CSST-based Dimroth condenser design/build

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CSST-based Dimroth condenser design/build

Postby fafrd » Fri Jun 15, 2018 2:45 pm

Didn't see a thread on this subject so I started one.

I'm planning a CCVM build ala Dad300 design and have started pulling together the parts for a Corrugated Stainless Steel-based Dimroth condenser.

I picked up a new 4' long CSST gasline for $3 st my local salvage yard. The outside diameter appears to be 21/32" (probably 5/8" if I press hard).

Any advice as to whether this 4' length is good enough to make a condenser for a 2" keg-based pot-still appreciated as well as pointers as to the best pipe diameter to use and the best configuration to use for the CSST.

If I merely fold the CSST in half, it will be ~2' long and have a widest cross-section of 21/16"' so I could make a simple Dimroth condenser using a ~22" long piece of 1-1/2" (or possibly 1-1/4") pipe.

Alternatively, I can wrap one 'side' around the other straight side which is still 21/16" across but reduces the length to 18".

Would greatly appreciate any inputs on which approaxh is better and what side pipe to target. 1-1/2" (or possibly 1-1/4") pipe would be the 'tightest' but ot mat actually be less expensive for me to use 2" pipe (great deal on scrap 2" copper pipe at my local salvage yard).

Would an 4' long spiraled CSST coil in an 18" piece of 2" copper pipe make a good product condenser?

Would a 4' long folded CSST design in a 22" piece of 2" copper pipe be better?

Thanks in advance for any help...
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Re: CSST-based Dimroth condenser design/build

Postby fafrd » Fri Jun 15, 2018 3:05 pm

I realize the title I wrote is general enough to cover both Reflux and Product Dimroth Condensers made from CSST, so here is a follow-on post with similar questions for the Reflux condenser.

My column is 2" and I have confirmed that when I wind one side of my 48" 21/32" CSST around the other 'central/straight' side of the CSST, the coil has just under a 2" cross-section (63/32" in theory, possibly as little as 1-7/8" if I compress as much as possible).

Meaning a tightly-wound coil will fit into my 2" column, but it's not going to be very long (6"?).

So what is so best way to use CSST to design a Dimroth Reflux Condenser? Do I want the coils packed as tightly together as I can get them or should I be spreading the coils out to allow / facilitate more vapor flow?

Do I want to make as many coils as possible even if that means a very short (6") condenser or do I want to straighten out after 4 or 5 coils to entend straight out of the top of the column (allowing a taller column section above the product port)?

This CSST smaterial is fantastic but I could sure use some guidance on the best way to exploit it...
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Re: CSST-based Dimroth condenser design/build

Postby OtisT » Sun Jun 17, 2018 12:00 am

FYI, Info on my Dimroth Product Condenser is in this thread.

viewtopic.php?f=16&t=70230

I use the same size copper coil for my reflux condenser. They will handle up to 5500 watts. The Domroth PC produces cold distillate up to 3500 watts with a cooling water flow of 3.5 lpm. Over 3500 watts and the distillate begins to get warm.

Otis
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viewtopic.php?t=52975
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Re: CSST-based Dimroth condenser design/build

Postby fafrd » Sun Jun 17, 2018 1:14 pm

OtisT wrote:FYI, Info on my Dimroth Product Condenser is in this thread.

viewtopic.php?f=16&t=70230

I use the same size copper coil for my reflux condenser. They will handle up to 5500 watts. The Domroth PC produces cold distillate up to 3500 watts with a cooling water flow of 3.5 lpm. Over 3500 watts and the distillate begins to get warm.

Otis


That's a georgeous design.

I've got access to pretty inexpensive CSST and plan to try to use that as a Dimroth 'coil' to start (in a 2" copper tube). But if the CSST fails to get the job done for whatever reason, making a nice copper coil out of 3/8" (or is it 1/4"?) to replace the CSST will be my plan to salvage the design.

What length of copper (and what OD) did you need to deliver that performance!
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Re: CSST-based Dimroth condenser design/build

Postby fafrd » Mon Jun 18, 2018 4:08 pm

Some more details on the CSST-Dimroth condenser I'm building.

The 48" long piece of 5/8" CSST had compression fittings on the end which I'm currently planning to use and to bend out over the column edges. I can get a asymmetrical-twist (one side close to straight, the other side loosely twisted around the straightish-side) about 17 inches long from bottom of 'U' to bottom-most edge of bend for fittings.

So a total of ~46" will be within the 2" shell and it will extend 17" into the pipe.

Most folks who have built CSST Dimroth condensers appear to have used longer lengths (7' for example) so I'm a tiny bit concerned this 4' piece may end up being too short for my design (2" pot-still).

Any inputs appreciated.

If no one has experience with a 4' long 5/8" OD CSST Dimroth condenser like this, I figure I'll just test it on a maiden run and if I feel like it's not able to keep up with the boiler, I can always get a longer piece of smaller-diameter CSST (7' of 1/2" CSST could be wound in a tighter 'true' coldfinger-like spiral, for example).
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Re: CSST-based Dimroth condenser design/build

Postby OtisT » Fri Jul 06, 2018 9:09 pm

fafrd wrote:What length of copper (and what OD) did you need to deliver that performance!


The coil is made from 12’ of 1/4” OD copper tubing. 26 winds around a 1” pipe, for an OD of 1.5”. There are 26 winds, with a 1/8” gap between each wind. To get a good flow rate you don’t want to crush the tubing. I packed the first 3’ of the tubing with salt prior to bending, as the tip section would flatten too much during winding and restrict flow too much, and get about 3.5 lpm with city water pressure.

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