Compact titanium heat exchanger

[nomsmon]

I'm looking for a compact titanium heat exchanger that I can use to chill water from a reeftank and I can run water or glycol through as the coolant; I'm struggling to find many options. Something 6"x6" or less would be ideal.

I'm seeing stuff like

This shell and tube exchanger with a plastic body, which looks like it has refrigerant style adapters and is rather large.
https://m.aliexpress.com/item/4000768851166.html?spm=a2g0n.productlist.0.0.7b6929e24BGgPF
This shell and tube pool heat exchanger which is very expensive and seems oversized. I'm also concerned about clogging due to biological build up.
https://chillxchillers.com/heat-exchangers/titanium-shell-and-tube-heat-exchangers-same-side
This immersion coil which could work but is bigger than I'd like and without corrugated/convoluted tubing won't be as efficient as I'd like.
https://m.fish-street.com/aquarium_titanium_evaporator
I'm not sure what consumer marine aquarium chillers are using for their titanium heat exchangers but I feel like nothing I've seen would fit that.

 

[Lasse]

In a DIY build I used a construction like the third picture but did it more compact and let a water pump give a contra flow through the helix. However I use plastic covered under floor heating pipes of aluminium. Because of the plastic cover - there was no contact between water and the aluminium helix. I placed the helix in the sump and control the chilling power with a solenoid valve and a temperature controller. The cooling fluid come from cooling machine in the building (the cold side of a heat pump). It works for many, many years

Sincerely Lasse

 

[nomsmon]

In a DIY build I used a construction like the third picture but did it more compact and let a water pump give a contra flow through the helix. However I use plastic covered under floor heating pipes of aluminium. Because of the plastic cover - there was no contact between water and the aluminium helix. I placed the helix in the sump and control the chilling power with a solenoid valve and a temperature controller. The cooling fluid come from cooling machine in the building (the cold side of a heat pump). It works for many, many years

Sincerely Lasse

Thanks Lasse. I've heard mention of coating metal heat exchangers for corrosion resistance, but no specifics.

What you describe sounds like it would work well for my purposes.

Would something like this PEX coated aluminum tubing be similar to what you describe?
Amazon product ASIN B07DV78CDC

 

[Lasse]

Yes - it looks like the type I used

Sincerely Lasse

 

[theatrus]

I'm not sure what consumer marine aquarium chillers are using for their titanium heat exchangers but I feel like nothing I've seen would fit that.

The JBJ Arctica unit I've had to repair (lost its R-134a pressure) had a about 4" diameter coil of titanium tubing inside a plastic cylinder. Looked like a made-to-purpose unit and was just using off the shelf fittings. I think that unit is in my shed so if you need more details I can crack it back open.

Its basically the guts of a window AC unit (Samsung compressor). Nothing special was done to the heat exchanger in terms of water flow - it was just a few loops of tubing with water circulating randomly around it.

https://www.mcmaster.com/89835K91/
Ti tubing is not cheap but also not super expensive, and can be flared or accept compression fittings so it is compatible with normal plumbing. No TIG welding needed to join up to it :)

You could pack this with fittings into a large section of ABS pipe, and if you're not using refrigerants but instead glycol don't need to worry about pressure of the fittings to the pipe section, and can probably use a flat end cap joining those, and bulkheads for water to the pipe. Use a smaller section of pipe to act as a form for the coil, though its still quite stiff and will take a ton of muscle to bend.

 

[nomsmon]

The JBJ Arctica unit I've had to repair (lost its R-134a pressure) had a about 4" diameter coil of titanium tubing inside a plastic cylinder. Looked like a made-to-purpose unit and was just using off the shelf fittings. I think that unit is in my shed so if you need more details I can crack it back open.

Ah interesting, sounds like a shell and tube with a coil; not what I expected, but fairly easy to replicate.

https://www.mcmaster.com/89835K91/
Ti tubing is not cheap but also not super expensive, and can be flared or accept compression fittings so it is compatible with normal plumbing. No TIG welding needed to join up to it :)

You could pack this with fittings into a large section of ABS pipe, and if you're not using refrigerants but instead glycol don't need to worry about pressure of the fittings to the pipe section, and can probably use a flat end cap joining those, and bulkheads for water to the pipe. Use a smaller section of pipe to act as a form for the coil, though its still quite stiff and will take a ton of muscle to bend.

Doh! I didn't think about flaring and definitely was not going to weld anything.

I've built similar coils out of copper as immersion chillers for brewing beer. I know there are some considerations for the overall diameter of the coil and distance between loops. I'm assuming the issues would be water flow over the chiller and turbulence/pressure from having tightly wound coils.