Anaerobic propulsion system. Anaerobic power plant

The Stirling engine, the principle of operation of which is qualitatively different from the usual for all internal combustion engines, once was a worthy competitor to the latter. However, they forgot about it for a while. How this motor is used today, what is the principle of its operation (in the article you can also find drawings of the Stirling engine that clearly demonstrate its operation), and what are the prospects for future use, read below.

Story

In 1816, in Scotland, Robert Stirling patented the one named today in honor of its inventor. The first hot air engines were invented before him. But Stirling added a purifier to the device, which in the technical literature is called a regenerator, or heat exchanger. Thanks to him, the performance of the motor increased while keeping the unit warm.

The engine was recognized as the most durable steam engine available at that time, since it never exploded. Before him, on other motors, this problem arose often. Despite its rapid success, its development was abandoned at the beginning of the twentieth century, as it became less economical than other internal combustion engines and electric motors that appeared then. However, Stirling still continued to be used in some industries.

External combustion engine

The principle of operation of all heat engines is that to obtain gas in an expanded state, greater mechanical forces are required than when compressing a cold one. To demonstrate this, you can conduct an experiment with two pots filled with cold and hot water, as well as a bottle. The latter is dipped in cold water, plugged with a cork, then transferred to hot. In this case, the gas in the bottle will begin to perform mechanical work and push the cork out. The first external combustion engine was based entirely on this process. True, later the inventor realized that part of the heat can be used for heating. Thus, productivity has increased significantly. But even this did not help the engine become common.

Later, Erickson, an engineer from Sweden, improved the design by suggesting that the gas be cooled and heated at constant pressure instead of volume. As a result, many copies began to be used for work in mines, on ships and in printing houses. But for the crews, they were too heavy.

External combustion engines from Philips

Such motors are of the following types:

• steam;
• steam turbine;
• Stirling.

The latter type was not developed due to low reliability and other not the highest rates compared to other types of units that appeared. However, Philips reopened in 1938. Engines began to serve to drive generators in non-electrified areas. In 1945, the company's engineers found the opposite use for them: if the shaft is spun by an electric motor, then the cooling of the cylinder head reaches minus one hundred and ninety degrees Celsius. Then it was decided to use an improved Stirling engine in refrigeration units.

Principle of operation

The action of the motor is to work on thermodynamic cycles, in which compression and expansion occur at different temperatures. In this case, the regulation of the flow of the working fluid is implemented due to the changing volume (or pressure - depending on the model). This is the principle of operation of most of these machines, which may have different functions and designs. Engines can be piston or rotary. Machines with their installations work as heat pumps, refrigerators, pressure generators and so on.

In addition, there are open-cycle motors, where flow control is implemented through valves. It is they who are called Erickson engines, in addition to the common name of the Stirling name. In an internal combustion engine, useful work is carried out after pre-compression of air, fuel injection, heating of the resulting mixture mixed with combustion and expansion.

The Stirling engine has the same principle of operation: at low temperatures, compression occurs, and at high temperatures, expansion occurs. But heating is carried out in different ways: heat is supplied through the cylinder wall from the outside. Therefore, he received the name of the external combustion engine. Stirling used a periodic change in temperature with a displacement piston. The latter moves gas from one cavity of the cylinder to another. On the one hand, the temperature is constantly low, and on the other, it is high. When the piston moves up, the gas moves from a hot to a cold cavity, and when it moves down, it returns to a hot one. First, the gas gives off a lot of heat to the refrigerator, and then it receives as much heat from the heater as it gave out. A regenerator is placed between the heater and the cooler - a cavity filled with a material to which the gas gives off heat. In the reverse flow, the regenerator returns it.

The displacer system is connected to a working piston, which compresses the gas in the cold and allows it to expand in the heat. Due to compression at a lower temperature, useful work is done. The whole system goes through four cycles with intermittent movements. The crank mechanism at the same time ensures continuity. Therefore, sharp boundaries between the stages of the cycle are not observed, and Stirling does not decrease.

