Re: [Distillers] Re: condensor
- --- Harry <gnikomson2000@...> wrote:
> 5. Turbulence.<snip>
How's that snipping for efficient use of bandwidth!
I have seen things that look like archimedes screws that insert into
pipe work. They are induced to rotate by the flow, and hence actually
break up the laminar pattern of flow further on.
Now I'd guess this wouldn't work with vapour (at least not on our
scale/vapour speed/volumes), but how about a fan at the top of a liebig
blowing down? (not the cold finger design being talked about though).
Just thinking out loud really.
p.s. Happy Easter Everyone! Remember, rum and chocolate go well
Don't get soaked. Take a quick peek at the forecast
with the Yahoo! Search weather shortcut.
- Not a physicist, but I am pretty sure that the optimal arrangement is a balance between
turbulence and laminar flow. Maximising laminar flow reduces heat exchange efficiency.
Maximising turbulence impedes coolant and/or vapour flow.
- --- Harry <gnikomson2000@...> wrote:
> 5. Turbulence. Either or both of the fluids being turbulent is moreTurbulence is related to flowrate. The greater the vapor speed will affect the
> efficient. Commonly it is accomplished by making sure there is
> something in the pathway of the vapour to force it to divert into
> the walls of the coolant carrier. It's automatic with coils as they
> are at rightangles to the vapour flowpath, and providing you put
> something in the centre space (like mesh) there's full turbulence.
turbulence, even through a parallel path. However, I like the mesh idea in
that it not only makes for the turbulent flow, but the contact with the heat
transfer surface effectively increases the surface area by means of conduction.
> There's no such diversion in the proposed design, hence only theIn all fluid flow through a parallel path, there is the laminar boundary layer
> edges of the vapours contact the copper transfer walls, leaving the
> middle of the vapour to continue on (it's laminar flow, not
> turbulent). You 'may' get some turbulence with the descending
> condensate using the same path.
at the edges where the fluid contacts the surface, but the ratio of laminar to
turbulent flow is proportional to the speed of the fluid...in our case, using
vapor as that fluid. However, in a case where there is a phase change, I think
it invalidates the laminar boundary layer as the density rapidly changes
creating a vacuum where that laminar layer would exist...I think. Thus, I
think the phase change would affect more turbulence than the droplets of
condensate in the vapor path.
> You 'may' also get some hold-up ofI suspect liquid 'hold-up' might be more of a factor proportional to how
> liquid in the condenser which could lead to problems. It's really
> a 'try it & see' situation (IOW, experiment). :)
tightly packed the mesh would be.
> 6. Flow direction. There's 3 basic types of condenser: Co-currentRegardless of the flow direction, this design is a multi pass because it passes
> (same direction of flow for both fluids), Counter-current (opposite
> directions, considered the most efficient of all) and Cross-current
> (fluids travel at rightangles to each other).
> In reality, most condensers are a combination of these. For
> instance the proposed design has both co-current and counter-
> current, therefore it's known as a multi-pass condenser (2 passes in
> this case).
through the two sections in series as opposed to in parallel. In light of
that, designing it as a single pass i.e. where the water is pumped into the
inner and outer pipes simultaneously as opposed to one after the other, it
could be more efficient. However, depending on the flowrate, that difference
could be negligible.
> Coils are both crossflow (rightangles) and either co- or counter-They also have a poor surface area to length ratio. For example, a Liebig with
> current, depending on which way you feed the coolant, top or bottom
> Crossflows are most useful in high-volume and phase-change
> situations, like steam recovery and our little application.
> If you consider all of the above you will see why Liebig-style
> condensers need to be so big or long. No turbulence is the culprit.
a 1/2" inner pipe and a 24" water jacket has 37.7 sq.in. heat transfer surface.
I have a counter-flow shotgun with 14 tubes with 1/4" id (think big, fat
Liebig with multiple tubes on the inside) and at only 12" long, has a surface
area of 132 sq.in.
The up-side: Liebigs are very easy to clean.
-really digging the idea of the cold-finger...condenser, you sick little monkeys!!!
- --- sn_cur <sn_cur@...> wrote:
> Not a physicist, but I am pretty sure that the optimal arrangement is aActually, no...turbulence is quite desirable. It's also a factor of flow, not
> balance between
> turbulence and laminar flow. Maximising laminar flow reduces heat exchange
> Maximising turbulence impedes coolant and/or vapour flow.
an impediment. The greater the flow, the greater the turbulence and the less
laminar flow. Turbulence is desirable because of the mixing effect in the
fluid where heat transfer is occurring.
However, in dealing with situations where a phase change occurs...vapor to
liquid in our case, we want more than just gross heat exchange. In our
coolant, pump like mad...the greater the flow, the better. There's the
turbulence in the coolant that makes it a more efficient heat transfer medium.
