Internal combustion internal combustion engine. Which Stirling Engine has the best design with maximum efficiency? Some details of the engine

This article is devoted to an invention patented back in the nineteenth century by a Scottish priest, Stirling. Like all predecessors, it was an engine external combustion... The only difference between it and the others is that it can run on gasoline, fuel oil, and even coal and wood.

In the 19th century, it became necessary to replace steam engines with something safer, as boilers often exploded due to high pressure couple and some serious design flaws.

A good option was the external combustion engine, which was patented in 1816 by Scottish priest Robert Stirling.

True, "hot air engines" were made earlier, back in the 17th century. But Stirling added a cleaner to the rig. In the modern sense, it is a regenerator.

He increased the productivity of the installation, keeping heat in the warm zone of the machine, at the moment when the working fluid was cooled. This has greatly increased the efficiency of the system.

The invention found wide practical application, there was a stage of rise and development, but then the Stirlings were undeservedly forgotten.

They made way steam engines and engines internal combustion, and in the twentieth century were reborn again.

In view of the fact that this principle of external combustion is very interesting in itself, today the best engineers and amateurs in the USA, Japan, Sweden are working on the creation of new models ...

External combustion engine. Principle of operation

"Stirling" - as we have already mentioned, a kind of external combustion engine. The main principle of its operation is the constant alternation of heating and cooling of the working fluid in a closed space and obtaining energy due to the resulting change in the volume of the working fluid.

As a rule, the working fluid is air, but hydrogen or helium can be used. In prototypes, they tried nitrogen dioxide, freons, liquefied propane-butane and even water.

By the way, water is in a liquid state throughout the entire thermodynamic cycle. And the "styling" itself with a liquid working fluid has a compact size, high power density and high working pressure.

Types of styling

There are three classic types of Stirling engines:

Application

The Stirling engine can be used in cases where a simple, compact thermal energy converter is required or when the efficiency of other types of heat engines is lower: for example, if the temperature difference is insufficient for using gas or.

Here are specific examples of use:

• Autonomous generators for tourists are already being produced today. There are models that operate on a gas burner;

NASA has ordered a version of a stirling generator that runs on nuclear and radioisotope heat sources. It will be used in space missions.

• "Stirling" for pumping liquid is much easier than the installation "motor-pump". As a working piston, it can use the pumped liquid, which will at the same time cool the working fluid. With such a pump, you can pump water into irrigation channels using solar heat, supply hot water from the solar collector to the house, pump chemical reagents, since the system is completely sealed;
• Household refrigerator manufacturers are introducing styling models. They will be more economical, and ordinary air is supposed to be used as a refrigerant;
• Combined Stirling with a heat pump optimizes the heating system in the house. It will give off the waste heat of the "cold" cylinder, and the resulting mechanical energy can be used to pump the heat that comes from the environment;
• Today, all submarines of the Swedish Navy are equipped with Stirling engines. They run on liquid oxygen, which is then used for breathing. A very important factor for a boat, low noise level, and disadvantages such as "large size", "need for cooling" are not significant in a submarine. The newest Japanese submarines of the Soryu class are equipped with similar installations;
• The Stirling engine is used to convert solar energy into electrical energy. For this, it is mounted at the focus of the parabolic mirror. Stirling Solar Energy builds solar collectors up to 150 kW per mirror. They are used in the world's largest solar power plant in southern California.

Advantages and disadvantages

The modern level of design and manufacturing technology makes it possible to increase the coefficient useful action"Stirling" up to 70 percent.

• Surprisingly, the engine torque is practically independent of the crankshaft rotation speed;
• The power plant does not contain the ignition system, valve system and camshaft.
• Throughout the entire service life, no adjustments and settings are needed.
• The engine does not "stall", and the simplicity of the design allows it to operate in an autonomous mode for a long time;
• You can use any sources of thermal energy, from firewood to uranium fuel.
• Fuel combustion occurs outside the engine, which contributes to its complete afterburning and minimizes toxic emissions.