Considering all of the above, the conclusion suggests itself that this engine is a reciprocating machine with an external heat supply, where the working fluid does not leave the enclosed space and is not replaced. The drawings of the Stirling engine well illustrate the device and the principle of its operation.

Work details

The sun, electricity, nuclear power, or any other source of heat can supply power to a Stirling engine. The principle of operation of his body is to use helium, hydrogen or air. An ideal cycle has a thermal maximum possible efficiency of thirty to forty percent. But with an efficient regenerator, it will be able to work with a higher efficiency. Regeneration, heating and cooling are provided by built-in oil-free heat exchangers. It should be noted that the engine needs very little lubrication. The average pressure in the cylinder is usually 10 to 20 MPa. Therefore, an excellent sealing system and the possibility of oil entering the working cavities are required here.

Comparative characteristics

Most engines of this kind in operation today use liquid fuels. At the same time, continuous pressure is easy to control, which helps to reduce emissions. The absence of valves ensures silent operation. Power to weight is comparable to turbocharged engines, and the output power density is equal to that of a diesel unit. Speed ​​and torque are independent of each other.

The cost of producing an engine is much higher than that of an internal combustion engine. But during operation, the opposite is obtained.

Advantages

Any model of the Stirling engine has many advantages:

• Efficiency with modern design can reach up to seventy percent.
• The engine does not have a high-voltage ignition system, camshaft and valves. It will not need to be adjusted during the entire period of operation.
• In Stirlings, there is no explosion, as in an internal combustion engine, which heavily loads the crankshaft, bearings and connecting rods.
• They do not have that effect when they say that "the engine has stalled."
• Due to the simplicity of the device, it can be operated for a long time.
• It can work both on wood, and with nuclear and any other type of fuel.
• Combustion takes place outside the engine.

Flaws

Application

Currently, the Stirling engine with a generator is used in many areas. It is a universal source of electrical energy in refrigerators, pumps, submarines and solar power stations. It is thanks to the use of various types of fuel that it is possible to use it widely.

rebirth

These motors have been developed again thanks to Philips. In the middle of the twentieth century, General Motors entered into an agreement with it. She led developments for the use of Stirlings in space and underwater devices, on ships and cars. Following them, another company from Sweden, United Stirling, began to develop them, including the possible use on

Today, the linear Stirling engine is used in installations of underwater, space and solar vehicles. Great interest in it is due to the relevance of the issues of environmental degradation, as well as the fight against noise. In Canada and the USA, Germany and France, as well as Japan, there are active searches for the development and improvement of its use.

Future

The obvious advantages that piston and Stirling have, consisting in a long service life, the use of different fuels, noiselessness and low toxicity, make it very promising against the background of an internal combustion engine. However, given the fact that the internal combustion engine has been improved over time, it cannot be easily displaced. One way or another, it is precisely such an engine that occupies a leading position today, and does not intend to give them up in the near future.

”, the Federal State Unitary Enterprise (FSUE) “Krylov Scientific Center” announced that the creation of the first submarine with an anaerobic, that is, air-independent, power plant (VNEU) will lead to a significant technological breakthrough in shipbuilding.

The scientific and technical groundwork for air-independent installations has been created. A steam reforming unit with an electrochemical generator based on solid elements has been developed. Its industrial design has been created. Of the fundamental technologies, it implements the production of hydrogen from diesel fuel, the creation of an electrochemical generator that extracts electric current from hydrogen, and the removal of waste products of the first cycle. That is, CO2 produced during the reaction. This problem is still being finalized, but with proper funding it will be solved.

- said the executive director of the specified enterprise Mikhail Zagorodnikov.

First of all, VNEU relieves the ship of the need to float to the surface to recharge the batteries and replenish the air supply necessary for the operation of diesel generators in a submerged position.

