Anonymous in Comments on November 5, 2018 has kindly provided details discussing the Kockum's Mark 5 Stirling engine that will likely be incorporated into the SAAB A26 and maybe into the SAAB-Damen Walrus replacement:
The SAAB A26 and SAAB-Damen Walrus concept, will likely have an evolution of the current (in Gotland class) Kockums Mark 3 Stirling engine v4-275R Mark 3 [4]. The evolution-next version being likely the Mark 5 [1], but there is little information on the Mark 5. The Mark 5 evolution is discussed at [2] and [3]. The evolution may provide increased diving depth and a longer submerged period.
[1] R. Bitzinger and Haris Vlavianos “Emerging Critical Technologies and Security in the Asia-Pacific” 2016, Page 100, “Sweden’s next generation submarine, Kockums A26-currently in development, will incorporate the latest and most modern and refined Stirling AIP technology-MK 5 version.”
[2] ibid, Page 101, “Stirling engine operates at a pressure of 20 bars, which limits the submarine’s depth to 200m, unless power consuming and potentially noisy exhaust gas intensifier is used.”
[3] https://saab.com/region/saab-australia/about-saab-australia/latest-news/stories/stories---australia/2015/super-stealthy-saab-submarines/
Scrolling down half way to “Air Independent Propulsion” you come to the diagrams, reproduced below.
- diagram on left (above) is the current Kockums Stirling Mark 3 (on Gotland class)
- diagram on right (above) is the Kockums Stirling Mark 5 to be fitted on the future A26s.
The combustor and insulator are omitted from this right diagram. For the Mark 5 to achieve higher
efficiency are improvements in:
= The heater (cylindrical pipes (inside of engine) connected top of piston cylinder) improves heat
transfer.
= The heat insulation has presumably reduced heat loss, thus elevating combustion temperature
and pressure. If the Mark 5 can tolerate pressure increases from 20 bars to 25 bars, the A26's
depth at which it can operate the AIP increases from 200m to 250m. This improvement will
provide a longer submerged period. But an significant increase in speed is not expected,
because speed is proportional to square-cubes of AIP output.
The Mark 5's generator is omitted (in the middle figure), but, the size of the generator does not seem to have changed. If the Mark 5's combuster size has not changed, the size of the Mark 5 AIP's (engine + generator) will not have significantly changed.
[4] Sweden's Gotland class submarines each use two v4-275R Stirling engines (each rated at 75kW)
see this Submarine Matters article. While Japan's Soryu Mark 1s use four Kawasaki Kockums
V4-275R. China's Type 039A Yuans may use three or four Kockums V4-275R.
More recent and detailed data on Kockum's Mark 5 Stirling engine may well alter this current appreciation.
Anonymous (with Pete translating into standard English)
The SAAB A26 and SAAB-Damen Walrus concept, will likely have an evolution of the current (in Gotland class) Kockums Mark 3 Stirling engine v4-275R Mark 3 [4]. The evolution-next version being likely the Mark 5 [1], but there is little information on the Mark 5. The Mark 5 evolution is discussed at [2] and [3]. The evolution may provide increased diving depth and a longer submerged period.
[1] R. Bitzinger and Haris Vlavianos “Emerging Critical Technologies and Security in the Asia-Pacific” 2016, Page 100, “Sweden’s next generation submarine, Kockums A26-currently in development, will incorporate the latest and most modern and refined Stirling AIP technology-MK 5 version.”
[2] ibid, Page 101, “Stirling engine operates at a pressure of 20 bars, which limits the submarine’s depth to 200m, unless power consuming and potentially noisy exhaust gas intensifier is used.”
[3] https://saab.com/region/saab-australia/about-saab-australia/latest-news/stories/stories---australia/2015/super-stealthy-saab-submarines/
Scrolling down half way to “Air Independent Propulsion” you come to the diagrams, reproduced below.
- diagram on left (above) is the current Kockums Stirling Mark 3 (on Gotland class)
- diagram on right (above) is the Kockums Stirling Mark 5 to be fitted on the future A26s.
The combustor and insulator are omitted from this right diagram. For the Mark 5 to achieve higher
efficiency are improvements in:
= The heater (cylindrical pipes (inside of engine) connected top of piston cylinder) improves heat
transfer.
