Submarines Present - Air Independent Propulsion
AIP Submarines Explained
Introduction
- In the Present Modern Naval warfare scenario, submarines have become the principal weapon. For being effective in the wartime submarines are required to be stealthier, virtual silent and for all this long endurance is required.
- Submarines are subsequently of two types- Conventional or Diesel-electric submarine and Nuclear Submarine. Conventional Submarines need atmospheric oxygen to run the diesel generator which in turn charges the batteries.
- for the above purpose Submarines need to surface frequently to charge their batteries, After a few days they need to surface again to recharge their batteries after getting drained underwater.
- Air Independent Propulsion System is a system that allows diesel-electric submarines to recharge their batteries without running their engine. They do not require to access atmospheric oxygen by surfacing or by using a snorkel. Air Independent Propulsion System is becoming quite attractive for the major navies.
- Using Snorkel or Surfacing will expose the Submarine to detection by the enemy and makes them an easy target. It can replace the diesel-electric propulsion system of a submarine , therefore AIP allows a submarine to remain underwater for a long time and retain the element of surprise.
-
Propulsion of underwater vehicles
The FCs onboard submarines used for AIP had been studied in the past worldwide especially by the Canadian, the Dutch, and the German navy with different partners. These studies were based on a hydrogen-fueled PEMFC technology supplied from a liquid oxygen (LOX) tank. The strong interest of the navies seems to be one reason why underwater vehicles already have such a comparable high technological standard. The requirements can be summarized as follows:
- •
-
operation without surface contact over longer periods;
- •
-
high efficiency/low heat transfer to the sea water;
- •
-
low noise level;
- •
-
low magnetic signature;
- •
-
small size;
- •
-
low weight;
- •
-
independence of diving depth; and
- •
-
low effort for maintenance/no extra crew.
The submarine class 212/214 is now commercially available. The submarine concept has been developed by Thyssen Krupp (former Howaldtswerke Deutsche Werft (HDW)) in Kiel and the PEMFC modules are delivered by Siemens. Figure 7 shows an overview of the FC-related part of the power generation system (silent operation in mission).
Figure 7. Principal fuel cell (FC) power system of the German submarine class 212/214. LOX, liquid oxygen.
The hydrogen is stored in metal hydride cylinders. To release the hydrogen, heat has to be supplied to the hydrogen storage cylinders. The heat source is the waste heat from the fuel cell. The thermal signature of this operating power system is disappearing because the waste heat is used to release fuel and oxygen from its storages. The class 214 submarines are equipped with two FC modules with 120-kW power output each. The FC is connected to the batteries via a DC/DC converter. The 120-kW modules have been developed from 1995 to 2001 based on the 34-kW modules used in 212 submarines. The following data of the 120-kW PEMFC module are given by the manufacturer:
The integration of the FC propulsion system into a class 212 A submarine is shown in Figure below.
Propulsion of underwater vehicles
The FCs onboard submarines used for AIP had been studied in the past worldwide especially by the Canadian, the Dutch, and the German navy with different partners. These studies were based on a hydrogen-fueled PEMFC technology supplied from a liquid oxygen (LOX) tank. The strong interest of the navies seems to be one reason why underwater vehicles already have such a comparable high technological standard. The requirements can be summarized as follows:
- •
-
operation without surface contact over longer periods;
- •
-
high efficiency/low heat transfer to the sea water;
- •
-
low noise level;
- •
-
low magnetic signature;
- •
-
small size;
- •
-
low weight;
- •
-
independence of diving depth; and
- •
-
low effort for maintenance/no extra crew.
The submarine class 212/214 is now commercially available. The submarine concept has been developed by Thyssen Krupp (former Howaldtswerke Deutsche Werft (HDW)) in Kiel and the PEMFC modules are delivered by Siemens. Figure 7 shows an overview of the FC-related part of the power generation system (silent operation in mission).
