Crossflow condenser vs triple coil

Anything cooling/condenser related.

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sergiolis
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Crossflow condenser vs triple coil

Post by sergiolis »

Hi Guys!!!
I have a 3,5" Boka LM and also a 4" Boka packed with SPP. Right now I'm running the 3.5" column with a triple coil condenser and a cold finger inside a 4" spool. The coil is made with 8mm OD copper tube and probably the 3 coils together have about 15m lenght and about 25cm height. Sounds overkilling but It's not because i'm running at about 9-10KW. Anyway for the 3.5" rig is working nicely.
The problem is when I try to run with the 4" coulmn. I don't know where is the issue but it holds less power than with the smaller column. Maybe the bigger diameter increases too much the amount of vapour.

I need to solve this problem and my idea is to build a 3.5" Crossflow with 19 copper tubes of 3/8" OD diameter (9.52mm) and 24" lenght. Total lenght of copper tubes would be about 11.5 m. (Less than my triple coil)
Do you think that a crossflow is more efficient than a coil condenser?
Thanks in advance
Best wishes!!
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Re: Crossflow condenser vs triple coil

Post by Oatmeal »

I am all for badass builds, but a cross-flow condenser maybe solves a height issue more than a needing more knockdown problem?

If I was a helpful member, mumble mumble, surface area, waves hands, some math and then a succinct answer with a actionable plan. (And a picture of a perfect build)

But alas.

I really like corrugated stainless gas pipe to build condensers with.

If you build it, post a picture!
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Hi Oatmeal,
I don't really know wich one is more efficient... a member told me that the crossflow has a faster action because its natural parallel position. In a crosflow cold water is travelling for different pipes with a shorter distance. So there is cold contact surface all the time and distributed in many pipaes at the same time. So probably a crossflow is much more efficient.
Thanks for your help Oatmeal.
regards
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Re: Crossflow condenser vs triple coil

Post by LWTCS »

That's 38 linear ft.
If your coil has the same diameter tube and same length then the only other determining factor is dwell time
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Hi LWTCS!
Last edited by sergiolis on Fri Jan 28, 2022 7:07 am, edited 1 time in total.
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

LWTCS wrote: Thu Jan 27, 2022 4:00 pm That's 38 linear ft.
If your coil has the same diameter tube and same length then the only other determining factor is dwell time
Hi LWTCS!
So... do you think an equal lenght for a Crossflow has more dwell time than a coil?
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Re: Crossflow condenser vs triple coil

Post by LWTCS »

sergiolis wrote: Fri Jan 28, 2022 7:06 am
LWTCS wrote: Thu Jan 27, 2022 4:00 pm That's 38 linear ft.
If your coil has the same diameter tube and same length then the only other determining factor is dwell time
Hi LWTCS!
So... do you think an equal lenght for a Crossflow has more dwell time than a coil?
Well if you are trying to "ride hard and put away wet",,,maybe not.
I guess it depends where you are in your education / goals?

Once upon a time I wanted to go as fast as I could make it go without compromising ABV. Once I got that out of my system and started thinking more about the finished product rather than how much I could flog my apparatus, I kinda came full circle on my approach.

Say I bet you could stuff some scrubber material into the cross flow to create a bit more dwell time. Or(!!!) offset the inlet and outlet on the crossflow to ensure a bit more dwell. See now look what you've done to me :lol:
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

You are right LWTCS! the most important is the finished product!
My goal is to get Neutral. As clean as possible with my equipment.
But let's say if I can do it a bit faster it would be a bit better :)
I'm running a 3.5" Boka packed with SPP. However, my challenge right now is to check if i'm able to run a 4" Boka.
I had to build a triple coil condenser and I can tell you I couldn't put away wet to make it... It was hard! :D
Some days ago I tested with the 4" column and vapours went to heaven. Is mounted in a 4" pipe, It's at least 38 linear ft but it's not enough :?
I would love to build an overkilling condenser. If I can do it I won't have more concerns about sneaky vapours.
There is also a valuable asset in an overkiller condenser, I will waste much less water.
I love the idea and the concept but I'm not good enough in physics to figure it out how much tubes do i need... even i don't know what power I will need for a 4" Boka. SPP consumes a lot of power (my max. power is 13.5 KW). With 3.5" column i'm in the rank of 9.4 Kw at equilbrium and 10.8 Kw at the end of the run.
I was thinking on a Crossflow to save space. The idea is about 20" or 24" lenght and 32 tubes 3/8" OD (0.8mm wall thickness)
we say here: Heavy metal!!!
But if such condenser is able to knock down 14Kw I would love to build it :)
According to the calculator are required 19m of 3/8" pipe
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Re: Crossflow condenser vs triple coil

