TKMS Type 212CD submarine propulsion issues, eg. FC AIP

Anonymous has kindly supplied the following details and Table. The following is necessarally speculative about the future TKMS-Norwegian Type 212CD propulsion characteristics as the 212CD may not be launched until around 2023. One of the innovative technologies for 212CD is adoption of metal hydride for hydrogen source. This is designed to achieve safer operation of the fuel cell (FC) AIP (see Table 1). A hydrogen cylinder is used in the current conventional FC AIP on the TKMS Type 214 and 212A.

But, in the new generation FC AIP, waste heat from the FC is effectively used to generate hydrogen. This should be more discrete.

Part of a prototype TKMS/tkMS and SENER methanol reforming FC AIP process. (Courtesy slide 26 of this SENER Presentation.)

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TKMS and Spain’s SENER (private engineering and technology group) are developing methanol reforming FC which is safer than hydrogen or metal hydride FC AIP (for Type 214, 212A or future 212CD).

But emissions from methanol reformer FC of carbon dioxide against the ocean’s water pressure limits a submarine’s diving depth to around 200m. In contrast hydrogen or metal hydride FC (used on Type 214, 212A and maybe future 212CD) produces water which does not limit diving depth.

(Above and below) Type 212A submarine cutaway indicating where the LOx tanks and hydrogen cylinders are. They are outside the pressure hull for greater safety. (These cutaways all over web.)

The diesel section of a Type 212A uses an outer light hull (diameter 6.8m) and a pressure hull (ca.5.6m?). The two LOx cylinders are arranged above the pressure hull. The LOx cylinder are shock resistant. These cylinder also and have an insulated “adiabatic structure” meaning they do not transfer heat to surroundings. This is totally different than if the LOx cylinders were within the pressure hull (as in a current 214)  as they may effect the temperature within the hull.

The Type 212A is equipped with 9 feul cells (8 x 34kW, and 1 x 34kW (auxiliary FC)). These are superior to the 2 x 120kW on a Type 214.

The hull diameter (8.4m) of a Type 212CD will be significantly larger than a 214’s (6.3m) which has single hull structure. The 214 has 2 x MTU396 diesels.

In contrast 3 x MTU (396 or 4000?) diesels could be installed in a future Type 212CD especially if it uses Lithium-ion Batteries (LIBs) to achieve a higher charge rate [2]. Or 2 x MTUs could be installed on a 212CD (especially those that retain existing Lead-acid Batteries (LABs). A relatively low charge rate using 1 or 2 loud diesels running a longer time (to charge LABs) may be less discrete than 2 or 3 diesels running a shorter time to charge LIBs quickly [6].

So, a double hull will presumably be adopted for the diesel section of the future Type 212CD, as with the current Type 212A. This suggests hydride cylinders will be installed between the 212CD’s light and pressure hulls.

Table 1.  Estimated Location of Cylinders and Submarine

Cylinder	Location		In Diesel section	Submarine type
	Inside pressure hull [1]	Between light and pressure  hulls [2]
Metal hydride cylinder [3]	Yes	No	No	214 218SG,
	No	Yes	Yes	212CD?
LOx cylinder	Yes [4]	No	No	214
	No	Yes [5]	Yes	212A, 212CD?

[1] Simple structure consists of single pressure hull.

[2] Complex structure consists of ligh and pressure hulls.

[3] Electrochemical reaction between oxygen and hydrogen generates electricity and heat in FC. Heat is transferred to metal hydride to generate hydrogen for FC. Metal hydride cylinder has adiabatic stucture.

[4] Cryogenic cylinder is used for oxygen storage located inside of pressure hull.

[5] This cryogenic cylinder is totally different from an ordinary LOx cylinder and is shock resistant to explosions (eg. depth charges) near the submarine.

[6] Three 12PA V200 SMDS with similar dimension to MTUs would likely be installed in the enlarged SAAB-Damen A26 single hull submarine design for the Netherlands Walrus replacement competition. The enlarged A26 design has a smaller diameter (of 8m) than 212CD submarine.

COMMENTS

Pete comments:

-  Dutch Walrus replacement competition? An enlarged SAAB-Damen designed A26 (once called the
    612) might be offered. Naval Group might possibly offer some design sharing Scorpene and 

    Australian Shortfin-Barracuda characteristics.

-  Given the long trans-Atlantic distances a Walrus replacement would need to travel the Netherlands

    may not want any type of AIP – AIP being of diminishing utility with distance and instead LIBs, 

    more than LABs, may stretch fully submerged travel.

-  Western companies are interacting with China on methanol reformer fuel cell generator technology

    for cars and trucks. Such technology is dual-use, China’s vast industrial base may easily reverse

    engineer Western technology for submarine use.

MHalblaub kindly provided the following comments for the previous closely related Submarine Matters’ article:

“The Type 212A always had metal hydride storages for hydrogen.

Also I can't see a problem to use a methanol reformer and metal hydride storages together. I guess a reformer may outproduces most of the time the need of hydrogen so some kind of interim storage would be necessary.

The boat has its own hydrogen producing facility. So just methanol and oxygen is required for the fuel cells.”

Anonymous, Pete and MHalblaub.