• Since the fuel burns outside the engine, heat is removed through the walls of the radiator, which is additional dimensions;
• Material consumption. To make a Stirling machine compact and powerful, expensive heat-resistant steels are required that can withstand high operating pressures and have low thermal conductivity;
• A special lubricant is needed, the usual one for Stirlings is not suitable, as it cokes at high temperatures;
• To obtain a high power density, hydrogen and helium are used in the Stirlings.

Hydrogen is explosive, and at high temperatures it can dissolve in metals, forming metal hydrites. In other words, the destruction of the engine cylinders occurs.

Also, hydrogen and helium are highly permeable and easily seep through the seals, lowering the operating pressure.

If, after reading our article, you want to purchase a device - an external combustion engine, do not run to the nearest store, such a thing is not for sale, alas ...

You understand that those who are engaged in the improvement and implementation of this machine keep their developments secret and sell them only to reputable buyers.

Watch this video and do it yourself.

This is the introductory part of a series of articles dedicated to Internal Combustion Engine, which is a short excursion into the history of the evolution of the internal combustion engine. Also, the article will touch on the first cars.

The following sections will detail the various ICEs:

Connecting rod-piston
Rotary
Turbojet
Reactive

The engine was installed on a boat that was able to climb up the Sona River. A year later, after testing, the brothers received a patent for their invention, signed by Napoleon Bonopart, for a period of 10 years.

It would be more correct to call this engine a jet engine, since its work consisted in pushing water out of the pipe under the bottom of the boat ...

The engine consisted of an ignition chamber and a combustion chamber, a bellows for air injection, a fuel dispenser and an ignition device. Coal dust served as fuel for the engine.

The bellows injected a stream of air mixed with coal dust into the ignition chamber where a smoldering wick ignited the mixture. After that, the partially ignited mixture (coal dust burns relatively slowly) entered the combustion chamber where it completely burned out and expanded.
Further, the gas pressure pushed water out of exhaust pipe, which made the boat move, after that the cycle was repeated.
The engine worked in pulse mode with a frequency of ~ 12 and / minute.

After some time, the brothers improved the fuel by adding resin to it, and later replaced it with oil and designed a simple injection system.
Over the next ten years, the project did not receive any development. Claude went to England to promote the idea of ​​the engine, but he squandered all the money and achieved nothing, and Joseph took up photography and became the author of the world's first photo "View from the window".

In France, in the house-museum of Niepses, a replica of "Pyreolophore" is exhibited.

A little later, de Riva mounted his engine on a four-wheeled vehicle, which, according to historians, was the first car with an internal combustion engine.

About Alessandro Volta

Volta was the first to put zinc and copper plates in acid to produce a continuous electric current, creating the world's first chemical source current ("Voltaic pillar").

In 1776, Volta invented a gas pistol, the “Volta pistol,” in which gas exploded from an electric spark.

In 1800, he built a chemical battery, which made it possible to obtain electricity through chemical reactions.

The unit for measuring electrical voltage - Volt - is named after Volta.

A- cylinder, B- "spark plug, C- piston, D- "balloon" with hydrogen, E- ratchet, F- exhaust gas dump valve, G- handle for valve control.

The hydrogen was stored in an "air" balloon connected by a pipe to a cylinder. The supply of fuel and air, as well as the ignition of the mixture and the release of exhaust gases were carried out manually using levers.

Principle of operation:

Air entered the combustion chamber through the exhaust gas discharge valve.
The valve was closing.
The valve for supplying hydrogen from the ball was opened.
The tap was closing.
By pressing the button, an electric discharge was applied to the "candle".
The mixture flashed and lifted the piston up.
The exhaust gas discharge valve was opening.
The piston fell under its own weight (it was heavy) and pulled the rope, which turned the wheels through the block.

After that, the cycle was repeated.

In 1813, de Riva built another car. It was a wagon about six meters long, with wheels two meters in diameter and weighing almost a ton.
The car was able to drive 26 meters with a load of stones (about 700 lbs) and four men, at a speed of 3 km / h.
With each cycle, the car moved 4-6 meters.

