Glycol chiller build

I am thinking of building a glycol chiller and would like to see if I am missing something. I want to use it for chilling a plastic conical fermenter using stainless tubing coiled inside and a pump hooked to a PID. I also plan on using it with a plate chiller for cooling down hot wort after brewing.

I have a "spare" small chest freezer and I was planning on using a 5 or 10 gallon bucket filled with glycol. This would then get plumbed to the coil as well as an outlet with a ball valve that will connect to a plate chiller when I brew. Depending on the time to "re-chill the glycol, I may have it go through a copper or stainless coil in the freezer before ending up back in the bucket. I could even hook up a fan to blow cold air on the coil to help the "re-chill process.

There are obviously a few details to be worked out, but in principal, am I missing something?

I don't think you will get it to re-chill very fast unless you have some sort of heat exchanger in close contact to the cooling coils. But the thing with glycol is you can chill it way down to like 25ºF, so it will be able to cool faster in the first pass.

Though I think most people who build Glycol chillers like you are talking about are used for controlling fermentation temps.

FYI. this is for sale down here in SD, might be worth a trip down here if you can talk him down...

http://sandiego.craigslist.org/csd/bfs/2553199925.html

Weighing in -

I've got a 5 gallon tank of glycol sitting in my kegerator (about 39ºF) that I pump over into my fermentation tank (water bath) on demand. Works great, I easily ferment at 62ºF but it didn't work until I got the glycol volume up to 5 gal.

Using glycol for the cooling of hot wort would probably require 50 gallons at 0ºF - that's totally a stab in the dark, but I'm not inclined to do the math... Consider, however, that the temp of the glycol will rise considerably - you'll have HOT glycol coming out of the plate chiller, adversely impacting the reservoir.

From what I'm reading the re-chill is the big problem here. I am wondering it I spend some effort putting a fan behind a copper coil both before the freezer and in the freezer if it might do the trick.

I looked at the craigslist find and it might do the trick. And it is 1 phase 120v power so I can just plug it in.

Glycol systems normally use a direct-contact heat exchanger with the freon system of the refrigeration unit (the glycol line is INSIDE the cold side freon). So using a cold-air-only exchanger would be quite inefficient.

For what it's worth... 10 gallon batch at near 212F would require roughly 40 gallons of glycol at 32F to get it down to pitching (70F) temperature.

The brewpub I briefly worked at used a double heat exchanger: First step was city water, and second step was glycol.

Formula is:

(X gallons * 32F glycol) + (Y gallons of beer * 212F) / (X+Y) = final temp

1gal @ 32 + 10gal@212 = 2152deg-gal = 11gal@ 195F
10gal @32 + 10gal @212 = 2420deg-gal/20 gal = 121F
20gal @32 + 10gal @212 = 2760/30gal = 92F
30gal @32 + 10gal @212 = 3080/40 = 77F
40gal @32 + 10gal @212 = 3400/50 = 68F

This doesn't take into consideration friction loss, the thermal mass of the sugars dissolved in the beer, and especially, the time it would take for all of it to balance out! When you get to a 10 degree difference, the cooling speed is abysmal.

M_C

No matter what, the freezer was never designed to remove heat as fast as you'd ask it to in a wort chilling operation. The best you can hope for is cooling in a single run based on a long term chill of a higher volume of coolant. The freezer can certainly cool 15 gallons of room temp glycol down to 15F, it will just take a few hours.

What you'd want to do is run it through your plate chiller and then collect it in a separate tank rather than back into the cold tank. The other thing is that it's not just an averaging of temps but the heat capacity plays in. Dense wort has more heat capacity than water, water has more heat capacity than a mixture of water/glycol. The only practical reason to use glycol is to get it lower than 32F without freezing which is not only practical for cooling but also required if you don't plan to put an external controller on the freezer. From some quick googling, chest freezers run -20F (ish) but I'll call it -10F for the examples.

Something like this:
gallons coolant/cool temp F/gallons wort/wort temp F/final temp


5 -10 5 212 101
10 -10 5 212 64
10 -10 10 212 101
15 -10 10 212 78.8
20 -10 10 212 64


I'd still add a few degrees for the heat capacity difference but I think twice as much glycol as wort is enough.

Edit: http://www.engineeringtoolbox.com/propylene-glycol-d_363.html

It looks like a 50% glycol by volume will not freeze at -20. Your connection tubing is going to sweat like a pig through and you better run the wort through the chiller fast enough to keep it from freezing up.

50% solution has a specific heat of .85 which I THINK means it's 15% less effective than water. I'm too stupid to know how to apply that to the table above. On the wort side, I think it's probably tied to specific gravity in some way. For example, a 1.06 wort gravity probably holds 6% more heat than water would. If these are correct assumptions:

gallons coolant cool temp coolant SG gallons wort wort temp wort SG final temp
without SGs considered:
5 -10 0.85 5 212 1.06 101
10 -10 0.85 5 212 1.06 64
10 -10 0.85 10 212 1.06 101
15 -10 0.85 10 212 1.06 78.8
20 -10 0.85 10 212 1.06 64
With Specific Gravities considered:
5 -10 0.85 5 212 1.06 108.11
10 -10 0.85 5 212 1.06 69.24
10 -10 0.85 10 212 1.06 108.11
15 -10 0.85 10 212 1.06 84.788
20 -10 0.85 10 212 1.06 69.24

What about making a 50' x 1/2" copper coil for the return, then place that coil into a 5 or 10 gallon bucket. Fill the bucket with water and place it into the freezer next to the glycol bucket?

You'll run the glycol @ ~32F to the plate chiller then from the plate chiller into a chiller coil that's sitting inside a block of ice before going back to the glycol reservoir. 50' of frozen copper should get those temps down considerably.

