Flat Vs Round Heat Exchange Coils

[sijani]

Hello brewers. I've been lurking for about two weeks reading and researching equipment and methods.

I've got a hundred questions but anyway this one first.

As the title says. Has anyone tried flat tube vs round tube for heat exchange? Looking at the profile (flat) it would seem the distance from the centre to the outside is much less so the liquid would heat or cool faster. Coiling it tightly is the only drawback. Unless it's a flat coil. I'm curious to know what the differences are in heat/cool times and would it make that much of a difference.

Anyone tried this before or anyone willing to flatten their round coil Wouldn't be that hard to with a set of rollers or patience with a mallet.

 

[newguy]

Do you mean the HE in a HERMS or are you talking about making your own counterflow wort chiller or an immersion chiller? The expensive counterflow chillers actually use kind of a "braided" structure....imagine flattening your coil N-S for a few cm, then changing the orientation of the flattening to E-W for a few cm, then back to N-S, and so on..... This type of arrangement pretty much guarantees turbulent flow within the coil, which leads to more efficient heat transfer. I hope this makes sense as it's damn difficult to convey what I mean without being able to draw it.

 

[Adamt]

I'm guesing you mean square tubing? In the end it doesn't really matter about "distance from the centre", although the integral-weighted average of this distance is smaller for a circle than a square (of same cross-sectional area). It doesn't matter as it is desirable to have turbulent flow through the chiller. Turbulence increases heat transfer within the fluid, among other things. With turbulence it can be assumed that the temperature is effectively constant throughout the cross section of the pipe, at any portion of the pipe.

Some brewers convolute their immersion chillers with a series of minor flattenings in the circular tube to aid achieving a turbulent flow. EDIT: This is what Newguy ^ is talking about.

 

[sijani]

....imagine flattening your coil N-S for a few cm, then changing the orientation of the flattening to E-W for a few cm, then back to N-S, and so on.....

I get what you mean. So turbulence is also an important factor.

Adamt, I meant round tubing flattened to an elipse.

I want to come up with 3 seperate designs for HERMS (seperate, small volume, fast temp response) and wort chilling (counter flow) and cooling/warming via an insulated jacket on the fermentor (slow circulation high efficiency).

I'm feeling the waters to see which type of heat exchanger works best for what.

Cheers.

 

[Hutch]

I get what you mean. So turbulence is also an important factor.

Adamt, I meant round tubing flattened to an elipse.

I want to come up with 3 seperate designs for HERMS (seperate, small volume, fast temp response) and wort chilling (counter flow) and cooling/warming via an insulated jacket on the fermentor (slow circulation high efficiency).

I'm feeling the waters to see which type of heat exchanger works best for what.

Cheers.

Hi sijani,

Just in relation to the wort temperature control, if you are implying using a coil internally, then my advice would be "stainless, NOT copper".
Many years ago I used a copper coil internally, not thinking too much about the effect of an acidic solution on copper over a prolonged period.
Not surprisingly the coil came out sparklingly clean after fermentation, and the beer had a very slight metalic twang (then again I wasn't making the best beer, so hard to tell how much copper was responsible!). Anyway, it is not advisable to ferment in copper, or use copper fittings/coils for long periods in the acidic environment of fermenting beer.
A better (though still cumbersome) option would be a cooling jacket around the fermenter. I also toyed with this idea for a while, though fabricating a perfectly sealed jacket to pump glycol around the HDPE fermenter proved very difficult. If it is suitable to your brewery, I seriously advise going down the well-troden path of "fridge + Fridge-mate" temp control. Very easy, and far more useful for fermentation, crash-chilling, lagering, kegging, etc.

Cheers,
Hutch.

 

[kirem]

I'd have to agree, although the thermal properties of copper are better than stainless steel. I found my Heat-exchanger gives great performance with a stainless coil.

I choose stainless, so I can use just about anything to clean and sanitise during a CIP run.

http://www.aussiehomebrewer.com/forum/inde...st&p=343611

 

[Tony M]

....imagine flattening your coil N-S for a few cm, then changing the orientation of the flattening to E-W for a few cm, then back to N-S, and so on.....

Let me put it in pictures for you. I did this with an old pair of multigrips that I ground the grippy bits off.

 

[sinkas]

where can you get the SS flat coils?

 

[kirem]

where can you get the SS flat coils?

Got mine on ebay

 

[kirem]

there is also the convoluted copper pipe
View attachment 24951
View attachment 24952

 

[sinkas]

what was/are they listed as?

 

[sijani]

The convoluted pipe looks the ducks guts. What's the price difference compared to standard pipe?

@ Tony M - great job! How is the flow? Do the squished bits reduce flow noticeably ?

I want to build a conical fermenter and wrap a coil of copper tubing around it then add an insulated jacket over that. But it's gonna be expensive (copper wise) slow to react and a total PITA isn't it.

How do you temp control a conical fermenter? i.e. for lagering.

Can you pre flush with a mild acid (citric or diluted acetic?) the H.E.(s) before the introduction of the wort?

 

[hockadays]

Put it in a upright freezer is the easiest option.

 

[kirem]

what was/are they listed as?

I forget what they were listed as.

I actaully won two of them and ended up selling the extra one.

Maybe stainless coil. They were out of a miracle box setup, so maybe look for glycol system, can't see any for sale at the mom.

Any news on quinine