this post was submitted on 18 Dec 2023
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Science Memes

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I've invented a 100% efficient combustion engine (aussie.zone)
submitted 10 months ago by [email protected] to c/[email protected]
27 comments fedilink hide all child comments
 

I use it to heat my house.

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[–] [email protected] 10 points 10 months ago (3 children)

Sorry, I’m a bit dumb for this one.

Could someone please explain?

[–] [email protected] 49 points 10 months ago (2 children)

There's no such thing as a 100% efficient "engine". But in this case, since the waste heat is put to use (heating the house), OP thinks there's a loophole.

But, house would also need to be soundproof. Any noise leaking to the outside is lost energy.

[–] [email protected] 24 points 10 months ago* (last edited 10 months ago) (1 children)

Ah, but that’s by design: it also acts as a soothing white noise machine.

Then you might point out the exhaust and all it’s associated wastes, but that’s by design: it produces a heady and aromatic product for recreational huffing.

Then you might point out the vibrations, but that’s by design: the engine also provides invigorating massages to relax taut muscles.

[–] [email protected] 13 points 10 months ago

You. Come sell my book

[–] [email protected] 5 points 10 months ago (1 children)

Let's allow a rounding error for 99.51% shall we?

[–] [email protected] 9 points 10 months ago

Don't tell anyone, but I actually only used 1 significant figure, so anything above 50% will do.

I'm also using the version of significant figures where I work backwards from the answer, otherwise I'd need 95% or higher and that's too difficult.

[–] [email protected] 30 points 10 months ago (1 children)

Most engines are less than 30% efficient at producing movement. The majority of the energy is lost as heat.

Thermodynamics tells us that pretty much all energy ends up as heat. In a closed system, any device that uses energy is 100% efficient at making heat. A 1000W computer will make exactly as much heat as a 1000W heater.

A 100% efficient engine can only exist if the desired output is heat, thus making it a pretty useless engine. Also, in a closed system, the exhaust cannot leave.

[–] [email protected] 10 points 10 months ago (3 children)

A 1000W computer will make exactly as much heat as a 1000W heater.

All space heaters should be coin miners (or some other borderline useless energy wasting tech, like AI training). Change my mind.

[–] [email protected] 6 points 10 months ago

We have enough of a chip shortage, tyvm

[–] [email protected] 3 points 10 months ago

If you want to be philanthropic, there are programs you can run that use your computer's idle time to process data for cancer research and such.

[–] [email protected] 2 points 10 months ago

You can sign up for research crunching.

[–] [email protected] 9 points 10 months ago (1 children)

Furnace.

[–] [email protected] 3 points 10 months ago (1 children)

But even a furnace/fireplace is subject to incomplete combustion, where some portion of the wood is transformed into byproducts that rob some of the energy of the fire. There's actually a big difference in the amount of energy you can get out of a fire, depending on the type of stove that's used.
That's some of what NGOs have tried to do for developing countries - find cheap and easily produceabke stove designs that can reduce the amount of wood needed and improve air quality in the home.

[–] [email protected] 2 points 10 months ago

Yes he is incorrect. NG furnace is 95% efficient iirc.