4 ms·

One thing that's notable is that an insulator for high temperatures (eg. Soft fire brick) is very different from an insulator for low temperatures (eg. Your fre

One thing that's notable is that an insulator for high temperatures (eg. Soft fire brick) is very different from an insulator for low temperatures (eg. Your freezer). High temperature stuff might get 0.3 W/mK. Low temperature stuff, for example polyurethane foam used in fridges, are 0.02 W/mK - 10x better! If someone can invent a high temperature insulator that is as good as low temperature insulators, then that could translate to lots of saved energy.

DiabloD3 4y ago
Such things exist but are incredibly expensive. For example, I can't remember where I saw it (some show I saw like 20 years ago), but some really expensive industrial process has a vacuum sealed double walled vessel. Basically, a Hydroflask shaped like an oven. It had low thermal conductivity, but the hard part was keeping the thermal expansion from cracking it open.
- chipsa 4y ago
  It’s now a regular commercial thing known as vacuum insulated panels. They are of course, expensive, and damage makes them useless.
bell-cot 4y ago
Remember those little white tiles on the outside of NASA's Space Shuttle? I don't have W/mK data...but cost and durability might be issues.
- HPsquared 4y ago
  Apparently the conductivity of the tiles is- 0.028 BTU/ft-hr-°F at 70°F and 1 atm 0.073 BTU/ft-hr-°F at 2000°F and 10^-4 atm Not sure how that translates to SI units though. So many conversions! Edit: 0.048 W m^-1 K^-1 at 21°C, 1 bar 0.126 W m^-1 K^-1 at 1093°C, 0.0001 bar
azalemeth 4y ago
Silica aerogels have a pressure-dependent thermal conductivity, and at atmospheric pressure it is approximately 0.03 W/mK – there are pictures of them on bunsen burners with ice-cream or flowers on top. Their "naked" density is on the order of 2 kg/m^3 -- comparable to that of air (~1 kg/m^3), as they are, unsurprisingly, mostly air. The melting point is around 1400 K (either not as high or comparable to the "2200 degrees" mentioned in the article – I'm unsure if that's ºC or ºF). The down side, of course, is the cost: all the "real" providers I can find have a price of "contact us", and on Amazon a ~35x25 cm^2 panel goes for about €30, in comparison to somewhere between half and a tenth the price for bricks or other forms of insulation... [1] https://en.wikipedia.org/wiki/Aerogel#Silica_aerogel https://en.wikipedia.org/wiki/Aerogel#Silica_aerogel
mikewarot 4y ago
>If someone can invent a high temperature insulator that is as good as low temperature insulators, then that could translate to lots of saved energy. I'm really not sure these are up to the task, but you can make them thicker as they are cheap. Here's a carbon foam process from AvE [1] [2] Also, if you only need one time use, there's StarLite [3] Which is a composite of Elmers Glue (PVA), Baking Soda and Corn Starch. Commercially, intumescent[4] materials are available that are essentially a one time use fire repellant paint. [1] https://www.youtube.com/watch?v=Wex_yKfrTo4 https://www.youtube.com/watch?v=Wex_yKfrTo4 [2] https://www.youtube.com/watch?v=L-qOIO6IQWk https://www.youtube.com/watch?v=L-qOIO6IQWk [3] https://www.youtube.com/watch?v=0IbWampaEcM https://www.youtube.com/watch?v=0IbWampaEcM [4] https://en.wikipedia.org/wiki/Intumescent https://en.wikipedia.org/wiki/Intumescent

DiabloD3 4y ago

Such things exist but are incredibly expensive. For example, I can't remember where I saw it (some show I saw like 20 years ago), but some really expensive industrial process has a vacuum sealed double walled vessel. Basically, a Hydroflask shaped like an oven. It had low thermal conductivity, but the hard part was keeping the thermal expansion from cracking it open.

chipsa 4y ago
It’s now a regular commercial thing known as vacuum insulated panels. They are of course, expensive, and damage makes them useless.

bell-cot 4y ago

Remember those little white tiles on the outside of NASA's Space Shuttle? I don't have W/mK data...but cost and durability might be issues.

HPsquared 4y ago
Apparently the conductivity of the tiles is- 0.028 BTU/ft-hr-°F at 70°F and 1 atm 0.073 BTU/ft-hr-°F at 2000°F and 10^-4 atm Not sure how that translates to SI units though. So many conversions! Edit: 0.048 W m^-1 K^-1 at 21°C, 1 bar 0.126 W m^-1 K^-1 at 1093°C, 0.0001 bar

azalemeth 4y ago

Silica aerogels have a pressure-dependent thermal conductivity, and at atmospheric pressure it is approximately 0.03 W/mK – there are pictures of them on bunsen burners with ice-cream or flowers on top. Their "naked" density is on the order of 2 kg/m^3 -- comparable to that of air (~1 kg/m^3), as they are, unsurprisingly, mostly air. The melting point is around 1400 K (either not as high or comparable to the "2200 degrees" mentioned in the article – I'm unsure if that's ºC or ºF). The down side, of course, is the cost: all the "real" providers I can find have a price of "contact us", and on Amazon a ~35x25 cm^2 panel goes for about €30, in comparison to somewhere between half and a tenth the price for bricks or other forms of insulation... [1] https://en.wikipedia.org/wiki/Aerogel#Silica_aerogel https://en.wikipedia.org/wiki/Aerogel#Silica_aerogel

mikewarot 4y ago

>If someone can invent a high temperature insulator that is as good as low temperature insulators, then that could translate to lots of saved energy. I'm really not sure these are up to the task, but you can make them thicker as they are cheap. Here's a carbon foam process from AvE [1] [2] Also, if you only need one time use, there's StarLite [3] Which is a composite of Elmers Glue (PVA), Baking Soda and Corn Starch. Commercially, intumescent[4] materials are available that are essentially a one time use fire repellant paint. [1] https://www.youtube.com/watch?v=Wex_yKfrTo4 https://www.youtube.com/watch?v=Wex_yKfrTo4 [2] https://www.youtube.com/watch?v=L-qOIO6IQWk https://www.youtube.com/watch?v=L-qOIO6IQWk [3] https://www.youtube.com/watch?v=0IbWampaEcM https://www.youtube.com/watch?v=0IbWampaEcM [4] https://en.wikipedia.org/wiki/Intumescent https://en.wikipedia.org/wiki/Intumescent