As indicated, at present, the Germans, who created the . In 2014, the French DCNS announced its success in this direction, equipping the Scorpene-class submarine with the installation in question. The company's larger submarine project, in demand by the Australian Navy, is the SMX Ocean (aka Shortfin Barracuda). In India, VNEU is being developed in relation to boats of the Kalvari type (based on Scorpene).

Unlike the mentioned foreign experience, the Russian VNEU implies a completely different method of operation: hydrogen is not transported on board, but is obtained directly in the plant using diesel fuel reforming.

Vladimir Shcherbakov, an expert in the field of naval armaments, believes that submarines with VNEU make it possible to successfully operate in waters tightly controlled by the enemy.

The ability not to surface is important where enemy anti-submarine forces are actively operating. Suffice it to recall what an easy prey for the Germans were our boats in the Baltic during the Great Patriotic War. A similar situation developed for German submariners in the North Atlantic towards the end of the war.

In his opinion, boats of this type have a high export potential, especially in countries that do not have a nuclear submarine fleet. For Russia, as he believes, at this stage it is enough to confine itself to a couple of boats of the Lada project for testing technologies and training specialists.

The well-mastered serial Varshavyankas are now quite coping with the protection of bases and coasts from enemy nuclear submarines.

At the moment, the Admiralty Shipyards in St. Petersburg are building: Kronstadt and Velikiye Luki. The lead submarine of this project, Saint Petersburg, is undergoing trial operation in the Northern Fleet. There is no anaerobic power plant on it yet.

Render of a submarine of the Amur-950 project with an anaerobic power plant

Central Design Bureau MT "Rubin"

A promising Russian anaerobic power plant, which is planned to be installed on the experimental submarine of project 677 "Lada" and the new non-nuclear submarine of the Kalina project, will receive a double-capacity battery. According to Mil.Press FlotProm, the electrical power of the improved battery will be one hundred kilowatts instead of 50 for the current sample. The development and testing of a new battery for anaerobic power plants of submarines is planned to be completed by 2020.

Modern diesel-electric submarines have several advantages over larger nuclear submarines. One of the main such advantages is the almost complete noiselessness of the course in a submerged position, since in this case only quiet electric motors powered by batteries are responsible for the movement of the ship. Recharging of these batteries is carried out from diesel generators in the surface position or at a depth from which it is possible to set the snorkel, a special pipe through which air can be supplied to the generators.

The disadvantages of conventional diesel-electric submarines include the relatively short time that the ship can spend underwater. At best, it can reach three weeks (for comparison, this figure for nuclear submarines is 60-90 days), after which the submarine will have to surface and start diesel generators. An anaerobic power plant, which does not require outside air, will allow a non-nuclear submarine to stay submerged for much longer. For example, a submarine of the Lada project with such an installation can be under water for 45 days.

A promising Russian anaerobic power plant will use highly purified hydrogen for operation. This gas will be obtained on board the ship from diesel fuel by reforming, that is, the conversion of fuel into hydrogen-containing gas and aromatic hydrocarbons, which will then pass through the hydrogen recovery unit. The hydrogen will then be fed into hydrogen-oxygen fuel cells, where electricity will be generated for engines and on-board systems.

Battery BTE-50K-E on the test bench

Krylov State Research Center

The battery, otherwise known as an electrochemical generator, is being developed by the Central Research Institute of Marine Electrical Engineering and Technology. This battery, which generates electricity through the reaction of hydrogen and oxygen, was named BTE-50K-E. Its power is 50 kilowatts. The power of the improved battery will be one hundred kilowatts. The new battery will be part of the power modules of promising non-nuclear submarines with a capacity of 250-450 kilowatts.

In addition to the electrochemical elements themselves, otherwise known as hydrogen fuel cells, such modules will include hydrocarbon fuel converters. It is in them that the process of reforming diesel fuel will take place. As one of the developers of the new battery told Mil.Press FlotProm, the hydrocarbon fuel converter is currently under development. Earlier it was reported that the development of an anaerobic power plant for submarines is planned to be completed before the end of 2018.