Post by LWTCS »

sergiolis wrote: Fri Jan 28, 2022 2:56 pm You are right LWTCS! the most important is the finished product!
My goal is to get Neutral. As clean as possible with my equipment.
But let's say if I can do it a bit faster it would be a bit better :)
I'm running a 3.5" Boka packed with SPP. However, my challenge right now is to check if i'm able to run a 4" Boka.
I had to build a triple coil condenser and I can tell you I couldn't put away wet to make it... It was hard! :D
Some days ago I tested with the 4" column and vapours went to heaven. Is mounted in a 4" pipe, It's at least 38 linear ft but it's not enough :?
I would love to build an overkilling condenser. If I can do it I won't have more concerns about sneaky vapours.
There is also a valuable asset in an overkiller condenser, I will waste much less water.
I love the idea and the concept but I'm not good enough in physics to figure it out how much tubes do i need... even i don't know what power I will need for a 4" Boka. SPP consumes a lot of power (my max. power is 13.5 KW). With 3.5" column i'm in the rank of 9.4 Kw at equilbrium and 10.8 Kw at the end of the run.
I was thinking on a Crossflow to save space. The idea is about 20" or 24" lenght and 32 tubes 3/8" OD (0.8mm wall thickness)
we say here: Heavy metal!!!
But if such condenser is able to knock down 14Kw I would love to build it :)
According to the calculator are required 19m of 3/8" pipe

I'm pretty sure that Harry's goal with the cross flow was to save ceiling height.
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Re: Crossflow condenser vs triple coil

Post by Yummyrum »

From a theoretical point , the crossflow isn’t ideal in my thinking .

Consider if the coolant flow is reduced so that the output side is warm to hot to touch , then the input side would be cold .
As it is a tee setup , the vapour is hitting the condenser midway and splitting each way . One end of the condenser would be more effective than the other end .

The distillate from one side would be warmer than that from the other .
Does this matter ? Probably not , I suppose the two returned reflux temps would average each other .

I’m thinking about over cooling of the top packing .
So if the coolant flow was increased so that the whole condenser is cold , instead of with a degree of gradient , would that lead to over cooling ?

Again , I’m just rambling some theoretical nonsense that I’d like to clarify .

Also , in that respect would a double wound coil minimise the effect as the in/out end would have both a cooler and warmer coil that would balance .
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Re: Crossflow condenser vs triple coil

Post by Saltbush Bill »

LWTCS wrote: Fri Jan 28, 2022 3:28 pm I'm pretty sure that Harry's goal with the cross flow was to save ceiling height.
The Jackson Crossflow, ceiling height was the main purpose as far as I remember it. :thumbup:
From memory there were no other advantages over other condensers used on top of reflux stills.
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Re: Crossflow condenser vs triple coil

Post by Oatmeal »

I'm still contemplating this. Any chance of some pictures of your two (current) condensing set ups? The 4" is allowing vapor to escape?

Could it be as stuffing some scrubbies in to increase cooling surface area?
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Hi Oatmeal!!!
Build 4" triple wound reflux condenser with coldfinger .
Build 4" triple wound reflux condenser with coldfinger .
Build 4" triple wound reflux condenser with coldfinger
Build 4" triple wound reflux condenser with coldfinger
This is my first version, I don't have pictures of the second one right now, but is improved with at least 3 more rounds. It's 30cm long, and 3/8" OD, 0.8mm wall thickness.
It's a beast and It is able to knock down about 11Kw but no more than that....
Is mounted in a 4" pipe but I'm using it in a 3.5" column working nicely, but when I tried to test it with 4" column It was working with quite less efficiency. I don't know why... maybe increasing the column diameter there is more vapour involved but it makes no sense....

Now my goal is to build one able to knock down 14kw... if having in mind some limits as space and money, I could go further I will do it.
I could add some scrubbers but there is not much space to push them...
Now I'm thinking to build a 4" quadruple wound with 1/4" OD tube. Smaller diameter but lenght would be significantly increased.
Thanks a lot for your help and ideas
Guys, so sorry about my catastrophic english :D ....
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Re: Crossflow condenser vs triple coil

Post by Salt Must Flow »

I would probably make a 4" or 6" Dephlegmator Reflux Condenser similar to this one. I'd make it anywhere from 12" to 14" or so. I'd probably use 1/2" OD copper pipes. Coils just don't have as much knockdown power per inch as Dephlegmators AKA shotgun condensers do. Shotgun condensers also use less water flow in comparison to coils (and Crossflow condensers if I'm not mistaken).

