My problem is, my walk in 8x8x8 freezer will not get cold enough. I’ve weathered stripped it, cleaned the condenser and I can only get it to -10 c. I need it at least -40 or -60c.
I know its needs to be serviced. My idea is to make a recirculating chiller for my ethanol. Basically I store 40 gallons in a 55 gallon barrel at a time for dunks. How can I make one? Any videos or how tools?
hey Rick. yeah, that was never a great idea, because that’s not what most walkin’s were designed for, and air makes a terrible heat transfer fluid unless you’re moving a LOT of it.
there are some great threads around here on how to roll your own chiller. with the right refrigerant you might even hit -40C/F (at least with no load). -60 is gonna require a cascade system and I still don’t remember if there is an open source version of that lying around here yet. so I’ll just call in @SidViscous 
to chill your solvent you want decent contact with your heat exchanger (HX). you also need flow and surface area, along with delta T, but I leave those calcs for others more inclined to such maths (looking at you @TheGratefulPhil)
I recommend a flat plate HX sized to give you on demand chilling to process temp as well as tuning your process (assuming you recirculate or use chilled jackets elsewhere)… but coils in a bucket are cheap and easy to implement.
if you really need more than -35C for a process temp I’m not sure rolling your own is gonna be a much fun as you think.
I’d offer a search query but I seem to have lost that skill for the now. maybe DIY Chiller?
To be honest, Rick, no one here can help until you let us know what kinda daily throughput you have and what type of budget you have.
I can help size a system to fit your needs but there’s a whole spectrum of solutions—some more affordable than others.
There is an open source chiller that can do -60c although it’s going to need some tweaking because the EEV temp sensor cuts out at -60. It’s a nontrivial build but would save a good $5-10k over purchasing. It can be found here:
Open Source LCO2 Recapture System - A Community Effort? - #21 by SidViscous
Thanks for the advice!
So I had another idea. Maybe I can make a pumped-power Wort immersion chiller. I basically have everything to make except for the coils.
I would put the coils in the barrel of ethanol. I would then get another empty barrel, and put a steel bucket inside. Fill the barrel around the bucket with Glycol/Water mix. Fill the bucket full of ethanol. Connect a hose from the bucket to the ethanol pump intake. Connect the pump outake with a hose to the coil intake. Connect coil out-take to bucket.
Before dunk fill bucket of ethanol with dry ice. Add ice every now and then. The glycol will eventually get cold and keep the chiller-ethanol cold.
Future 4200, tell me every way this won’t work?
Hey, Rick. I dont think it will work. what is the low temp of the ethanol do you need? Dry ice cant provide enough cooling capacity for the bucket.
most (but not all) try to avoid direct addition of dry ice with their solvent. there are at least a couple of decent write-up for why around here somewhere.
water and CO2 make carbonic acid (same stuff that carves us limestone caves) this can cause problems down line. I don’t like it because it makes my solvent harder to pump. and essentially impossible to move with vacuum.
glycol will slush up around -45C.
having thrown 500+ lb of dry Ice a day at getting ethanol to -50C, I would have to say that really depends on the size of the bucket.
Found out copper and ethanol, erodes, I don’t want my distalite tasting like pennies. So I found steel coils instead of copper.
What if same plan but using glycol in my lines…
I would have my dunking barrel with ethanol and the coil. I would also have a barrell with a steel bucket. I would surround the bucket in the barrel with dry ice pellets. Buy a glycol pump (advice on this please lol).
I would put the intake hose from glycol to the pump. Then hose from the pumps outake hose to the coil intake. Then a hose from the coils outake back in the glycol bucket.
I could even put insulation above the dry ice to, so I can maybe do multiple dunks in like two days.
5 gallon plastic or steel bucket
Probably not steel bucket because it will make the dry ice melt faster, so plastic.
I was using kegs. They seal better than buckets.