Co2 Wort Chiller

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Chilkoot

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I've been doing a little lurking, and the preferred method of wort chilling seems to be running cold water through length of copper pipe, taking about 15 minutes. While this certainly works, it seems to me that Co2 would be a much faster cooling medium.

The idea would be nearly identical to a standard wort chiller, except instead of connecting the chiller up to a faucet or fountain pump you hook up a bottle filled with liquid Co2, either a scuba or the 4 - 20oz varieties used with paintball guns. The phase change from a liquid to a gas requires a lot of energy, and as it runs through the copper pipe the conversion will reduce the pipe's temperature drastically and nearly instantly. It seems to me with a quick enough bleed you could get the wort to room temperature in MUCH less than 15 minutes.

anyone play paintball? those tanks can ice over in 90 degree heat from bleeding for a few seconds, expanding liquid co2 soaks up a lot of heat. Any volunteers want to try running liquid co2 through their wort chiller in a 3gal pot of boiling water to see if it soaks up enough heat to be a viable alternative?

Possible advantages could be a faster cold break, cleanliness (read: no superhot waste water or potential for spilling) and simplicity (self-contained bottle of self-propelled co2 vs. bucket of ice water/pump) and the negation of tap water temperature.

Apologies if it's a stupid question that's been discussed before, I didn't see anything when I searched.
 
Just to play the other side of this, here's some problems I see with that:

First and foremost, co2 is expensive compared to water. I get my 5lb tank filled for $13, running it open for 5 minutes would probably empty it let alone 10 or 15.

Next, that 5lb tank has no liquid co2 in it... it's all gas. Room temp needs about 870psi(wikipedia). My tank is sitting about 500psi.

The paint ball tanks would be in no way sufficient, way to little volume.

If you could re-use the co2, like re-pressurize it back into the bottle, I see this as an awesome idea.
 
I was totally with you until you said

z987k said:
Next, that 5lb tank has no liquid co2 in it... it's all gas.

It's mostly liquid except for a small amount of gas in the headspace. Once you get it up to a certain PSI, it changes to a liquid. That's why donor bottles for filling either sit upside down or use a dip tube so that the liquid flows into the bottle you're filling.

I still agree that dumping CO2 is a bad idea. It's expensive not only in pure materials cost but also having to keep driving to get fills. Then there's the environmental concern about needlessly evacuating CO2 into the atmosphere.
 
It could work.
Road racers use CO2 tanks for the same purpose.

CO2 is a refrigerant. When the liquid boils to gas, it absorbs lots of heat, so road racers run lines from the co2 tank, and wrap them around there fuel lines to chill the fuel. Basically what you are building by attaching the co2 tank to the wort chiller is HALF of an air conditioner (the expansion coil).

The problem with the above system is you would need a special co2 tank called a SIPHON TANK. You want the liquid to flash into gas IN THE CHILLER, and NOT THE TANK. This is critical for it to work correctly. Or you could hold the 20oz tank UPSIDE DOWN to get the same effort.

EDIT: However, I suspect that if the wort is some circulating, it will freeze whatever is touching the copper tubing, and then insulate it from the hot wort. Still a good idea though. If it insulates the siphon, then it might also prevent the liquid from flashes until it actually exits the copper tubes, minimizes the useful energy.
 
siphon tubes can be installed into a Co2 tank for ~$20, it only requires removal of the valve, and it's always stored as a liquid inside the tanks.

I was thinking it'd take maybe 16oz. to cool 3 gallons bleeding over just a couple of minutes, averaging about $2 in Co2 per batch, but i base this on nothing and it could very well be way off. Either I'm being stupidly optimistic about the expansion characteristics of liquid co2 or z is being unnecessarily pessimistic. it will take some testing, but I won't be able to brew until August when I get my loft so I was hoping someone would be curious enough to do some testing with water.

I think some of you might be surprised how much heat 16oz. of liquid Co2 can soak up.

As for environmental concern...I think it's a non-issue provided you aren't bleeding bulk tanks daily.

If there are issues with freezing the line or it not completely expanding in the tubing, you could just slow the bleed.
 
I think that if this were a cost effective way to chill, the big boys would be doing it already. Since buying CO2 in huge tanks is very cheap compared to what we pay, it would seem even more likely. Water is what, a penny a gallon? I use about 30 gallons of coolant for $.30.

I think 16oz is optimistic. I think you'd have to dump a 5lb tank minimum, and I think it would only be effective for a counterflow or plate chiller though unless you had a wicked whirlpool going for an IC.

Testing this out is right up my alley but I don't have a way of connecting my chiller directly to the tank valve.
 
Bobby_M said:
I think that if this were a cost effective way to chill, the big boys would be doing it already. Since buying CO2 in huge tanks is very cheap compared to what we pay, it would seem even more likely.

The simplest answer is usually the right one.

I'll try it out when I get my brew closet set up in August, but I suppose I should tone down the high hopes.
 
