[WaterFarmFan]

So, I thought that I would create a thread to document my experiments on a budget DIY recirculating chiller that uses a dry ice/ethanol/propylene glycol slurry with an external magnetic drive pump. My target temps will be in -50C to -60C range, but I have no idea how the pump will handle it over the short or long term. This is a couple hundred dollars compared to the lab versions at MANY thousand dollars, which most only get to -30C. Yes, it takes dry ice, but not that much to justify the difference.

Here is the pump that I am using:

https://www.amazon.com/CHUGGER-PUMP-...dp/B01N9HERFS/

HOME BREWING PUMP - The CHUGGER PUMP can be used to ease transfers between kettles, cool wort via a counterflow chiller, or recirculate ice water for quicker chilling!
HIGH QUALITY MATERIALS - Stainless steel pump head, Magnetic Drive w/ base, Teflon thrust washer, Clear Silicone O-ring, Ryton/Teflon Impeller, 55" cord with plug.
PREMIUM PERFORMANCE - Featuring a max flow rate of 7 GPM and 18 Feet of head to handle back-pressure. Capable of handling liquids up to 250 degrees F.
The CHUGGER PUMP is the only home brew pump with ETL certification and USFDA food compliant materials tested for safety and performance standards.
3/4" MPT inlet and 1/2" MPT, allowing easy configuration for any application!

I choose 2x (6L and 15L) relatively thin stainless stock pots as the system reservoir. I used 8lb density 2-part Liquid Urethane foam kit (2 quarts total) to create a thermal barrier, which varies from 2 1/2 inches at bottom to ~ 1 1/2 inches at the top. The 8lb cured absolutely rock hard and was quite difficult to cut by hand. I used every drop of the 2 quarts for this outer shell. 8lb density (4lb actual weight kit) yields roughly 1/2 cubic feet, but varies depending on room temperature. I think mine had a little less expansion resulting in an even denser foam.

After the foam set (and cooled), I cut off the top to make smooth surface for lid. Using a set of cobalt and titanium step bits, drilled 2 separate holes for pump inlet and return line from condensers. The outer hole is just big enough to squeeze the outer washer for the bulkhead thru. The inner hole is slightly larger than the 1/2" NPT male bulkhead fittings. I had to use a drill bit to clean up the inside of the foam to make sure there was a flush surface for silicone o-rings.

Most of this equipment is for beer brewing, so I used lots of stainless 1/2" NPT to 3/8" barb adapters. Just as with my heated nitrogen backfill, I am using stainless/nylon braided ptfe lined tubing in -8AN size, which is slightly larger than 3/8", but secures very tightly when 3/8" barbs are sufficiently wrapped in ptfe tape and fastened with hose clamps.

I created a lid out of ~2" thick foam and notched the edges to drop into the inner pot. Foam bottom is covered with aluminum foil, and radiant barrier material was used to create a layered border insulation system. The outer pot lid is secured to foam and RB material with foil tape.

This has many applications depending on temp range, but I will be using this at these very low (-58F to -76F) temperatures for terpene extraction.

I am still waiting on a few things (stainless mash tun to filter dry ice from entering pump) and will post a final parts list once tested, but here a few pics of the work in progress:

[Itsgotatail]

Excited to see what you're doing here! I'm also exploring a lot of different options for subzero cooling. I'm considering all options, from immersion chillers plumbed to AC units, to dry ice, to cascaded peltier elements. All three of these should be able to be built for much much cheaper than commercial lab chillers ($500-3000/HP(or ~750W cooling power).

[WaterFarmFan]

Originally Posted by Itsgotatail

Excited to see what you're doing here! I'm also exploring a lot of different options for subzero cooling. I'm considering all options, from immersion chillers plumbed to AC units, to dry ice, to cascaded peltier elements. All three of these should be able to be built for much much cheaper than commercial lab chillers ($500-3000/HP(or ~750W cooling power).

Thanks! It really depends on your lowest target temps and of course means of reliable throughput. I like this system because I can vary the ethanol/PG ratio to bring the temp up or down, and just keep enough dry ice (an inch or two) to maintain the slurry at its max temp. Dry ice floats to top and pump draws from bottom via a 150 micron tube screen.

