I was thinking about this today. Funny you should bring it up @pangea!! Let’s figure this out… now, what about plumbing what you linked to to a plate exchanger of sort? Like 100 plate one? Isn’t that all one would need?
Yes rated plate type evaporators would work, I was thinking more of counter current coil or immersion probe style, but the style matters little compared to understanding how to pair and match them with the condenser unit. Along side the evaporator we need the correct expansion valve.
Yeah lol, I’ve been humming and hawing about buying a compressor or modifying one appropriate for refrigeration gases, and then just using a brazed plate as the expansion chamber. Take out some middle men (one of my favourite hobbies) in process.
Im currently working on a diy chiller using an old window ac unit… Looking at the condenser you posted, May i ask how you actually use it, and what will you be using it to chill? Or is it to chill an area/room. Seems interesting. Im new to this stuff so its hard to picture the end goal sometimes
I want to use it as a chiller as well. Mainly chilling solvents and cooling injection/recovery coils, cold traps etc. Once I get this basic setup figured out I want to try to get the advanced tek down for a cascade or autocascade type setup to get into the -80 range. One could also hook it up to a walk in freezer or reg ac air type evaporator as well. This is basically one part of a refrigeration unit, the condenser/compressor. The other side being the evaporator.
I’ve uploaded a great resource for TXV sizing from sporlan. You can also just call them up , ask for an applications engineer, and they’ll size one for you (although honestly i’ve had them undersize me twice now lol so maybe go one side larger).
For very low temp, you face big issues with hunting if you use a mechanical TXV. The off-the-shelf superheat controllers only function down to -60C so that’s a problem as well. You can either mess with getting a mechanical valve to work or write your own logic on something like a Siemens Logo (which is pretty easy honestly).
For ye DIY’ers looking at big compressors for cheap, go get 'em but beware of compression ratios that are too high. Multi-stage will almost certainly be required but it’s not as difficult as it is daunting.
As you mentioned, oil management is a concern for sure, especially with compressors in series. Read up on discharge side oil separators. If you’re building your own skid, you can afford $400 for a spiral separator and a solenoid for oil return.