= The heat insulation has presumably reduced heat loss, thus elevating combustion temperature
and pressure. If the Mark 5 can tolerate pressure increases from 20 bars to 25 bars, the A26's
depth at which it can operate the AIP increases from 200m to 250m. This improvement will
provide a longer submerged period. But an significant increase in speed is not expected,
because speed is proportional to square-cubes of AIP output.
The Mark 5's generator is omitted (in the middle figure), but, the size of the generator does not seem to have changed. If the Mark 5's combuster size has not changed, the size of the Mark 5 AIP's (engine + generator) will not have significantly changed.
[4] Sweden's Gotland class submarines each use two v4-275R Stirling engines (each rated at 75kW)
see this Submarine Matters article. While Japan's Soryu Mark 1s use four Kawasaki Kockums
V4-275R. China's Type 039A Yuans may use three or four Kockums V4-275R.
More recent and detailed data on Kockum's Mark 5 Stirling engine may well alter this current appreciation.
Anonymous (with Pete translating into standard English)
7 comments:
Hi Pete
In SAAB A26 and SAAB-Damen Warlus-concept, the evolution of Kocknums Stirling engine from v4 275r Mark 3 to Mark 5 is expected [1], but there is little information on this evolution. Here, the evoluation is originally discussed [2, 3]. The evoluation may provide increase in diving depth and extension of submerge period.
[1] “Emerging Critical Technologies and Security in the Asia-Pacific”2016, R. Bitzinger, Haris Vlavianos
Page 100, “Sweden’s next generation submarine, Kocknums A26-currently in development, will incorporate the latest and most modern and refined Stirling AIP technology-MK 5 version.”
[2] ibid
Page 101, “Stirling engine operates at a pressure of 20bar, which limits the submarine’s depth to200m, unless power consumming and potentially noisy exhaust gas intensifier is used.”
[3] https://saab.com/region/saab-australia/about-saab-australia/latest-news/stories/stories---australia/2015/super-stealthy-saab-submarines/
See “Air Independent Propulsion”, left figure: currrent Kocknums Mark 3, middle figure: Kocknums Mark 5, right figure: perspective of side Kochnums Mark 5.
In Mark 5 (right figure: combustor and insulator are omitted in this figure), heater (cylinderical pipes (inside of engine) connected top of piston cylinder) and heat insulation presumably are improved to achieve higher efficiency. The former improves heat transfer and the latter reduces heat loss elevating combustion temperature and pressure. If a pressure increases from 20 bar to 25 bar, submarine’depth increases from 200m to 250m. Though this improvement will provide longer submerge period, significant increase in speed is not expected, because speed is proportional to square-cubes of AIP output.
Generator of Mark 5 is omitted (middle figure), but, size of generator does not seem to be changed. Unless combuster size of Mark 5 is not changed, size of Mark 5 AIP (engine + generator) is not significantly changed.
Regards
Hi Pete (continued 5/11/18 5:52 PM) Part I
One of the most reliable report on Kocknums v4-275R (v4 and 275 means V4 engine and a cylinder volume of 273cm3) shows that pressure of combustion is 22bars and waste gases are evaculated directly until diving depth of 200m [1]. For deep diving submarine (6500m = 650-700Ma), research on Stiring engine drived by high pressure combustion was conducted years ago in Japan and combustion of 70MPa was achieved. The continued research was yet reported (come to an end?). So, further increase in combustion pressure of Kocknums v4-275R may be possible to achieve higher efficiency and deeper diving.
Full LIB system was adpopted in Soryu Mark II instead of Stirling AIP-LIBsystem, presumably because of i) weight and balance change by consumption of LOx [2], ii) low output and iii) limitation of diving depth (200m) in Stirling AIP-LIB of Soryu Mark I. But, I do not think high price of LIBs affects on the selection of full-LIBs or Stirling AIP-LIBs, because Stirling AIP is also very expensive.
[1] http://www.robertstirlingengine.com/saga_uk.php
SAGA submarine, symposium ISM 90, the 3, 4 and 5 December 1990 in Toulon, J. Mollard and D. Sauzade
SAGA is the first prototype of a new generation of industrial submarines capable of carrying out underwater operations using divers or robots at close proximity to the work site without surface assistance. SAGA is equipped by a diesel engine and two Stirling engines (Kochnums v4-275R, 75kW) for surface and submerge, respectively.