[Gray Wolf]

[quote=WaterFarmFan;8153523]So, I thought that I would create a thread to document my experiments on a budget DIY recirculating chiller that uses a dry ice/ethanol/propylene glycol slurry with an external magnetic drive pump. My target temps will be in -50C to -60C range, but I have no idea how the pump will handle it over the short or long term. This is a couple hundred dollars compared to the lab versions at MANY thousand dollars, which most only get to -30C. Yes, it takes dry ice, but not that much to justify the difference.

Here is the pump that I am using:

https://www.amazon.com/CHUGGER-PUMP-...dp/B01N9HERFS/

HOME BREWING PUMP - The CHUGGER PUMP can be used to ease transfers between kettles, cool wort via a counterflow chiller, or recirculate ice water for quicker chilling!
HIGH QUALITY MATERIALS - Stainless steel pump head, Magnetic Drive w/ base, Teflon thrust washer, Clear Silicone O-ring, Ryton/Teflon Impeller, 55" cord with plug.
PREMIUM PERFORMANCE - Featuring a max flow rate of 7 GPM and 18 Feet of head to handle back-pressure. Capable of handling liquids up to 250 degrees F.
The CHUGGER PUMP is the only home brew pump with ETL certification and USFDA food compliant materials tested for safety and performance standards.
3/4" MPT inlet and 1/2" MPT, allowing easy configuration for any application!

I choose 2x (6L and 15L) relatively thin stainless stock pots as the system reservoir. I used 8lb density 2-part Liquid Urethane foam kit (2 quarts total) to create a thermal barrier, which varies from 2 1/2 inches at bottom to ~ 1 1/2 inches at the top. The 8lb cured absolutely rock hard and was quite difficult to cut by hand. I used every drop of the 2 quarts for this outer shell. 8lb density (4lb actual weight kit) yields roughly 1/2 cubic feet, but varies depending on room temperature. I think mine had a little less expansion resulting in an even denser foam.

After the foam set (and cooled), I cut off the top to make smooth surface for lid. Using a set of cobalt and titanium step bits, drilled 2 separate holes for pump inlet and return line from condensers. The outer hole is just big enough to squeeze the outer washer for the bulkhead thru. The inner hole is slightly larger than the 1/2" NPT male bulkhead fittings. I had to use a drill bit to clean up the inside of the foam to make sure there was a flush surface for silicone o-rings.

Most of this equipment is for beer brewing, so I used lots of stainless 1/2" NPT to 3/8" barb adapters. Just as with my heated nitrogen backfill, I am using stainless/nylon braided ptfe lined tubing in -8AN size, which is slightly larger than 3/8", but secures very tightly when 3/8" barbs are sufficiently wrapped in ptfe tape and fastened with hose clamps.

I created a lid out of ~2" thick foam and notched the edges to drop into the inner pot. Foam bottom is covered with aluminum foil, and radiant barrier material was used to create a layered border insulation system. The outer pot lid is secured to foam and RB material with foil tape.

This has many applications depending on temp range, but I will be using this at these very low (-58F to -76F) temperatures for terpene extraction.

I am still waiting on a few things (stainless mash tun to filter dry ice from entering pump) and will post a final parts list once tested, but here a few pics of the work in progress:

View Image
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Good experiment! The proof will be in the testing.

Extreme thermal cycling can cause threaded fittings to loosen, so we ended up welding couplings through the tank walls, instead of using bulkhead fittings on the WolfWurx tricore heat exchangers, that used an alcohol dry ice bath.

I have the same questions regarding the suitability of the chugger pump at low temperatures as well, but they have to have some added tolerance to be able to rate them at -40C, sooo, ah wate with bait on mah breath!

