Brewing Physics, Question

[Brewmarc]

I use a homemade copper tube immersion chiller to cool my wort to yeast piching temp. heres the question:- Will my beer cool more quickly if I increase the flow of cold water through through chiller? Obviously immersion chillers work by heat exchang, but will it cool faster if I increase the flow? the water outlet temp decreases with increased flow so is heat exchange more or less efficient?

 

[jamesb]

WARNING: It's early and I haven't had enough caffeine yet.

I'd have thought you'd want the lowest flow possible to make the water out as warm as possible as there would be more heat transfer.

The basic principles of an IC is to make the temperatures of the wort and the cooling water equal. If the water flows too fast, there's not enough time for the temperatures to try and equalise.

I'm sure someone will be along soon to correct me :thumb:

 

[BrewStew]

that's exactly what i do... i try and get the temps to match and as the wort cools i slow down the water speed. but that's mainly to save water as i'm on a meter

 

[Aleman]

The most efficient use of water will be when the coolant exiting the chiller is at just below the temp of the wort . . . This does mean that you need to reduce the flow rate as cooling proceeds

The quickest cooling is achieved when you blast the water through the chiller as quickly as possible and stir the wort . . . . but you waste a lot of water

The physics of the thing is that it is all to do with the difference in temperature between the coolant and the wort. the larger the difference the quicker the cooling (Big Delta T).

Generally I control the flow of the coolant until the wort hits about 30C and then leave it set at that point to try and speed up the cooling for the last 15C which normally takes the longest time.

 

[Brewmarc]

Some good points :thumb: I have thought about this a little more :wha: but Im not sure Iv come up with the right answer yet :wha: its true that heat transfers more efficiantly with a slower flow, but if there were no flow the coolent would reach the same temp as the wort, & the wort would not cool down so the key to the cooling must be the flow which carries the heat away, hence the hot exhaust coolent! My chiller has the cold water entering the bottom (I could start another discusion about this) & I have noticed that the wort cools at the bottom of the copper more quickly than the top & I keep the chiller running during the run off to fermenter, the best method to employ though impractical would be to use an inert gas such as nitrogen from a presurised vessel through the chiller as the presure drops from high to low the tempreture would drop dramatcally well below freezing.

 

[Muddydisco]

Having gone through my thermal dynamics books! Won't bore you with pages of calculations!!!

The Higher the flow rate, the high the cooling capacity.
The larger the surface area the larger cooling capacity.
The Larger the temp difference the quicker the cooling (brine solution at -25 degrees will be awesome but tap water is good the colder the better!) Might try to see if I can make a brine imersion cooler now Bet nnone you you shiny guys have them!!!

Here's one for you spiral imersion cooler guy's the optimal distance between wraps of the spiral is 1.25 the diameter of you piping used, so 8mm piping X 1.25 = 10mm so you need a 10mm gap between wraps of the spiral for optimal Performance!

Hope That Helps!

 

[Aleman]

The Higher the flow rate, the high the cooling capacity.
The larger the surface area the larger cooling capacity.

Is that not the Surface area to Volume ratio rather than just surface area? . . . If you have a High SA with low Volume and a high Flowrate you should get maximal Heat exchange :hmm:

Might try to see if I can make a brine imersion cooler now Bet nnone you you shiny guys have them!!!

How Much :twisted: :twisted: :twisted: :twisted:

Here's one for you spiral imersion cooler guy's the optimal distance between wraps of the spiral is 1.25 the diameter of you piping used, so 8mm piping X 1.25 = 10mm so you need a 10mm gap between wraps of the spiral for optimal Performance!

Hope That Helps!

Now that certainly does MD . . . 10mm gap between coils will be incorporated into the next IC I build . . . I'll only have three then

 

[Muddydisco]

Is that not the Surface area to Volume ratio rather than just surface area? . . . If you have a High SA with low Volume and a high Flowrate you should get maximal Heat exchange

Yes your right, God never thought brewing would equate to so much thermal dynamics and so much head sratching.
:hmm: :wha: :? :idea:

Regards the brine chiller looks to much hard work I might as well use a cut up fridge from work!!!

 

[Vossy1]

The Larger the temp difference the quicker the cooling (brine solution at -25 degrees will be awesome but tap water is good the colder the better!) Might try to see if I can make a brine imersion cooler now Bet nnone you you shiny guys have them!!!

Adding salt to an ice bath for use as a IC coolant reservoir, has been used for many years

Now that certainly does MD . . . 10mm gap between coils will be incorporated into the next IC I build . . . I'll only have three then

Here's something to aspire to then :P ...maybe not :lol:
Finished today, a single feed/outlet, quad IC, 5m of 8mm copper in each coil, roughly 10mm between coils, horizontally and vertically. Will it work better then my cfc, I doubt it, but you can only try :lol:

 

[tubby_shaw]

'Tis a thing of beauty V

It's hard to see from the photo, do you have any method of balancing the flow to each coil ?

 

[Frisp]

Flippin eck Vossy, You have used enough copper there to create a world shortage.......
I take it your latest boiler is in teh shape of a fish kettel? about 3 feet long and 9 inch wide .... :lol:

 

[Brewmarc]

Is there enough room in your boiler for the beer as well as that contraption vossy, I bet it cools your wort down faster than light travels, or is that another physics question.

 

[Brewmarc]

P.S ,I bet light travels slower than i can drink a pint LOL

 

[Vossy1]

It's hard to see from the photo, do you have any method of balancing the flow to each coil ?

Assuming water will take the easiest path, and all the coils are identical, I didn't see the need for individual flow control.
I'm thinking only the manifold may create a problem here...we'll see :hmm: I intend to pump wort around thr kettle when chilling, to speed things up.

Is there enough room in your boiler for the beer as well as that contraption vossy

I hope so :lol: