- #1
William_S
- 5
- 0
Hello everyone!
Just the forum I was hoping to find! There are really not many ppl to ask about this subject.Had nothing to do about a month ago so I thought that it would be quite fun and interesting to build a cryocooler, it will be a long time project though since I lack many things right now.
Since it will be a fun thing I had no plan to use it to anything special only a goal to get it as cold as it would get whatever that now might be since I doubt it would be even remotely possible to get close to any temperatures to fex make liquid air, which would be really fun.
Ok, before anyone say it so yes I have gone through around 40+ patents during the month of how they are constructed and what regenerator material that could be used and stuff and looked on many pages on the internet.
I have found much info in these patents but I lack the answers to some questions that I hope someone here might be able to answer to me:
1. The compression in a stirling cryocooler don't seem to be much over 1.5 if I have got things right which as I see is hardly any pressure at all. Wouldn't a higher pressure make a bigger volume of chilled helium and thus bigger active work or it is just not needed due to the high pressures in these?2. The regenerator materials that is seemed to be used (that I can get my hands on that is) is lead, stainless steel and even some plastics. However these materials are more to be used in the area of 80K and lower which I unfortunately don't think I will even get close to. What materials would work good about over 80K? I guess stainless would work quite long but I have not found any sharts to over 80K for materials in general, but if there are better ones over 80K then stainless I am all ears. I have not found any info on this mainly because cryocoolers are not normally used in the upper Kelvin segment.3. Normal say small football sized cryocoolers, fex those you see on Ebay sometimes and YouTube, seem to draw around 100W or so. For a compressor with no physical resistance that only have to compress something 1.5 times seem to be dam high, or have I miss something here? Sure its around 300 psi of helium in them but still they still compress from 1 Atm to 1.5 sort of speak since its all in the same pressurized atmosphere.4. I am quite sure the length of the regenerator have to be a length that accommodate the volume in the bottom at the cold finger and have read about strokes at around 20 - 25 mm here, which are smaller then I thought. But the lengths of the regenerator I have seen on patents have a much much bigger volume then this then what is really needed for that or the compressors 1.5 pressure increase, so what is going on here?
A longer regenerator then necessary can´t be of any advantage since all the helium will not go thought it all but only the first portion and not go back to be compressed so there is obviously something I miss here.5. I am sure that the regenerator material (or regenerator it self) should come as close to the bottom of the cold head as possible to get as much of the helium volume into it?
Thanks guys!
Regards William
Just the forum I was hoping to find! There are really not many ppl to ask about this subject.Had nothing to do about a month ago so I thought that it would be quite fun and interesting to build a cryocooler, it will be a long time project though since I lack many things right now.
Since it will be a fun thing I had no plan to use it to anything special only a goal to get it as cold as it would get whatever that now might be since I doubt it would be even remotely possible to get close to any temperatures to fex make liquid air, which would be really fun.
Ok, before anyone say it so yes I have gone through around 40+ patents during the month of how they are constructed and what regenerator material that could be used and stuff and looked on many pages on the internet.
I have found much info in these patents but I lack the answers to some questions that I hope someone here might be able to answer to me:
1. The compression in a stirling cryocooler don't seem to be much over 1.5 if I have got things right which as I see is hardly any pressure at all. Wouldn't a higher pressure make a bigger volume of chilled helium and thus bigger active work or it is just not needed due to the high pressures in these?2. The regenerator materials that is seemed to be used (that I can get my hands on that is) is lead, stainless steel and even some plastics. However these materials are more to be used in the area of 80K and lower which I unfortunately don't think I will even get close to. What materials would work good about over 80K? I guess stainless would work quite long but I have not found any sharts to over 80K for materials in general, but if there are better ones over 80K then stainless I am all ears. I have not found any info on this mainly because cryocoolers are not normally used in the upper Kelvin segment.3. Normal say small football sized cryocoolers, fex those you see on Ebay sometimes and YouTube, seem to draw around 100W or so. For a compressor with no physical resistance that only have to compress something 1.5 times seem to be dam high, or have I miss something here? Sure its around 300 psi of helium in them but still they still compress from 1 Atm to 1.5 sort of speak since its all in the same pressurized atmosphere.4. I am quite sure the length of the regenerator have to be a length that accommodate the volume in the bottom at the cold finger and have read about strokes at around 20 - 25 mm here, which are smaller then I thought. But the lengths of the regenerator I have seen on patents have a much much bigger volume then this then what is really needed for that or the compressors 1.5 pressure increase, so what is going on here?
A longer regenerator then necessary can´t be of any advantage since all the helium will not go thought it all but only the first portion and not go back to be compressed so there is obviously something I miss here.5. I am sure that the regenerator material (or regenerator it self) should come as close to the bottom of the cold head as possible to get as much of the helium volume into it?
Thanks guys!
Regards William
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