Wort Chiller Just Ain't Chillin

[pk.sax]

OK, in the same vein, a question I don't think I've ever heard answered with any clarity.
What time frame actually constitutes chilling, and why does it even matter?

Just for the sake of the argument, say its pertinent for the reason of hop aroma / chill haze / hot break or whatever to have the wort temp reduced from 90 deg to 30 in X amount of time.
If truths exist about chilling at all, there must be a window in which optimum results are obtained, anything outside X must see desirable results taper off sharply.

It seems a given that we strive for the quickest chill possible, but is there really any justification in time / effort / expenditure of $$$ to shave 10 minutes off the time it took to drop down to pitching temp?

Would, given identical everything else, an ale that took 30 minutes to chill from 90 to 20 deg turn out demonstrably better than the same wort that took an hour to cool?

I'm interested because we obviously calculate bitterness and hop additions around chill / no chill, but what about slow chill? At what point does it cross the line?

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I take if as knock it below isomerization temp and then knock it down quick enough to prevent infection. Then pitch quick enough to avoid spores activating and taking hold. In that sequence.

I fact, I find dunking in a large body of water to be the most efficient - if possible.

 

[Ducatiboy stu]

This was the reply I got back. Written by someone who has a Phd

" Heat transfer is proportional to the mass flow rates of the two liquids concerned, so if you increase the flow rte of the cold liquid, you will increase the heat transfer. You can also increase it by reducing the temp of the cooling water. The formula is Q=mc(T2-T1) where Q is the quantity of heat being transferred, m is the mass flow rate, c is the heat capacity of the fluid ( a unique constant for any fluid) and T2 and T1 are the initial and final temperatures. So the important variable is the mass flow rate. So, make he coil with fatter tubing and up the flow rate to maximise the cooling. Where you will reach a limit is in the max flow rate you can get through the tube: fluids basically choke and reach a max flow rate.

 

[pk.sax]

That choke is called getting to compressibility and the ability of the source to supply the energy for the fluid to compress.

Like I said before, there are actually ways to trick the system to use good flow while getting optimal water usage. Flow rate isn't the only variable, fluids and heat transfer behave in ways.

Take that analogy of thousands of people running by a fire, well, the material of fire (pipe) will play a small part. I have a hunch steel is more radiative than copper. Copper is more conductive. Convection works a bit as well. Why some of the measured equipment will use slower flow is also because slower speed flow cases can be analysed to achieve best bang for the buck. High speed and compressible flows are more expensive to compute for their peculiarities.

Like, for example, if I am getting buffeting due to flow separation behind something in the wind I might try to put spoilers in the flow behind the object splitting the flow. It will cause the slower laminar flow to separate from the surface and mix with the faster vortex, effectively absorbing energy and reducing the buffeting effect of the separated flow.

In a pipe, a lower speed flow could be manipulated, creating local compression and decompression with minimal energy input required from the water source. Such tricks will ensure the water getting out is not laminar and has absorbed as much energy as possible in the time it took for it to make it from point a to b.
Really fast flow though is too energetic, there are less ways to create mixing as the pipe itself will channel the flow and cause it to get laminar. This is the source of inefficiency.

 

[Ducatiboy stu]

So can i buy a manipulator at Bunnings or the plumbers shop ?

 

[pk.sax]

If you so desire.

 

[Ducatiboy stu]

You got a description of said part so when I go in I can describe it to the bloke behind the desk

 

[pk.sax]

Vice grips

 

[Ducatiboy stu]

So your talking crimped tubing

 

[dago001]

You got a description of said part so when I go in I can describe it to the bloke behind the desk

Its right next to the variable flatuator. Aisle 6 I think. Ask for it, he will know what your talking about.

 

[Ducatiboy stu]

I love a pure engineers respons

Yes. Heat transfer is more efficient if the flow is turbulent.

 

[Ducatiboy stu]

.