On the vapor side, however, if we raise the flowrate, i.e. vapor speed, too
much, then there isn't enough time spent in contact with the heat transfer
surface to affect sufficient heat transfer for condensation to occur. Overall,
there will be a greater magnitude of energy (in the form of heat) transferred
from the vapor to the liquid...that's not what we're after. We're not making
water heaters. Thus, the balance becomes one of heat input to condenser
capacity. But what we're broaching now is the geometry of the rig as a
whole...the power of the heat input, the size (i.d.) of the column, the area of
the vapor space within the condenser, the flow characteristics of the vapor
path through the condenser, the same regarding the coolant through the
condenser, the relative paths of each, the physical size, the temperature of
the coolant, the flow of the coolant...yadda, yadda, yadda.
...then combine all of this with the simple fact that we, at home, can only
construct something *so* elaborate without resorting to a full blown machine
shop (not that some of us don't fantasize :) ).
It can be enough to make one scrap it and grab a bottle of Jack from the store
to make the voices stop :)
- Thanks for your considered and interesting responses, Trid
>Actually, no...turbulence is quite desirable. It's also a factor of flow, not an impediment.The greater the flow, the greater the turbulence and the less laminar flow. Turbulence is
desirable because of the mixing effect in the fluid where heat transfer is occurring.
I agree that a fair bit of turbulence is highly desirable, for the mixing effect. But
presumably there has to be a limit to the amount of turbulence before it starts introducing
resistance to flow. As I understand it, minimising (or at least controlling) turbulence is one
of the main aims in designing large fluid delivery pipes, because turbulence (or at least
uncontrolled and excessive turbulence) increases pumping costs, and the size of the pipe
needed. Although at the flow rates used in stills it may not be an important factor.
Actually, it is even more complicated than that, because I think the aim is to generate a
small controlled turbulence layer at the interface between the fluid and the container
(pipe), because that reduces friction there. But the central bulk of the fluid should be
relatively turbulence free. I think that is also the way ship hull design is moving, smooth
surfaces are out and special (geometrically regular) roughened ones are in these days. The
idea came from shark skin.
>However, in a case where there is a phase change, I think it invalidates the laminarboundary layer as the density rapidly changes
The dynamic density changes (phase state changes) seem to me a very important factor in
figuring out the behaviour of condensing heat exchangers. The phase state changes alone
will introduce turbulence, and maybe that is all that is needed.
It seems to me that it is a question of the amount and location of the turbulence, not
simply of maximising overall turbulence.
Like I said, I am no physicist, and we are getting into some serious physics here, the
interaction between thermodynamics and fluid dynamics. Love it, but can't say I
understand it real well. I could be wrong about this stuff.
>It can be enough to make one scrap it and grab a bottle of Jack from the store to makethe voices stop :)
LMAO! Please, Doctor, make the voices go away! Don't worry son, just take these special
pills, fire up your still, and start swilling.
And it is getting pretty damn late here, so good night.
Zymurgy Bob, a simple potstiller
>From: Trid <triddlywinks@...>----snip----.
>Subject: Re: [Distillers] Re: condensor
>Date: Thu, 5 Apr 2007 06:54:36 -0700 (PDT)
>--- Harry <gnikomson2000@...> wrote:
> > 5. Turbulence. Either or both of the fluids being turbulent is more
> > efficient. Commonly it is accomplished by making sure there is
> > something in the pathway of the vapour to force it to divert into
> > the walls of the coolant carrier. It's automatic with coils as they
> > are at rightangles to the vapour flowpath, and providing you put
> > something in the centre space (like mesh) there's full turbulence.
> >That's what I hope I'm addressing in my "modified Liebig" design. The last
> > If you consider all of the above you will see why Liebig-style
> > condensers need to be so big or long. No turbulence is the culprit.
1/4 or so of the 1/2" copper pipe vapor path is cross-drilled with 1/4"
holes, spaced along the axis of the Liebig center on about 3/4" centers, and
each rotated 90 degrees from the previous (and next) bore. Each of these
bores has a segment of 1/4" copper tubing swaged and soldered into place,
such that the last part of the vapor path is multiply interrupted by
water-cooled copper, in a patter to induce turbulence.
The reason for this design was experience with a wood-fired still I had many
years ago, dealing with the wide range of energy utputs of a wood fire. In
an earlier incarnation, the vapor path was reduced from 1/2" (nominal)
diameter to 1/4" OD copper tubing as it entered the cooling jacket, and this
condenser arrangement could be overwhelmed by large energy excursions of the
wood fire, whereupon it would blow out the relief valve. When I extended
about 10" of the 1/2" copper pipe inside the cooling jacket, my overpressure
days were over, and I still got all the vapor cooling I could ever want.
That's why my Liebig has perhaps 11" of unobstructed 1/2" copper vapor path
to start, and a lot of turbulence and cooling surface at the end.
>MY downside: Should I ever need to clean it, it would not be a pull-through.