In February last year, researchers at the Georgia Institute of Technology on the development of a compact four-stroke piston unit for catalytic methane reforming and hydrogen production. New units can be chained together, thereby increasing the hydrogen yield. The installation is quite compact and does not require strong heating. The reactor operates on a four-stroke cycle. On the first stroke, methane mixed with steam is fed into the cylinder through valves. In this case, the piston in the cylinder smoothly lowers. After the piston reaches the bottom point, the mixture supply is blocked.

On the second stroke, the piston rises, compressing the mixture. At the same time, the cylinder is heated to 400 degrees Celsius. Under conditions of high pressure and heating, the reforming process takes place. As hydrogen is released, it passes through the membrane, which stops carbon dioxide, also produced during reforming. Carbon dioxide is absorbed by the adsorbent material mixed with the catalyst.

On the third stroke, the piston descends to its lowest position, sharply reducing the pressure in the cylinder. In this case, carbon dioxide is released from the adsorbent material. Then the fourth stroke begins, in which the valve opens in the cylinder, and the piston begins to rise again. During the fourth stroke, carbon dioxide is squeezed out of the cylinder into the atmosphere. After the fourth measure, the cycle begins again.

Vasily Sychev

"Foreign Military Review" No. 6. 2004. (p.59-63)

Captain 1st rank N. SERGEEV,

captain 1st rank I. YAKOVLEV,

captain 3rd rank S. IVANOV

Submarines with a traditional diesel-electric power plant (PP) are quite an effective tool for solving their specific tasks and have a number of advantages over submarines, especially when operating in coastal and shallow water areas of the sea. These advantages include a low noise level, high maneuverability at low speeds, and strike power comparable to the PLA. In addition, the inclusion of non-nuclear submarines in the Navy is largely due to the low cost of their creation and operation. At the same time, they have a number of disadvantages, in particular, a limited time spent in a submerged position due to a small amount of energy in the storage battery (AB). To charge the AB, the submarine is forced to float to the surface or use the diesel engine under water (RDP) mode, as a result of which the probability of its detection by radar, infrared, optoelectronic and acoustic means increases. The ratio of the time of navigation under the RPD, necessary to charge the batteries, to the period of discharging the battery is called the "degree of negligence".

There are several ways to increase the cruising range under water, the main of which are scientific, technical and technological developments in order to improve the traditional power plant of non-nuclear submarines and its components. However, in modern conditions, the implementation of this direction cannot fully ensure the solution of the main problem. The way out of this situation, according to foreign experts, is to use an air-independent power plant (VNEU) on the submarine, which can serve as an auxiliary one.

The successful results obtained in the course of work on this topic made it possible to equip newly built auxiliary VNEUs and retrofit diesel-electric submarines in operation. In the latter, an additional compartment crashes into the robust case, containing the power plant itself, tanks for storing fuel and oxidizer, tanks for replacing the mass of consumable reagents, auxiliary mechanisms and equipment, as well as control and management devices. In the future, VNEU is planned to be used on submarines as the main one.

Currently, there are four main types of air-independent power plants: a closed-cycle diesel engine (DZTs), a Stirling engine (DS), fuel cells or an electrochemical generator (ECG) and a closed-cycle steam turbine plant.

The main requirements for VNEU include the following: low noise level, low heat generation, acceptable weight and size characteristics, simplicity and safety of operation, long service life and low cost, the ability to use the existing coastal infrastructure. To the greatest extent, these requirements are met by auxiliary power plants with a Stirling engine, ECG and a closed-cycle steam turbine plant. Therefore, the navies of a number of countries are actively working on their practical application on non-nuclear submarines.

