Thought I could do it, but need your help

Alright long story short I am turning a 53 gallon oak barrel into a keggerator with two cornys inside. Basically I have a garbage can inside the barrel with an inch of "great stuff" foam between it and the side walls of the barrel. In side the garbage can are my two kegs and my CO2.

My plan and the way things currently are relies on using water to exchange heat within the barrel system. I have a mini fridge (really mini maybe 2.0 CU ft) with 2.5 gallons of water in it that gets pumped (by a submerged low power water pump) directly into the trash can inside the barrel. The barrel simultaneously drains water back into the mini fridge. So the kegs and CO2 are actually in a water bath that is 80% of their height.

This system has an enormous thermal mass, basically there are 10 gallons of liquid in the kegs and probably another 6 in the garbage can. I turned it on for the first time last night and here is what I have for data after 5 hours of running.

At Start:
Fridge temp 60F
Water inside barrel 74F

4 Hours after
Fridge Temp 57.5F
Water inside barrel 67.5

I am worried at this point that I don't have the cooling capacity with this small fridge. I would consider it a success if I was able to get the beer to 42F even if it took a full week to chill it. I would also be somewhat happy if I had to spike the barrel with a few frozen water jugs whenever I added warm beer to the kegs as long as the system cool keep a cool temp on it's own after that initial ice spike. At this point I am waiting to see if things cool down, but also want to start planning other options.

Other options include:

Larger fridge or freezer (off craigslist) same idea of water pump and water bath in the barrel. This would give me the ability to have more water in the fridge and also more cooling capacity. Your thoughts?

Putting a cooling unit of a fridge or freezer directly in the garbage can inside the keg. Don't know how to do this, I would definitely need to run lines external to the barrel and there also isn't much room in there.

What are your thoughts on this whole system. Obviously it's way out there, but I'm going for something unique and If I can just figure out how to chill it I'll have the coolest keggerator.

Thanks

First thing you need to decide is how much you are willing to spend to having something unique. I don't think there is anything wrong with the setup, the cooling capacity doesn't appear to be adequate.

Sounds like you are going to need that bigger refrigerator. The question then becomes why bother with the second enclosure (the barrel) when I can just put the kegs in the refrigerator? You could probably buy some nice serving taps, CO2 manifold, etc to make that fridge a sweet kegerator for the money it is going to take to make the barrel idea work.

Then there is a question of capacity...a regular sized fridge will hold 4-5 kegs instead of your barrel only holding two kegs. So there is a opportunity loss going with the barrel idea there as well.

But again, there is value to you in uniqueness--which leads me back to my original question.

broadbill said:

First thing you need to decide is how much you are willing to spend to having something unique. I don't think there is anything wrong with the setup, the cooling capacity doesn't appear to be adequate.

Sounds like you are going to need that bigger refrigerator. The question then becomes why bother with the second enclosure (the barrel) when I can just put the kegs in the refrigerator? You could probably buy some nice serving taps, CO2 manifold, etc to make that fridge a sweet kegerator for the money it is going to take to make the barrel idea work.

Then there is a question of capacity...a regular sized fridge will hold 4-5 kegs instead of your barrel only holding two kegs. So there is a opportunity loss going with the barrel idea there as well.

But again, there is value to you in uniqueness--which leads me back to my original question.

Click to expand...

For me it's worth it. I've already got everything that is needed. I have a tower mounted on top of the barrel, which thanks to me now has a hinged lid. Tower has 2 perlick 525 taps. I've also got a dual regulator already setup. Basically nothing was spared in the expense of setting this thing up. As for chilling with a larger fridge my only issue is I don't want to have the large fridge around- at that point it basically does defeat the purpose.

Is there a smaller water chiller or something that might do the job of the mini fridge more efficiently?

It's going to be an awesome keggerator and as soon as she's done I will post pictures.

You said it yourself, this thing has enormous thermal mass. 4-5 hours isn't even going to come close. Run this thing for a week and maybe you'll see what the system can really do. You could accelerate that as you say by spiking it with cold water or ice.

I assume the kegs were warm when you put them into the barrel? That will take a long time to cool no matter what.

dbrewski said:

You said it yourself, this thing has enormous thermal mass. 4-5 hours isn't even going to come close. Run this thing for a week and maybe you'll see what the system can really do. You could accelerate that as you say by spiking it with cold water or ice.

Click to expand...

Yeah in all honesty I'm an engineer and this has been an idea of mine for a while, so I really have thought it out. I did intend to use a larger fridge, but since I already had this one I figured try it first.

I did spike the water this morning with a few cold packs, but tonight I'll have 4 gallons water frozen in bottles waiting for it. I should know by Sunday what I'm dealing with. I guess I just wanted to see if people though I was completely insane. A couple of my brewing buddies think the idea is nuts. I probably have about $400 in the project so far if I ignore the cost of kegs and CO2, but all the components are top notch.

onthekeg said:

I assume the kegs were warm when you put them into the barrel? That will take a long time to cool no matter what.

