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Compressed air chiller to cool

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Donasay

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Hey everyone I was thinking, the other day that the air that comes out of my air compressor is pretty cold, due to the gas expansion and thermal properties and all. What if I hooked the compressor up to my immersion chiller and blasted the freezing cold air through the chiller to cool the metal and thus cool the beer? Anyone have any experience rigging something like this up?

The thermodynamic properties of air make it a less efficent conductor of heat than water. But the air sometimes comes out of the compressor at very cold temperatures, sometimes below freezing. Perhaps if I tried it out with a longer section of copper pipe. Also are there any dangers I need to worry about such as hot air blowing out through the outlet tube?
 

Funkenjaeger

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I'd say a possible first step would be back-of-the-envelope calculations for how much air you're going to need based on how long it takes to drain wort through the chiller, and how high of a flow rate you need to maintain to keep the air cold enough. My guess is that you would need a very high flow rate of air to achieve the same cooling rate as even a slow flow of cool water. So you'd either need a huge compressor, or a huge tank of air to begin with.

Offhand, I'd guess that it's going to be rather impractical... But I think that trying to run the calculations to determine its feasibility would be pretty complicated as well. If you're determined to find out, I'd say a simple experiment with your compressor, chiller, a pot of boiling water, a thermometer, and a stopwatch is probably in order - you can run it for a few minutes and then compare it against the same scenario with water instead of air.
 

jcb317

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Off the top of my head i'd say that the temp fluctuation due to pressure drop from say 90psi - 0psi wont happen until the air exits your cooler. The pressure gradient through the pipe will be small in comparison. Kind of like how pressure is lost in your keg's beer out line. If you had 0psi anywhere in your line you would have no flow since nature dictates flow direction goes from high to low pressure. In air conditioners where they use the freon for this effect the compressed gas is pushed through a very small 'pin-hole' to get a larger pressure gradient.
 

balto charlie

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Bobby_M said:
Run it through a prechiller immersed in liquid nitrogen. First get some liquid nitrogen...
FUnny you should mention LN. I have been thinking about it lately. In the lab where I work we have a few160L tanks of the stuff. I can be very dangerous if you don't know what you're doing w/ it. It goes from a liquid to a gas quickly at RT. I have been trying to think of a way to harness its -196 degree C into a wort chiller. I thought placing thick hunks of sanitized metal(CU, AL,SS) into a container of LN then after they reach equilibriurm placing them into the wort. I better wear goggles!!
 

kinison_fan

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Another couple practial issues-

-How long will your compressor run before shutting down? (i.e. the motor is overheating).
-If water will cool a batch in 20-30 minutes, how long would less efficient cold air take?
-Depending how far away your compressor is, you'll go deaf (longterm), unless you wear ear plugs...

Just so I'm not being all negative-kudos for thinking out of the box for a new approach to an "old" problem.
 

z987k

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while we're at it, just go buy some solid co2 and drop them in the hot wort.
 
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