CHARACTERISTICS OF THE STIRLING ENGINES:
Gas of work: Helium (130 bars). Pressure of combustion 22 bars. Speed 2400 rpm. Fuel consumption 260 g/kWh.Oxygen consumption 980 g/kWh. Maximum power 75 kWh. Recoverable heat from the combustion gases 18 kW. The main problems of development (skip). The waste gases, being at a pressure of 22 bars, are evacuated directly for immersions lower than 200 meters. Beyond and until the maximum immersion of the SAGA (600 meters), it is necessary to pressurize these gases and the condensates, which required the development of a specific compressor produced by GIE SAGA.
[2] Combat Technology of Submarine, 2015, H.Yamaichi. Ex-captain of JS Setoshio (SS-575, fierst Setoshio) and ex-professor of National Defense Academy of Japan. “Weight of goods (water, food, etc) is strictly controlled in submarine.”
Regards
Hi Pete (continued 5/11/18 5:52 PM) Part II
According to MoD, exchange of Stirling AIP-LABs by LIBs provides longer submerge. In simple thinking, this statement seems to be faulse because energy from Stirling AIP is nearly 100MWh larger than that from LIBs (50Mw). But, if Stirling AIP-LIBs Soryu is operated under depth of 200m, submarine operation is controlled by LABs. Japanese submarines are operated in the Sea of Japan and West Pacific Ocean which are much deeper than 200m, and in the situation, LIBs Soryu may shows longer submerge period than AIP-LABs Soryu. MoD selects LIBs Soryu for the full range operation of depth.
Bby repeating of charge in a calm sea, Soryu Mark II can be operated for longer period than Soryu Mark I whose operation period is controlled by amount of LOx.
In the case of latest Chinese 039 submarines for which Stirling AIP-LABs are adopted, the situation seems to be a bit different form Japanese submarines. These Chinese submaines are intended the operation in the East China Sea [3] which is largely shallow (almost three-fourths of the sea is less than 200 m, and its average depth is 350 m). Then, Stirling AIP-LABs system is still effective.
For the same reason, SAAB A26 is effective in shallow Baltic Sea. Stirling AIP seems to compatible LIBs. LIBs is used for operation under depth of 200m, and Stirling AIP improves endurance in shallw water and the recovered heat from the combustion gases of Stirling engine can be used for heating of LIBs to avoid thermal runaway at low temparature. Warlus, 212A/CD and A26 are used in cold sea such as the North Sea or the Baltic Sea.
Though Naval Group and TKMS have already reported LIBs for submarine as a result of collaboration with SAFT, the development by SAAB is yet reported.
[3] https://www.britannica.com/place/East-China-Sea
Regards
A comment about the A26, the A26 will get 3 Stirling engines and 3 small marine Diesel engines compared to 2 Stirling engines and 2 conventionell submarine Diesel engines used in the Gotland class.
link https://www.fmv.se/sv/Projekt/Ubat-typ-A26/A26-del-for-del/ (in Swedish)
"For transit to and from the operating area, A26 uses three small marine Diesel engines that are enclosed in modules. The cost of these is significantly less than for conventional submarine diesel engines. They also require less maintenance, which provides high cost efficiency."
/Kjell
Hi /Kjell
If the two A26s for Sweden have "3 small marine Diesel engines" that may be useful for mainly defensive, only in the Baltic Sea, Swedish submarines.
But "3 small marine Diesel engines" means that the diesels and many associated systems on these first A26s will be of little use to potential medium-long range oceanic customers.
The good for Baltic Sea assumption earlier provided many problems in the full sized diesels needed for Australia's Swedish heritage Collins.
eg. India and Canada would have little use for A26s that have only been operationally tested with "3 small marine Diesel engines".
Will Sweden's A26 be using safely tested and standard MAN, Kawasaki or MTU diesels or something from a small company, obscure and therefore risky, like the diesels on the Collins?
Regards
Pete
Shouldn't you be able to simply store the exhaust gasses in tanks that you empty only from time to time? I can see two main advantages with this, one is that you would be able to operate on depths under 250 meters most of the time, the other being that it would limit the submarine's thermodynamical signature.
Hi Anonymous (Sep 9, 2019, 12:07)
Re your: "Shouldn't you be able to simply store the exhaust gasses [from a Mark 5 Stirling engine] in tanks that you empty only from time to time?"
A good question. Is space, for an exhaust collection tank, limited or pressure buildup too great? Probably only someone from Saab Kockums can supply a definitive answer.
Regards
Pete
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