As HP points out, most of the cooling occurs where the liquid flashes to gas. To get liquid CO2 into the wort will require lines that can handle full tank pressure. Thicker walls means higher costs and lower heat transfer. Using water is so easy & cheap, why bother? If you capture the first five gallons or so, you have hot cleanup water at no extra cost.
 
Bobby_M said:
I was totally with you until you said



It's mostly liquid except for a small amount of gas in the headspace. Once you get it up to a certain PSI, it changes to a liquid. That's why donor bottles for filling either sit upside down or use a dip tube so that the liquid flows into the bottle you're filling.

I still agree that dumping CO2 is a bad idea. It's expensive not only in pure materials cost but also having to keep driving to get fills. Then there's the environmental concern about needlessly evacuating CO2 into the atmosphere.

I was going off of what I read on the wiki. I thought about it, then looked it up and then went and looked at my tank (jut filled), and it's right at 500psi at ~40F. It just says room temp (70s?) and 870psi. I figured 370psi was more than the 30F temp difference and would make it all gas.

Chilkoot, not trying to be overly pessimistic, just trying to point out the flaws I see, so maybe they can be corrected if this is a viable form of chilling.
 
I was thinking about doing the same thing with an air compressor a while back, it never actually panned out, the temperature change would have worked and all, but there is a lot of pressure variables to deal with and no guaranteed payoff after investing all that time and money
 
My CO2 tank has ~800 PSI when full at 70 degrees or so but will drop to 500-600 ish at fridge temps. The CO2 in the bottles is liquefied or you'd only have a very small amount of CO2 to work with.
 
The state of Co2 (gas, liquid, solid) is dependent both on temperature and pressure. You can make it turn to liquid by dropping the temp or raising the pressure or both. Check out this triple point diagram showing the various phases on the temp/pressure scale. http://upload.wikimedia.org/wikiped...ioxide_pressure-temperature_phase_diagram.jpg

The line that separates liquid and gas not only dictates the gaseous pressure created in the tank given a fixed temp, but also dictates how much pressure at a given temp it takes to liquify co2.

Kelvin and Bar is not something we non scientists can grasp but 295K is 71F and 80bar is 1160psi.
 
I have two 15lb bottles of nitrous I can hook up and give it a try... now I can link my motorsports and brewing hobbies in a safer way than Smokey and the Bandit!


Someone send me a wort chiller :p
 
A common mistake showing up here is confusing temperature with energy.....just because something is really cold, doesn't mean it can absorb a lot of heat. In this case, water contains a lot more energy per degree than CO2...and once you get past the phase change, it doesn't take much energy to quickly raise the temp of the co2.

Good example....put some dry ice in a bowl of room temp water (like you'd do for the 'fog effect'), even though the dry ice is quite cold....it takes a fair chunk to significantly drop the temp of the water.
 
The basic point is that CO2 is self regulating. This means that the pressure in a co2 tank will remain around 800psi as long as there is some liquid co2 in the tank.

A 5lb tank holds 5 pounds of liquid co2.

If you hooked the siphon tank to your immersion chiller, then tubing would not have to be rated for 800psi, since it is simply venting to atmosphere. The danger would be if the tubing is restrictive enough that the pressure spikes faster then it can vent.

Here is an example of the frosting technique. This paintgun is hooked to a 20oz SIPHON tank. When the gun fires, liquid co2 enters the barrel, and flashes to vapor. This process absorbs heat, and makes the barrel frosty:
frozen.jpg


Certaintly it would cool the wort some amount. The only issue is how to quantify it. Is a 20oz tank (like in the picture) enough to rapidly chill 5 gallons of 200 degree wort down to 70 degrees? I don't really think so. Maybe a 5lb tank with sufficient swirling though.
 
Bobby_M said:
The state of Co2 (gas, liquid, solid) is dependent both on temperature and pressure. You can make it turn to liquid by dropping the temp or raising the pressure or both. Check out this triple point diagram showing the various phases on the temp/pressure scale. http://upload.wikimedia.org/wikiped...ioxide_pressure-temperature_phase_diagram.jpg

The line that separates liquid and gas not only dictates the gaseous pressure created in the tank given a fixed temp, but also dictates how much pressure at a given temp it takes to liquify co2.

Kelvin and Bar is not something we non scientists can grasp but 295K is 71F and 80bar is 1160psi.

Right, and I was looking at that trying to figure it out, but I was like damn it Kelvin and bar, wtf is that, and didn't want to bother googling for a conversion.

But basically that is saying co2 will be liquid above ~80bar(1,160psi) and within any temperatures we're dealing with. Just trying to figure out where 500psi(34bar) and 40F(277K) fall since the pressure scale is weird (10-100 = 100-1000). I think it's right there on the line.
 
you're right about co2 being a liquid under pressure, but it's the pressure that is keeping it a liquid. with the temperatures we're dealing with it is naturally a gas.

