Shotgun Proportions

[Demy]

I am a happy user of a simple liebig (1/2 "tube with coiled wire) and it works perfectly despite being only 50 cm long. I have small changes in mind so I would need to shorten the size and I thought about this type of condenser.
Questions for owners: 1) by calculating the volume (inside the tube) of my liebig I would have a guide on what (minimum) volume to keep with the shotgun (adding the volume of all tubes) right?
2) Is it possible to use 1/4 diameter pipes or are there any contraindications? I would like to keep things small and light, that work but not too oversized. 3) Regarding the water jacket, is it the same as the liebig (i.e. a minimum thickness = little space between the pipes where the steam flows)?

[Bushman]

Not sure I would use 1/4” but here is a video for calculating fluid contact area. I believe that is what you are asking for. On my product condenser I went for the wow look and it is an overkill. The water I throw at mine is about a trickle because of the length and twisted tubes.

[Demy]

Thanks Bushmann, I think this outweighs my need for refrigeration ... too scientific
I just wanted to apply the volume of my current liebig which I know works well in a small rifle.

[Setsumi]

if using 1/4" tube for vapour path your vapour will speed up.... if you use enough to give the same as say 3 x 15mm tubes, maybe but bigger vapour paths slow vapour and increase efficiency.

[Bushman]

Thanks Bushmann, I think this outweighs my need for refrigeration ... too scientific
I just wanted to apply the volume of my current liebig which I know works well in a small rifle.

I have read a lot of technical books on formulas for calculating this and that. This video for me was the clearest explanation I have found so far.
You joined after I built my newest still below is a picture of my setup and you can see that my product condenser is way overkill.

[Demy]

if using 1/4" tube for vapour path your vapour will speed up.... if you use enough to give the same as say 3 x 15mm tubes, maybe but bigger vapour paths slow vapour and increase efficiency.

Thanks, the concept of vapor acceleration is correct but I thought that the same vapor is distributed over multiple pipes (even if small in diameter) so I believe there is a balance, but that's just my thought.
P.S. Only if you want to answer, how are your eyes?

[Demy]

Thanks Bushmann, I think this outweighs my need for refrigeration ... too scientific
I just wanted to apply the volume of my current liebig which I know works well in a small rifle.

I have read a lot of technical books on formulas for calculating this and that. This video for me was the clearest explanation I have found so far.
You joined after I built my newest still below is a picture of my setup and you can see that my product condenser is way overkill.
5B024A66-E033-4FDA-AE9B-2BE87F1E2CC0.jpeg

It is an authentic work of art, it looks like a statue. I think it is really oversized!

[Bushman]

Yes it is oversized but like I said I was shooting for the looks as well as performance. Also I must say that it is not my design although I helped build it. The design was first introduced to the forum by a member that past a few years back, was a professional glassblower, and came up with the jig to bend the tubes. I learned a lot about manufacturing from him his name was Mash Rookie.

[Setsumi]

if using 1/4" tube for vapour path your vapour will speed up.... if you use enough to give the same as say 3 x 15mm tubes, maybe but bigger vapour paths slow vapour and increase efficiency.

Thanks, the concept of vapor acceleration is correct but I thought that the same vapor is distributed over multiple pipes (even if small in diameter) so I believe there is a balance, but that's just my thought.
P.S. Only if you want to answer, how are your eyes?

eyes are fine, thanks for asking

[Demy]

Yes it is oversized but like I said I was shooting for the looks as well as performance. Also I must say that it is not my design although I helped build it. The design was first introduced to the forum by a member that past a few years back, was a professional glassblower, and came up with the jig to bend the tubes. I learned a lot about manufacturing from him his name was Mash Rookie.

It's a great job, it deserves all my appreciation, it was a compliment. I looked for the profile of the user you mentioned, you were right to remember it, thank you very much for the thought.

[Demy]

eyes are fine, thanks for asking

This is the most important thing, I'm happy.

[Berserk]

The exchange area of your cooler is more important than the volume when calculating cooling capacity, since that's where the hot vapors and cool water meet (with copper in between, of course).

The distance between the center of tubes in a shell-and-tube heat exchanger (shotgun condenser) should be between 1.25-1.5 of the outer dimension for optimal performance. So 10mm OD tubes should be spaced with 12.5-15mm center to center, or 2.5-5mm distance between the outsides of the tubes.

If you're going to use 1/4", make sure that the distillate actually can flow out of the pipes and don't get stuck due to surface tension etc.

[Demy]

The exchange area of your cooler is more important than the volume when calculating cooling capacity, since that's where the hot vapors and cool water meet (with copper in between, of course).

The distance between the center of tubes in a shell-and-tube heat exchanger (shotgun condenser) should be between 1.25-1.5 of the outer dimension for optimal performance. So 10mm OD tubes should be spaced with 12.5-15mm center to center, or 2.5-5mm distance between the outsides of the tubes.

If you're going to use 1/4", make sure that the distillate actually can flow out of the pipes and don't get stuck due to surface tension etc.

Thank you very much, I have read somewhere this distance but I have never been interested in shotguns. It is a good point. So I guess a thin water area around the pipes is better, like in the liebig.