[Old Gold]

Chugger pumps suck, I couldn't even get one to push liquid up a 25 ft coil (roughly 8-12" head) and it had a gallon of priming reservoir directly overhead. Based on its viscosity rating, it can handle ethanol all the way down to below -100°C

I had much better luck with this:
https://m.grainger.com/mobile/produc...ene-115V-5FZW1

I've run that thing for hours and hours on end at -40°C and seen it push as cold as -55°C alcohol with no flow issues. The only thing that kills it is ANY amount of dry ice being put directly into the "chiller fluid" stream instead of the external cooling bath (which I've tried just to cheat the time needed to cool 10 gallons). Even if there are no solid chunks of dry ice left in the alcohol, it shuts itself off for a healthy few hours.

Mounting an explosion proof motor would be a good idea, even if only for ethanol recirculation.

[WaterFarmFan]

Originally Posted by Gray Wolf

Good experiment! The proof will be in the testing.

Extreme thermal cycling can cause threaded fittings to loosen, so we ended up welding couplings through the tank walls, instead of using bulkhead fittings on the WolfWurx tricore heat exchangers, that used an alcohol dry ice bath.

I have the same questions regarding the suitability of the chugger pump at low temperatures as well, but they have to have some added tolerance to be able to rate them at -40C, sooo, ah wate with bait on mah breath!

Thanks. How exactly did you weld the couplings?

EDIT - I thought about just filling my voids with some kind of resin to create a leak proof seal. Downside would be that I could not replace bulkhead nipple. Any recommendations on an epoxy (from jbweld or other) that when cured could withstand potentially -78C? I need to seal the top exposed foam with epoxy as well.

[WaterFarmFan]

Originally Posted by Old Gold

Chugger pumps suck, I couldn't even get one to push liquid up a 25 ft coil (roughly 8-12" head) and it had a gallon of priming reservoir directly overhead. Based on its viscosity rating, it can handle ethanol all the way down to below -100°C

I had much better luck with this:
https://m.grainger.com/mobile/produc...ene-115V-5FZW1

I've run that thing for hours and hours on end at -40°C and seen it push as cold as -55°C alcohol with no flow issues. The only thing that kills it is ANY amount of dry ice being put directly into the "chiller fluid" stream instead of the external cooling bath (which I've tried just to cheat the time needed to cool 10 gallons). Even if there are no solid chunks of dry ice left in the alcohol, it shuts itself off for a healthy few hours.

Mounting an explosion proof motor would be a good idea, even if only for ethanol recirculation.

Appreciate you sharing your experiences with the Chugger. I need mine to pump up about 3 feet to a pair of inverted 400mm Dimroth condensers. I am hoping that gravity from the coils helps this thing "chug" along. If it does not cut the mustard, I will return it and go with another option.

[WaterFarmFan]

Mash tun filter arrived today. It is 150 mesh not 150 micron, but should work just fine. I need to get my ptfe hose cut, but should be ready to test tomorrow.

[Gray Wolf]

Originally Posted by WaterFarmFan

Thanks. How exactly did you weld the couplings?

EDIT - I thought about just filling my voids with some kind of resin to create a leak proof seal. Downside would be that I could not replace bulkhead nipple. Any recommendations on an epoxy (from jbweld or other) that when cured could withstand potentially -78C? I need to seal the top exposed foam with epoxy as well.

I TIG welded the 304SS couplings in the 18-8 stainless pot using 316SS wire.

Solly, not familiar with low temperature epoxies.

[SkyHighLer]

Originally Posted by WaterFarmFan

Thanks. How exactly did you weld the couplings?

EDIT - I thought about just filling my voids with some kind of resin to create a leak proof seal. Downside would be that I could not replace bulkhead nipple. Any recommendations on an epoxy (from jbweld or other) that when cured could withstand potentially -78C? I need to seal the top exposed foam with epoxy as well.

Is J-B Weld resistant to water and/or gasoline?
When fully cured, J-B Weld is completely resistant to water, gasoline, and about every other petroleum product or automotive chemical. For wet-surface or submerged water or gasoline repairs, try our SteelStik or WaterWeld.

Will J-B Weld hold up to extremely cold temperatures?
Original J-B Weld has proven to maintain its characteristics to temperatures as low as -67º F.

Just says "maintain it's characteristics," as long as it doesn't crack or loose adherence it may still be durable enough for your purposes.

https://www.jbweld.com/pages/faqs