| berndj | heh, "shrink to the 12.5µ node" has surely not been heard in 30 years | 20:35 |
|---|---|---|
| Sync | :D | 20:36 |
| berndj | azonenberg, what will you do about contacts? won't you need to futz with tungsten and the like? | 20:37 |
| berndj | Sync: how's your grasp on thermodynamics? | 20:37 |
| azonenberg | berndj: unknown at this point | 20:37 |
| azonenberg | My first goal is to get litho working reliably at the 12.5um node | 20:37 |
| azonenberg | once i can do patterning, i'll take it from there | 20:38 |
| Sync | berndj: first rule of thermodynamics, you do not talk about thermodynamics | 20:38 |
| berndj | that must be the -1th law :) | 20:38 |
| Sync | what's the problem? | 20:39 |
| berndj | joule expansion. besides eliminating moving parts, what's the advantage? | 20:39 |
| berndj | isn't adiabatic expansion hugely more efficient? | 20:39 |
| berndj | you're the one working on DIY cryo, aren't you? | 20:40 |
| Sync | yes | 20:40 |
| Sync | yes adibatic expansion is more efficient but it has drawbacks | 20:41 |
| berndj | for a small liquefier it's no issue of course, you go for the fewest-moving-parts method. but if you're doing tonnes a day i'd expect energy costs to start mattering | 20:42 |
| Sync | I'm currently waiting for some gasses to arrive then I can investigate some autocascading systems | 20:42 |
| Sync | yes but then your are doing it differently | 20:42 |
| Sync | bah -r | 20:42 |
| berndj | actually i though J-T expansion was how the commercial air separation plants worked. i may be mistaken | 20:43 |
| Sync | that depends | 20:43 |
| Sync | there are some that use adibatic expansion | 20:43 |
| Sync | but yes the majority ist J-T | 20:43 |
| berndj | maybe the plant predates the green revolution | 20:44 |
| Sync | I guess the idea is to have highly optimized compressors for your load | 20:44 |
| Sync | also most processes are low pressure now | 20:45 |
| berndj | ah. i can see adiabatic expansion being a lot more sensitive to load variations than a J-T system | 20:45 |
| berndj | you're [going to be] running at ~100bar IIRC/ | 20:46 |
| berndj | s,/,?, | 20:46 |
| Sync | yes, but plans are slowly changing | 20:46 |
| Sync | the cascade cooling system is far too large if I run at that pressure | 20:47 |
| Sync | I can get much smaller with advanced cooling concepts | 20:47 |
| berndj | why was it necessary to run at such a high pressure in the first place? | 20:47 |
| berndj | is the cooling just plain not enough at lower pressure? | 20:47 |
| Sync | because you need a high pressure differential to get enough temperature drop | 20:48 |
| berndj | in general, or to have a system that can start up? (as µ rises as air gets cooler) | 20:48 |
| Sync | that is a good question | 20:49 |
| Sync | I do not know how startup in larger air destillation plants works | 20:49 |
| Sync | I'd say they prime them | 20:49 |
| berndj | classic bootstrap problem | 20:49 |
| Sync | I now plan to run the N2 at something managable like 25bar but chill it using an autocascading system | 20:50 |
| Sync | thus eliminating the need for huge compressors | 20:50 |
| Sync | but that is a long term project now that I have LN2 on tap | 20:51 |
| berndj | by the way, what do you think of http://chemistry.stackexchange.com/questions/785/why-does-oxygen-not-condense-onto-open-dewers-of-liquid-nitrogen | 20:52 |
| berndj | if you cool air, do you get a mixture of N2 and O2, or one or the other, or what? | 20:52 |
| Sync | you get a mixture | 20:52 |
| Sync | and you need to destill the o2 off | 20:52 |
| berndj | i'm still not 100% confident of my reasoning in the answer i gave to that Q | 20:53 |
| Sync | also most dewars are capped off when filled | 20:53 |
| berndj | distillation, yet another major project | 20:53 |
| Sync | so they have a ever so slight amount of nitrogen coming out | 20:53 |
| Sync | that replaces all oxygen | 20:54 |
| Sync | you can indeed make LO2 with LN2 :P | 20:55 |
| Sync | been there done that | 20:55 |
| Sync | fun stuff | 20:55 |
| berndj | just using the LN2 as heat sink to condense the O2? | 20:55 |
| Sync | yes | 20:55 |
| berndj | that's what i'm unsure about in my Q; the way i read O2's vapour pressure graph, it only just starts to condense out of air at LN2's boiling point | 20:56 |
| berndj | *in my A to that Q | 20:57 |
| Sync | just look at the standard condition points | 20:58 |
| berndj | yeah, then it's 90K as opposed to N2's 77K | 20:59 |
| berndj | but oxygen isn't at 1atm in the air | 20:59 |
| Sync | I'm not so sure if the PPO2 is important there | 20:59 |
| Sync | for condensing out O2 from the air probably, but for liquifiying O2 from the bottle not so much | 21:00 |
| berndj | well, the ambient temperature is under 100C, yet it isn't raining | 21:00 |
| berndj | ah, sure, out of the bottle it'd be at or (way) above 1atm | 21:00 |
| Sync | I think you are right, the BP at the PPO2 in air is so close to the BP of N2 that it barely condenses out | 21:01 |
| berndj | i guess that's why you get a mixture when you liquefy air | 21:02 |
| Sync | no | 21:02 |
| Sync | that is just because you have both gasses in the air | 21:02 |
| Sync | the pressure differential is enough to liquify both | 21:03 |
| berndj | if PPO2 were a bit higher, you'd first get O2 condensing out though, wouldn't you? | 21:03 |
| Sync | gah I should go to sleep | 21:03 |
| berndj | i guess it depends on just how big the T drop is in the expansion | 21:04 |
| Sync | when I'm liquifying air the PPO2 just determines what I end up with | 21:04 |
| Sync | condensing out from the air is different | 21:05 |
| --- Wed Aug 1 2012 | 00:00 | |
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