3 ms·

Fair point about water pipe corrosion, my mistake. Although thinking about it more carefully what is strength saving you there other than cost? This material is

Fair point about water pipe corrosion, my mistake. Although thinking about it more carefully what is strength saving you there other than cost? This material is going to be at least a 10x cost premium judging by the elemental composition. And if we're talking household temperatures I expect there are polymer coatings that would work better. The heat exchanger point is interesting. However doesn't stainless already lose out to 3D printed aluminum for the sort of applications where the optimization is worth the cost? This material is even heaver than steel and substantially more expensive. It's tangential but I wonder how amenable to 3D printing this material will prove to be.

kragen 2y ago
https://news.ycombinator.com/item?id=43816979 https://news.ycombinator.com/item?id=43816979 suggested that the raw materials imply about a 6x cost increase over stainless, which is less than 10x. I haven't done the numbers myself. High-energy cryogenic ball milling of 10 grams for four hours in a continuous flow of liquid nitrogen under an argon atmosphere with <1ppm oxygen (https://www.science.org/action/downloadSupplement?doi=10.1126%2Fscience.adr0299&file=science.adr0299_sm.pdf https://www.science.org/action/downloadSupplement?doi=10.112...) sounds expensive, but maybe they only did it that way because it was a low-risk way to ensure the alloying worked with the lab equipment they had on hand, not because it's the cheapest way to make the material. Hopefully cheaper ways are found. I'm no expert in heat exchangers, but my calculations suggest 3-D printing is or will be an enormous boost there, and may reverse the gradient of merit for wall material thermal conductivity, favoring good thermal insulators over good thermal conductors like copper and aluminum. As for aluminum, it is only suitable for low temperatures.
- fc417fc802 2y ago
  6x for the raw materials before you account for the production process. I'm curious. What mechanism would lead to an insulator being favored in a heat exchanger? Fair point about aluminum and temperature. As a layman an engine block is high temperature to me. I guess this would be extremely useful for more exotic stuff.
  - kragen 2y ago
    If the fluid path through the heat exchanger is very short and the contact area is very large, preventing lengthwise conduction of heat from one end of the fluid path to the other, rather than getting enough conduction between the fluids, should become the performance-limiting factor. See https://dercuano.github.io/notes/capillary-heat-exchanger.html https://dercuano.github.io/notes/capillary-heat-exchanger.ht.... I could be wrong about this, but I didn't just make it up; I got it from Lingai Luo's book on heat and mass transfer intensification, which hopefully I've understood correctly.
    - fc417fc802 2y ago
      No I think you've understood that correctly. I'd count that as one of those things that's blindingly obvious once it's pointed out but not until then. With 3D printing I wonder if you could insert bands of insulator into an otherwise conductive wall? But you're dealing with large (potentially ridiculously so) temperature ranges so I wonder if it would prove difficult to match the thermal properties of the two materials closely enough. I now have the weirdest desire to play with heat exchanger designs that I have absolutely zero use for. I've been nerd sniped.

kragen 2y ago

https://news.ycombinator.com/item?id=43816979 https://news.ycombinator.com/item?id=43816979 suggested that the raw materials imply about a 6x cost increase over stainless, which is less than 10x. I haven't done the numbers myself. High-energy cryogenic ball milling of 10 grams for four hours in a continuous flow of liquid nitrogen under an argon atmosphere with <1ppm oxygen (https://www.science.org/action/downloadSupplement?doi=10.1126%2Fscience.adr0299&file=science.adr0299_sm.pdf https://www.science.org/action/downloadSupplement?doi=10.112...) sounds expensive, but maybe they only did it that way because it was a low-risk way to ensure the alloying worked with the lab equipment they had on hand, not because it's the cheapest way to make the material. Hopefully cheaper ways are found. I'm no expert in heat exchangers, but my calculations suggest 3-D printing is or will be an enormous boost there, and may reverse the gradient of merit for wall material thermal conductivity, favoring good thermal insulators over good thermal conductors like copper and aluminum. As for aluminum, it is only suitable for low temperatures.

fc417fc802 2y ago
6x for the raw materials before you account for the production process. I'm curious. What mechanism would lead to an insulator being favored in a heat exchanger? Fair point about aluminum and temperature. As a layman an engine block is high temperature to me. I guess this would be extremely useful for more exotic stuff.
- kragen 2y ago
  If the fluid path through the heat exchanger is very short and the contact area is very large, preventing lengthwise conduction of heat from one end of the fluid path to the other, rather than getting enough conduction between the fluids, should become the performance-limiting factor. See https://dercuano.github.io/notes/capillary-heat-exchanger.html https://dercuano.github.io/notes/capillary-heat-exchanger.ht.... I could be wrong about this, but I didn't just make it up; I got it from Lingai Luo's book on heat and mass transfer intensification, which hopefully I've understood correctly.
  - fc417fc802 2y ago
    No I think you've understood that correctly. I'd count that as one of those things that's blindingly obvious once it's pointed out but not until then. With 3D printing I wonder if you could insert bands of insulator into an otherwise conductive wall? But you're dealing with large (potentially ridiculously so) temperature ranges so I wonder if it would prove difficult to match the thermal properties of the two materials closely enough. I now have the weirdest desire to play with heat exchanger designs that I have absolutely zero use for. I've been nerd sniped.