Point taken. Complex machinery on the inside seems like it would be a pain to maintain. A hoist that lowers patients from the top could be simplest. Computer controlled for precision and safety (perhaps still human operated).
Rather than shelves, I suspect steel boxes of a cubic meter or more would be used to contain the patients. Stacking the heads in a heap sounds like a recipe for crushed skulls and mixed-up brain matter. (Though who knows what nanotech can solve, eh?) In the cold-air version of the system (above LN2 temperature), these would act as heat sink and thermal conductor while providing strength. Fans would probably also be used to circulate the air to prevent stratification.
Stacking directly in LN2 might prove interesting. A reason to use cold-air temperatures over LN2 might be to make the stacking mechanism easier to design. Remember, the process of stacking patients is only going to take a few years, and it can be filled with cryogen later.
Cooling to LN2 temps over that last few degrees could be done at a rate that takes months (or even years), which I assume would induce fewer cracks. Then it would be filled with LN2. If we use the steel boxes, the inside of the boxes might need to be filled as well in which case they would need to have openings. (Perhaps they should be cages rather than solid boxes.) This is just to maximize cryogen volume; you could always keep it cool by just cooling the outside.
Point taken. Complex machinery on the inside seems like it would be a pain to maintain. A hoist that lowers patients from the top could be simplest. Computer controlled for precision and safety (perhaps still human operated).
Rather than shelves, I suspect steel boxes of a cubic meter or more would be used to contain the patients. Stacking the heads in a heap sounds like a recipe for crushed skulls and mixed-up brain matter. (Though who knows what nanotech can solve, eh?) In the cold-air version of the system (above LN2 temperature), these would act as heat sink and thermal conductor while providing strength. Fans would probably also be used to circulate the air to prevent stratification.
Stacking directly in LN2 might prove interesting. A reason to use cold-air temperatures over LN2 might be to make the stacking mechanism easier to design. Remember, the process of stacking patients is only going to take a few years, and it can be filled with cryogen later.
Cooling to LN2 temps over that last few degrees could be done at a rate that takes months (or even years), which I assume would induce fewer cracks. Then it would be filled with LN2. If we use the steel boxes, the inside of the boxes might need to be filled as well in which case they would need to have openings. (Perhaps they should be cages rather than solid boxes.) This is just to maximize cryogen volume; you could always keep it cool by just cooling the outside.