Few of his contemporaries took this invention seriously, and the French Academy of Sciences argued that an internal combustion engine would never compete in performance with a steam engine.

In 1833, American inventor Lemuel Wellman Wright, has registered a patent for a water-cooled two-stroke gas internal combustion engine.
(see below) wrote the following about the Wright engine in his book Gas and Oil Engines:

“The engine drawing is very functional and the details are meticulous. The explosion of the mixture acts directly on the piston, which rotates the crank shaft through the connecting rod. By outward appearance the engine resembles a high-pressure steam engine in which gas and air are pumped from separate tanks. The mixture in the spherical containers was ignited during the rise of the piston at TDC (top dead center) and pushed it down / up. At the end of the stroke, the valve would open and discharge the exhaust gases into the atmosphere. "

It is not known if this engine was ever built, but there is a blueprint for it:

In 1838, English engineer William Barnett received a patent for three internal combustion engines.

The first engine is a single-acting two-stroke (fuel burned only on one side of the piston) with separate pumps for gas and air. The mixture was ignited in a separate cylinder, and then the burning mixture flowed into the working cylinder. The inlet and outlet was carried out through mechanical valves.

The second engine repeated the first, but was double-acting, that is, combustion occurred alternately on both sides of the piston.

The third engine was also double-acting, but had inlet and outlet ports in the cylinder walls that opened at the moment the piston reached the extreme point (as in modern two-strokes). This made it possible to automatically release the exhaust gases and admit a new charge of the mixture.

A distinctive feature of the Barnett engine was that the fresh mixture was compressed by the piston before being ignited.

Blueprint for one of Barnett's engines:

In the years 1853-57, Italian inventors Eugenio Barzanti and Felice Matteucci developed and patented a two-cylinder internal combustion engine with a capacity of 5 l / s.
The patent was granted by the London Office because Italian law could not guarantee sufficient protection.

The construction of the prototype was entrusted to Bauer & Co. of Milan " (Helvetica), and completed in early 1863. The success of the engine, which was much more efficient than the steam engine, was so great that the company began to receive orders from all over the world.

Early, single-cylinder Barzanti-Matteucci engine:

Barzanti-Matteucci two-cylinder engine model:

Matteucci and Barzanti entered into an agreement for the production of the engine with a Belgian company. Barzanti left for Belgium to supervise the work in person and died suddenly of typhus. With the death of Barzanti, all work on the engine was discontinued, and Matteucci returned to his former job as a hydraulic engineer.

In 1877, Matteucci claimed that he and Barzanti were the main creators of the internal combustion engine, and the engine built by August Otto was very similar to the Barzanti-Matteucci engine.

The documents concerning the patents of Barzanti and Matteucci are kept in the archives of the Museo Galileo library in Florence.

The most important invention of Nikolaus Otto was the engine with four-stroke cycle- the Otto cycle. This cycle is at the heart of most gas and petrol engines to this day.

The four-stroke cycle was Otto's greatest technical achievement, but it was soon discovered that a few years before his invention, the exact same engine principle was described by the French engineer Beau de Roche. (see above)... A group of French industrialists challenged Otto's patent in court, the court found their arguments convincing. Otto's rights under his patent were significantly curtailed, including the revocation of his monopoly on the four-stroke cycle.

Despite the fact that competitors have launched the production of four-stroke engines, the Otto model, worked out by many years of experience, was still the best, and the demand for it did not stop. By 1897, about 42 thousand of these engines were produced. different power... However, the fact that a luminous gas was used as a fuel greatly narrowed the scope of their application.
The number of lighting and gas factories was insignificant even in Europe, while in Russia there were only two of them - in Moscow and St. Petersburg.

In 1865, French inventor Pierre Hugo received a patent for a machine that was a vertical, single-cylinder, double-acting engine that used two rubber pumps driven by a crankshaft to supply the mixture.

Hugo later constructed horizontal motor similar to the Lenoir engine.

Science Museum, London.

In 1870, Austro-Hungarian inventor Samuel Marcus Siegfried designed an internal combustion engine running on liquid fuel and installed it on a four-wheeled cart.

