There are a number of calculators to figure out plate-chiller cooling capacity, but I was wondering if anyone knew how to figure out cooling capacity for a simple immersion chiller?
Let’s say I know my start and end temps, and the temp of the fluid in the chiller, and I want to know how much area I need for the chiller to achieve those.
I’ve never seen one but my philosophy has always been bigger is better. Not much help I know… Cheers!!!
I know there are a ton of other variables, but I’m curious if anyone has any idea how to get a ballpark figure. I’m planning on making a 1bbl system soon, and was thinking about using an IC for both wort chilling and fermenter chilling. It seems like it’d be a lot cheaper to set up an aquarium pump and recirc cold water through the chiller inside the fermenter instead of using a keezer or a jacketed conical to control temps.
I don’t know of any calculators per say but it’s a heat tranfer mechanism. The more surface area of the copper or material transferring the heat that one has, the more heat that can be transferred. Which means bigger is better. The other variable is the cooling water or medium temp. The colder the water, the quicker the chilling.
I have an IC that uses 50 ft of 1/2" copper tubing and ground water that is about 60 degree (average) and I can chill 11 gallons of beer from boiling to 62 degrees in about 10-15 minutes.
There are too many uncontrolled variables and too many poor designs for a useful calculator. Initially as you are cooling you can expect there to be natural convection. Eventually natural convection will cease to be effective and you will get hot and cold spots which will require you to stir the kettle. It is pretty complicated to model this system in a useful generic way. I’ve been happy with two 20 foot coils of 3/8" copper in parallel occupying most of the kettle connected to a 1/2" manifold for cooling 10-12 gallons of wort. I do get a thin warm layer on top with a cold bottom that requires some stirring at the end (sometimes I use an aeration stone for this purpose getting two birds with one stone).
If you’re whirlpooling the wort at the same time (on a 1 bbl system I assume you’ll have a pump) you could probably get a reasonable answer by assuming 100% heat transfer efficiency (Newton’s Law of Cooling), integrating over the time of the whirpool/chill, and building in a fudge factor of maybe 25%.
Q’ = -hAdT
This can be problematic though perhaps not impossible - first, the coil presents a long term cleaning/sanitizing challenge. I know there was a copper tube version of this idea in zymurgy (a couple issues back), but I would think that the acids of the wort/beer would eat at the copper tubing and change the flavor of your beer.
I was planning on using a stainless steel coil, like for a jockey box. I’ve heard bad things about CuSO4 getting into the beer, so I wouldn’t use copper for fermenter chilling.
Ok good start. Now - the cleaning and sanitizing issue. Will your coil be permanently installed or removable? What’s the fermentation vessel?
Removable. Don’t know what fermenter yet. It’s still in the planning stages, but probably some kind of stainless vessel.
I do this, internal chiller in my conical. I use the Brewhemoth brand conical, and a 20 foot length of 1/4" stainless tubing for the chiller. It is an option with the Brewhemoth. Running 30 degree glycol thru it, I can drop the temp 20 degrees below ambient using a 1/6 hp pump. This is no insulation on the fermenter. Normally I’m 10-15 degrees below ambient for my ales. The stainless coil comes attached to the lid, cleanup is a hosing krausen off the tube, and dropping the coil into a corny full of starsan. Could not be easier!
I hadn’t heard of brewhemoth before. It’s smaller than I was planning, but the price is really good, what with the price of steel these days.
I was originally planning to repurpose some sort of dairy vessel or drum, but if I can’t find one for cheap enough, I’ll probably just buy one of those.
the lid (with seal) attachment is the best idea I’ve seen so far.
sidenote: hey, stlaleman, what does the inside of your fermenter look like? I’m curious about the surface finish and welds. Are there any threads on the inside of the fermenter?
The welds are nice and smooth. There is an all tri-clamp option, tho mine is the version with threaded fittings. Been using it regularly for over a year now, with no issues of sanitation.
Grab a homebrew, this gets geeky… But you asked…
Newton’s Law of Cooling is part of the answer. Given that you also know the amount of time you want to achieve your temperature transition from hot to cold (t), your overall heat transfer coefficient referenced to the external area of your chiller (Uo), your coolant mass flow rate (m’), and the amount of heat you need to dissipate (Q), then your external chiller area (A) is:
A = -m’c/Uo * ln(-Q/m’ct(LMTD) + 1)
where c is the heat capacity of the coolant (presumably water) and LMTD is the log mean temperature difference between the wort temp and the coolant entrance temp.
ooooooooo, must drink beer. Getting geeked.
Note: always, always, always check my math.
Hey all if you want my made up wort chiller calcs to justify buying a 50 ft copper chiller or to compare chill water temps use the link below. I made several assumptions, but I have empirically tested several temps, lengths of chillers, and types of chiller (i.e. copper and stainless) and the calculator is approximately correct.
https://www.dropbox.com/s/h90mx6idjmvxoec/Wort%20Chiller%20Calcs.xlsx?dl=0