Summary
A. SWEDEN Saab-KockumsRichard Scott for Jane's International Defence Review reported June 17, 2019 in part, “Sweden set to test ‘Double Stirling’ AIP plant”
Like other systems (eg. combat systems, batteries, diesels and hull stealth) AIP is a major technology arena to give a seller of submarines the edge over the opposition.
Pete and Anonymous
Germany’s TKMS and Sweden’s Saab-Kockums have released latest generation Air Independent Propulsion (AIP)details. AIPprolongs submerged endurance of diesel electric submarines. The overall strategy is likely:
- TKMS packaging its latest AIP in submarine Types 214, 212A, 212CD, South Korean KSS-IIIs
and Israeli Dolphin 3s.
and Israeli Dolphin 3s.
- while Sweden is likely offering its latest Stirling AIP in the three A26 submarine sizes.
The release of details may be with a view to sales in the long running future submarine competitions for:
- up to 4 submarines for Poland’s long running ORKA Program,
- 6 submarines for India’s 75 (I for India) with Saab-Kockums and TKMS still on the shortlist of 4
Analysis and Background in More Detail
TKMS appears to be developing its (see B. below) 4th Generation Fuel Cell (FC4G) technology in competition against:
- Saab-Kockums'A.5th Generation Stirling AIP, and
- D. methanol reforming fuel cell (MRFC) that TKMS itself is co-developing with Spain’s SENER.
So, in C. TKMS indicates its 4th Generation Fuel Cell technology is superior to reformer AIP of which D.TKMS’ co-development with SENER could be an example, and A. Sweden’s Stirling engine technology.
A. SWEDEN Saab-KockumsRichard Scott for Jane's International Defence Review reported June 17, 2019 in part, “Sweden set to test ‘Double Stirling’ AIP plant”
“Saab Kockums and Sweden's Defence Materiel Administration (FMV) are preparing to begin testing of a prototype 'Double Stirling' air-independent propulsion (AIP) system aimed at a nascent Swedish future submarine programme.
The 150 kW module, which occupies the same footprint as the original 75 kW Type A19 Gotland-class installation, represents the fifth generation of Stirling cycle AIP to be developed for Swedish submarines.
Saab Kockums' Stirling engines burn oxygen (stored in liquid form [LOX] in cryogenic tanks) and diesel fuel in a pressurised combustion chamber to generate electricity for propulsion or for charging batteries within a conventional diesel-electric plant. The company has iteratively developed Stirling AIP technology since testing a prototype plant that went to sea in 1989; the latest Mk 4 version was refitted to HMS Gotland and HMS Uppland as part of the Gotland-class mid-life update (MLU).
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B. GERMANY TKMS- on September 11, DEFPOST reportedTKMS unveiled the 4th Generation Fuel Cell (FC4G) for submarine indicating that:
after having finished an extensive test program with more than 70,000 operating hours in the test environment, an improvement over TKMS existing fuel cell AIP which has been used by customers for over 15 years.
TKMS indicated FC4G has “huge improvements in availability, redundancy, and stealth.”
“The FC4G is designed to be a high-availability modular system composed of redundant components to retain a maximum performance at all times. In terms of H2-storage, the systems rely on the well-proven and exceptionally safe system of metal hydride cylinders as previous generations. These cylinders do not contain any active components; thus, reducing failure to a minimum holding hydrogen molecules safe in place in the crystal lattice of the hydride. Since hydrogen is fed to the system in its purest form, no chemical conversion is required and, therewith, the efficiency of the overall system remains very high.”
Overall signatures of the FC4G are the most favourable ones on the market. No by-products put overboard, the thermal and the acoustic signatures are kept to a minimum while the overall system efficiency is twice as good as any combustion engine.”
“Philipp Schön, Head of Product Sales Submarines: “These are the reasons, why 38 [submarines with AIP] systems [have been sold to] 7 customer navies, another 10 [submarines with AIP] systems presently being under negotiation.”
C. TKMS compares its fuel cell AIP with competing AIP technologies
DEFPOST continues“In contrast, reformer systems inevitably create CO2 out of a liquid fuel such as diesel oil leaving a trace of CO2 – and potentially other by-products contained in diesel oil such as Sulphur – that must be dissolved into the surrounding sea water by operating electrical pumps.
The same applies to AIP systems based on other principles, such as Stirling engines, closed-cycle diesels, or closed-cycle steam turbines. Not so the FC4G system. The only by-product besides electrical energy is pure water, which is stored on board for weight compensation. H2 is easily available where ever chemical industry is operative, typically in every customer country, or may be produced by utilizing green energy sources by splitting water into H2 and O2.”
D. Anonymousadvised on September 12, 2019 that Germany’s TKMS is also developing another AIP technology with SENER of Spain.
TKMS is developing methanol reforming fuel cell (MRFC) technology with SENER to minimise hydrogen risks. Carbon dioxide exhaust, which is a major issue of MRFC, has been improved [1]. I once heard that improved fuel cell AIP would be developed before the establishment of MRFC. Development of MRFC in SENER started in 2012. When does TKMS expect MRFC-AIP development to be completed? Germany's Siemens, which developed hydride fuel cell technology, does not welcome any adoption or competition from MRFC.
MK III V4-275R for Japan's Soryu submarines is a 4-cylinder double acting type Stirling engine which is compact and high performance. The fifth generation Stirling engine (MK V V4-275R?) belongs to this family [4]. Though the footprint of MK V is as same as MK IV, its output increased twice (150kW). The combustion chamber of the MK V may have been significantly improved.
Like other systems (eg. combat systems, batteries, diesels and hull stealth) AIP is a major technology arena to give a seller of submarines the edge over the opposition.
Pete and Anonymous