 

[Ollieb]

Hi guys

So today was brew day and plumbed up the chiller all good and proper with new fittings from Bunnings.

Tested both theories that have been discussed with much enthusiasm on this thread.

Theory One: Increased/fast water flow will cool faster.

Theory Two: Decreased/slow water flow will cool faster.

Any one want to quickly wage a bet???

Drum roll please.... the winner is Theory Two; slower water flow cooled it faster.

Someone somewhere back on page who knows what suggested agitating the wort chiller every few minutes to assist in speeding up the process. This can also be confirmed and made a HUGE difference.

So there it is guys, thanks everyone for your input and I guess regardless of your theory or argument the results speak for themselves.

Thanks everyone for your input -until the next argument (ahem debate) chat soon and thanks for your time.

Ollie

 

[Black n Tan]

Hi Oilie glad to hear things went better. How did you compare the methods?

 

[Burt de Ernie]

Hi guys

So today was brew day and plumbed up the chiller all good and proper with new fittings from Bunnings.

Tested both theories that have been discussed with much enthusiasm on this thread.

Theory One: Increased/fast water flow will cool faster.

Theory Two: Decreased/slow water flow will cool faster.

Any one want to quickly wage a bet???

Drum roll please.... the winner is Theory Two; slower water flow cooled it faster.

Someone somewhere back on page who knows what suggested agitating the wort chiller every few minutes to assist in speeding up the process. This can also be confirmed and made a HUGE difference.

So there it is guys, thanks everyone for your input and I guess regardless of your theory or argument the results speak for themselves.

Thanks everyone for your input -until the next argument (ahem debate) chat soon and thanks for your time.

Ollie

I assume that you did two brews today and tested them side by side and agitated equally.

What flow rate did you run each chiller at?

 

[Ollieb]

I assume that you did two brews today and tested them side by side and agitated equally.

What flow rate did you run each chiller at?

Hey Burt - so I was not that technical and didn't do a side by side brew but i def agitated the same way and with the same energy. Basically a circular motion in the kettle which almost created a gentle whirlpool....

For the flow rate I tested a quarter turn of the tap and a half turn to figure out the flow rate.

I was very clear that the slower water flow worked better. As soon as you turned up the tap to the half turn mark it started flowing luke warm then after about 5 seconds to almost cold water.
Slow it down and within about 10-15 seconds the temp of the outflow increased heaps. Then agitate the chiller in the kettle and it dropped again.

Took me 30 mins to get it from boiling to 25 degrees. I was really happy with the results.

 

[Bribie G]

How about attaching a vibrator (massage type vibrator) to the copper pipe to break up laminar flow?

 

[Burt de Ernie]

Cool, now I understand....but I think you missed the point.

Nobody disputed that lower flow equals higher temperature discharge however, the temperature of the discharge water is not an indicator on how fast the wort is cooling.

The whole point to your thread is that you wanted to drop the wort temperature faster, not increase the temperature of the discharged cooling water.

The positive is that your experiment findings are useful if your intention is to use hot cooling water for cleaning your brewing gear.

 

[Burt de Ernie]

How about attaching a vibrator (massage type vibrator) to the copper pipe to break up laminar flow?

I don't think his mum will let him use it for that!

 

[TheWiggman]

Just as important as the flow inside the tube is the flow outside, as you found out. The more you move it around the better it'll work, otherwise you just chill the liquid in contact with the pipe. You want it to chill everything. 30 mins isn't all that long really. Though in Orange it maxed at 6°C today and I reckon it would have done the same just sitting there.
I'll bet a bag of snakes cranking the water up would have dropped your time, but it wouldn't have been much. Conserve water and carry on I say.

 

[TheWiggman]

Actually while you're experimenting, move the chiller around a bit with moderate flow until the water's coming out almost scalding hot. Then, drop it there and don't move it. Give it a min or 2 until it starts coming out cooler and then agitate the chiller again. It's crazy how much hotter it will come out just by doing that.