This calculator helps with determining what diameter pipes and pipe length is ideal for planning your condenser builds. Play around a LOT with this calculator. Your planning is the most important part of the build. If you use 12" long 1/2" OD copper pipes and at least 19 pipes ... you should have plenty of knockdown power for 11,000W.
Last edited by Salt Must Flow on Sun Jan 30, 2022 9:02 am, edited 1 time in total.
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Re: Crossflow condenser vs triple coil

Post by Saltbush Bill »

Salt Must Flow wrote: Sat Jan 29, 2022 6:19 pm Dephlegmator Reflux Condenser
A Dephlegmator , and a Reflux condenser do two different jobs , dont confuse to the two. A dephlegmator is a device arranged for the partial condensation of a multicomponent vapor stream.
https://www.thermopedia.com/content/691/
A reflux condenser is designed to knock everything down.
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Re: Crossflow condenser vs triple coil

Post by Yummyrum »

Salt Must Flow wrote: Sat Jan 29, 2022 6:19 pm Shotgun condensers also use less water flow in comparison to coils (and Crossflow condensers if I'm not mistaken).
I’m not sure I agree .
Its all about transferring heat into the water .
For the same flow of water , it doesn’t matter what design the condenser is . So long as there is sufficient dwell time to transfer the heat from one side of the copper to the water side . IE you are not exceed the vapour speed so it shoots past the condenser .

The material the condenser is made of will have a bigger bearing . IE , glass condensers are very poor , stainless better , but copper with its high conductivity is significantly better than stainless .
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Re: Crossflow condenser vs triple coil

Post by Salt Must Flow »

Saltbush Bill wrote: Sat Jan 29, 2022 7:01 pm
Salt Must Flow wrote: Sat Jan 29, 2022 6:19 pm Dephlegmator Reflux Condenser
A Dephlegmator , and a Reflux condenser do two different jobs , dont confuse to the two. A dephlegmator is a device arranged for the partial condensation of a multicomponent vapor stream.
https://www.thermopedia.com/content/691/
A reflux condenser is designed to knock everything down.
That's why I said, "Dephlegmator Reflux Condenser similar to this one". And I said, "Coils just don't have as much knockdown power per inch as Dephlegmators AKA shotgun condensers do".

I also elaborated with my final paragraph regarding 100% knockdown power (100% reflux). I am not confusing anything. I'm pointing out that coil designs do not have the same knockdown power per inch as Dephlegmator/shotgun reflux condenser designs do.

Do you have an argument against any of my claims or are you just trying to argue semantics? Are you claiming that the design I proposed is less effective than a coil?
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Re: Crossflow condenser vs triple coil

Post by Salt Must Flow »

Yummyrum wrote: Sat Jan 29, 2022 7:18 pm
Salt Must Flow wrote: Sat Jan 29, 2022 6:19 pm Shotgun condensers also use less water flow in comparison to coils (and Crossflow condensers if I'm not mistaken).
I’m not sure I agree .
Its all about transferring heat into the water .
For the same flow of water , it doesn’t matter what design the condenser is . So long as there is sufficient dwell time to transfer the heat from one side of the copper to the water side . IE you are not exceed the vapour speed so it shoots past the condenser .

The material the condenser is made of will have a bigger bearing . IE , glass condensers are very poor , stainless better , but copper with its high conductivity is significantly better than stainless .
I made a 2" Shotgun product condenser with just over 24" of water jacket with 7 copper pipes and it easily knocks down 5500W with a single element in stripping runs as a product condenser. I also made a nearly identical length 2" double copper coil condenser and it could NOT handle 5500W at full water flow on my home water pressure for stripping runs. The shotgun worked flawlessly and used SIGNIFICANTLY less water flow. For that reason I pulled the double coil and made it a shotgun condenser so both shotgun condensers could be joined together to handle 11,000W for stripping runs.

The Dephlegmator/shotgun style design is more efficient with water consumption and has more knockdown power per inch than coil condensers (and Crossflow condensers if I'm not mistaken). Sure you can use a less effective & less efficient coil condenser and turn down your power to allow it to do do what they can do, but that was not he point of my original post. My original post was to point out that there is a more effective and a more efficient reflux condenser design. That is all.
Last edited by Salt Must Flow on Sat Jan 29, 2022 10:04 pm, edited 3 times in total.
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Re: Crossflow condenser vs triple coil

Post by Saltbush Bill »

Salt Must Flow wrote: Sat Jan 29, 2022 7:27 pm Do you have an argument against any of my claims or are you just trying to argue semantics?
I'm not arguing anything , I was simply pointing out a fact, the way that you wrote ""Dephlegmator Reflux Condenser" could easily cause confusion for some people.
There is enough confusion already with many newbs not knowing the difference between the two.
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Re: Crossflow condenser vs triple coil

Post by Oatmeal »

Let's see. Creo que el englese tuo es mejor que el espanol mio!

A modular type shotgun condenser seems like a pretty pragmatic solution to increase your cooling needs, and you get to build something too.

(Clever suggestion salt must flow!)

