Closed cycle internal combustion engine/generators in space

[Stormbringer]

If we never develop fusion reactors but need more power than a reasonably designed solar array or two can provide is it feasible to use a closed cycle combustion engine in space? They are used in submarines but it is a different environment with different problems and different resources. here is a wiki on the use in subs:

https://en.wikipedia.org/wiki/Air-independent_propulsion

the reason i got to thinking about it is there is a new engine on the block and it is impressive:

http://www.nextbigfuture.com/2016/12/darpa-funds-30-kw-x4-liquid-piston.html

of course you still need fuel tanks and air tanks and some plumbing and pumps. but this thing starts off with a large mass advantage before all that other stuff gets added in. but that other stuff is admittedly a downer.


So in what world would you justify putting one of these on a space craft, station or installation?

Bearing in mind it does not necessarily have to be designed to consume diesel. It could be methane or alcohol or something.

[1]

Do a search on this site for Integrated Vehicle Fluids (IVF) and similar topics. You'll find those ideas have been around for a long time, and have been in the works for some years now.

Here's a (somewhat old) ULA publication on the topic.

[Asteroza]

Wasn't the ACES IVF powerplant a chevy smallblock inline 6 cylinder engine actually? Though I guess that doesn't count as "closed" per se. It isn't the "best" engine in standalone efficiency, but it had a number of desirable traits, including exhaust temperature that caused it to bubble up as their choice of IC engine.

[Damon Hill]

The baseline IVF internal combustion engine is an in-line flathead six, custom-built by a company specializing in racing engines.  Uses direct injection oxygen and I think it has a 'blown' crankcase to scavenge any oxygen blow-by.  A big IC engine is going to need a serious radiator; the IVF is cooled by cold hydrogen gas and I think its peak power is about 20 HP.

[CameronD]

The baseline IVF internal combustion engine is an in-line flathead six, custom-built by a company specializing in racing engines.  Uses direct injection oxygen and I think it has a 'blown' crankcase to scavenge any oxygen blow-by.  A big IC engine is going to need a serious radiator; the IVF is cooled by cold hydrogen gas and I think its peak power is about 20 HP.

That's a shame.. a big-block Chevvy V8 with chrome pipes would look a lot more impressive!! 

[1]

A big IC engine is going to need a serious radiator; the IVF is cooled by cold hydrogen gas and I think its peak power is about 20 HP.

A much more recent publication puts the engine size about 750cc. For anyone unfamiliar, this is about the same as a moderately sized motorcycle engine. I didn't see an explicit power output listed, but racing bikes of that size can go well over 100 HP. This thing could conceivably be quite powerful, though I suspect these engines will be optimized for something other than sheer power.

In somewhat serendipitous timing, the old IVF thread has woken up; and IVF-specific topics are probably best discussed there.

[Stormbringer]

well i posted this one because the engine in the op is tiny for the power developed meaning a lot less mass with the intent to discuss the viability for either an APU or for main power if that application makes sense due to the other mass considerations. because of this i am not sure it fits in the thread you linked to because it is about a different engine and is already part of a system design. That said the other thread topic is very interesting as well.

The engine is low mass/ small footprint / good power output/ high efficiency and i have no clue if the rest of the necessary design components would make this a contender for an APU or main power system for a few space applications or not.

[IRobot]

Do a search on this site for Integrated Vehicle Fluids (IVF) and similar topics. You'll find those ideas have been around for a long time, and have been in the works for some years now.

Here's a (somewhat old) ULA publication on the topic.

Get rid of GHe, Hydrazine, large Batteries & high pressures

Use only hydrogen and oxygen already on board for vehicle functions

Interesting presentation, SpaceX's ITS follows similar ideas: reduce number of fuels/He to the bare minimum. Wonder if they read it...

[acsawdey]

A big IC engine is going to need a serious radiator; the IVF is cooled by cold hydrogen gas and I think its peak power is about 20 HP.

A much more recent publication puts the engine size about 750cc. For anyone unfamiliar, this is about the same as a moderately sized motorcycle engine. I didn't see an explicit power output listed, but racing bikes of that size can go well over 100 HP. This thing could conceivably be quite powerful, though I suspect these engines will be optimized for something other than sheer power.

Also piston IC engines running on hydrogen make far less power than gasoline ones. The worked example I have is the BMW "Hydrogen 7" -- the 6L V12 in that makes 256 HP, and the gasoline version of the same engine produces 439 HP. Possibly running on pure O2 rather than air would help somewhat.

[Lee Jay]

well i posted this one because the engine in the op is tiny for the power developed...

Not really.  40HP in 30 pounds for 1.33 HP/pound.

Off-the-shelf R/C airplane piston engine:

https://www.desertaircraft.com/products/da-120

12.5 HP, 5 pounds for 2.5HP/pound - about double the one in the OP (yes, I know they don't post HP anymore, but they used to and that's what it would take to turn the props they turn at the speeds they turn them).

Turbine engines can be 10 times that power dense.