Coming up next...
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Update: Haven't blown myself up yet, but I've successfully liquefied nitrogen (albeit a tiny quantity).
This was about a month ago, and I've been spending a lot of time and effort trying to increase the yield rate. I'm still working through a few more bugs, so the next video won't be until next month.
This should be the last part of this series, after which I'm expecting to upload on a more frequent basis.
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Down to around 20-30 watts of heat lift at -147C (the critical point of nitrogen), so it looks like I'll be making some LN2 in the near future with the mixed-gas joule-thomson system. As a slightly easier test, i managed to liquify a little bit of methane from my natural gas line (highlighted in red), which is at -162C at 1 atmosphere of pressure. A lot of it boils off, so some extra heat exchangers are gonna need to be used to capture the cooling energy of the boiloff gas. For the video-after-next I'm planning to make some more liquid and then freeze it under vacuum (-182C).
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Hey all,
Just wanted to let everyone know the joule-thomson cryocooler project *is* still being worked on after taking a break to do other projects. I've added a couple of things for part III of the series:
-150cc cold head reservoir to bottle up cryo fluid before ejecting it into a thermos/dewar
-Addition of a heater resistor pack to measure ultimate temperature(s) at various loads
-Removal of electronic expansion valve - this became unnecessary once I figured out the right capillary tube size
-Addition of flare fittings to the cold head for easily swapping different capillaries
I'm also gonna add an automatic oil separator drain valve using a motorized ball valve on an arduino timer (since solenoid / EEV didnt work for this application for some reason).
Right now I'm able to consistently and repeatably hit unloaded temperatures between -150C to -160C with mixes of propane, argon, and a tiny bit of ethylene, and around 5-10W between -135C to -145C depending on gas mixture. This is at the point where it's *just barely* capable of liquifying high pressure air, so there's a few other things I'm gonna have to try.
For one, my current compressor is from a 5,000 BTU A/C unit, but my pre-cooling compressor is from a 12,000 BTU unit. This arrangement is actually totally backwards, and the main compressor should be larger, so I might swap the main/precooling stage compressors to get more power.
Additionally, my attempt at vacuum insulation was pretty crappy, and the entire outside of the vacuum pot still gets to nearly freezing temperatures during operation. This probably represents well over 100W of heat leakage, so I think I just need to bundle it up in huge amounts of glass wool to keep the heat out.
With these changes I *should* be able to produce reasonable amounts of liquid air...maybe 100-200cc per hour.
Once that's done I'll probably make a separate video as a step-by-step tutorial for making your own air/nitrogen liquefier.
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For those of you following along for the Mixed-gas joule-thomson cryocooler project, I'm currently down to -172C unloaded with a -30C precooling stage and a 30/70 mix of propane and argon. Looks like around 10-15W of heat lift will be available at a temperature of around -140 to -150 based on tests with load resistors mounted to the cold head. However, there's still a lot of debugging of random problems that keep arising, so I expect part III of this video series to be 2-3 videos down the road.
I've also cross-referenced this thermocouple reading against a PT1000 thermistor mounted next to my thermocouple, and the temperature reading does indeed appear to be accurate.
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Joule-Thomson Cryocooler project is still in the works, and as of last night it's currently cold enough to make liquid nitrogen under pressure (25 bar at -153°C).
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Dear Viewers,
I have not blown myself up (yet), but there will be some delays in my next video, because I'm currently having my air conditioning replaced in weather conditions near ~40C approaching 100% humidity. I understand the irony of this, given the subject matter of my recent content.
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In recent weeks, a handful of people suggested I set up a Patreon account, so if you're interested there's now a link for that in the channel description page.
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Working on the next phase of my cryocooler project for liquifying nitrogen/air - this time using the joule-thompson effect for cooling. On the left is a 33 ft (10m) long insulated coaxial heat exchanger with a cold head sticking out at the bottom. On the right is a compressor and aftercooler taken from a 12K BTU portable air conditioner. Aiming for at least -150°C, but very possible that it could reach as far as -170°C.
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A variety of electronic / chemical / mechanical tinkering projects, ranging from small circuit boards to whole vehicles.