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Development of the Stirling AIP system

Daniel Nilsson, Senior Development Engineer



Stirling AIP system explained

2

Area of interest

Transit area

Stealth=Battery+AIP

Safe area

Diesel engineusage Battery=Days

AIP=Weeks

Why AIP?




3

Stirling AIP is a part of the Energy system

The battery of the submarine is the center of the energy system

Energy supply

Diesel engine

Land connection

Stirling engine

Energy usage

Propulsion & maneuvering

Sonar & weapons

Auxiliaries




System layout

Cycle gas

Purge gas

Consumables




Stirling AIP usage

• Charging of batteries

• Diesel engines

• Grid connection in harbour

• Stirling AIP

• Low power, high energy density

• Maintain battery capacity

=>Always ready for a sprint

Diesel module, transit and charging



Stirling engine development

Since antiquity knowledge about substances such as air and water and the affection by heat is documented.

Early ideas of useful internal combustion engines and heat engines was both in the 17th century

Internal combustion engine consists mainly of Diesel and Otto engine today

Torque is created to the crankshaft by the combustion inside the cylinders

Combustion generated torque Christian Huygens explosion engine

1673

Aeolipile ”hero’s engine”




TH TC

QH

QC

W

Heat engine principle

A heat engine converts a part of a energy flow into mechanical work




Understanding the behaviour of gases

Around 1650 the correlation between

pressure, volume and temperature was

noticed




1816 Robert Stirling introduced a “heat economizer” to create

a regenerative heat engine – a Stirling engine




Thermodynamics

Sadi Carnot 1796-1832

Derived early theoretical models of heat

engines and therefore a founder of

modern thermodynamics.

Carnot efficiency - thermal efficiency

𝜂𝐶𝑎𝑟𝑛𝑜𝑡 = 1 −𝑇𝐿𝑇𝐻

= 𝜂𝑡ℎ𝑒𝑟𝑚𝑎𝑙




Development of modern engines

The development of more useful Stirling

engines was initiated by Philips in the

Netherlands in 1938




Development of larger engines

• Beta type of Stirling engines

• Aim was a 200 horsepower engine for

busses, construction equipment and

submarines

• Philips design, 4-235, with high engine

pressure and speed.

• United Stirling design ,4-615, with

lower engine pressure and speed.

Intended service interval of 10 000

hours.




Development of smaller engines of double acting alfa type

• Ford Pinto with the Stirling engine V4X31 (to the right)

• Ford Taunus with the Stirling engine V4X35 (to the left)




The project ASE (Automotive Stirling

Engine) started 1978.

• ASE was a 10 year long cooperation

between Mechanical Technology Inc.(MTI)

Latham NY, NASA-Cleveland and United

Stirling Sweden.

• The funder of the project was U.S.

Department of Energy

• About 125 million USD (1978) was

invested in the project.

• The first part of the project was to install a

P40 Stirling engine in a Opel Rekord




Concentrated solar power




The many years of Stirling engine development was transferred to the

submarine technology



Stirling engine charateristics

Signatures

• Well balanced, low mechanical signatures

• Sinusoidal like pressure variation

• Exhaust cooled in Stirling module

• Exhausts consist of water and carbon dioxide

• Directly connected to generator



Stirling AIP development

The MkIII Stirling module

• Engine and auxiliaries installed in a insulated module

• Fire safety and protection

• Air borne noise reduction

• EMC reduction

• Controlled environment

• Resilient mounting for improved shock resistance and reduced vibrations




• The V4-275R MkI engine was

developed in the 80´s

• 1984 Test section for Stirling AIP




• 1987: SAGA research submarine

(Comex) was operated with two

Stirling engines supplied by Kockums

• 1988: HMS Näcken fitted with two

Stirling engines supplied by Kockums

as a retrofit

• Successful trials

• Operational 1989



Stirling AIP development• HMS Gotland

• 1995: The world's first naval submarine with Stirling AIP integrated

as new built

• Stirling AIP as a retrofit

• 2001: Japan, Kawasaki Heavy Industries made a Stirling AIP

retrofit of the Japanese submarine Asashio

• 2003-2004: Two submarines in Swedish Västergötland-class was

equipped with Stirling AIP

• 2005: The last two Submarines in the Västergötland-class was

modified with Stirling AIP. Deployed in Singapore

• 2005-> Japan continues with Stirling AIP in the Soryu class submarine.

AIP system included from the beginning

• 2007 Japan starts domestic manufacturing of Stirling engines under

license from Kockums

• 2010: New generation of the Stirling AIP system developed for A26 and

Gotland class mid life upgrade

Gotland Class

Stirling AIP upgrade of

Västergötland class

submarine with an ”plug –in”

section




Kockums Stirling AIP

Test Section

HMS Näcken

Refit

Mk I Mk II Mk III Mk IV

Kockums Gotland

Class

Kockums

Södermanland Class

Kockums Archer Class

Kockums A26

1980 1990 2000 2010




Size reduction of Stirling modules




• Size reduction

• Heat recovery

system

• Permanent

magnet generator

• Upgrades of

auxiliaries

• New control

system

PEM-generator

Higher efficiency, smaller unit

Heat recovery total efficiency >40%

Improved exhaust system enables deeper diving

New control system

Stirling AIP Module

fuel and lox calibration




• Exhaust heat recovery




• Why exhaust heat recovery

• Every engine produces up to 30 kW of high quality heat

• High quality heat could be retrieved and could for instance

be used for

• Air revitalization (explained in session: New

regenerative air purification system for Swedish AIP

submarines)

• Heating of Submarine

• Absorption cooling

• Increase of overall efficiency




Basic solution of the Stirling AIP system

Use pure oxygen instead of air!

• Use of pure oxygen efficient way to store the oxidizer for combustion

• The oxygen is also be needed for the crew




Pure oxygen in liquid form

LOX=Liquid OXygen

• Strong oxidizer but non-flammable

• Nontoxic

• Density similar to water- Gaseous oxygen more than 700 times bigger

• Temperature is pressure dependant




Liquid oxygen-usage

• In the chemical and petroleum industries

• Metal industries in conjunction with acetylene and other fuel gases for metal cutting, welding, scarfing, hardening, cleaning and melting.

• The pulp and paper industry uses oxygen as a bleaching and oxidizing agent

• Hospitals




Exhausts

Condensed

water

Cold CO2



Stirling AIP logisticsTactical logistics

• Replenishment

• Preventive and

corrective maintenance

at sea

• Maintainable by crew

• Stirling engine fit

through the hatch

• Engine replacement in

24 hours Replenishment at sea



Stirling AIP logistics

• Tactical logistics

• Multi fuel capacity




Supply of spare parts using AM (Additive Manufacturing)

• Ongoing research and development using AM

• AM is suitable for Stirling engine components

• AM has the potential to decrease production time from

months to weeks




Results of AM R&D

• AM has been successfully verified to work as a

production method for the gas cooler

• AM project is ongoing for production of heater and

regenerator

• AM has the potential to improve function and

performance of components and the overall system

• AM is decided to be a new production method

Thermocouple holder –now produced

by Additive manufacturing



Thank you!

Questions?

Documents

Development of the Stirling AIP system - UDT 2020 · • Ford Taunus with the Stirling engine V4X35 (to the left) COMPANY RESTRICTED | NOT EXPORT CONTROLLED | NOT CLASSIFIED Your