I'm just guessing though... simply an idea.

32F glycol is counterproductive. Less heat capacity than water.

I'm planning to build a glycol chiller like this. It's still quite slow, but in SoCal I have to watch my water usage, and in summer the water doesn't get cold enough.

I think with any tank based coolant system, the real key is to not dilute the cold coolant with spent/warmed coolant until the operation is complete. Collecting in buckets is easy enough and it will reduce the overall amount of coolant you need to prechill.

JohnTheBrewist said:

I'm planning to build a glycol chiller like this. It's still quite slow, but in SoCal I have to watch my water usage, and in summer the water doesn't get cold enough.

Click to expand...

I built one similar to that for a local brewery to control fermentation temps. As long as your batch sizes aren't too big, and you aren't too worried about flow rates, it should work well.

For reference, here's how the numbers work out:

For a 10 gallon batch going from 212 to 70 you are looking at removing around 12,000 btu's of heat, so the chiller by itself could cool it down in probably 1.5 hrs (assuming some effeciency losses) By running the chiller ahead of time and cooling down the glycol, you'll reduce the total time needed.

I thought about having two separate chambers for supply of glycol (cold) and return of glycol (hot). I am just not sure about volume needed to chill 5 gallons of wort. Looking at the info by some of the posts in this thread - it may be much more than I anticipated.

This makes me think that doing some sort of combination of imersion chiller with whirlpool using city water first to get to 100* or so and then putting it through a plate chiller with pre chilled water might work better. I'm still wasting a lot of water this way but I don't think the glycol thing is going to work.

I completed my glycol unit last month, it works beautifully for maintaining my fermentation temps in ferm chambers. The plan is to phase in a prechiller for knockout next. While large brewers use their glycol to cool their brew, I don't really want to swap 200 degrees for 35 degree glycol. My plan is to put in a plate chiller and pre chill my TX tap water and then go into my CFC with the pre-cooled tap water and boiling brew. By doing it this way I am only having to remove a little bit of heat and not a lot. I know from brewing in Wyoming, 55 degree tap water in winter is more than adequate to knock out at 65 at a good flow rate. I have a 5k btu a/c unit with a large $20 cooler from Wal-Mart that holds about 7 gallons.

tag

To all of you that want to make a Glycol Chiller big enough to chill 6.5 gallons of wort from 212 to 68 degrees F in 10 mins on the fly with no reservoir, like a plate chiller does, you need a 46,000 btu of cooling power or a 3.8 ton ac unit. I think they sell for around 5 grand. You can use a lot of water for that price. Here is the web page that did the math for me http://www.infinitepower.org/calc_watts.htm Better off cooling it with tap water to a reasonable point then finish it off with the glycol chiller.

Cooling and heating work about the same meaing a BTU of heat and a BTU of cooling are the same. I use an electric setup that has 36,000 BTU of heat, to heat 10 gallons of strike in water from 55 degrees takes about 10 min. It would take the same BTU to cool it back in 10 min.

bnhocking said:

To all of you that want to make a Glycol Chiller big enough to chill 6.5 gallons of wort from 212 to 68 degrees F in 10 mins on the fly with no reservoir, like a plate chiller does, you need a 46,000 btu of cooling power or a 3.8 ton ac unit. I think they sell for around 5 grand. You can use a lot of water for that price. Here is the web page that did the math for me http://www.infinitepower.org/calc_watts.htm Better off cooling it with tap water to a reasonable point then finish it off with the glycol chiller.

Cooling and heating work about the same meaing a BTU of heat and a BTU of cooling are the same. I use an electric setup that has 36,000 BTU of heat, to heat 10 gallons of strike in water from 55 degrees takes about 10 min. It would take the same BTU to cool it back in 10 min.

Click to expand...

While the maths right, from a practical standpoint, you won't be doing it without a reservoir.
A common hacked window unit into a cooler glycol chiller will end up with around 12 gallons of chilled glycol, which it can spend a couple hours prior to use to chill everything down and use a much smaller chiller. The down side is you're typically growth limited because a too small chiller might get quickly overwhelmed, and the glycol may reach unsafe temps for the a/c unit.

Ultimately I went with 2 plate chillers in my setup. I have a Keg Cowboy 50 plate running with the Texas tap water, which gets my boiling wort down to about 100, then from that I go into a 40 plate chiller running off of my glycol at 30 degrees. Most days I can knock out 10 gals in 20-25 minutes. Works pretty well, but could waste less water.

Hi- I'd appreciate any help as I'm building a glycol chiller using a 7 cu.ft. chest freezer. I'll also disclose that I'm making wine, not beer. Thus, I only need to chill from 70F to 20F to chill must and cold stabilize wine.

I know all about chest freezers having limited BTU capacity but I already have a freezer and don't want to build a new one with a dehumidifier or window AC unit with a cooler unless absolutely necessary.

Bottom line, I'm trying to decide between/amongst the following designs for a 100 gallon volume:

1) Have a reasonable volume (20 gallons) of glycol solution in the deep freeze at -11 degrees (coldest temp in freezer settings)

2) #1 PLUS a pre-chiller wort chiller coil (50') in an ice bucket to minimize heating of glycol in freezer by return line.

3) More simple, put wort chiller coil in volume of glycol solution and have a closed loop glycol loop.

4) I guess I could have two coils, one pre chill in ice bucket and one in the freezer

I'm sure there are some thermodynamic equations we can calculate this, but at this point my head hurts.

Thanks in advance.

Ok, am I reading correctly that you're trying to chill to a final temp of 20F? How quickly do you need to get there? How good of insulation do the vessels have?