Super Efficient Pre-Chiller

[ChemE]

I finally got around to making my pre-chiller since water temperature here in South Carolina are already climbing. I brew ales so I don't need a system which cools the wort any colder than about 64°F. I also have no interest in spending $2-3 each brew for a bag of ice since that would be a significant fraction of the total cost of a 5 gallon batch which typically cost me about $10. To that end I wanted a system which could bring 5 gallons of wort from 90°F down to 65°F in a reasonable amount of time and using a bare minimum of water.

Exploded view of pre-chiller system

Pre-chiller installed in system

Note the the inlet to both the pre-chiller and the chiller utilize the same male garden hose disconnect which matches the female garden hose quick disconnect on the garden hose. This allows me to switch in the pre-chiller once the wort reaches a temperature close to ground water by moving the garden hose from the chiller inlet to the pre-chiller inlet and then jumpering the pre-chiller to the chiller with my jumper. It too has quick disconnects which match the pre-chiller outlet and chiller inlet. Switching the pre-chiller inline takes about 5 seconds (seriously).

Tomorrow I'm just going to charge the pre-chiller with 4 gallons of cold water from the refrigerator as well as a half dozen freeze packs from the freezer.

 

[JonK331]

Cool! I'll be curious to see how this works. It's getting time for me to get out the pre-chill set up as well.

 

[ChemE]

I should note that I fooled around with table salt, ice cubes from the freezer, and a carefully calibrated thermometer and I was able to get a small glass of water down to 6°F just by adding salt to cold water and stirring crushed ice into it. Had I saturated the water with salt it should have gone down to -6°F. It would take 10 pounds of salt to saturate the 4 gallons of water in the pre-chiller (and if I ever did this I would save the brine and keep it in the freezer) but this setup could easily bring 5 gallons of wort from 80°F down to lager temperatures if I started with -6°F water in the pre-chiller.

My goal is to determine for my brewery how little salt and ice I need to quickly get to 64°F.

 

[SnidelyWhiplash]

In on chemical engineering party. I actually work on some related stuff.

If you didn't already use this, you could see how low your freezer goes, and use just enough salt to keep it liquid there. http://people.ucalgary.ca/~kmuldrew/cryo_course/figures/fig6_1_1.gif


If you want to go completely crazy, I'd also recommend CaCl2, it has a higher heat capacity (73 J/molK compared to 50) and better phase diagram for keeping a liquid solution. Since your freezer can get down to the -21C freezing point of saturated NaCl, CaCl2 can go to -60 and it would take a few % less CaCl2 to get to any temp.
http://www.phasediagram.dk/binary/CaCl2.gif

also heads up the brine will be corrosive, not sure how much to copper, but washing it off of the chiller would be a good idea.

 

[Phyrst]

Very cool idea. I have a 25' immersion chiller now. Someday I plan to upgrade to a 50' chiller and convert my current chiller to a pre-chiller. Glad to see someone has already forged that path.

Here's a thought though. Why not pipe a bypass around your prechiller? Just put valves on the inlet and outlet and a bypass line with a valve on it. Then you could use regular water to chill the wort below 100 F and then all you have to do is open the inlet and outlet valves and close the bypass and put the water through the prechiller.

 

[BigPatBrewer]

This is the system I use now. I usually use the hose water to knock it down to around 120 and then switch to the pre chiller in a bucket of ice water. I have not messed around too much with salt yet but I will soon. Unfortunately, in the middle of the summer I still had a hard time getting it below 80 for a 10 gallon batch. I once used 100 lbs. of ice to get it to 70 in August when water temperature is in the high 90s. I have found the pre chiller to work much better with 5 gallon batches. I am currently plumbing up my system for a whirlpool chiller. This has just been my experience in Tucson, AZ and it might be different for you. Best of luck!

 

[Bobby_M]

It works much better if you keep that prechill solution moving just in the same way it helps to whirlpool the wort. At the crazy price of copper these days, it's more economical to replace the prechiller coil with a pond pump (if you don't already have the copper on hand).

 

[ChemE]

Snidely: Thanks for the link on the phase diagram of aqueous calcium chloride solutions! I just happen to have 30lbm (getting all ChemE) sitting in my garage that now has a new purpose.

Bobby_M is correct and that is exactly what I saw last brew day. I was able to get lower temperatures at the pre-chiller outlet by stirring the water in the pre-chiller. For the edification of anyone stumbling upon this thread later this happens because all fluids have some thermal resistance and if they form an essentially stagnant layer against surfaces (like the outside of the copper coils). Thus while stagnant they insulate the copper from the bulk fluid.

In general I should note that the no ice trial was largely a failure. I did some back of the napkin calculations and determined that I would need either a much larger pool of chiller water, or to drop its temperature much lower. Better still is tapping into the latent heat of fusion of water which is significant. It takes 4.18 joules to heat or cool 1 gram of water 1C but it takes 334 joules to change 1 gram of 32°F ice to 1 gram of 32°F water. Next time I'm going to use a brine of some type which has been in my freezer for a few days and to that add more good cold ice (not all ice begins at the same temperature).

 

[PistolsAtDawn]

I can verify how hot water is in South Carolina in the summer! A simple 25' immersion chiller just does not do the job.

I like the project, and it flows along the lines (pun intended) of my own thinking - as far as saving water goes at least. I don't mind the $3 in ice we buy from a bulk machine.

I incorporated an inexpensive submersible fountain pump ($16ish, 265 GPH) from Harbor Freight Tools into the ice bath I'm already using for the keggle. I let the hose water cool it down a bit while the keggle sits on the concrete, then I move it to the ice bath and hook up the pump.

I think your system probably uses even less water than that, but mine was really easy since it only required the addition of the pump.

Edit: Bobby_M beat me to the pump suggestion. Guess I should work on finishing my replies faster!

 

[drksky]

Resurrecting a semi-dead thread:

The last batch I did here in Illinois in early July, I was only able to get the wort down to 80 using hose water, and had to use a LOT of water to get it that low. I've been pondering using a pre-chiller and recirculating the water from my rain barrel using a 500GPH pond pump.

Has anyone done something similar to this? Pros/Cons?

 

[McCuckerson]

Resurrecting a semi-dead thread:

The last batch I did here in Illinois in early July, I was only able to get the wort down to 80 using hose water, and had to use a LOT of water to get it that low. I've been pondering using a pre-chiller and recirculating the water from my rain barrel using a 500GPH pond pump.

Has anyone done something similar to this? Pros/Cons?

Check this out: http://www.mrmalty.com/chiller.php All right reserved by the great one - all hail the Pope!

 

[Night-Man]

Where did you get the garden hose quick disconnects?

 

[ChemE]

I'm pretty sure they came from Lowes though it might have been Home Despot.