Power plant with Stirling engine. In 1982, the Swedish company Kokums Marine AV began its development by order of the government. Experts initially considered VNEU with a Stirling engine as an auxiliary one, working in conjunction with a traditional diesel-electric power plant (DEEU). Their studies have shown that a new installation, created as the main one (without the use of a traditional diesel electric power plant), will be too expensive to manufacture and the technical requirements for a submarine power plant will be difficult to meet.

The Royal Swedish Navy chose VNEU with a Stirling engine for several reasons: high power density, low noise level, well-developed technologies for the production of diesel engines, reliability and ease of operation.

The high specific power of DS is achieved by burning diesel fuel in combination with oxygen in the combustion chamber. On the submarine, the necessary supply of oxygen is stored in a liquid state, which is ensured by modern cryogenic technologies.

The Stirling engine is an external combustion engine. The principle of its operation provides for the use of heat generated by an external source and its supply to the working fluid located in a closed circuit. DS converts the heat produced by an external source into mechanical energy, which is then converted by the generator into direct current. The regenerator, which is part of the closed working circuit of the engine, takes the thermal energy from the working fluid, which is formed after its expansion, and returns it back to the cycle when the gas changes direction.

The DS uses double-acting pistons. The space above the piston is the expansion cavity and the space below the piston is the compression cavity. The compression cavity of each cylinder is connected by an external channel through the cooler, regenerator and heater to the expansion cavity of the neighboring cylinder. The necessary combination of expansion and contraction phases is achieved using a crank-based distribution mechanism. A schematic diagram of the Stirling engine is shown in the figure.

The thermal energy required for the operation of the DS is generated in the high-pressure combustion chamber by burning diesel fuel and liquid oxygen. Oxygen and diesel fuel in a ratio of 4:1 enter the combustion chamber, where they are burned.

In order to maintain the required temperature of the working process and ensure sufficient heat resistance of materials, a special gas recirculation system (GRC) is used in the design of the DS. This system is designed

to dilute pure oxygen entering the combustion chamber with gases generated during the combustion of the fuel mixture.

During the operation of the Stirling engine, some of the exhaust gases are vented overboard, which can lead to the formation of a trail of bubbles. This is due to the fact that the combustion process in the DS goes with a large excess of unused oxygen, which cannot be separated from the exhaust gases. To reduce the number of bubbles formed when the exhaust gases dissolve in sea water, an absorber is used in which gases and water are mixed. In this case, the exhaust gases are pre-cooled in a special heat exchanger from 800 to 25 °C. The working pressure in the combustion chamber makes it possible to remove exhaust gases at different submersion depths of the submarine, up to the working one, which does not require the use of a special compressor for this purpose, which has increased noise.

Since the process of external heat supply is inevitably accompanied by additional heat losses, the efficiency of a diesel engine is less than that of a diesel engine. Increased corrosion does not allow the use of conventional diesel fuel in DS. Low sulfur fuel required.

For the Swedish program, a V4-275 type DS from United Sterling was adopted. It is a four-cylinder engine (the working volume of each cylinder is 275 cm3). The cylinders are arranged in a V-shape to reduce noise and vibration. The working pressure in the combustion chamber of the engine is 2 MPa, which ensures its use at submarine immersion depths of up to 200 m. For engine operation at great depths, exhaust gas compression is required, which will require additional power consumption to remove exhaust gases and lead to an increase in noise level.

The first power plant based on the DS was equipped with a Necken-type submarine launched after modernization in 1988. The Stirling engine, storage tanks for diesel fuel, liquid oxygen and auxiliary equipment were placed in an additional section with zero buoyancy, embedded in the strong hull of the submarine. Due to this, the length of the boat increased by 10 percent, which slightly affected the change in its maneuverability.

