Liquid nitrogen is pretty cheap, but providing it constantly over such a long time is hard.
I did some back of the envelope estimation and it seems to me that it can be practical (and in fact fairly cheap) to pre-load enough liquid nitrogen for couple centuries. The MRI magnets are example of keeping something cold for years without re-loading. If i were to sign up for cryonics I’d have to design my own coffin, it seems.
edit: note on the MRI magnets—i found out they do use refrigerator on the outer side of the dewar, not sure how necessary is this though if you can add reflector shields into dewar.
edit: I got even better idea. The dewar interior can be magnetically levitated using superconductors on the cold side. The vacuum can be maintained by charcoal cold trap on the cold side (as per standard practice). Nested lightweight reflective enclosures can be suspended around it on thin filaments. Other coolant than liquid nitrogen will have to be used (there will be no vent); i’m thinking of a gas that can be chemically absorbed at low temperature such that evaporation and absorption are net endothermic. Alternatively, solid-liquid phase change could be utilized instead of liquid-gas. This needs a huge and detailed study analysing multiple alternatives to determine the most cost effective approach.
Well, it is way simpler than hard drive in your computer. The problem is that it is not mass manufactured, and needs a lot of engineering work. (also i’m considering just the brains).
Frozen ethane looks promising, half the per-kg latent heat of the liquid nitrogen, and it’s probably denser. The freons also have very low melting temperatures and may have high latent heat of fusion but I cant find any data.
It’s also hard to estimate the rate of heat transfer through multi layered reflector. I’ll think it over when I have time. I’m quite rusty on this. For those who want to calculate, the radiation is proportional to temperature to the 4th power (Stefan–Boltzmann law), and in the equilibrium the shield radiates as much as it absorbs, and I dunno how to model shiny metals.
In any case it would be great to just boost maintenance-free time to a couple years. Not sure everyone wants to wake up after event that maintenance was suspended for decades or a century. Anything can happen incl. show trial for some nonsense crimes. edit: or worse yet the copyright expiration on yourself as IP.
I did some back of the envelope estimation and it seems to me that it can be practical (and in fact fairly cheap) to pre-load enough liquid nitrogen for couple centuries. The MRI magnets are example of keeping something cold for years without re-loading. If i were to sign up for cryonics I’d have to design my own coffin, it seems.
edit: note on the MRI magnets—i found out they do use refrigerator on the outer side of the dewar, not sure how necessary is this though if you can add reflector shields into dewar.
edit: I got even better idea. The dewar interior can be magnetically levitated using superconductors on the cold side. The vacuum can be maintained by charcoal cold trap on the cold side (as per standard practice). Nested lightweight reflective enclosures can be suspended around it on thin filaments. Other coolant than liquid nitrogen will have to be used (there will be no vent); i’m thinking of a gas that can be chemically absorbed at low temperature such that evaporation and absorption are net endothermic. Alternatively, solid-liquid phase change could be utilized instead of liquid-gas. This needs a huge and detailed study analysing multiple alternatives to determine the most cost effective approach.
You think we could set things up so there was no maintenance needed? This would give cryonics many of the advantages of plastination.
It sounds really expensive, though.
Well, it is way simpler than hard drive in your computer. The problem is that it is not mass manufactured, and needs a lot of engineering work. (also i’m considering just the brains).
I’m looking at this table for the solid coolants:
http://physics.info/heat-latent/
Frozen ethane looks promising, half the per-kg latent heat of the liquid nitrogen, and it’s probably denser. The freons also have very low melting temperatures and may have high latent heat of fusion but I cant find any data.
It’s also hard to estimate the rate of heat transfer through multi layered reflector. I’ll think it over when I have time. I’m quite rusty on this. For those who want to calculate, the radiation is proportional to temperature to the 4th power (Stefan–Boltzmann law), and in the equilibrium the shield radiates as much as it absorbs, and I dunno how to model shiny metals.
In any case it would be great to just boost maintenance-free time to a couple years. Not sure everyone wants to wake up after event that maintenance was suspended for decades or a century. Anything can happen incl. show trial for some nonsense crimes. edit: or worse yet the copyright expiration on yourself as IP.