New Stirlingmotor Technology vs. Combustion Engine + AIP
1. Submarine concept with combustion engine + AIP:
2. Submarine concept with New Stirling Engine:
Size proportions adapted as far as possible to realistic proportions of the U-216
X= space gained compared to the AIP version
Typical features and characteristics:
1. Submarine concept with combustion engine + AIP
The propeller is powered electrically. There are three sources of electrical energy that can be used alternatively or in combination:
- Main engine, designed as a Diesel GenSet
- AIP (Air independent propulsion), designed as an H2 fuel cell system
An additional hull section wth an AIP drive is installed. AIP is using fuel cells and require tanks for liquid oxygen and storage for H2 (such like Magnesium borohydride with 15 % by weight of H2)
The main engine (MTU 396 series) is used for surfaced travelling. AIP of apr. 360 kW is used for submerged stay or submerged slow travel.
AIP normally allows submerged travelling speeds up to apr. 4 knots for apr. 15...20 days.
The generation of 1000 kWh by the AIP requires apr. 55 kg H2, storage capacity of metal-hydride of apr. 380 kg as well as apr. 460 kg O2.
Cryo-Oxygen is stored in the outer section. Since H2-storage is limited due to weight and space, the onboard-production of H2 by reformer plants is considered.
2. Submarine concept with New Stirling Installation
The propulsor is electric driven and will be fed with power by the main engine or the batteries.
One engine for all purposes, an additional hull section wth an AIP drive is not required. The New Stirling GenSet generates electric power at surfaced and submerged travelling.
Compressed oxygen for burning the fuel at submerged travel is stored in the outer section. The decompression will be used to generate additional electric power by an turbine and deep temperatures for cooling the engine (reduced cooling water temperature and heat signature).
Conclusion: It is more efficient to use space for O2 than for batteries or H2. Then there is no longer a difference between submerged or surfaced range.
Two or three mid-sized New Stirling GenSets share a common regenerator. If only few power is required, only one New Stirling GenSet is in operation. However, it uses the entire size and capacity of the regenerator and its performance. Efficiency and heat signature are optimized.
In total, a New Stirling Engine provides better performance (submerged range, fuel consumption, drive power), considerably less complexity and requires less space. As a result, a New Stirling Drive is obviously significantly less expensive.
The space gained (see illustration above) is sufficient, for example, to install a Mk 41 vertical launch system with eight cells for missiles .
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