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.
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- 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)