Click to expand...

Yes the everything in the barrel last night was basically 74F. It's going to take a while I just hope I can get there eventually. I'll posts temps when I get home tonight.

The next time you fill it up and it gets to 74*F, drain it and refill it with tap water. I'm guessing your ground water is about 55*F or so. That would be a very quick way to reduce the temp.

I agree that there is a lot of thermal mass there, so you've got to measure this over a longer time to draw any meaningful conclusions about cooling capacity.

Another thought.. what kind of insulation do you have on the top and bottom of the barrel? What about on the lines between the barrel and your fridge? If you're an engineer then I'm preaching to the choir here, but Anything you can do to eek a few more percentage points of effective R value out of your system will really help. If you have room, you could even add a layer of insulation inside the garbage can (since you've already filled the outside with great stuff, there isn't much you can change there).

You might also try to collect some data on how often the compressor in your mini fridge runs and for how long. If its duty cycle is low maybe there are some changes you could make the the fridge. Either increasing the efficiency of heat transfer between water and the fridge, or maybe somehow get the temp probe for the fridge thermostat in contact with the water in the fridge?

My guess is that if you chilled 6-7 degrees in only four hours, you have enough chilling capacity. Have you given any thought about the kegs wanting to float when they are nearing empty?? Search around, people have disassembled minifridges and used the cooling plates and motors for builds such as this as well.

wilserbrewer said:

My guess is that if you chilled 6-7 degrees in only four hours, you have enough chilling capacity. Have you given any thought about the kegs wanting to float when they are nearing empty?? Search around, people have disassembled minifridges and used the cooling plates and motors for builds such as this as well.

Click to expand...

Glad there are so many people chiming in.

The kegs are held down by cord and cannot float without the cord being unhooked.

I certainly should have used cooler water when I filled it, but at the same time the temperature drop between 74-55 will be the easy part. I am fearful of the <50F portion though.

The there is about an inch of great stuff foam around the entire perimeter and also underside of the barrel (actually more like 2" on the bottom). The hoses are insulated with foam covers. As far as I can tell the fridge is going non stop. It's on it's coldest temp setting and last I checked it was still more than 50F in there, which to me means I am getting good thermal transfer.

When I was looking at options for cooling a ferm chamber build (still on the drawing board) I came across this calculator meant to help calculate the size of peltier required to cool a given application:

http://www.tetech.com/Cooling-Assembly-and-Heat-Load-Calculator/index.php

It will give you numbers as well as reccomend the right peltier from their line. If you can figure out a ballpark "heat load" plugging in numbers for your application and then estimate the cooling capacity of your mini fridge (I'll leave that as an excercise for the reader, aka I don't know about that) you might be able to figure out how close you are to what you need. If you are in the right ballpark, then maybe you can tweak the design, but if you are like a factor of 2 or 10 from what you need, you should be able to tell that as well.

spook said:

When I was looking at options for cooling a ferm chamber build (still on the drawing board) I came across this calculator meant to help calculate the size of peltier required to cool a given application:

http://www.tetech.com/Cooling-Assembly-and-Heat-Load-Calculator/index.php

It will give you numbers as well as reccomend the right peltier from their line. If you can figure out a ballpark "heat load" plugging in numbers for your application and then estimate the cooling capacity of your mini fridge (I'll leave that as an excercise for the reader, aka I don't know about that) you might be able to figure out how close you are to what you need. If you are in the right ballpark, then maybe you can tweak the design, but if you are like a factor of 2 or 10 from what you need, you should be able to tell that as well.

Click to expand...

Thanks for that link. I'm not sure what the BTU rating on the fridge is I'll have to look it's model number up this weekend. It seems like 100-200 BTU is what I need per that calculator, but my system is by difficult to model. I have foam insulation and then wood, multiple metal radiating bodies (kegs and CO2), and also some unknown heat added to my system by the pump.

I think it's going to be close. If I can get it to 45F as it stands now, I think I can make a couple changes to get to 40F.

I think for modeling purposes you could assume a barrel with a nominal amount of liquid in it and ignore the thin stainless kegs. The other issue is the design duty cycle for your mini fridge's compressor. Most big fridges/freezers have a thermal protection for the compressor motor so it will eventually shut off and cool down.

Sounds like you are close at least. Cool (pun intended, groan if you must)!

I don't know what the setup looks like and I'm no engineer but air space around the water reserve in the fridge will make heat transfer very slow.
Take a frozen turkey and put it in your fridge. The volume is a couple gallons and the differential in temp is 20-30 degrees but it takes a week for it to thaw.

Brewskii said:

I don't know what the setup looks like and I'm no engineer but air space around the water reserve in the fridge will make heat transfer very slow.
Take a frozen turkey and put it in your fridge. The volume is a couple gallons and the differential in temp is 20-30 degrees but it takes a week for it to thaw.

