DIY Recirculating Cooler to Cool a Vapor Condenser in a distillation process

[VARocketry]

I found this site following a search for articles on DIY Aquarium cooling projects.

Various articles point out that mini-refrigerators cannot be used such as:
http://www.beananimal.com/articles/dorm-fridge-aquarium-chiller.aspx

A Carnegie Mellon Universitry researcher concluded that directly in actual tests and moved on to use of a window A/C which is more appropriately designed for the higher cooling loads and continuous duty cycle.
Notes on a do-it-yourself (DIY) reef aquarium chiller http://www.cs.cmu.edu/~cap/raid/chillers/diy/

He built a small acrylic box around the A/C evaperator coils and plumbed the fishtank water through.

Question: Is it not possible to remove the A/C unit evaporator coils into a LARGE container of water to be cooled (larger heat sink)?. I suppose they could be cut and extended with metal lines, then recharged.

I want to create a recirculating cooling tank that to absorb large heat amounts from a vapor condenser cooled by this water. I don’t want to waste clean water by simply cooling without recovery.

Any thoughts about this idea. This is an Alabama Redneck's attempt to engineer a solution. I imagine you might have much more knowledgeable suggestions.

[VARocketry]

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I created a diagram of my idea - admittedly no technical knowledge in this area.

[Rob White]

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See

http://www.refrigeration-engineer.com/forums/showthread.php?35231-Cooling-water-in-a-tank&highlight=fish+tank

http://www.refrigeration-engineer.com/forums/showthread.php?36347-Aquarium-evaporator-calculation-please-help&highlight=aquarium

http://www.refrigeration-engineer.com/forums/showthread.php?32404-Aquarium-flash-cooler&highlight=aquarium

http://www.refrigeration-engineer.com/forums/showthread.php?2021-DIY-aquarium-chiller&highlight=aquariumnh

http://www.refrigeration-engineer.com/forums/showthread.php?15931-Water-Inlet-Outlet&highlight=aquarium

A little light reading to get you going.

Rob

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[Brian_UK]

You basic concept is correct, it can be done and would work. There is the chance of freezing your water tank though as you do not show a circulating pump.

However, are you increasing your energy usage by having the water tank and pump circuit?

If you wrapped the copper tubing around your vapour condenser directly and made that the evaporator then you would save costs and improve performance. There may be a need to improve the control of the fridge circuit but I'm sure that there is a get-around somewhere.

[VARocketry]

Ok, it looks like this gent has followed up earlier work and really demonstrates its capability:
http://forums.morebeer.com/viewtopic.php?f=15&t=27957&hilit=+glycol+wort+chiller

Rob - thanks, I've been reading everything I can find to point me in the correct direction.

The idea behind the pictured design was to MINIMIZE risk of poisonous chemicals coming into contact with desired fluid stream when INTERNAL coils or tubes are used in a condenser such as these pictures.
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Brian - If I understand your suggestion, you suggest the EVAPORATOR Coils can be attached DIRECTLY to outside of the vapor pipe thereby creating a condenser, as is done in this Beer Wort cooler:
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Is that correct?

The design then might be something like this:

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[VARocketry]

To increase surface as in an Evaporator, employ a shotgun design:

10181

[Brian_UK]

Yep, that's my idea to a tee.

[Tesla]

Hi VAR
Re: design was to MINIMIZE risk of poisonous chemicals coming into contact with desired fluid stream
I have built one of these before and used it around 40 times (20 years ago). I would and did use a continuous process method not the batch method you propose to use. A book "The Lore of STILL Building" by Howard & Gibat will be very helpful. Pg 68 - 71 shows this still which is better because it has a simple reflux column, is smaller for the same capacity and can process any amount without being switched off. I don't think the cooling water needs to be below 10degC and should be leaving (condenser) at around 18degC. The one I built produced a very clean sweet fire water which was diluted with a little water. I would process in lots of 200 to 400 litres at a time. The hardest part was the patience in waiting.
Simplest compact method would be to build a directly refrigerated tube in shell condenser like this. one cu tube 6"long x 4"diameter - start with a much longer tube to allow holding onto it with a vice. Then use 3/8" cu tube filled with dry sand,sealed ends with nitrogen in it (to stop it from crimping), heat till cherry red with gas set just where it needs it and bend it around the 4" tube in a spiral with a gap of about 1/4" between the spirals. Now you should have a 4"D pipe with 3/8" tube wrapped around it about 9 times and you want the 3/8" tube with an almost 90degree bend at each end so as it runs along the 4" tube. Try to do this in one piece and not use welded elbows. If all good cut ends and shake out sand - careful of the nitrogen.
second part is to use a 4 1/2" diameter tube 6" long to sleeve it with 2 x 1/2" tubes sticking out of it perpendicular for the chilled water or refrigerant to go through. Of course the two ends will need to be welded with some flat rings where the 4" and 4 1/2" tubes end.
If using water it is helpful to use a valve on each of the water pipes in and out.

[VARocketry]

Tesla:

It's good to hear advice from an experienced hand. Can I ask a couple clarifying questions:

1. Are you describing using a 4" tube as a mandrel to bend 3/8 tube around to form a coil and then take it off and install inside a larger tube? If correct, I understand and there are plenty of sites and descriptions for building a condenser that way.

2. Are you suggesting to run Coolant from a/c through the coil inside the tube? Or running vapor through the coil?

I understand the coil spacing to allow room for flow and turbulence around the coil -- if installed internally.

I'm assuming in the external mount, one would want the coil wound tight and close to maximimize thermal transfer.

4. Is there any type of BRAZE Filler/Solder than has improved thermal transfer and not act like an insulator.?

[Tesla]

1. No. Use a 3/8 coil of tube with a 4" on inside and 4 1/2" on outside to form a tube in shell condenser with a hole in the centre of it.

2. Run vapor through the 3/8 tube (the good stuff you want to drink later), run cooling water or refrigerant around the 3/8 tube.

I'm assuming in the external mount, one would want the coil wound tight and close to maximimize thermal transfer. No need for thermal contact as the cooling fluid will surround the 3/8 tube almost totally.

4. Use refrigeration grade welding rod for dissimilar metals - it will have 45% silver content in it. The standard cu to cu stuff has 15% and plumbers has 5 -10%.

Check out the reflux tower using stainless wool for efficiency too. I will try to find an old photo and scan it.
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[VARocketry]

Back on topic of Refrigeration Engineering, how would you begin to dissect a large portable A/C unit for this use?

Do you have to match copper pipe size when moving/extending or creating a new Evaporator coil?

How would you need to change any of the controls? Temperature sensors?