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Hi all,

I've put together an idea for a custom shotgun condenser (and by put together I mean I was too anxious and already have the materials on order). Here's a cross section of CAD drawing that I will try to explain.

6x 3/8ID copper tube
2x 2"OD x 1/2 thick copper discs. These discs will have counterbored holes that the 3/8 tube will be soldered into. The top disc will be tapered to prevent liquid pooling.
1x 2" copper pipe as a jacket
2x 2" copper caps for each end
Inlet and outlet fittings for water

The 6 tubes will be soldered into the two discs. That assembly will then be soldered into the 2" pipe. Then the caps will be soldered on each end. Plan is to make it 12" long based on the calculator on the parent site. I'm using propane at approximately 1kw of power based on my calculations and I plan on circulating room temp water with a small pump. Calculator says I would need .5m of copper tube so with 6 tubes and the large 1/2 thick discs acting as heat sinks I think 12" long should be more than sufficient.

I'd appreciate your thoughts on the design.

Please get in the habit of posting pictures locally, here on the HD server... Some here, including myself, will not view externally hosted images for security reasons... We have a lot of shotgun examples here to adapt from... See the Image Uploading and Posting Etiquette topic...

Are you happy having only 1kw of power?, do you think you might upgrade in the future?. Just thinking if you would, you'd be better off doubling the length, if you don't plan on upgrading, then ignore me lol. It will work fine, it's a general shotty design, heat sinks wouldn't do much in it I don't imagine, shotties are very good in standard form, it will be solid and strong though, but a bit heaver than normal, not to heavey for the column?. Good luck.

rad14701 wrote:Please get in the habit of posting pictures locally, here on the HD server... Some here, including myself, will not view externally hosted images for security reasons... We have a lot of shotgun examples here to adapt from... See the Image Uploading and Posting Etiquette topic...

Apologies, post has been edited. I did drool over quite a few shotgun designs I saw on here as I was working on mine, especially those fully welded stainless ones. I modified mine so I could do a little milling and turning to make the building process a little more fun

googe wrote:Are you happy having only 1kw of power?, do you think you might upgrade in the future?. Just thinking if you would, you'd be better off doubling the length, if you don't plan on upgrading, then ignore me lol. It will work fine, it's a general shotty design, heat sinks wouldn't do much in it I don't imagine, shotties are very good in standard form, it will be solid and strong though, but a bit heaver than normal, not to heavey for the column?. Good luck.

Based on the calculator I should be able to go up to around 4kw with this set up so I did leave room for potential future plans. Good point on the weight though, I overlooked that. Probably a bit too heavy for the column but nothing an extra stand can't take of. Just a reason to do a little more fabricating lol.

Personlly I think you are wasting your time with the 1/2" end plates . You' d be better off inserting a baffle or offsetting the in/out pipes or twisting the shotty tubes in the housing by about 30- 45 deg .IMO that would inprove your efficiency more .

I don't think you are going to knock down 4kw with a 2" × 12" shotty.

The vapor inlet looks small. My shotgun has a 1" inlet. What you want is the vapor to slow down slightly as it enters the shotgun. But the tubes bank should present roughly 125% to 150% of the cross sectional area of the vapor flow area of the inlet piping (at least).

Also, put 3 or 4 baffles in the water jacket so that the cooling water swirls around your tube bank. That'll help it take the heat out (improves efficiency).

And I'd estimate you'll need 6 x 3/8" ID tubes x 22" long to handle a 5.5kW input (with baffles in the water jacket). You may get away with a slightly shorter (18") shotgun, but you don't want to make it too short for your power input...you only want to build it once. Also, you can actually get 7 tubes in a 2" shell. In fact, my shotguns are both 1-1/2" pipe and I have 7 x 3/8" ID tubes in them, although it is a very tight fit.

Another option would be 5 x 1/2" ID tubes...probably easier to make too.
ss