Homemade Liquid Nitrogen Generator Using Joule Thomson Effect

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Introduction: Homemade Liquid Nitrogen Generator Using Joule Thomson Effect

Step by step guide to building your own liquid nitrogen generator. Using easily obtained materials you can liquefy nitrogen or air. The unit cools  to -320F in under 50 minutes. Production is about 350 cc/hr. A full tutorial and plans are at http://homemadeliquidnitrogen.com

If you like the extreme cold, you might like the extreme hot. Here is a video of an induction heater
http://www.youtube.com/watch?v=Q6Zrnv4OtbU
You can view a complete tutorial on building one at http://inductionheatertutorial.com

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27 Comments

Do you turn nitrogen gas to liquid when pressed 230 atm?

I think this project is inspiring. I've known of liquid nitrogen since I was very young (as I think most people on the planet have), and I think liquid nitrogen represents science in a very pure, advanced, and beyond-the-ordinary way. To see that someone can actually produce some at home, with accessible materials, using knowledge, ingenuity, critical thinking, and perseverence is incredible to me. I've picked up a subscription to instructables.com on the strength of this project. I've set a personal goal to replicate the project myself within the year. Thank you, imsmooth!!!

What do you think about design? These turbines are pretty simple. Air under pressure at right angles to the turbine axis of rotation. Would there be much to be gained by actually giving the turbine "work" to do ie coupling a second turbine to the driven blades to act as a simple compressor for return flow vs just having the jet of gas spin the single turbine itself without a specific useful load.

By the way, although you have a very high pressure gas with up to 4 SCFM air flow, what volume through put do you really get through the throttle? It can't be anywhere near 4 CFM, right? What is the throttle diameter? Is it a capillary tube of X length and Y ID or is it a dimple pinch off of the high pressure line? I'd really be interested in the actual measured flow at the JT throttle.

Turbulence is good

Teflon was expensive even when bought from china

Copper refrigerator tubing is a better conductor

You need good insulation to prevent heat loss through your stainless steel tubing

Also this. Will increase the cooling time because of the higher heat capacity of the metal. You could also use an outer copper tube which is easier to bend

1/2 will give you little room and the outflow resistance will be too high

You also need space for your fittings. Use bigger diameter

You need to think through how you will bend and creat a coaxial helix

Let me know how you plan to do that

I could go to 3/4" on the corrugated stainless. As far as bending the corrugated pipe, that will be easy. It's designed to coil. The copper will be bent with a harbor freight planetary bending tool. It would be nice to orient it coaxially, but I don't think that will matter too much. I'd like to find 24" Sono Tube, but that is tricky around here. I might look at a plastic system to cover the SS vacuum flask. Your bottom siphon arrangement to remove the LN2 is likely pressure driven. That's how we would transfer from our 30l dewars to out working vessels.

I don't think it will be possible for me to get a 200BAR compressor, but I might try a 10-20BAR compressor with 10+SCFM Volume.

Sounds good
If you build it I would like to include the cool down data for comparison

have you looked at make shift turbo expanders as a means to improve efficiency? Would putting a dental turbine cartridge (<$20 on ebay for ceramic bearing version rated at more than 100,000 RPM) at the JT throttle add to the workload of the expanding gas?

I've definitely thought about turbo expanders, but I don't have a CNC to make my own and I did not know where to get a small one cheap enough. If you found one that cheap it is worth a try as long as it can withstand the pressure. Turbo expanders are way more efficient.

I see the turbine cartridges on Ebay. Did you see a housing for them? It would not be hard for me to test one and measure the temperature drop.

check out the Kleemenko mixed gas refrigerant cycle. It's a variation n the JT cycle but recently has been applied to desktop liquid nitrogen production.

The patent is by a guy named William A Little from Stanford Univeristy.

I've heard about it and know someone who said he
Was going to try it

I didn't feel like dealing with refrigerants