[RC Al]

The same topic also gave guidelines for baffles, 37% cut out and spaced at 1/2 diameter, but with a minimum of 2"

The very small diameter will make soldering intresting to say the least

[Demy]

The very small diameter will make soldering intresting to say the least

I read in your mind ..... good luck! (quite right?)

Now I'm serious, thanks for the info!
I think this was the original post, right? https://homedistiller.org/forum/viewtop ... 87&t=67493
Perhaps the use of deflectors is a bit exaggerated as emphasized by someone in that post.

[Berserk]

That is indeed the post.

Adding baffles might be a bit overkill, depending on how big and long you intend to make the shotgun. If you're using a boatload of 1/4" tubes it might not be worth the effort soldering, but it will increase the efficiency of the condenser.

I read a study on baffles and the conclusion was that baffles make tube-and-shell heat exchangers 20-35% (IIRC) more efficient. NB: in the study they used water both in the shell and the tubes, so I'm not sure how applicable it is to our usage.

Baffles should be spaced with a distance that is max the ID of the shell, and min 1/5 of the shell ID OR 2", whichever is greatest. The min 2" is a standard from the American Heat Exchanger Builders Organization (or something like that), but I believe it's not necessarily applicable to our condensers since they mostly handle big industrial heat exchangers that need to be cleaned shellside etc, and anything spaced under 2" might be hard to reach/clean.

[Twisted Brick]

Now I'm serious, thanks for the info!
I think this was the original post, right? https://homedistiller.org/forum/viewtop ... 87&t=67493

I love that post! Not only for the anecdotal evidence on heat transfer but for its investigation into a condenser geometry with performance potential to exceed even the most effectively modified and lengthy liebig. For me, it was a perfect example of the average distiller's nagging need to monkey around with distilling stuff and confirmed that its okay to question current practices with the hopes of improving things. Kind of like the thinking that led to the CCVM still or the constant debate over which column packing is the most effective.

The data Zapata compiled was thoroughly researched and presented, I must have read it a dozen times. It made quick work of deciding on specs for my condenser for sure. I went with a 4 x 1/2" vapor tube design, but there is an elegant 3-vapor tube build here somewhere. It might scale nicely to your still and has the potential to provide unlimited stripping speeds.

Perhaps the use of deflectors is a bit exaggerated as emphasized by someone in that post.

If you're referring to detractors of shotgun condensers, one cannot argue with the fact that a liebig is a no-brainer for cost and ease of construction. A liebig is perfect for the distiller who wants to build his condenser, doesn't mind supporting the length and wont be applying the energy to overpower it.

With the manageable 50cm length of your liebig, I'm curious why you want to change it? How much power are you applying to your boiler and how short do you want to go? The reason I ask is that a shotgun condenser is inherently effective at dividing the incoming vapor from the boiler and slowing it down to maximize condensing dwell time. I don't have hard data, but I believe a 35cm (14-15") copper shotgun (with an unofficial equivalent to a 56-60" liebig) would provide even more performance you might be looking for. Another member is currently on track to test this shorter length and will be able to report how much power it can effectively handle.

[Twisted Brick]

Adding baffles might be a bit overkill, depending on how big and long you intend to make the shotgun. If you're using a boatload of 1/4" tubes it might not be worth the effort soldering, but it will increase the efficiency of the condenser.

On long spirit runs my 30gal coolant reservoir tends to get hot (120F) and that is when I appreciate having 7 baffles in my 20" shotgun.

I read a study on baffles and the conclusion was that baffles make tube-and-shell heat exchangers 20-35% (IIRC) more efficient. NB: in the study they used water both in the shell and the tubes, so I'm not sure how applicable it is to our usage.

Baffles should be spaced with a distance that is max the ID of the shell, and min 1/5 of the shell ID OR 2", whichever is greatest. The min 2" is a standard from the American Heat Exchanger Builders Organization (or something like that), but I believe it's not necessarily applicable to our condensers since they mostly handle big industrial heat exchangers that need to be cleaned shellside etc, and anything spaced under 2" might be hard to reach/clean.

A friend of my wife's builds and repairs commercial shell and tube condensers and the head designer and I have spent a number of hours discussing condenser design and baffle performance . One aspect we tend to forget is that shell and tube condensers operate with a specific internal pressure that affects heat transfer, and baffles help create that pressure.

Some examples of their work.

.

[Berserk]

Twisted Brick, that's very cool!

Don't get me wrong, I'm all for baffles and optimizing the shotgun and intend to cram a whole bunch in my shotgun once I build it. I'm just saying that it will take some effort getting all the baffle holes to line up if one uses 12-15x 1/4" tubes instead of for example 4x 1/2".

When I first read zapata thread I read through the chapter on tube and shell exchangers in the Heat Exchanger Design Handbook and got to thinking: why don't we route the vapor through the shell?

What I've gathered from some googling is that some larger distilleries do it this way, which I think makes sense. The vapor path is wider, so the velocity will be slower, and the cooling area of the tubes will be bigger since it's the outsides of the tubes not the insides. The only drawbacks I can think of is smearing, being a PITA to clean, and probably being a bit harder to manufacture. Still, it intrigues me.

