How to produce liquid nitrogen at home for $1.29 per liter using salvaged AC parts | TechSpot

WTF?! Folks who are into extreme overclocking and cryogenic experiments swear by liquid nitrogen. With a boiling point of -320°F, this super-chilled liquid can push computer components to blistering speeds. But getting your hands on liquid nitrogen isn't exactly easy; you typically need specialized equipment or a direct supplier. That is, until now.

YouTuber Hyperspace Pirate has demonstrated how to produce real liquid nitrogen at home. He built his own cryocooler entirely from salvaged parts, including components from old window air conditioning units and a few electronic parts for motorized valves. No fancy, off-the-shelf cryocoolers were involved in this process.

The core of his creation was the principles of the Joule-Thomson effect. By compressing a gas mixture, removing the heat, then allowing it to rapidly expand through a tiny opening, the gas plunges to liquid nitrogen temperatures. It's the same tech used in high-end cryocoolers.

Hyperspace Pirate walked through the process of assembling the compressors, counterflow heat exchangers, liquid tanks, and intricate piping to make it all work. The final rig is a Frankenstein's monster of parts mounted on a rolling bench, which he built himself. The main compressor and pre-cooler components were placed on the top level, while the nitrogen feed compressor was situated on the bottom level. The compressors on the top fed down to a liquid nitrogen tank placed underneath an insulated cold box, which housed the counterflow heat exchanger for liquefaction.

After about an hour of run time, sucking in regular nitrogen gas and progressively chilling it, the system hit -177°C (-286°F) and started liquefying the nitrogen. From there it was a slow accumulation process until Hyperspace Pirate had a nice batch of homemade liquid nitrogen to play with.

The mad scientist then proceeded to demonstrate some of liquid nitrogen's fun superpowers, such as levitating a small magnet over a superconducting YBCO puck, and freezing an orange and some salad. He also stated that the same cooler can be used to liquefy argon, which is slightly easier because it has a boiling point of -302°F (-186°C).

There were definitely some limitations too. The relatively low yield of just 130cc per hour and high 1400W power draw make this more of a novelty than an efficient liquid nitrogen generator. But Hyperspace Pirate is optimistic about scaling up production through further refinements.

Ideas floated include extracting pure nitrogen from the air using pressure swing adsorption, as well as liquefying oxygen, which requires additional safety precautions due to its highly flammable nature.

Of course, if you couldn't already tell, there's a lot of technical know-how involved and not everyone has the time to pull something like this off. The whole experiment took a "year and a half of engineering," according to the YouTuber. But the experiment still goes to show what's possible with some scrappy ingenuity.