Click to expand...

Yes I agree with this. Both the in and out lines in the fridge are coiled up and run near or in the freezer box, which is the coldest part of the fridge (surface temp -4F). The water moves fast so it doesn't get below freezing at least not at this point, but this setup does allow some decent heat transfer. One upgrade I will make if necessary is copper condensing tube in place of plastic tubing inside the fridge. I won't do this though until I am seeing an air temp in the fridge that is far below the water temp in the fridge. At this point they are still close which indicates efficient thermal transfer.

What about putting copper lines in a bucket of water inside the fridge? You could then ice that water as well to speed the cooling process. Then once you have cooled the system you would have even more thermal mass to help keep the system cool.

Edit: nevermind, just realized you already have a bucket. I thought you just had a heat exchanger coil in the fridge.

Ignore me.

What about using a small freezer and putting rv antifreeze in your water? You'd have a greater temp differential then. Also, if you don't want the antifreeze solution around your kegs (rv antifreeze is non-toxic though) you could have a large container of that in the freezer with a copper coil in that, and run your straight water through that coil, and the coil in your trash barrel. In essence a closed lop of cold water.

Well I am happy (or at least somewhat happy) with the progress I made this weekend.
Summary on Thermal issues:
Internal temp is now 40-45F.
Fridge temp is 30's
Water in Fridge is 40F

I have needed to put a large frozen water bottle in the barrel twice a day, but that isn't that big of a deal and it's taking about 12 hours for the bottles to completely melt. So the thermal loss is minimal, and to be honest I'm not even sure so sure if the bottles are needed, but with a party on Friday and two beers to be kegged within the next couple days I need it really cold in there.

I installed a copper coil (meant for ice makers) in the fridge to help super cool liquid going into the barrel. It runs though the ice box which is typically sub zero. I think this has helped a lot.

I've got everything setup inside, although it is a little tight in there. Here is what see looks like on the outside, I'll have to take some better pictures soon.

kklowell said:

What about using a small freezer and putting rv antifreeze in your water? You'd have a greater temp differential then. Also, if you don't want the antifreeze solution around your kegs (rv antifreeze is non-toxic though) you could have a large container of that in the freezer with a copper coil in that, and run your straight water through that coil, and the coil in your trash barrel. In essence a closed lop of cold water.

Click to expand...

I have a set up like described above. I built an insulated cabinet using the unused space off to the side of my fridge in a corner in the basement. It houses three cornies and i used insulted foam panels, great stuff and silicone, with a rubber weatherstrip around the door closure. I am at prob like 50 percent glycol (i got it from a school we ran snowmelt for, but you can use automotive- go online to get a spec gravity chart to check your strength against your temps). I have a coil in the freezer section of my refrigerator, on the discharge side of my pump that is prob about 100' of 1/4" tubing, i have two coils on the suction side, in the cabinet- one on the back wall (1/2"-25') and one against the top above the kegs (3/8"-30'). Now, i use a full size refrigerator and i keep the temps pretty low in the fridge section, between 36 and 41- but i don't use a temp control- i mounted an outdoor dig temp sensor and monitor the temp. I have not had a problem with more than a two or three degree swing, unless it was recently loaded. For the pump, i use a JCI temp controller, with a cooling setpoint enabled to open switch. I have been able to keep my kegs as low as 34 in the cabinet, and i'm sure if the coils and kegs were housed in an insulated water bath, it would be even more stable a setup. The only complaint that i have is that, in the summer, when i have to change a keg (which usually means i am filling a couple bottles of the last legs, to cellar and note) if i don't do it quickly, i get a lot of condensation on the top coil that drips down and gets everything wet- so i have to towell it up and work fast. In the winter, it is no problem. I did put an automatic airvent near the pump, as extracting air from the lines took a little while (i still top every now and then, when my gauge shows a little drop). You pump the glycol in and then use a hose for makeup water, to get your loop to like 15 psi. I am really happy with this setup. You could get a plate exchanger, or even use a regular radiator coil in the freezer section, but a coiled loop of copper in your water bath would probably be the tits for heat exchange (size, shape). This solution came to me after my wife and i had a fight about use of the refrigerator and she made me feel like an irresponsible drunk, demanding that she keep the fresh vittles for the fams away from my precious nectars. I realized that all i needed was an insulated box and a way to get the heat out of it and into the freezer section of the fridge- the space of a refrigerator isn't real champion for cornies anyway- the chest freezers work great, but we have a stand up. Nowadays, the fridge is mostly still filled with beer, but there is a little bit of room in it and every one is happy. I can post some pics (even though my piping looks ****ty because i suck at insulation and wrapped everything in rubatex- prob should have taken photos of the erection inspiring pipework, prior)- and if you need any help with the antifreeze setup (ie what used for fittings for the fill and bleed, connections to the fridge, etc). Good luck getting cool!!