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From: BGB <cr88192@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: C23 thoughts and opinions
Date: Tue, 4 Jun 2024 13:46:00 -0500
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On 6/3/2024 3:23 PM, Tim Rentsch wrote:
> scott@slp53.sl.home (Scott Lurndal) writes:
> 
> [ ... (internal-combustion) engines, ... ]
> 
>> It's pretty clear that the ICE is becoming a dinosaur.
> 
> Kind of makes it full circle, doesn't it?  ;)

Though, annoyingly, there isn't a great alternative in some use cases:
   Batteries: Lower energy density and require charging (slow);
   Fuel Cells: More expensive and finicky.
   Internal combustion engines: Noise.
     Reciprocating ICE: Bulky and noisy;
     Rotary Engine: Inefficient.
     Gas turbine: Very inefficient at smaller sizes.
   Rankine cycle engines:
     Difficult to scale down effectively.
       Small turbines are still inefficient;
       Reciprocating designs are still noisy.


One promising technology is "light cells":
Burn fuel to release heat inside of a chamber;
Heat causes contained sodium metal to glow and release monochromatic 
orange light through a quartz envelope or similar;
Use solar cells to convert light to electricity.

Though, seems this would make more sense in combination with batteries:
Batteries run low, so start up light cell to recharge, then shut down 
when batteries are full.

Could almost try to convert heat to electricity more directly via the 
Peltier Effect, but this is inefficient.


Mostly, things get annoying, if one wants a mobile power-supply between 
500W and 2kW. Where these are too big for batteries to be ideal, but 
small enough that using ICE's is rather annoying (due to noise any/or 
smokey/stinky exhaust).


Ideally want something to run on a fuel like Ethanol or Isopropanol 
(with no need for the addition of 2-cycle oil or similar), mostly so 
that it burns cleanly.


Though, arguably, a small Rankine cycle engine with Ethanol could make 
sense, if one also uses the ethanol as a working fluid for the turbine, 
this adds heat and vaporizes it making it easier to use in combustion 
(can use a nozzle that uses the high-pressure vaporized fuel stream to 
pull in air intake for the combustion process, which is then used to 
vaporize more fuel). Though, if using pistons, they would still make noise.


....