How hot an ambient temperature can we design a functioning machine for? Can we build an engine, say, that can exist indefintely, and function normally, at 100C (I’m sure yes.) 200C? (Maybe…?) 500C? The temperatures of Venus? 1000C?
What about electronics? I know most standard electronics is intended to operate in maybe 80C, and I’m sure that there are specialised parts for higher temperatures. Can we make parts that will run at 200C or 500C?
And what about cold? Can we build a machine to run indefinitely at, say, liquid nitrogen temperatures?
It’s pretty much going to be defined by materials. If you define a “machine” as something that does work you can have a tungsten or tantalum alloy “machine” operating up to around 6000F. A machine made of carbon could work up to 8000F in a vacuum.
If you consider the magnetic bottles and containment fields used in various physics experiments “machines” they contain and “work” with temperatures hotter than the interior of a star.
Venus has a surface temperature somewhere north of 400°C and the Soviets were quite proud of the fact that their Venera 8 lander lasted 50 minutes on the surface before succumbing. Fifty minutes is a long ways from ‘indefinitely’ so I think we have an upper bound, at least for the present.
No, the Venera lander doesn’t provide an upper bound. For one thing, building a “machine” and a “machine that can manage a landing from above the atmosphere, take pictures, communicate with a distant planet, and survive a sulphuric acid rich atmosphere” are very different. For another thing, that was almost 40 years ago.
The hottest functioning machines I know of are carbon/carbon-boron thermocouples that run at well over 2000°C. If you don’t like calling a thermocouple a machine, consider oven components used in the metals industry. These things, such as hooks and rollers and hinges and levers and whatnot, often operate red hot or higher, around 1000°C or more.
Interresting. So could we build, say, a steam engine (using some working fluid other than water) that would run at 1000C? Could we design electronics that would work at 1000C?
The machines I used in a “rubber base” factory to test the rubber’s ability to react with itself, and its hardness once reacted, worked at 300C. That’s the temperature used by our customer’s heated presses, as well; those heated presses work a lot more continuously than our little testing machine.
One of the problems with newbie workers in those factories is that the machines don’t look hot. I saw many a coworker with burn scars on their hands and wrists.
>So could we build, say, a steam engine (using some working fluid other than water) that would run at 1000C?
If you count turbines, we go to over 1000 °C already in at least some non-steam cases, and to at least around 500 °C in steam. If you’re picturing something with pistons, that’s uglier because sliding surfaces are more difficult at high temperatures. I don’t know how much hotter than gasoline or diesel engines the piston mechanism is used, nor do I know how hot they get.
>Could we design electronics that would work at 1000C?
O yeah. Diamond, for instance, in principle works like silicon does in making transistors and integrated circuits. However, it is only useful at higher temperatures. IIRC an article in Scientific American some years back described diamond transistors that operated red hot. Temperature sensors of various electronic type work at high temperature by nature, of course.