Two DS type V4-275R work on DC generators with a capacity of 75 kW. The motors are housed in noise-insulating modules on vibration-isolating structures with two-stage damping. As tests have shown, the DS is capable of generating a sufficient amount of electricity necessary to power the on-board systems of the submarine, to ensure recharging of the battery and to move the boat at a speed of up to 4 knots. To achieve higher travel speeds and power supply to the main propulsion motor, it is planned to use the motor together with the AB.

Thanks to the use of a combined power plant, the time of navigation in a submerged position increased from 3-5 to 14 days, and the patrol speed - from 3 to 6 knots. As a result, the stealth of submarines has increased.

According to Swedish experts, the Stirling engine demonstrated high reliability and maintainability in shipboard conditions. Its noise emission does not exceed the noise of a propulsion motor and is 20-25 dB lower than that of a diesel engine of equivalent power.

The Swedish Navy is equipping this auxiliary VNEU submarine of the Gotland type. The contract for the construction of three submarines of this type was signed by the government of the country with Kokums in March 1990. The first submarine of this series - "Gotland" - was put into service in 1996, the next two: "Apland" and "Halland" - in 1997. During the modernization, it is planned to equip Västergotland-type submarines with auxiliary power plants of this type.

According to foreign sources, Swedish submarines equipped with DS propulsion systems have already shown good results in practice. In particular, during the exercises, the superiority of the Halland submarine over the Spanish Navy submarines with a traditional diesel-electric power plant was proved, and its improved performance characteristics were demonstrated during joint navigation with nuclear submarines of the US and French navies.

Power plant with ECG. An electrochemical generator is a plant in which the chemical energy of a fuel is directly converted into electrical energy. The basis of ECG is fuel cells (FC), in which the process of generating electricity occurs, arising from the interaction of fuel and oxidizer, continuously and separately supplied to the fuel cell. In principle, a fuel cell is a kind of galvanic cell. Unlike the latter, fuel cells are not consumed, since the active components are supplied continuously (fuel and oxidizer).

During the research, various types of fuels and oxidizers were tested. The best results were achieved when using the reaction between oxygen and hydrogen, as a result of the interaction of which electrical energy and water are generated.

The generation of direct current by cold combustion of hydrogen and oxygen has been known for a long time and has been successfully used to generate electricity in underwater vehicles. This principle of generating electricity was used on submarines only in the 1980s. In PA, oxygen and hydrogen were stored separately in high-pressure, durable tanks. Although electrochemical generators are more efficient than storage batteries, their use on submarines was hampered by the fact that the supply of fuel reagents stored in a gaseous state did not allow for the required duration of diving.

The most optimal way to store oxygen is in a liquid state (in a cryogenic form - at a temperature of 180 ° C), hydrogen - in the form of a metal hydride.

By the mid-1980s, the German GSC (German Submarine Consortium), including IKL (Ingenieurkontor Lubeck), HDW (Howaldtswerke Deutsche Werft AG) and FS (Ferrostaal), developed and built an experimental onshore ECG unit with Siemens fuel cells to check the joint operation of its components - fuel cells, hydrogen and oxygen storage systems, pipelines, control systems, as well as the interaction of work with a traditional power plant

PL. The ECG prototype was structurally designed in such a way that, upon completion of the tests, it could be installed on the operating submarine without modifications. The results of coastal trials have shown that the PU with ECG can be effectively used on submarines.

In 1989, in the interests of the German Navy, a nine-month series of sea trials of the U-1 submarine of project 205, equipped with an auxiliary VNEU with ECG, was successfully completed at the HDW shipyard. As a result, the leadership of this type of aircraft abandoned the further construction of submarines only with a diesel-electric power plant and decided to use "hybrid" ones (DEPU as the main and auxiliary power plant with ECG). Further research is aimed at developing such installations with ECH as the main one.

Structurally, ECG is an electrochemical module with polymer membranes (REM). All modules are installed on a single frame and can be connected both in series and in parallel.

