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Brews & Views Bulletin Board Service * Brews and Views Archive 2004 * April 13, 2004 * Cooling Conicals - How much coil? < Previous Next >

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Cal Downey (65.27.21.143)
Posted on Monday, April 05, 2004 - 01:20 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

As I get ready to cut the coil for my internally cooled conicals I am wondering how much coil will be enough to control the temperature?

I have 30' of 1/4" stainless coil available for each 14.7 gallon fermenter, but don't want to have excess coil that displaces fermenting wort, especially if the coolant is thermally exhausted for a portion of the circuit.

A solenoid valve hooked to a Johnson controller will open when cooling is required. The glycol/water mixture will be pumped from the reservoir in the freezer compartment of a refrigerator through the coil in the fermenter. Before returning to the reservoir, the coolant will run through 50' of copper coil on the bottom of the freezer compartment.

The pump is rated at 1.4 gallons/min, but that flow could be distributed to up to 6 fermenters.

Any help is much appreciated.

Cal
 

Belly Buster Bob (131.137.245.199)
Posted on Monday, April 05, 2004 - 02:28 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

just curious...why not cool from the outside? N woories about leaks or displacement issues. Commercial manufacturers do this for a reason.
 

Cal Downey (65.27.21.143)
Posted on Monday, April 05, 2004 - 03:02 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Correction on pump flow. It is 3.3 gal/min.

Cal
 

Cal Downey (65.27.21.143)
Posted on Monday, April 05, 2004 - 05:21 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

BBB - Good question. I thought I had a hard answer...but you forced me to question my previous assumptions. Thanx.

I believed that the efficiency of an external coil system would overwhelm my pump, thereby further dropping efficiency. I also felt the efficiency of the internal cooling system would allow me to get by with one pump. As a result of your question, I've figured out that the money I save by not buying stainless tubing and fittings will allow me to by copper tubing and an extra pump.

Thanx again.

Back to how much would it take... Will 50' of copper coil be sufficent for each fermenter, or would I have thermally exhaused fluid running through a portion of the circuit?

Cal
 

davidw (199.239.30.126)
Posted on Monday, April 05, 2004 - 05:31 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I would hazard a guess that of the small percentage of homebrewers that use conical fermenters only an extremely small percentage of them use an external or internal cooling system. I would guess the majority of them ferment in a fridge or chest freezer with a temp controller when temperature control is an issue.
 

Walt Fischer (63.253.115.18)
Posted on Monday, April 05, 2004 - 08:18 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Yup... I stick my conical in the cooler if i need to control its temp...

Walt
 

Belly Buster Bob (142.177.80.220)
Posted on Monday, April 05, 2004 - 09:42 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Walt now uses a reefer truck to house and cool each batch.
Didn't mean to throw you off Cal. I just cringe at the idea of running something foreign through my beer even if it is housed in stainless. Fitting almost always leak "sometime".
I can't answer your question although I think 50' would do the job especially if you insulate. remember you are keeping cool not cooling from hot. Not much energy required.
 

Lennart Persson (216.165.243.15)
Posted on Monday, April 05, 2004 - 09:37 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

It is hard to calculate.

1. Is the coil there only to cool down to surrounding temp while the ferment adds heat? I have seen 5-10 degrees higher temp inside an uninsulated 6.5 Gal carboy than surrounding temp.

2. If it is not to only compensate heat gain during ferment, but also to keep temp significantly cooler than surrounding temp, how well will you insulate the fermenter?

Just a couple of comments:

Since you will pump really cold liquid through the coil, I dont think it will take a full 30 feet. I assume that the coil will go through the fittings in the fermenter, then you don't have to worry about leaks of glycol.

I think you will get a pretty drastic pressure drop already after one coil of 30' of 1/4". To feed 6 of them will take a good pump.

Is it possible to put the fittings through the lid? I think that would help cleaning a lot. Leave quite a bit of space between the turns in the coil so brake material and yeast can flow freely

Stainless will transfer a lot less heat than a coppper coil (which I would not like to have in the wort anyway), and you don't have much surface area on a 1/4" coil.

I suggest a test run with one coil and an electric heater. Add 50W of heat and see how fast the temp in the ferneter rises. If this is close to a regular ferment, start circulating through a coil and see what it does to the temp. Even though wort and water acts slightly different, it will show you if you are far off without starting to cut your material. If you know how much a standard ferment increases the temp and how fast, then you can calculate exactly how many watts you need to add for the test.

Sounds like a cool project. One day I will do something similar but use a long 3/8 copper coil on the outside, and insulate on the outside of that.
Good Luck!
 

