Calling math nerds

[aeviaanah]

We run a 7bbl brewhouse and with Covid 19 we are preparing to decrease in house sales in place of distribution.

One idea we thought of is to move our Cold Liquor Tank out of our cold storage to make room for cans and kegs. The CLT is a 500gal HDPE vessel in which we plan to insulate and add an immersion coil which we would plumb to our glycol header.

The question here is regarding line diameter and length. Rather than take a stab in the dark which would be 100' 1/2" diameter, we thought it would be wise to look a little closer.

-Steve

 

[aeviaanah]

Anyone have a better stab at this?

 

[cfosty]

So you want to know what length and diameter the immersion coil will have to be to keep the CLT cold? I can take a stab at the calcs but more info is needed such as:

What's the ambient temp where it will be stored?
What's the temp of the glycol being fed to it?
What temp do you want your CLT liquid to stay at?

 

[SanPancho]

Why donot you you figure out the size of the coils used on small homebrew conicals to get the surface area and then extrapolate to your size?

put your tank near a drain. It’s gonna sweat like nobody’s business.

 

[Vale71]

More importantly, you need to know the heat loss coefficient of your insulated tank otherwise you're still taking a stab in the dark.

 

[SanPancho]

True but probably unrealistic. More practical is to simply match the insulation of a typical CLT. I’m guessing 3” of insulation on a normal tank. That’s for stainless which obviously is much higher in heat loss vs hdpe. Maybe you could do with 2”?

Don’t forget to insulate the bottom.

 

[MMP126]

Almost an engineering question. But, more info is needed.

1. What are you doing with the vessel? Just cold water? Keeping beer cold (brite tank application)?
2. Max. ambient temp?
3. What type and thickness of insulation do you have?
4. Are you cooling beer down once it gets into this vessel? Or are you using this vessel to additionally chill the beer. If so, what temp are you starting with, and what temp are you ending at?

 

[aeviaanah]

So you want to know what length and diameter the immersion coil will have to be to keep the CLT cold? I can take a stab at the calcs but more info is needed such as:

What's the ambient temp where it will be stored?
What's the temp of the glycol being fed to it?
What temp do you want your CLT liquid to stay at?

Yes looking for volume or surface area requirement to better select coil diameter and length.

California central valley here ambient temp can get up to 105F.

Not sure of what temp the glycol being fed to it. I'd assume 25-27F. I need to double check with our chiller manufacturer to ensure it can go that low.

Can't say for certain what temp we want the CLT at but I think 38F-42F is probably a fair start.

Why donot you you figure out the size of the coils used on small homebrew conicals to get the surface area and then extrapolate to your size?

put your tank near a drain. It’s gonna sweat like nobody’s business.

Thought about taking surface area and volume of our 10bbls and extrapolating out. I'm not sure how overkill or underkill homebrew fermenters are designed when comparing coil size to volume of fermenter.

More importantly, you need to know the heat loss coefficient of your insulated tank otherwise you're still taking a stab in the dark.

The tank is HDPE and is currently uninsulated. We can run 2" sticky back Poly Urethane.

True but probably unrealistic. More practical is to simply match the insulation of a typical CLT. I’m guessing 3” of insulation on a normal tank. That’s for stainless which obviously is much higher in heat loss vs hdpe. Maybe you could do with 2”?

Don’t forget to insulate the bottom.

Will do thankyou for the recommendation.

Almost an engineering question. But, more info is needed.

1. What are you doing with the vessel? Just cold water? Keeping beer cold (brite tank application)?
2. Max. ambient temp?
3. What type and thickness of insulation do you have?
4. Are you cooling beer down once it gets into this vessel? Or are you using this vessel to additionally chill the beer. If so, what temp are you starting with, and what temp are you ending at?

1. The vessel will be used to knock down the kettle from 212F to pitch temps. Hot water from HEX out will be transferred to HLT for use with the next batch.
2. 105F in summer (California central valley)
3. Not yet insulated but we're thinking 2" sticky back Poly Urethane.
4. The vessel is strictly for filtered brewing water and knocking down kettle to pitch temps. Kettle will start at 212 and end at pitch temps 52-70F

 

[dwhite60]

There's an organization, ASRAE, American Society of Refrigeration and Air Conditioning Engineers. You might find their local chapter and find a professional you can ask.

 

[cfosty]

I'm assuming you're going to have the coil fixed in the CLT with no agitation? This will change the assumed convection coefficient by quite a bit.

Also, are you recirculating the CLT water back into the CLT after running it through the hot wort in the kettle?

The heat transfer calculations aren't really difficult, it's just collecting all the numbers and making some semi-accurate assumptions.

 

[aeviaanah]

I'm assuming you're going to have the coil fixed in the CLT with no agitation? This will change the assumed convection coefficient by quite a bit.

Also, are you recirculating the CLT water back into the CLT after running it through the hot wort in the kettle?

The heat transfer calculations aren't really difficult, it's just collecting all the numbers and making some semi-accurate assumptions.

We will transfer approx 300gal to the hot liquor tank- the remaining will either be drain to waste or out back in CLT. Might even run tap to waste (or reclaim for CIP) then finish off with water from CLT to HLT.

We have the option to recirculate CLT if it makes sense to do so. If that's the case perhaps a counterflow would be more efficient?

 

[aeviaanah]

Bump

 

[RufusBrewer]

As I understand it, (and it make sense to me) there is a law of diminishing returns when it comes to coils and heat transfer.

The greatest factor in transferring heat is the difference between the temps of the two liquids. As the glycol travels down the coil and absorbs heat from the beer, it becomes less effective at accecpting heat. After some length, and the liquids get closer to equal temps, the extra coil length is virtually useless.

To be achieve more heat transfer, the variables are #1 push colder glycol down the coil and/or #2 push the glycol at a faster rate.

I am sure there is an engineered/calculation answer to your question. Before I made any decisions, I would request calculation for Y feet of tubing and then 2 times Y and 4 times Y and compare. I would also ask for calculations for with different glycol temps and faster pump rates,.

The optimum solution might not be in more feet of tubing but a pump with greater gallons per minute. Or a better glycol chiller.

 

[SanPancho]

If you have a spare pump maybe easier to rig up a recirc line from clt to a plate chiller. Forget the coils. Probably a lot easier to find sizing info too.