Auxiliary in the power plant with ECG are the cooling system using outboard water and the residual gas system. The latter ensures the afterburning of residual hydrogen in the AB ventilation system and the use of residual oxygen for onboard needs. The power plant control system is integrated with the security control system, the monitors of which are located in the central post.

Energy conversion in fuel cells is silent. As part of the power plant, there are no nodes that perform rotational or oscillatory movements. It has a low heat release, as a result of which it does not have a significant effect on the formation of physical fields. The only auxiliary system with rotating parts is the cooling system, but it is not so noisy as to greatly affect the level of the acoustic field of the submarine.

The initial activation of reactions in fuel cells does not require a lot of electricity in order for the metal hydride stored in cylinders located in the double-side space to begin to release hydrogen and begin to evaporate oxygen stored in a liquid state in shock-proof cryogenic tanks made of low-magnetic steel.

This type of power plant is quite efficient, it has a high efficiency - up to 70 percent, and by this indicator it significantly outperforms other air-independent power plants. Comparative data on the dependence of the efficiency of different types of VNEU on the relative level of output power are shown in the graph. The energy conversion process takes place at a low operating temperature (60-90 °C). A small amount of heat generated by the system during operation is required to maintain the initially initiated electrochemical process. Part of the heat generated by the ES can be used for domestic purposes such as heating. The amount of heat that needs to be removed from the installation is small, so the forced cooling of the power plant with outboard water does not require a long time (up to a day of its operation). The water produced during the reaction, after appropriate treatment, can be used for drinking.

The combination of compact fuel, series-connected cells allows you to get any required voltage. Voltage regulation is achieved by changing the number of plates in fuel cell assemblies. The highest power can be achieved by connecting these elements in series.

The work of the ED with the ECG does not depend on the depth of the submersion. The electricity generated by such a power plant goes directly to the main switchboard of the boat. 65 percent it is spent on movement and ship needs, 30 percent. - for the cooling system and the system of residual gases of the power plant, 5 percent. - for additional power plant equipment. The auxiliary power plant can operate both in parallel with the battery, providing the electric propulsion of the submarine and powering other consumers, and for recharging the battery.

It is planned to equip four and two submarines of the 212A type, which are being built for the German and Italian navies, respectively, as well as an export version of the 214 boat for the Greek and Republic of Korea navies, with an auxiliary power plant with an ECG.

Two submarines from the first sub-series of boats of type 212A for the German Navy are equipped with an auxiliary power plant with an ECG with a rated power of about 300 kW with nine fuel cells of 34 kW. The boats of the second sub-series are planned to be equipped with two 120 kW fuel cells. They will have practically the same weight and size characteristics as fuel cells with a power of 34 kW, but at the same time their efficiency will increase by 4 times. Submarine type 212A will be able to stay submerged for about two weeks. The rated power of this installation will allow to develop a speed of up to 8 knots without the use of AB.

The modular design of power plants based on fuel cells not only facilitates their installation on submarines under construction, but also allows them to be equipped with previously built ones, even those that were built under licenses at the shipyards of countries importing German submarines.

In addition, such a power plant, according to German experts, is highly maintainable and has a longer service life.

Steam turbine plant (STU) of a closed cycle. PTU MESMA (Module d "Energie Sous-Marin Autonome), operating on a closed Rankine cycle, was developed by the shipbuilding department of the French Navy DCN for export sales. The French companies Teknikatom, Thermodyne, Air Liquide, participate in its production, "Bertin", as well as the shipyard "Empresa Nacional Bazan" (Spain).

MESMA is a two-circuit plant. In the primary circuit, as a result of the combustion of ethanol in oxygen, a heat carrier (steam gas) is formed, which passes through the steam generator path and gives off heat to the water circulating in the second circuit. The water is converted into high pressure steam, which drives a steam turbine connected to a generator. Oxygen is stored on board the submarine in special containers in a liquid state. The products of the combustion reaction are water and exhaust gases discharged overboard. This can lead to an increase in the visibility of submarines.