Nice coil by the way sergiolis! I'm assuming 11,000 watts is working towards a semi- aquatic environment? Seems like alot of power. I did better last time keeping my flood towards the base, rather than the top of the packing, but still learning to drive....errr; drifting off topic here, sorry!
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Re: Crossflow condenser vs triple coil

Post by LWTCS »

Yummyrum wrote: Sat Jan 29, 2022 7:18 pm
Salt Must Flow wrote: Sat Jan 29, 2022 6:19 pm Shotgun condensers also use less water flow in comparison to coils (and Crossflow condensers if I'm not mistaken).
I’m not sure I agree .
Its all about transferring heat into the water .
For the same flow of water , it doesn’t matter what design the condenser is . So long as there is sufficient dwell time to transfer the heat from one side of the copper to the water side . IE you are not exceed the vapour speed so it shoots past the condenser .7

The material the condenser is made of will have a bigger bearing . IE , glass condensers are very poor , stainless better , but copper with its high conductivity is significantly better than stainless .
Good point that I didn't include yummy.
Yes copper is a much better heat sink.

I didn't mean to over simply. Copper sure did turn out to be perhaps the most amazing material ever. A miracle really.
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Thank you very much for all your comments.
Finally I decided to connect a piece of 30cm, 6" tube to make more space for one or 2 coils more. I think is the easiest solution
A quintuple coil reflux condenser sounds good !
Thanks!!!!
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Done!
quadruple coil coldfinger reflux condense, webr.jpg
quadruple coil coldfinger reflux condenser, about 30m of 8mm OD copper tube :)
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Re: Crossflow condenser vs triple coil

Post by Yummyrum »

Whoo :esurprised: ….Love it :thumbup:
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Re: Crossflow condenser vs triple coil

Post by Oatmeal »

Yep. Really sweet!
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Re: Crossflow condenser vs triple coil

Post by still_stirrin »

sergiolis wrote: Mon Feb 28, 2022 1:40 am Done! —> quadruple coil coldfinger reflux condenser, about 30m of 8mm OD copper tube
Boom! Can you say, “overkill”? Massive knockdown!
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Re: Crossflow condenser vs triple coil

Post by zapata »

Looks like I'm late to the party. I'm pretty sure the crossflow was designed to serve 3 purposes in equal measure. 1. Save height 2. be water and energy efficient 3. be an innovative design because that was Harry's 2nd favorite part of the hobby :) I'm pretty sure his introduction was even titled something about saving water, and included the relatively novel at the time circulating pump and radiator. They are more efficient than equal length of equal D coils because they have much lower pressure drop on the coolant side (ie far more flow than typical coils under equal pressure/pump). Also they maintain a higher average delta T than a coil because of the more, shorter tubes each being fed fresh coolant.

Anyway, I have one, I love it, I wouldn't build it again. And in fact I didn't build it again even though I long ago outgrew the designed power of the original. If I wanted the height savings, I'd go with more of a Thor's Hammer approach using a coil to replace the cross tubes. But I'd make that coil from CSST. I think with CSST you can minimize the advantages the crossflow style has over traditional smaller diameter coils while simplifying the build significantly.

Or you could just build a crazy quad coil, but might as well turn it sideways to save the height :)
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Boom! Can you say, “overkill”? Massive knockdown!
Yes it has more efficiency than the required but the idea is to get just a slight difference between vapours temp. and condensate temp. Looks like it helps to compress heads. If it's true you can save time and booze.... I would like to see output water at 75ºC, meaning that a great amount of higher alcohols are evaporated and not returning to the column...
They are more efficient than equal length of equal D coils because they have much lower pressure drop on the coolant side (ie far more flow than typical coils under equal pressure/pump). Also they maintain a higher average delta T than a coil because of the more, shorter tubes each being fed fresh coolant.
I build it with individual coils to reduce the pressure back, There are 4 coils but also 4 water paths. It's only a supposition but for a given water flow in a crossflow condenser it will be divided between all of the tubes resulting less efficiency per tube than in a coil... :D it's complicated, there are several factors involved. We would need many tests with different condensers to get real facts. I just decided to enlarge an old triple coil because it was the easiest and cheapest solution for me..... i was also worried about the weight of a big Crossflow...
CSST is wonderful for a 2" or 3" columns because a simple dimroth do the job but if one wants to build a double or triple coil is too complicated because CSST is too flexible. It would need a grid or structure just to place the different coils. Anyway a long horizontal CSST coil sounds really good!!!!!
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Re: Crossflow condenser vs triple coil

Post by Oatmeal »

Nice comment Zapata, informative as always - and my ignorance once again astounds me!

I think I'll keep my eyes open for a scrap of 3/4 csst to build a larger diameter coil with, just to see.

Have you run with your condenser yet Sergiolis? I hope you'll share your results!
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Re: Crossflow condenser vs triple coil

Post by sergiolis »

Have you run with your condenser yet Sergiolis? I hope you'll share your results!
Not yet, I,m waiting to have more feints.... :)
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