Rumoured "mini-nuke/diesel" Submarine SSK-N(?) thread

[AndrewS]

And this is the article of Chinese micro reactor to produce 10 MWt or roughly 3-4 MWe quite small footprint

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Old article above from 2016 on development of a micro reactor

• 10MWth
• Measures around just 20 feet (6.1 metres) by 8.5 feet (2.6 metres)
• Lead-based

---

I recall the Alfa's reactors had problems with the reactors being bricked if the lead ever cooled down and solidified.

But a notional SSKN would have onboard batteries to provide emergency short-term heating if electricity supply from ashore is cutoff.
And perhaps the small size of the reactor means it is possible to reheat the entire reactor from cold.
Plus Stirling engines could operate in reverse and convert mechanical motion into heat for the reactor if necessary?

Just speculation here

 

[AndrewS]

Yeah. Likely. The Type 214 achieves 6 knots with 240 kW. The Yuan has almost double the displacement so its power requirement for the same speed should be like 60% higher. It also has a 33% bigger crew.

Yes. Also hydrogen for fuel cell equipped subs. As far as I understand, fuel cells can work in reverse too but the sub wouldn't have much time to regenerate propellants from waste water. I wonder how AIP subs handle CO2. They carry tons of oxygen. If they have something to get rid of the CO2, in theory they can get away with snorkeling for long periods.

If I look at the Type-214, it has a total of 240KW for everything on the boat.
So if a Yuan hull requires 60% more power for propulsion, call it "roughly" 384 KW for the same speed of 6 knots.

And if it has 6 x 320KW available, that translates into a sustained speed of roughly 14 knots, given that the hotel/sensor/crew/air load doesn't scale upwards like propulsion.

That matches up with the 14 knot figure mentioned by the "source"

@tphuang
@Blitzo

 

[AndrewS]

https://twitter.com/i/web/status/1777288839481934237

Is that a photo of a micro-reactor vessel with 4 Stirling? engines on top

 

[tphuang]

Old article above from 2016 on development of a micro reactor

• 10MWth
• Measures around just 20 feet (6.1 metres) by 8.5 feet (2.6 metres)
• Lead-based

---

I recall the Alfa's reactors had problems with the reactors being bricked if the lead ever cooled down and solidified.

But a notional SSKN would have onboard batteries to provide emergency short-term heating if electricity supply from ashore is cutoff.
And perhaps the small size of the reactor means it is possible to reheat the entire reactor from cold.
Plus Stirling engines could operate in reverse and convert mechanical motion into heat for the reactor if necessary?

Just speculation here

of course it must have onboard batteries and not a small amount either
that allows submarine to go faster than power generation rate for a small period of time

If I look at the Type-214, it has a total of 240KW for everything on the boat.
So if a Yuan hull requires 60% more power for propulsion, call it "roughly" 384 KW for the same speed of 6 knots.

And if it has 6 x 320KW available, that translates into a sustained speed of roughly 14 knots, given that the hotel/sensor/crew/air load doesn't scale upwards like propulsion.

That matches up with the 14 knot figure mentioned by the "source"

@tphuang
@Blitzo

as i said, it's not just a matter of speed, but also sensors, computation power, atmospheric control system ....

The MWe level stirling engine in that article sounds reasonable. sticking 6 Stirling together takes up a lot of space

 

[AndrewS]

as i said, it's not just a matter of speed, but also sensors, computation power, atmospheric control system ....

Propulsion (at full speed) is what requires the vast majority of available power.

If we use the figure of 133KW for oxygen electrolysis for the crew, it's only 7% of available generation capacity. Sensors and computational power requirements should be way lower than just oxygen electrolysis alone.

Just think about how a Type-214 uses 240KW for literally everything. I see that the active sonar pulses are only 4KW for example, and modern sonars should be using fibre optics instead of power-hungry electromechanical transducers like previously.

The MWe level stirling engine in that article sounds reasonable. sticking 6 Stirling together takes up a lot of space

 

[tphuang]

Propulsion (at full speed) is what requires the vast majority of available power.

If we use the figure of 133KW for oxygen electrolysis for the crew, it's only 7% of available generation capacity. Sensors and computational power requirements should be way lower than just oxygen electrolysis alone.