>They also have a poor surface area to length ratio. For example, a Liebig
>a 1/2" inner pipe and a 24" water jacket has 37.7 sq.in. heat transfer
> I have a counter-flow shotgun with 14 tubes with 1/4" id (think big, fat
>Liebig with multiple tubes on the inside) and at only 12" long, has a
>area of 132 sq.in.
>The up-side: Liebigs are very easy to clean.
>-really digging the idea of the cold-finger...condenser, you sick little
Mortgage refinance is Hot. *Terms. Get a 5.375%* fix rate. Check savings
- --- Robert Hubble <zymurgybob@...> wrote:
> >The up-side: Liebigs are very easy to clean.Sounds like a nice, long, stiff-bristled brush at about 3000rpm might be in
> MY downside: Should I ever need to clean it, it would not be a pull-through.
Which brings me back to a previously visited topic of cleaning. I mostly
poststill and of course, that entails lots of "flavorful" residue on the vapor
side of my condenser tubes...especially when doing a batch of Absinthe. I
can't even imagine trying to get all that stuff out of a worm if one were to do
a batch of something else, say rum or whisky, lest it contaminate the flavor at
the very least.
I use a modular setup where my components are either slide-together (sealed
with silicone tape or plastic wrap if even necessary) or assembled with unions.
My cleanliness/flavor-contamination paranoia drove me to make everything
detachable, and with no more than a single 90 degree bend. So, as you would
deduce, I have a bucket full of elbows (both 45 and 90) all with unions on each
end. Then, if I need more cooling than one condenser can handle, I just put
another one on...if space is limited, I can put a couple elbows between them
and make a 180 degree bend and tweak the angles to fit. Since I graduated to
the shotgun condenser, I haven't encountered a need for additional cooling
capacity, so my modular rig has condensed (no pun intended) to where I only
need to direct the distillate spout towards the collection vessel. It's all
disassembleable so I can get a soapy brush to just about every surface that
will contact the vapors and get as much remaining residue off from the previous
batch as possible.
Concerning a number of prior posts questioning their cloudy spirit, often the
suggested culprit is tails left over from the previous batch. If this is the
case, then wouldn't this dictate discombobulating the head/condenser between
each and every spirit run such that tails don't contaminate the subsequent
batches? However, it doesn't quite add up...would this also necessitate
commercial pot still setups to thoroughly clean their stills between all runs?
I just can't imagine that allowing any kind of efficient business. Are tails
really such a contamination potential? Do sufficient heads rinse the tails
gunk out maybe? Perhaps it's too much of the tails-y heads in the middle?
...or am I just being neurotic? :)
--- In Distillers@yahoogroups.com, Trid <triddlywinks@...> wrote:
> Concerning a number of prior posts questioning their cloudy
spirit, often the
> suggested culprit is tails left over from the previous batch. If
this is the
> case, then wouldn't this dictate discombobulating the
> each and every spirit run such that tails don't contaminate the
> batches? However, it doesn't quite add up...would this also
> commercial pot still setups to thoroughly clean their stills
between all runs?
> I just can't imagine that allowing any kind of efficient
business. Are tails
> really such a contamination potential? Do sufficient heads rinse
> gunk out maybe? Perhaps it's too much of the tails-y heads in the
> ...or am I just being neurotic? :)
> -neurotically yours
You're gonna give your brain a hernia, Trid. :)
The simplest method of keeping condensers clean between runs
is...household white VINEGAR. It's not strong enough to eat away
your copper, but it does keep it REAL shiny.
At one time or another I've used Liebigs, coils and crossflows.
Assuming you have made them so they can be detached, do this...
Liebigs: Plug the outlet end with a cork. Fill the tube with
vinegar. Plug the other end with another cork. Store it until
Coils and Crossflows: Drop them in a bucket of vinegar, enough to
cover the condenser completely. Put a lid on the bucket. Store
It only takes overnight to remove any residues in the condensers.
In all cases, RINSE WITH FRESH WATER BEFORE USE, as the vinegar will
turn blue (Sweitzers reagent, not really dangerous but I wouldn't
Cleaning is that simple.
- Forgot to mention...the blue vinegar cleaning solution is reusable.
Throw it out when it starts getting too much gunk in it. I typically
reuse it for about a year.
- --- Harry <gnikomson2000@...> wrote:
> Forgot to mention...the blue vinegar cleaning solution is reusable.What's the typical concentration that you use?
> Throw it out when it starts getting too much gunk in it. I typically
> reuse it for about a year.
> regards Harry
-humblest apologies for the brain hurty :)
- --- In Distillers@yahoogroups.com, Trid <triddlywinks@...> wrote:
>Standard white table vinegar, it's 5% acetic acid. Use it neat. In
> What's the typical concentration that you use?
> -humblest apologies for the brain hurty :)
Oz we buy cheap homebrand stuff from the supermarkets for about 50
cents per litre. I get 5 x 4lt plastic containers of it about once a