Combustion in the combustion chamber occurs at a pressure of 6 MPa, as a result of which the unit can operate at depths of up to 600 m, so a compressor is not required to remove combustion products overboard.

The efficiency of a power plant with a MESMA STP is 20 percent, which is due to large losses during multiple energy conversion - fuel combustion, superheated steam generation, three-phase current generation and its subsequent conversion to direct current.

The entire installation as a whole is quite compact and is mounted in a section of a pressure hull 10 m long and 7.8 m wide. Oxygen is stored in a liquefied state in cylinders mounted on special shock-absorbing mounts inside the pressure hull of the submarine in a vertical position.

In September 1998, bench tests of a prototype MESMA power plant were completed. In April 2000, at the shipyard in Cherbourg, the first ship power plant was manufactured, located in the pressure hull section. After completion of the acceptance tests, the module with the power plant was to be sent to Pakistan to equip the Ghazi submarine of the Agosta 90V type, which is being built there under the French license. This is the first submarine of this type, on which an auxiliary air-independent power plant will be installed during construction. Two other submarines, built earlier, are planned to be retrofitted with them later - in the process of modernization and repair.

The use of auxiliary air-independent power plants on non-nuclear submarines made it possible to improve their performance characteristics in terms of the duration of diving, which increased the stealth of boats and expanded their combat capabilities. In addition to submarines under construction, auxiliary VNEU can be equipped with existing diesel submarines in the process of their modernization. Further development of technologies and obtaining on this basis qualitatively new characteristics of VNEU, most likely, will allow non-nuclear submarines to solve problems inherent in nuclear ones.

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that is, unlike an internal combustion engine, an internal combustion engine, where the working fluid is simultaneously combustible fuel inside the cylinder, in Stirling the fuel burns outside, heats the working fluid (air) inside the cylinder, and then, as usual, the crank, etc.

in this article, I didn’t see the actual main positioned chip, anaerobicity, that is, just as an internal combustion engine needs oxygen for combustion, the same combustion process is used in stirling, that is, oxygen is still needed
just burning is transferred from the inside to the outside and that's it. Well, Stirling also burns constantly, and not in an explosive impulse, as in an internal combustion engine, hence its noiselessness, which is useful for a submarine. But that's all the pluses

I thought that instead of burning, some other exothermic chemical reactions would be used, for example, with the participation of water instead of oxygen, which is logical, there is a lot of oxygen around on land, and water itself under water.
I don’t know, pour it into the cylinder or outside it, well, at least quicklime, but pour it with water, convert the generated heat into rotation
why claim an anaerobic engine and still use oxygen

further, if we develop the idea - the project uses an electric motor as the main marching motor, and the stirling will only be needed to recharge the batteries, so isn’t it easier then to focus on the means of directly obtaining EMF through chemical reactions without mechanics?
This reminded me of how, in the summer, in a country house without light, I connected a 220 inverter to a car battery, to which I connected energy-saving light bulbs, on LEDs, in which there is a low voltage. Then it dawned on me that it was stupid to first increase the voltage from 12 to 220, and then it drops again in the light bulb, I made a home-made LED for 12v and the battery began to last three times longer ..

In Soviet times, dry-charged batteries were made in Podolsk, on the plates of which a composition was pressed that corresponded to the charged state of a lead battery. Such a battery can be stored in a warehouse for a very long time and be charged, then the buyer pours electrolyte into it and immediately puts it on the car. Load, for example, dry plates with electrolyte onto the submarine, which are consumed during the movement and are replaced with fresh ones, and then new material is loaded in the dock as fuel, and the spent material is unloaded and regenerated under factory conditions into a new dry-charged one. All. No double conversion with steam locomotive efficiency, no oxygen, really anaerobic circuit.

Well, with a lead-acid battery, this is just an offhand idea, you can come up with a much more perfect process, for example, on lithium, this is still minus weight and minus dangerous acid