Need help with fermenter cooling system!!

Hey All!

I needs some ideas for improving my cooling system. I made a bit of an error in my design. I have a freezer with coolant in a bucket. I have temp sensors and controllers. Selenoid valves and stainless immersion chillers. The failed link is my submersible pump. I did not even consider the heat that thing puts off. My coolant only stays cold for about 15 minutes of running the system.

What are my options. I was thinking some other kind of continuous duty pump. It has to be strong enough to pump three lines with distances of up to 75 feet each line. plus the lines are 7 feet in the air.

Here are a couple of pictures of what I have going so far.

Use an external pump outside of the cooler? I like your pictures and where you are going with it all Why not build a cold box around the fermentors though?

Are you sure the reason is the heat given off by the pump? Trying to temp control 3 fermenters with a 75 foot line run with just one bucket of glycol seems impossible.

how big is the bucket of glycol in the freezer?

what you want is the largest thermal mass of coolant in the freezer....like a large trashcan or something.....or just fill the entire freezer up with glycol, that should do the trick

I want people to see the fermenters. Part of the decor of the place. They are right up front near the bar. The wall where the controllers and valves are, that is the walk in cooler. I have three more tanks in there for tax determination and clearing.

infection said:

Are you sure the reason is the heat given off by the pump? Trying to temp control 3 fermenters with a 75 foot line run with just one bucket of glycol seems impossible.

how big is the bucket of glycol in the freezer?

what you want is the largest thermal mass of coolant in the freezer....like a large trashcan or something.....or just fill the entire freezer up with glycol, that should do the trick

Click to expand...

I have a 10 gallon tank filled, with the lines filled too. It works well. The return fluid is coming back to the freezer at about 49 degrees. Going out it was 29 degrees. I have to think the motor is bringing the fluid up to 69 degrees.

It's not realistic to look at the performance when the 10 gallon reservoir is already cold. You might need to run it warm, and see how much the system can realistically pull the temperature down, over a given time.

You need to look at the volume of your lines, coils, and tank.

For instance,
If you have 3 lines that are 1/2" ID and 75 feet long with return, they are holding 1060 cubic inches of coolant - Or about 4.6 gallons.

If your reservoir is 10 gallons, you have about 33% of your coolant being heated at any given time.

That means your coolant is actually being "cooled" for 2 units of time out of 3. So if it takes 30 seconds for the coolant to leave the chiller and return, it will have 60 seconds to chill before leaving again.

If it's losing 20 degrees in 30 seconds, do you really expect a chest freezer to chill it 20 degrees in 60 seconds, by letting it sit in a bucket? I couldn't heat a 10 gallon bucket of water 20 degrees in a microwave in 60 seconds...

I would take a serious look at chillers on eBay or CL. I have seen them go for less than $500, and they are designed to handle that kind of thermal load.


All that said, if you have a more efficient way to accomplish the heat exchange in the freezer you could be more successful. A tank has very little surface area to exchange heat with the cold air. Running it through a radiator of some sort with fans moving the cold air across it would probably help significantly.
But then you run into the issue of putting a huge and constant thermal load on a home chest freezer that's not designed for it.

I'll be curious to see how this works out for you! I'll be following this thread :rockin:

Ok That makes sense. The values are a bit off but close. The lines are 3/8 the return line is shared and is 1/2. So I guess i will start with a larger maybe two stage design in the cooler. maybe run the return through a copper chiller in the freezer too before dumping into first reservoir. Have the first reservoir fill from bottom exit from top into next bucket then draw from bottom of bucket to external pump?

I guess I could put some computer fans blowing across the copper coils too.

I am hoping this will be just a start-up system. If we start doing well we are going to purchase jacketed tanks, larger system and proper glycol system. We would like a 7bbl system ultimately. This was a much cheaper way to prove our concept to investors and possible lenders.

I'm thinking something along the lines of a pre-chiller before the warm glycol gets back into the chest freezer.

I would seriously consider a much better heat exchanger. For that kind of volume, you need a LOT of transfer, and you have very little time to do it.

There are 3 ways (That I can think of right now ) to get where you want to go;
1) Time - Leave the coolant in the freezer for longer (Larger reservoir)
2) Temperature - A larger differential in temperature will transfer faster (Colder freezer)
3) Surface area - More surface area will exchange more heat, faster.

Of course all 3 are even better. A larger reservoir, with huge surface area, and slower flow rate will perform much better.

But then the problems compound as well... Slower flow (more time inside the cold) means you lose more cold to ambient on the way to the fermenters. Insulation would help a great deal here.
And when you do reach maximum thermal transfer in the cooler, you're going to put an enormous load on the freezer. I would be shocked if it could actually keep up...

If you're interested, we had some dialog about this in my chiller build here:

There are a bunch of other threads about chilling.

Hey - Ping this guy - He's got a chiller :rockin:

thanks!

Here is another strange detail I just noticed. My tanks just dropped 7 degrees on their own while I have been sitting in front of the computer. The only thing that has changed is that the ceiling heater kicked on and is blowing the ambient air over top of the fermenter. (about 8 feet above). So it is moving the cold air around the tanks. Our ambient air inside right now is 58. Sucks i know. It snowed here yesterday.

So maybe if I get some air moving around the tanks as well. I like the car radiator idea with fans blowing across it to pre chill return line before dumping into the tank. I still need to figure out a good pump.

Any 100% duty cycle pump should be just fine. Put it outside the keezer and you won't have to worry about the heat it puts off.

How does your cooling setup look now? Do you have a proper glycol setup? Did you find the pump(s) you were looking for?

I found an external pump. I mounted it outside of the freezer. It works ok. Does the job for now but it would be much better if I could run the fluid through a heat exchanger and have a compressor cooling the heat exchanger plates. I am not going to worry about it too much. When we upgrade to a commercial 7bbl system I am going to purchase a proper glycol chiller for the new tanks.

Brewmoor said:

I found an external pump. I mounted it outside of the freezer. It works ok. Does the job for now but it would be much better if I could run the fluid through a heat exchanger and have a compressor cooling the heat exchanger plates. I am not going to worry about it too much. When we upgrade to a commercial 7bbl system I am going to purchase a proper glycol chiller for the new tanks.

Click to expand...

I like your choice of words.

Did you try any of the improvements (time, temperature, surface area) that sweetsounds suggested, or is he full of $h!t? Just kidding...

Hope you don't mind a slight thread detour. I had been considering the stainless immersion chiller in the conical idea, but it was shot down for various reasons. Most notably sanitation and the coils getting in the way of happy yeast movement.

Have you been using this type of chilling long? Have you had good success with it?

Thanks!

-Joe

Late to the thread but a quick way to see how much the heat load would be from the pump is to look at the wattage and compare it to the freezer wattage. A wild guess would put the pump efficiency at around 25/50% tops. The rest would be heat.

It seems like the freezer would be the worst way to go. Freezers are meant to keep something at a temperature not cool something down. I window AC unit with a heat exchanger as the evaporator would be a better solution.

Smaller too.