
INCORRECT! Stainless would be less efficient as a heat conductor, but aluminum is at least as good a heat conductor as copper, if not better.

Not sure if I'd say that... if that was the case wouldn't we see aluminum bottoms on expensive pots instead of copper? Not saying that I know this... just trying to follow the thought of the bottom of expensive pots thats all :)
 
Beer Snob said:
Not sure if I'd say that... if that was the case wouldn't we see aluminum bottoms on expensive pots instead of copper? Not saying that I know this... just trying to follow the thought of the bottom of expensive pots thats all :)
I already acknowledged my mistake, but a lot of expensive stainless pots have a sandwiched aluminum core for exactly the same reason.
 
Yuri_Rage said:
I already acknowledged my mistake, but a lot of expensive stainless pots have a sandwiched aluminum core for exactly the same reason.

Oh sorry. My bad. Did not read far enough down:)
 
well... stainless is around 8.

Aluminum is next best to copper but gold and silver are better than either.

I'm sure that both are adequate for chilling wort but I'm not sure if I want to spring for Silver! :D

here is the website: http://www.engineersedge.com/properties_of_metals.htm

I'm still thinking that $21 for 30 ft of aluminum is better than $30 for 15 feet of copper.

Maybe I'm being overly cheap, even though it's 50% that's only 10 bucks.
 
How easy is aluminum tubing to bend/coil? I have no idea. With twice the tubing you could do an outer coil and an inner coil to make sure it all fits in your pot (and hopefully doesn't displace too much wort).

Edit: I mean bend/coil without crimping it.
 
Baron von BeeGee said:
How easy is aluminum tubing to bend/coil? I have no idea. With twice the tubing you could do an outer coil and an inner coil to make sure it all fits in your pot (and hopefully doesn't displace too much wort).

Edit: I mean bend/coil without crimping it.
Ok, this I DO know for a fact. Aluminum fuel line is REALLY easy to form. Easier than copper, even.
 
The coils at OSH were about the same shape/size as the copper and seemed just as easy to work.

On the topic of wort chillers, I know that you want the feed to be cold in the top and hot out the bottom but if I make 2 concentric coils is it best to alternate coils, one inside, one outside or just make them serially? If serially should the cold water go in the inside or outside coil?
 
The only common metal that is a better heat conductor than copper is silver, and it is impractical for use in wort chiller tubing due to rapid oxidation and high cost. Below copper in terms of heat conductivity is gold, then aluminum. Stainless Steel is way down the list, although not as bad as mercury. Of course, it's kinda hard to make tubing out of a metal that is liquid at room temperature anyway.

So if copper is not an option, then aluminum would be a better choice than stainless steel, at least from the perspective of heat conductivity.
 
Yuri_Rage said:
Nice find! I guess I was slightly incorrect about aluminum being as efficient as copper. Even so, there's a reason they make aluminum radiators... The heat transfer potential also depends on the thickness of the tubing.


They use aluminum for radiators because they can form larger, thinner tubes with it, which allows for more heat transfer in a given area. But more important, it weighs less than copper or brass. Oh, and it's cheaper.
 
dantodd said:
well... stainless is around 8.

Aluminum is next best to copper but gold and silver are better than either.

Doh, I misread the article I posted, as beer4breakfast said copper is better than gold at thermal conductivity.
 
Yuri_Rage said:
... The heat transfer potential also depends on the thickness of the tubing.

I think what you mean here is that the thickness of the tubing has an impact on the efficiency of the heat exchanger right? This would be because the thicker tubing takes longer to change temperature. The thermal resistance of most common metals is practically zero. Tube wall thicknesses in any heat exchanger (wort chiller) that a homebrewer might build are probably only detectable with laboratory equipment.
 
So, not being a materials guy (AT ALL) I have to ask.

What is the difference between thermal conductivity (i.e. the data in the link I posted above) and thermal resistance?
 
dantodd said:
So, not being a materials guy (AT ALL) I have to ask.

What is the difference between thermal conductivity (i.e. the data in the link I posted above) and thermal resistance?
Thermal resistivity is the reciprocal of thermal conductance, i.e., the higher the conductivity, the lower the resistance.
 
That is what I would have thought knowing a little more about how holes flow than heat. If that is the case, Rocket's statement seems contrary to the data posted.
 
I was really referring to the statement about tube wall thickness, which for realistic values does not have a measurable impact on heat exchanger (wort chiller) efficiency. Reading it in the afternoon, it isn't exactly a clear statement. I shouldn't post in the mornings.:)

In the case of a home built wort chiller, I think there are two significant factors (from an analysis point of view):
1) Convective heat transfer coefficients
For the homebrewer, this really means flowrate. What is the flow rate of the hot wort through the exchanger and what is the flowrate of the cooling fluid? I won't get into the math, but the convective heat transfer coefficient is related to the flowrate. The wort's flowrate should be lower than the cooling water's flow rate.

2) Tube material thermal conductivity
This is important, but for decent materials, not as important as proper flow rates. There is only one term in the overall heat transfer coefficient that depends on thermal conductivity.

These two parameters are related to the minimum length needed to achieve the change in temperature required. Hmm... I should try to get the calculations together for a few heat exchanger types and post them.

A counter-flow heat exchanger is probably the most efficient that a homebrewer could build. Some kind of plate heat exchanger might be more efficient, but it would not be very practical to build.

Ugh, back to copper vs. aluminum. The thermal conductivity for copper is about 385 and about 210 W/m^2*K for aluminum. This is a % difference of about 45%. I don't know what average tube thicknesses are, but if it's possible, you could use aluminum tubing that's 45% less thick than the copper. Unfortunately, I doubt you could bend it.

I'm sure this post is less than clear as well. I should sleep at night.
 
well, we are talking about an immersion chiller so, while less efficient than a CFC the conductivity differential should (assuming same or similar wall thickness) be overcome by a longer chiller. Since aluminum is 45% (I didn't check the math so...) less efficient but 1/3 the cost it seems a wise choice to build out of aluminum assuming it won't give you Alzheimer's and the chiller will still fit in the brew kettle effectively.

I think the point beer4breakfast was making is that stainless would be a bad choice since it's conductivity is in the single digits.
 
Hi Tom,

Can you point me to a source that discusses the brittleness of Aluminum in these temperature ranges? I looked on Google but most of those sources list aluminum as relatively non-brittle.
 
You can get 25' of 3/8" aluminum fuel line at www.jegs.com for $15.99. From experience, this bends easily by hand. I'm tempted to make one of these just to prove that it works. The massive speculation seems a bit unnecessary. Thin tube, be it copper or aluminum, is quite conductive, very malleable, and should work pretty well.

EDIT: To answer the brittleness question - the aluminum line I've worked with is very easy to bend (down to about a 3" radius) without kinking or cracking. Metal only becomes more malleable at higher temperatures, so I don't think you have anything to worry about.
 
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