New Material Breaks World Record Turning Heat into Electricity • Hacker News Board

Re: New Material Breaks World Record Turning Heat into Electricity

#161

Post by adw » Fri, Jan 03, 2020, 2:14 AM UTC

infinite8s wrote: post #82

diegoperini wrote: post #54

Earlier quoted context omitted.

> A reasonable approximation for a crystalline structure is balls – point masses – connected by springs, where the springs are covalent bonds, plus electrostatic effects between point charges. Thanks! This is a great analogy.

This is the model used by most chemical simulation codes (that don't account for quantum chemistry). See for example the LAMMPS simulation software ( https://lammps.sandia.gov/ )

If anything I wrote has been original, it would have been a big red flag :-)

Re: New Material Breaks World Record Turning Heat into Electricity

#162

Post by nullc » Fri, Jan 03, 2020, 10:58 AM UTC

grecy wrote: post #127

UncleEntity wrote: post #118

Earlier quoted context omitted.

You could use the waste heat that goes up the chimney to warm the fluid with something like an automotive intercooler and set the system up backwards, maybe?

Ohhh, I hadn't thought of that idea. Interesting. I will be sure to experiment with that!

If you cool the exhaust gases too much they will condense in the flu, and the condensation is incredibly corrosive. Stoves/furnaces etc. (except for condensing ones) intentionally waste a lot of heat intentionally keeping the exhaust gases hot just to prevent this.

The hot exhaust also helps create airflow that moves the combustion products out of your living space.

It would be neat to recover otherwise totally wasted heat, just be careful.

Re: New Material Breaks World Record Turning Heat into Electricity

#163

Post by amluto » Tue, Jan 07, 2020, 7:55 AM UTC

abdullahkhalids wrote: post #134

amluto wrote: post #46

Earlier quoted context omitted.

You have some kind of error here: with T_c = T_h, not only does Wikipedia’s formula give 0% efficiency, but it must : any power at all generated with no temperature difference would make a perpetual motion machine.

For T_c=293 and T_h=303, you get efficiency = 1.4% for zT=5 and efficiency = 1.0% for zT=2.5. So about a 40% relative increase as OP calculated and negligible absolute change.

Improving from 1% to 1.4% is a huge improvement. It’s 40% more cooling for a given power input or 40% more power output for a given amount of heat consumed. Alternatively, it means you consume only 1/1.4 the resources to achieve your goal.

This does not imply that 1.4% efficiency is enough to be useful for most applications, of course.