John McElver (144.29.1.16)
Posted on Tuesday, April 06, 2004 - 11:41 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Commercial fermenters are cooled on the outside, which is better, but a jacket costs big $. Not a lot if one is going to sell the product, but it'd probably double the cost of a homebrewing conical, assuming a stainless jacket welded onto the outside.

A coil mounted on the lid is easier to plumb and should be easy to clean. Further, direct contact with a coil in the liquid would transfer heat better than a coil wrapped around the outside. Of course, the coil would have to be stainless, as copper would corrode in beer.

My fermenter has a chill plate with about 160 square inches of surface area and I can knock 40 degrees off ambient with it.

A coil of 3/8" would have to be 12.5 feet in length to be roughly equal the surface area of my plate (surface area of a cylinder = 2*Pi*r-squared + 2*Pi*r*h)

John
 

Joseph Listan (66.192.83.65)
Posted on Tuesday, April 06, 2004 - 01:27 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

My thoughts on creating a thermal jacket:

Wrap cone tightly in aluminum foil.

Wrap coils around the outside of the cone, ensure they make good contact with cone sides. Add some durable spacers poking out, preferrably some short (1.25" or 1.5") stainless steel bolts, head facing inward toward cone.

Find some sort of epoxy or Bondo or some such hardening paste (I'm favoring the Bondo) and spread out over coils, forming a solid conical jacket with coils embedded and spacers poking out.

Make an outer jacket out of thin plastic or sheet metal and put over coils using spacers to leave about an inch of air space.

Fill air space with Mega Hardware foam insulation sealant.
 

Cal Downey (198.26.125.13)
Posted on Tuesday, April 06, 2004 - 04:41 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Joseph - After yesterday's counselling by BBB, I'm going external. My plan may not be as efficient than yours, but it certainly seems easier in the short run.

The current plan - After plumbing for the racking arm and thermowell are installed, I'll wrap the cone with 1/4 copper coil, affixing it with duct tape. I think there will be enough surface area to accomodate about 25' of the coil. I'll insulate with a quilted aluminum hot water heater blanket.

I assume the foil in your approach will allow you to try again without getting foam stuck to the conical?
 

Joseph Listan (66.192.83.65)
Posted on Tuesday, April 06, 2004 - 08:57 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

The purpose of the foil is to keep the "hardening paste" from sticking to the cone. The foil is not there to provide any heat transfer. I figure it will peel off or get shredded when you remove the conical for cleaning, etc. My "design" allows for the jacket to be removed.

The water heater jacket is a definite possibility though, but I am attracted to the potential durability of the outer jacket and foam insulation.

If I ever do it, I will post pics, but don't hold yer breath.
 

John McElver (144.29.1.16)
Posted on Tuesday, April 06, 2004 - 09:21 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I think (no data) that coils wrapped around the outside would not work near as well as on the inside. Mostly, they'd cool the air and not the beer.
Fefore I got the Stainless Steel Specialist Fermenter, I was tempted by cutting a hole in an appropriately sized bucket and somehow glueing (gorilla glue or JB weld) it to the sides above the cone. Then use appropriate fittings and voila, a jacketed fermenter. If it leaks, it's on the outside.
John
 

Kent Fletcher (206.170.107.30)
Posted on Wednesday, April 07, 2004 - 02:32 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Cal, do yourself a favor and do a trial run before doing all of the actual installation. First, hook up your pump to the 30 to 50 foot of tubing and check your flow rate. Pumping through 1/4" tubing you'll have tremendous head losses. As Lennart pointed out, your pump might not be up to the task.

If you get a decent flow rate, you can do a furter dry run by just immersing the coil in a bucket of water, check the water temp when starting and again after an hour and calculate how much heat you've extracted. Use V x delta T x 8.33 = BTUs. Somebody (Steve A, IIRC) posted calcs on heat generated by fermentation on the Digest a couple of years back, you should be able to find it with the search.

Definitely better on the outside, IMHO. Another insulation option is the relatively new foil faced cellular product, brand name escapes me at the moment. Very easy to trim, and you can use spray adhesive to stick it on to your CCF.
 

Cal Downey (65.27.21.143)
Posted on Wednesday, April 07, 2004 - 11:38 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Joseph - Had not considered that the jacket could be removeable. Cool thought.

John/Kent - Initially thought because it would tranfer temp faster than a larger I.D. After further consideration, I think I'll run a test of 1/4" and 3/8" before settling on a final solution.

I have a second pump on order, so each 3.3gpm pump is responsible for three fermenters.

Cal

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