Re: Absurdly simple thermoacoustic-steam "rice" engine – What's going on here?
Posted: Thu Nov 17, 2022 4:53 am
Maybe cellulose fiber (paper) could substitute for the rice. Might be worth experimenting with:
https://www.sciencedirect.com/science/a ... via%3Dihub
There seems to be quite a bit of current research into these "wet" so-called "thermoacoustic" engines.
I get the idea of compression and expansion with phase change, but the significance of any "acoustic" element escapes me.
Sometimes any engine of just about any kind will "resonate" at some audible frequency, but most of the time even so-called thermoacoustic Stirling engines do not produce any tone when actually running.
Anyway, the implication of using paper is that absorption does play some roll, if only as a means of making the water readily available with a lot of surface to air interface.
It would seem just about anything that provides a lot of surface area for condensation and holds water in a way that promotes rapid evaporation will do.
Obviously, I think, just having a puddle of water in the bottom of the can is at best inefficient. Having many small (microscopic?) water droplets suspended on some substrate where both rapid condensation and evaporation may transpire is likely optimal.
Maybe instead of cellulose/paper fiber, which I think has some undesirable characteristics, being an organic substance like rice, subject to getting mushy or moldy or even burning if it dries out, maybe something like the ceramic fiber I've been testing for displacer material would work.
Having a damp fibrous material might make a more compact substrate with more surface area in less space, unless perhaps the added thermal mass or heat transfer capacity of the pebbles, glass beads or copper BB's and the like proves to be essential.
Don't have full access, but just the abstract alone is interesting.A stack made of cellulose paper strips was designed to ensure sufficient liquid supply and rapid liquid absorption during the phase-change thermoacoustic conversion
https://www.sciencedirect.com/science/a ... via%3Dihub
There seems to be quite a bit of current research into these "wet" so-called "thermoacoustic" engines.
I get the idea of compression and expansion with phase change, but the significance of any "acoustic" element escapes me.
Sometimes any engine of just about any kind will "resonate" at some audible frequency, but most of the time even so-called thermoacoustic Stirling engines do not produce any tone when actually running.
Anyway, the implication of using paper is that absorption does play some roll, if only as a means of making the water readily available with a lot of surface to air interface.
It would seem just about anything that provides a lot of surface area for condensation and holds water in a way that promotes rapid evaporation will do.
Obviously, I think, just having a puddle of water in the bottom of the can is at best inefficient. Having many small (microscopic?) water droplets suspended on some substrate where both rapid condensation and evaporation may transpire is likely optimal.
Maybe instead of cellulose/paper fiber, which I think has some undesirable characteristics, being an organic substance like rice, subject to getting mushy or moldy or even burning if it dries out, maybe something like the ceramic fiber I've been testing for displacer material would work.
Having a damp fibrous material might make a more compact substrate with more surface area in less space, unless perhaps the added thermal mass or heat transfer capacity of the pebbles, glass beads or copper BB's and the like proves to be essential.