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Registered Member #190
Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567
Because of the negative JT coefficient? No, I am not messing with helium. I just realize that if I get the compressed gas to do work I can more efficiently drop the temperature than just throttling the gas.
Turbo expanders are expensive. I called one place and the smallest was 35...35,000 dollars. These, however, are industrial. I don't know where I can get a small hand-sized unit.
If I try to play with one I may have to build my own using a CNC mill. I just got a Sherline mill. I will learn how to use it. Maybe in a few months if I get good I'll upgrade to a CNC. If I make one it will have to be able to withstand high pressure and cryogenic conditions. It would be easier to just find a small one.
I just don't have the skill right now to build an expander engine (piston or turbine) to do this properly.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Hi sir
Have you researched mixed gas JT cryocoolers? I posted a thread a while ago, and thought it may interest you too. it seems like the most probable way for reaching boiling point of nitrogen for amateurs, which can be made with off-shelf air conditioner or fridge parts and a couple of meters of copper pipe.
Constructing a turbine sounds like an extremely difficult task, requiring extraordinarily good balancing just not to fall apart from vibrations. I'd probably first research whether some off the shelf turbines could be used as an improvisation.
If I had an adequate lathe, mill and welding machines I'd much rather build a stirling type cryocooler instead though!
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turbo expanders