Figure 7. Principal fuel cell (FC) power system of the German submarine class 212/214. LOX, liquid oxygen.
The hydrogen is stored in metal hydride cylinders. To release the hydrogen, heat has to be supplied to the hydrogen storage cylinders. The heat source is the waste heat from the fuel cell. The thermal signature of this operating power system is disappearing because the waste heat is used to release fuel and oxygen from its storages. The class 214 submarines are equipped with two FC modules with 120-kW power output each. The FC is connected to the batteries via a DC/DC converter. The 120-kW modules have been developed from 1995 to 2001 based on the 34-kW modules used in 212 submarines. The following data of the 120-kW PEMFC module are given by the manufacturer.
-
Propulsion of underwater vehicles
number of cells: 320 rated power: 120 kW rated current: 560 A rated voltage: 215 V operating temperature: 80 °C dimension: 176×53×50 cm3 weight (incl. pressure vessel): 900 kg rated efficiency: at 20% load: 68% at rated load: 56% The integration of the FC propulsion system into a class 212 A submarine is shown in Figure below.
The Japan Maritime Self-Defense Force (JMSDF) commissioned its 12th and final Soryu-class diesel-electric attack submarine (SSK) in a ceremony held on 24 March in Hyogo Prefecture in west-central Japan.
Named JS Toryu (with pennant number SS 512), the 84-m-long boat was inducted into the Escort Division 6 of Escort Flotilla 2, which is homeported at the Yokosuka naval base in Kanagawa Prefecture, shortly after being handed over by shipbuilder Kawasaki Heavy Industries (KHI) at its facility in Kobe.
It is the sixth submarine of the class built by KHI, with the other six having been constructed by Mitsubishi Heavy Industries (MHI). Toryu, which is also the second boat of the class to be equipped with lithium-ion batteries, was laid down in January 2017 and launched in November 2019.
The total procurement cost of the submarine was about JPY69 billion (USD635 million), a JMSDF spokesperson told Janes.
The commissioning comes after GS Yuasa, a Kyoto-based developer and manufacturer of battery systems, announced in February 2017 that Japan would become the first country in the world to equip SSKs with lithium-ion batteries in place of lead-acid batteries.
According to Janes Fighting Ships, the Soryu class has a beam of 9.1 m, a hull draught of 8.4 m, and a displacement of 2,947 tonnes when surfaced and of 4,100 tonnes when submerged.
The previous boats of the class have been fitted with two Kawasaki 12V 25/25 diesel generators and four Kawasaki Kockums V4-275R Stirling air-independent propulsion (AIP) engines, and use lead-acid batteries for energy storage.
Type 214 is a class of diesel-electric submarine developed by exclusively for export by Howaldtswerke-Deutsche Werft GmbH (HDW).[2] It features diesel propulsion with an air-independent propulsion (AIP) system using Siemens polymer electrolyte membrane (PEM) hydrogen fuel cells. The class combines the design principles of the Type 209 submarine family and the features of the Type 212A submarine.[2] However, as an export design, it lacks some of the classified technologies of the Type 212 such as the non-magnetic steel hull that makes it difficult to detect using a magnetic anomaly detector.[3]
Due to improvements in the pressure hull materials, the Type 214 can dive nearly 400 metres (1,300 ft).[4] It can also carry food, fresh water and fuel for 84 days of operation.
A contract to build four submarines for the Hellenic Navy was signed 15 February 2000 and a fourth unit was ordered in June 2002. The first submarine was built at HDW in Kiel, Germany and the rest at the Hellenic Shipyards Co. in Skaramangas, Greece. The Hellenic Navy named them the Papanikolis class.
The Republic of Korea Navy has ordered nine Type 214 submarines, designated as Son Won-Il class, to be built in Korea by Hyundai Heavy Industries and Daewoo Shipbuilding & Marine Engineering; three first batch models entered service since 2007, and six second batch models entered service from 2012.
