new AIP for subs

[erich hartman]

i came across a new type of engine for cars soon to be released run on compressed air.

google for 'the air car' to find the website for this new engine.

this would seem ideal for subs instead of carrying a huge tank of liquid oxygen have a huge tank of compressed air.
i doubt you would get the same range with the compressed air but you can always refill the tank out at sea which you cant do with liquid oxygen.

the engine seems very simple.
if the car proves to be a success it could be a cheap practical AIP for diesel electric subs.

 

[Ryttare]

Sterling engines

The Swedish AIP subs with sterling engines should be able to work with compressed air. AFAIK there were some reports that it has been tested, but I could be wrong.

 

[StingrayOZ]

You don't get the energy density you need. Maybe you could pressurise the entire sub, but Im sure any humans inside would complain. Compressed air has been used in torpedos before. Your range would be terrible. You could also use a rubber band and store energy by twisting it. But again you would get bad range.

Why not get some sort of phase change. Liquify the air instead of just compressing it. You will get far greater energy density and a handy heat sink to hide your heat signature. You can refill it at sea (take a while though). But if you might just want to go fuel cell.

 

[Ryttare]

The Swedish AIP subs with sterling engines should be able to work with compressed air. AFAIK there were some reports that it has been tested, but I could be wrong.

Hm, I was a bit quick in my reply, of course Sterlings can't run on compressed air only, it needs diesel too...

The energy density of compressed air only is as StingrayOZ says quite low, unless the tanks are extremely strong and then they will weigh a lot.

 

[erich hartman]

Hm, I was a bit quick in my reply, of course Sterlings can't run on compressed air only, it needs diesel too...

The energy density of compressed air only is as StingrayOZ says quite low, unless the tanks are extremely strong and then they will weigh a lot.

according to the website the tanks on the car are made of carbon fibre and can handle 300bar pressure.
much lighter than steel and safer since they only tear if holed.........steel tanks would explode and send shrapnel everywhere.

they claim to get 100 kilometers for the car on those small tanks and the AIP engines would not be that much bigger.

 

[EnigmaNZ]

The stirling AIP engine generator sets are about the size of a small Japanese van. We are talking 150,000 watts per set. Thats a little bit bigger than the engine in the aircar, which, if it's the french one, is about the size of the motor from a small Kw generator set. Once Lion batteries become more reliable and are rated for submarine use, that will make a big impact, perhaps allowing a fortnight under water at slow speed without the additional complication of AIP, and they can be recharged. Replace diesels with larger stirling engines, and they can be recharged quietly as well while snorkeling. That maybe the way to go for the future of non-nuclear AIP.

 

[erich hartman]

The stirling AIP engine generator sets are about the size of a small Japanese van. We are talking 150,000 watts per set. Thats a little bit bigger than the engine in the aircar, which, if it's the french one, is about the size of the motor from a small Kw generator set. Once Lion batteries become more reliable and are rated for submarine use, that will make a big impact, perhaps allowing a fortnight under water at slow speed without the additional complication of AIP, and they can be recharged. Replace diesels with larger stirling engines, and they can be recharged quietly as well while snorkeling. That maybe the way to go for the future of non-nuclear AIP.

it will be interesting to see if these engines can be made bigger to the required size for sub use.
lion batteries would be too expensive for subs and it depends how large the stirling engines need to be to deliver the same power output as the diesels......otherwise i'm sure someone would have thought of this already.

 

[KGB]

Wouldn't all that compressed air need to be vented out eventually, leaving detectable bubbles?

 

[EnigmaNZ]

Yes, just like the air bubbles from that WW2 movie of a torpedo approaching a ship. Air powered torpedoes were around 150 years ago so its hardly new technology. Perhaps a little history lesson. The early torpedoes, whiteheads etc, were powered by compressed air carried in a flask that ran a recipercating motor driving the propellor. Range was hundreds of yards and speed 8 to 10 knots, adequent for use against an anchored ship.

Then someone got the bright idea of heating the air with alcohol with the air providing the oxygen, hot air expands even more and the range and speed increased. But the burners on the practice torpedoes used to burn out quickly, until someone came up with the idea of spraying them with water to cool them. The resulting steam had the unintentional effect of greatly increasing the efficiently of the propulsion system so this became the standard by WW1.

The whole idea of going back to compressed air is a non starter today.
The air powered car is a scheme for a cheap simple short ranged citycar, a criteria that can't apply to military submarines, maybe civilian and private home built though, but thats another subject.