[RC Al]

The original post on MD was a bit more in depth, there was even an excel calc for the baffles. Zapta ran some numbers, on paper a single baffle in a 4" RC was worth an additional 40% of knockdown.

Take from that what you will, bit it seems silly not to use them in short condensers if even half that level of improvement is obtained.

[Demy]

With the manageable 50cm length of your liebig, I'm curious why you want to change it? How much power are you applying to your boiler and how short do you want to go? The reason I ask is that a shotgun condenser is inherently effective at dividing the incoming vapor from the boiler and slowing it down to maximize condensing dwell time. I don't have hard data, but I believe a 35cm (14-15") copper shotgun (with an unofficial equivalent to a 56-60" liebig) would provide even more performance you might be looking for. Another member is currently on track to test this shorter length and will be able to report how much power it can effectively handle.

Right question. Mainly for a practical question, I want to create a head (with a cap) to be placed on various columns (pot-still, CCVM etc ...), the terminal part (where the product comes out) will be adjustable and separable. I do not use tri-clamp But welds. I would like to maintain the length on 30cm always for a matter of adaptability of my idea.

[Demy]

I am trying to read as much as possible on the subject and it seems that the 1/2 "inner tubes are the most efficient / used. But I would like to use a diameter of 30 mm for the main tube, so I think 3/8 will fit better (I think there are 4 tubes), I did not do calculations it is just an idea on the fly, thoughts on this? Another question, the length will only be 30 cm, is a deflector necessary? Do you have a good design? Consider that I start from tubes in a roll so i should straighten up.

[StillerBoy]

Here's what my 14 x 1 1/2 x 5 - 3/8" tube with 3 inner baffles looks like.. knocks down up to 4500 watt of power with less than a liter of water flow..

Mars

[Twisted Brick]

That is one tidy (and shiny) shotty, Mars.

[StillerBoy]

Thanks TB.. it was made some yrs back now, and its had lots of distillate flow through it and well it works.. and have made a good number of both shotguns and dephfametor, and their efficiency is in the number of baffle plates and their design..

The points that makes a shotgun effective are the number of baffle plates used, their placement and how the baffle plates restrict the water flow.. a condenser requiring a fast water flow through the condenser is not an efficient condenser..

Mars

[Twisted Brick]

have made a good number of both shotguns and dephfametor, and their efficiency is in the number of baffle plates and their design..

The points that makes a shotgun effective are the number of baffle plates used, their placement and how the baffle plates restrict the water flow.. a condenser requiring a fast water flow through the condenser is not an efficient condenser..

Mars

I'm with you on baffles and their effect on efficiency. With my 4 x 1/2" shotgun, the coolant crossflow removes all of the heat from the incoming vapor at the first baffle (3" in) and the remaining length of the shotgun stays cold. This efficiency may be a function of the shotgun dividing the incoming vapor into four cooling tubes, but I have never been able to establish a temperature gradient along my condenser's length. Have you been able to establish a gradient on any of your shotguns?

[Zeotropic]

have made a good number of both shotguns and dephfametor, and their efficiency is in the number of baffle plates and their design..

The points that makes a shotgun effective are the number of baffle plates used, their placement and how the baffle plates restrict the water flow.. a condenser requiring a fast water flow through the condenser is not an efficient condenser..

Mars

I'm with you on baffles and their effect on efficiency. With my 4 x 1/2" shotgun, the coolant crossflow removes all of the heat from the incoming vapor at the first baffle (3" in) and the remaining length of the shotgun stays cold. This efficiency may be a function of the shotgun dividing the incoming vapor into four cooling tubes, but I have never been able to establish a temperature gradient along my condenser's length. Have you been able to establish a gradient on any of your shotguns?

How hot is your discharge water?

[Twisted Brick]

In the summer, its cool. In the winter its cold.

In either case, the same thing happens when the coolant reservoir heats up. The heat transfer capability diminishes and the condenser shell slowly starts to heat up, but still, no gradient. Same temp over the length of the shotty. The weak link in the system is the reservoir volume, not the condenser.

[Demy]

=StillerBoy post_id=7657160 time=1614210524 user_id=61884]
Here's what my 14 x 1 1/2 x 5 - 3/8" tube with 3 inner baffles looks like.. knocks down up to 4500 watt of power with less than a liter of water flow..

Mars

Thank you very much for the pictures I had seen them in the original post, but I meant pictures of the intermediate baffles. I think they are the same as the exteriors but cut on one side.

[StillerBoy]

I think they are the same as the exteriors but cut on one side.

I don't cut the baffles on one side as that method creates dead spot areas.. the baffles I make are of the full size of the inner tube.. what I do is V the plates where the tube are and drill small holes in the space between the tubes..

There is plenty of leakage with full plates anyways... leakage around the outer edge of the plates and the tubes, by adding the extra holes turbulent is create where is needed to be.. but same principal and concept apply to shotgun..

The attached pictures are of a 3 x 5 3/4" x 7 tubes (1/2") dephlegmator.. it was able to knockdown 5500w at 1.3 liter of water flow with no vapors flow through..

Mars