Wort Chiller Just Ain't Chillin

[dago001]

Oh ****. I give up. Argue amongst yourselves, telling each other how smart you are. The flat earth society is gaining new members by the minute.

 

[The Judge]

Any other Chemical Engineers out there ?

I'm a Process Engineer, specialising in thermohydraulics!

 

[pk.sax]

Sorry mate I do not agree with the first part of this statement. More water flow will result in more heat exchange, but the result is just less temperature difference in the water in vs out. I do not disagree however, with the expense part. Of course you will use more water in the process which costs more.

Any other Chemical Engineers out there ?

Chem engineers are girls

 

[Goose]

It will take longer if the flow rate is too fast. What I said in my first post. They are both relative. Heat transfer efficiency is effected by flow rate. Feldons post sums it up nicely.

With all due respect, this is incorrect. Do not be confused by heat (change in temp x specific heat x weight of medium) vs temperature change alone.

I believe the theory is that the faster the flowrate the higher the turbulence in the pipe and the faster it will conduct heat away from the surface it contacts.

Anybody got a copy of the classic text "Process Heat Transfer" by Kern ?

 

[Not For Horses]

I'm just theorising here but could it have something to do with boundary layers?

Pipes have a relative roughness (k value from memory) causing a turbulent boundary layer between the pipe and the liquid flowing through it. A slow flow rate would have much less or even no boundary layer.
A boundary layer would mean that the cool water was no longer in contact with the hot copper but rather with the hot water in the boundary layer.
Water to water is a much slower conducter of heat than water to copper resulting in less heat transfer at higher flow rates.

I say again, only theorising.

 

[Burt de Ernie]

Its not that hard. Theory and science are all very well. But you have know how to apply it.

When cooling your wort with an immersion coil you want the exit cooling water to be as hot as possible. This means that the water is extracting the heat in the wort to the maximum potential of your cooling system (ie. whatever type of coil you use; whatever mains water pressure you have; whether or you jiggle the coil or not, etc, etc, etc).

This is incorrect. Slowing the flow will bring efficiency to water consumption at the loss of time to chill wort.

I get that you will have hotter discharge water however I would rather exchange 100 watts of heat using ten litres of water in one minute than 100 watts using five litres of water in two minutes.

 

[Burt de Ernie]

Any other Chemical Engineers out there ?

Im hydraulic!

 

[Goose]

Many examples out there:

 

[Burt de Ernie]

Oh ****. I give up. Argue amongst yourselves, telling each other how smart you are. The flat earth society is gaining new members by the minute.

I don't know you personally...im sure you are a nice guy but this is an arrogant statement and surely not needed.

I believe it was you who qualified yourself first as a heat exchange expert all because you have been cleaning them for the last 25 years.

 

[Feldon]

This is incorrect. Slowing the flow will bring efficiency to water consumption at the loss of time to chill wort.

I get that you will have hotter discharge water however I would rather exchange 100 watts of heat using ten litres of water in one minute than 100 watts using five litres of water in two minutes.

You need to re-read my post and try (really hard) to understand it.

 

[Burt de Ernie]

You need to re-read my post and try (really hard) to understand it.

I do understand it.....you are arguing that faster flow doesn't chill faster which is contrary to all evidence presented in this thread.

 

[Feldon]

I do understand it.....you are arguing that faster flow doesn't chill faster which is contrary to all evidence presented in this thread.

I'm not saying that at all. I'm saying that the cooling system has an upper limit after which increasing water flow will not have any further effect.

You are saying that the system has infinite cooling potential. By your reckoning if you could squirt a billion litres of water through the coil in a few seconds it would cool the wort almost instantly. It won't.

I understand you've gone out on a limb here, but time to climb down from your tree.

 

[Burt de Ernie]

You are saying that the system has infinite cooling potential. By your reckoning if you could squirt a billion litres of water through the coil in a few seconds it would cool the wort almost instantly. It won't.

Ummm....I never said anything like this I think you are putting words in my mouth.

I have said that you will lower chill time by increasing chiller surface area and also that I disagreed that by slowing flow chill time will decrease .

That's it

 

[Parks]

This is exactly the misunderstanding that is turning this thread sour.

Feldon is saying that increased flow won't necessarily make it cool faster.
LagerBomb is saying that at a point increased flow actually cools slower.
Others are talking about heat exchange efficiency and wasted water.

 

[Not For Horses]

And I'm now scratching my head thinking about turbulent and laminar flow...

 

[danestead]

Mods...... this thread has turned pathetic

 

[pk.sax]

Crybaby

 

[Goose]

And I'm now scratching my head thinking about turbulent and laminar flow...

Reynolds number

 

[Ducatiboy stu]

One thing I have noticed, in a pure practicall suck it and see method is that the temp drop from say 100*-70* is quicker than from 40*-20*. As for the the theory as to how & why, I couldnt care less.

As for flow rate v time v temp drop....I have no idea. But know someone who used to lecture thermo dynamics at Melb Uni so they prop would.

 

[wide eyed and legless]

Just purely from a logical point of view, what we are doing is exchanging the heat from the wort through the copper (copper is a far better conductor of heat than s/s ) to the water running through the copper tube, there would I imagine, be a set flow rate for the efficient transfer of heat from the copper tube the the cold water, so just thinking logically for the cold water to pick up the heat from the copper I wouldn't imagine it travelling to fast.