I was counting on the phase change to be the cooling mechanism, not necessarily its low temperature. Of course, as already stated by others, you would need to ensure you were feeding liquid co2 directly into the copper tubing, but seeing as it's only co2 if you were to ensure that it was completely gaseous by the time it reached the end of the tube you could have it vent at the bottom of your wort and the co2 bubbles would naturally mix it, unless there's a sanitation issue i'm not seeing. (edit: this is actually a really bad idea, it would get a little bit messy with the amount of gas we're talking about. nevermind)

A nitrous supply would not have the same effect. The gas expansion would cause minor chilling of the bottle, but would not be at all viable because no phase change takes place.

Even if it took 2.5lbs of co2 to cool a batch of wort, would the $5 expense be worth it if you could flash-chill the wort? is there anything to be gained by cold-shocking it faster than immersion chillers are capable of?
 
wouldn't dropping blocks of solid co2 be just as effective, and there's no clean up there. No equipment or anything.
 
if by that you mean dry ice, I don't think so. The liquid->gas phase change is the key, and dry ice will go straight from a solid to a gas.
 
I would expect that in the long term given the cost of CO2 and the trouble of re-filling. It would be cheaper in comparison to just rig a refridgeration coil using a food grade glycol system.
 
Chilkoot said:
Even if it took 2.5lbs of co2 to cool a batch of wort, would the $5 expense be worth it if you could flash-chill the wort? is there anything to be gained by cold-shocking it faster than immersion chillers are capable of?

My point was it's gonna take a lot more than 2.5 lbs of co2 to cool a 5 gallon batch...

If you run the math, it works out to about 10-15lbs of co2 to cool a 5gal batch from 212F to 65F, assuming you get high efficiencies (these numbers were based off dry ice....but the numbers aren't that much different)

Open loop systems just aren't efficient enough for this type of cooling.
 
Glycol would work alot better. Simply make a chiller reservoir and pump the chilled glycol through the copper lines. It wouldn't take much and reusable glycol is relatively inexpensive. The reservoir could be an aluminum box in an ice chest, using a pond pump to recirc.


Problems?

:drunk:
 
Is waiting 15 minutes for a regular immersion chiller such a terrible thing?

I make good use of those 15 minutes...sanitation of my racking equipment and fermenter, putting away my propane tank, general cleanup. Seems like once I'm ready to rack, the wort has cooled sufficiently and everything works out great.
 
This comment may be a little late in coming but I wanted to add my 2 cents.
Anyway I think this might be a viable idea for the brewer that has everything,
but why not go a step further and hook up an actual refrigerant line to the setup.
Counterflow refrigerant thru heat exchanger in an evaporater. get a glycol unit have it pull double duty, wort chiller and conical chilling all thru heat exch. of course. Check out Integrated Marine Systems fish hold refer.

One more silly note co2 is heavier than air and will suffocate you in your confined spaces.
 
Chilkoot said:
if by that you mean dry ice, I don't think so. The liquid->gas phase change is the key, and dry ice will go straight from a solid to a gas.

The heat of sublimation is greater then the heat of vaporisation. Thou its easier to pump the liquid. It takes 574 joules per gram to vaporize co2 @ -78c, and 184 j/g to melt it, its heat capacity as a gas 28.2 joule per mole kelvin or 0.64 joule per gram kelvin. Say we had 1kg of liquid co2, neglecting the heat change before boiling. We get 574kJ of energy to vaporize and then the heating from -78c to 100c(boiling water) is 113.9kJ . For a total of 688kJ of heat absorb by 1kg of CO2.

Water has a heat capacity of about 4.4kj per kg kelvin. Assume a 20L brew(5gal ish) is about 20kg of water. Need 80.8kJ/C, the 688kJ of cooling from the CO2 would provide about 7.8 deg Celsius(or kelvin).

One kilogram of water from a prechiller ariving at 0 deg C and going to 100 deg C on exit would Use 440kJ. If any of that water changed into steam it would consume 2260kJ/kG.

Best results would be to use a water based coolant on a recirculation and dry ice to chill the coolant.

But water is cheap, easy to use and gives good results. The main problem is in the heat exchanger from hot wort to cooling fluid.
 
Yeah basically what Salzar is saying above is you would need around 10kg of Co2 to cool 5 gallons of wort. When I was in college I had a job in an engineering research lab, we have liquid nitrogen on tap, and would frequently use it to chill down beers when working at night, now N2 is much colder than Co2 in a liquid state, (Co2 does not really exist at a liquid unless it is under pressue).

However it would take around 12fl oz of Liquid nitrogen to chill one beer, water holds or absorbs a lot of heat (latent heat for phase change or specific heat for same phase temperature changes). Much more than many other common materials. That is why it is such a good fluid to use for heat transfer.

Putting your hand in steam will often burn you, but putting your hand in the same mass of vapor of boiling n2 or co2 will most likely not freeze you even though the temperature extremes are greater on our bodies.
 
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