Solid fuel internal combustion engine? Is it possible?

[JovanD]

Im not asking if it's practical or worth it, just is it physically possible for such a thing to exist?

You know how stuff like flour, sawdust etc. can explode when mixed with air in fine dust cloud...

Can that be done inside an engine and make it run assuming somehow you can inject the air/fuel dust?
Maybe a hot-bulb engine with forced induction that has teflon(or some other solid lubricant) coated cylinder walls and pistons?
Could that work? Probably not for long time, but can it at all?

[ARikozuM]

@mariushm

@Taf the Ghost

 

[mariushm]

I'm not sure, as you'd also have to take care of the burned residue somehow ... I'm not really an expert on engines, not really the most qualified.

I guess it may be possible to use shitty fuels like sawdust in big engines like the huge ones on shipping container boats which spin at 100rpm and run on really crappy diesel fuel (but eat tens of liters of fuel a minute)

 

If you look at it as a workaround and basically loosen it to just converting solid fuel to something then there's options...

Maybe see https://en.wikipedia.org/wiki/Wood_gas_generator

Not sure if this classifies, as it involves hot sodium (turned to liquid) but i should mention it : https://en.wikipedia.org/wiki/Alkali-metal_thermal_to_electric_converter

 

 

I'm sure there's other solutions that can combine a solid fuel with some liquid  to produce a chemical reaction (ex drop some xx over yy to produce heat which boils water and produces gas therefore pressure which can move wheels.

 

[Metallus97]

Wellll I study engineering

Sure possible but at GREAT losses and with a SUUUUPER complex system! With material dust it gets easier. Modern gas engines also work with LIIIIITLE drops of fuel mixed with air basically. Thats not that far from dust. But yes residue buildup would be the biggest problem. Some (Audi VW ehhhmmm) engines already have problems with buildup. But this is not only coming from how they burn fuel 

[harryk]

Check out the gunpowder engine idea, which was tested on Mythbusters. Ultimately they were unable to get a modern IC engine to run on gunpowder.

 

Challenges include:

- Igniting the fuel in the cylinder

- Efficiently burning all the fuel

- Dealing with getting the exhaust and leftover participates out of the cylinder

 

I don't know if it actually exists but I could imagine using a solid fuel that only produced gas as byproduct. Furthermore rather than trying to use solid particles as a replacement for a gas-air mixture why not use something like a fuel rod or pellet which is inserted into the top of the cylinder and directly ignited for each piston cycle.

[Mira Yurizaki]

The funny thing is we've had the basics for a gunpowder based engine. It's just the energy isn't being used to drive a crankshaft.

 

It's called a machine gun.

[Taf the Ghost]

3 hours ago, JovanD said:

Im not asking if it's practical or worth it, just is it physically possible for such a thing to exist?

You know how stuff like flour, sawdust etc. can explode when mixed with air in fine dust cloud...

Can that be done inside an engine and make it run assuming somehow you can inject the air/fuel dust?
Maybe a hot-bulb engine with forced induction that has teflon(or some other solid lubricant) coated cylinder walls and pistons?
Could that work? Probably not for long time, but can it at all?

It's more of a "but why?". You'd also not likely use a cycle that looks like a gasoline powered engine, but maybe something like an opposed diesel engine. Hot-Bulb or some older approaches might work, but there wouldn't be many solid fuels with enough energy density to make it worthwhile. But the biggest issue would be clearance of waste. There's a reason Steam Powered Machinery was so important & so long-lived. It's a generally more efficient way of using solid fuels.

 

Having a hard time getting beyond "just build a steam engine" as logical way to approach it. IC engines work so well because they control extremely small amounts of fuel being precisely combusted.

[Bitter]

GM had a car with a turbine engine that ran on coal dust in the 80's on their proving grounds as a proof of concept. Turbine engines are technically internal combustion, right? Turbines can run in just about anything if they're designed for it and lots of things they're not designed for, I believe this engine needed to warm up on liquid fuel then it could be switched to coal dust once it was running hot or required a little normal fuel to help burn the coal dust, but it was running on a solid fuel.

 

In reality it never made it past a demo model doing laps around a small test track. It was prohibitively expensive, would never meet emissions regulations, and likely had issues with cold starts in low temps if they even got that far in testing. This was a time when domestic auto makers would fund internal pet projects like money was going out of style, then junk them and move on.

 

 

[Bananasplit_00]

i instantly think of dropping in an explosive pill like thing and having a flame/compression and heating light it. Reminds me of the Orion project from NASA though thats more of an external combustion engine

[Bitter]

1 hour ago, Bananasplit_00 said:

i instantly think of dropping in an explosive pill like thing and having a flame/compression and heating light it. Reminds me of the Orion project from NASA though thats more of an external combustion engine

Ever heard of a Coffman engine starter? It's a shotgun cartridge used to get the engine spinning and started in place of a glow plug for fast starts in adverse climates. Used on airplanes and tractors in the 20's through 40's.

[Bananasplit_00]

2 minutes ago, Bitter said:

Ever heard of a Coffman engine starter? It's a shotgun cartridge used to get the engine spinning and started in place of a glow plug for fast starts in adverse climates. Used on airplanes and tractors in the 20's through 40's.

just have an ammo belt and a very fast reloading system and you got an engine right there but thats more of a hot gas pumping engine

[Mira Yurizaki]

I think the issue with dirty combustion is more of an issue of how clean the fuel is and the combustion process. Even petrol can be dirty if it's not clean enough, it doesn't get enough oxygen to burn things off, or the byproducts cool off too soon.

 

If anything though, I think the only reason why solid fuel for motor engines hasn't really taken off is because of how much harder it is to transport the fuel into the combustion chamber. Fluids are stupid easy. Solids, not so much.

[PlayStation 2]

As someone pointed out earlier in the thread, General Motors attempted to build a coal-powered engine. While it's possible you could build an efficient enough engine revolving around solid fuel, it's both impractical and not really logical considering modern engines' designs that are designed around exploiting liquid fuels.

[Bitter]

58 minutes ago, Mira Yurizaki said:

I think the issue with dirty combustion is more of an issue of how clean the fuel is and the combustion process. Even petrol can be dirty if it's not clean enough, it doesn't get enough oxygen to burn things off, or the byproducts cool off too soon.

 

If anything though, I think the only reason why solid fuel for motor engines hasn't really taken off is because of how much harder it is to transport the fuel into the combustion chamber. Fluids are stupid easy. Solids, not so much.

The combustion process actually plays a HUGE role in the products that come out the other side of the engine. GDI engines are more sooty that PFI engines, high cylinder temperatures form way more NOX compounds, lean or rich mixtures affect exhaust quality greatly as well. Initial fuel quality has a part to play for sure, but even the cleanest fuels can be combusted in ways that make the exhaust more or less 'dirty'.