Just think about how a Type-214 uses 240KW for literally everything. I see that the active sonar pulses are only 4KW for example, and modern sonars should be using fibre optics instead of power-hungry electromechanical transducers like previously.

i'm saying that you were extrapolating energy requirement for 14 knots based on energy requirements for 6 knot. That doesn't make sense.
non motor related power requirement is more or less fixed in this case.

So if that's X then, you need to base your calculation for 14 knots based (6 knot power - X) * (14/6) ^3 + X

Now, I was told you need 250-300kW on something the size of Yuan for hotel load to operate at maybe 0-4 knots Let's say for example you have 90% energy efficiency on electrical system and 80% on electric motor.

Then if your electrical system takes 200kW to run, then maybe you need to allocate 220kW for that.

Leaving 80kW @ 80% efficiency for 4 knots.

if you want your bottom to move at 12 knots, then you would need 27 * 80 = 2.16MW
at 10 knots, it would be 80 * (2.5)^3 = 1.25MW.

if we add in atmospheric control and additional computing system, then maybe you need 450kW to run. Using 90% energy efficiency, then you need 500kW power

so in total about 1.75MWe of power generated by your steam turbine or stirling

 

[AndrewS]

Now, I was told you need 250-300kW on something the size of Yuan for hotel load to operate at maybe 0-4 knots Let's say for example you have 90% energy efficiency on electrical system and 80% on electric motor.

Looking into the Type-212 a bit more, it looks like sustained AIP underwater speed is actually 8 knots with 240KW in total available, rather than the 6 knots figure mentioned previously. Source here. asiatimes.com/2021/01/germanys-type-212-sub-propulsor-offers-stealth-efficiency/

80% efficiency on the electric motor looks a little on the low side, given that car motors are in the 90%+ range these days.

But in any case, it means 1.2MWe generated would be a maximum power requirement to allow a SSKN to sustain 14 knots, based on the Type-212 figures above.
That should leave enough for a 300KW hotel load plus other etc

But I still do think a 300 KW hotel load seems high when compared to the Type-212 which manages everything on just 240KW.

 

[latenlazy]

80% efficiency on the electric motor looks a little on the low side, given that car motors are in the 90%+ range these days.

You are talking about a much bigger motor.

 

[Staedler]

i'm saying that you were extrapolating energy requirement for 14 knots based on energy requirements for 6 knot. That doesn't make sense.
non motor related power requirement is more or less fixed in this case.

So if that's X then, you need to base your calculation for 14 knots based (6 knot power - X) * (14/6) ^3 + X

Now, I was told you need 250-300kW on something the size of Yuan for hotel load to operate at maybe 0-4 knots Let's say for example you have 90% energy efficiency on electrical system and 80% on electric motor.

Then if your electrical system takes 200kW to run, then maybe you need to allocate 220kW for that.

Leaving 80kW @ 80% efficiency for 4 knots.

if you want your bottom to move at 12 knots, then you would need 27 * 80 = 2.16MW
at 10 knots, it would be 80 * (2.5)^3 = 1.25MW.

if we add in atmospheric control and additional computing system, then maybe you need 450kW to run. Using 90% energy efficiency, then you need 500kW power

so in total about 1.75MWe of power generated by your steam turbine or stirling

My impression is the power cube "law" is applicable for surface combatants only and is due to the interplay of wave-making and skin frictions. Wave-making resistance increases dramatically with speed, skin friction does not. Submerged vessels mainly operate by skin friction which would make the total resistance closer to squared than cubed.

 

[ACuriousPLAFan]

Some updates on the SSK-N:

Both

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and

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on Weibo have claimed that the SSK-Ns (nominally named the Type 041-class) are already under construction.

It is mentioned that there would be 4 boats for the 1st batch of the 041 SSK-N, with the order equally split between Jiangnan and Wuchang.

Both of them also claimed that there are photos (satellite-view and/or ground-view) which proves the above to be the case. However, until now, I'm still unable to find it, so if anyone manages to get their hands on those photos, kindly share it here.

The Army Recognition website has also reported on the matter:

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