Reflux Coil with a Difference

[Andrew_90]

Getting ready to make a single helix 2" reflux coil so wanted opinions.

1. I can make a single helix and stuff it with copper scourers?

or

2. I can use a piece of 1.5mm x 32mm OD copper tube as the former and keep the former as part of the reflux coil. Just soldering in one or two strategic spots to keep the helix attached to the tube. I can fill the tube with copper scrubbers.

Which would be more efficient?

[shadylane]

I know it sounds counter intuitive, but
Either design will work better without the copper scrubbers.

[Andrew_90]

I was concerned that with the tube in place, that the condensate path downwards on the outside would be hindered by the helix being attached to the tube.

Curious on you scrubbers position?

[tiramisu]

... or you could use some csst and save a bunch of work and money.

I just bought a 48" 5/8 od 1/2 id length of uncoated csst off of fleabay for about 30USD.
"gas flex line"
there is also 1/2 od 3/8 id if you are feeling like being more matchy matchy with copper dimension.

On a 3" column I need to twist up about 12" so that should be around 36" with 6" on the end left over and the come pre-fabbed with 1/2 compression fitting so hook the water up so no fabrication required.

I really like the idea of copper but the CSST is too hard to pass by given the price and convenience.

[Andrew_90]

Will have a look, thanks.

Is the theory still that the coldest part of the coil is furthest away from the condensation as with a Liebig? So water would come in at the top and work its way down?

[Yummyrum]

Is the theory still that the coldest part of the coil is furthest away from the condensation as with a Liebig? So water would come in at the top and work its way down?

Yes

2. I can use a piece of 1.5mm x 32mm OD copper tube as the former and keep the former as part of the reflux coil. Just soldering in one or two strategic spots to keep the helix attached to the tube.

I wouldn’t . The vapour hitting the inner area will tend to flow straight though it In a laminar flow and 32mm is relatively big so there will be an area in the middle that is not cool .Obviously some vapour will contact the coil in the space between the coil and outer wall .

If you remove the 32mm former tube , the vapour will tend to be more turbulent as it spirals up the inside of the coil . This will cause more of the vapour to contact the cool area around the coil.

However , you will probably have the bottom end of the coil return up the middle of the coil or use a bigger cold finger which should help with the centre laminar flow issues but I still think that It will be superior without the former soldered in place .

[Andrew_90]

I do agree, I was a little worried about the flow.

Thanks all.

[Birrofilo]

Is the theory still that the coldest part of the coil is furthest away from the condensation as with a Liebig? So water would come in at the top and work its way down?

I am confused by the answer given by @Yummyrum.

Water normally in a Liebig condenser, as in any condenser and in a dephlegmator as well, comes from the bottom and works its way up. That's because if you insert the water from the top and let it fall, it will not flood the condenser. You want the condenser to be full of water to work at its best. Cold water always comes from the bottom.

[Deplorable]

I know it sounds counter intuitive, but
Either design will work better without the copper scrubbers.

+1
I've only done 2 runs with mine, but this has been my experience.
It was a lot more efficient without the copper mesh.

[Andrew_90]

[/quote]
+1
I've only done 2 runs with mine, but this has been my experience.
It was a lot more efficient without the copper mesh.
[/quote]

Thanks for the confirmation.

[Andrew_90]

[/quote]
I am confused by the answer given by @Yummyrum.

Water normally in a Liebig condenser, as in any condenser and in a dephlegmator as well, comes from the bottom and works its way up. That's because if you insert the water from the top and let it fall, it will not flood the condenser. You want the condenser to be full of water to work at its best. Cold water always comes from the bottom.
[/quote]

So yes flooding on the Liebig is part of it but I think the other part of it is to have temperature gradient.

[Yummyrum]

Ideally a condenser should run in counter flow to the vapour to minimise shook cooling where they meet .

In the case of a liebig , the vapour hits the top of the condenser first , so the cool water should enter the bottom .

In a reflux condenser , the vapour hits the bottom of the coil first , so the cool water should enter the top .

Same goes for a Deflagmator . But 99.9% of deflags are tube in shell types and not coils . In practice it has been found that filling and running a tube in shell Deflag in counterflow is difficult because of air pockets that develop unless air bleed off valves are fitted .

So it has become the norm to run a Tube in shell deflag in contra flow , IE cool in the bottom even though it is not the ideal way to run a condenser .

Using a coil condenser is less prone to developing air bubbles so it can be run in counterflow .