Today this car is well known as "The first Marcus Car".

In 1887, in collaboration with Bromovsky & Schulz, Markus built a second car, the Second Marcus Car.

In 1872, an American inventor patented a two-cylinder constant-pressure internal combustion engine powered by kerosene.
Brighton named its engine "Ready Motor".

The first cylinder served as a compressor that forced air into the combustion chamber, into which kerosene was continuously supplied. In the combustion chamber, the mixture was ignited and through the spool mechanism entered the second - the working cylinder. A significant difference from other engines was that the air-fuel mixture burned out gradually and at constant pressure.

Those interested in the thermodynamic aspects of the engine can read about the Brighton Cycle.

In 1878, Scottish engineer Sir (knighted in 1917) developed the first two-stroke engine with ignition of the compressed mixture. He patented it in England in 1881.

The engine worked in a curious way: air and fuel were supplied to the right cylinder, there it was mixed and this mixture was pushed into the left cylinder, where the mixture from the candle was ignited. Expansion took place, both pistons went down, from the left cylinder (through the left branch pipe) exhaust gases were emitted, and a new portion of air and fuel was sucked into the right cylinder. Following inertia, the pistons rose and the cycle was repeated.

In 1879, built a completely reliable gasoline two-stroke engine and received a patent for it.

However, Benz's real genius manifested itself in the fact that in subsequent projects he was able to combine various devices. (throttle, battery spark ignition, spark plug, carburetor, clutch, gearbox and radiator) on their products, which in turn became the standard for all mechanical engineering.

In 1883, Benz founded the Benz & Cie company to manufacture gas engines and in 1886 patented four-stroke the engine that he used in his cars.

Thanks to the success of Benz & Cie, Benz was able to start designing horseless carriages. Combining his experience in making engines and his long-standing hobby of designing bicycles, by 1886 he had built his first automobile and named it "Benz Patent Motorwagen".

The design strongly resembles a tricycle.

Single-cylinder four-stroke internal combustion engine with a working volume of 954 cm3. Installed on " Benz Patent Motorwagen".

The engine was equipped with a large flywheel (used not only for uniform rotation, but also for starting), a 4.5 liter gas tank, an evaporative-type carburetor and a slide valve through which fuel entered the combustion chamber. Ignition was carried out with a spark plug of Benz's own design, the voltage to which was supplied from the Rumkorf coil.

Cooling was water, but not a closed cycle, but evaporative. The steam escaped into the atmosphere, so the car had to be refueled not only with gasoline, but also with water.

The engine developed 0.9 hp. at 400 rpm and accelerated the car to 16 km / h.

Karl Benz is driving his car.

A little later, in 1896, Karl Benz invented the boxer engine (or flat engine), in which the pistons reach top dead center at the same time, thereby balancing each other.

Mercedes-Benz Museum in Stuttgart.

In 1882, English engineer James Atkinson invented the Atkinson cycle and the Atkinson engine.

The Atkinson engine is essentially a four-stroke engine Otto cycle, but with a modified crank mechanism. The difference was that in the Atkinson engine, all four strokes occurred in one revolution of the crankshaft.

The use of the Atkinson cycle in the engine reduced fuel consumption and noise during operation due to lower exhaust pressure. In addition, this engine did not require a gearbox to drive the gas distribution mechanism, since the opening of the valves set the crankshaft in motion.

Despite a number of advantages (including circumvention of Otto patents) the engine was not widely used due to the complexity of manufacturing and some other disadvantages.
The Atkinson cycle provides better environmental performance and economy, but requires high rpm. At low revs, it gives out a relatively small torque and can stall.

Now the Atkinson engine is used on hybrid vehicles « Toyota Prius"And" Lexus HS 250h ".

In 1884, British engineer Edward Butler, at the London bicycle exhibition "Stanley Cycle Show" showed drawings of a three-wheeled car with gasoline internal combustion engine, and in 1885 he built it and showed it at the same exhibition, calling it "Velocycle". Also, Butler was the first to use the word petrol.

The Velocycle was patented in 1887.

The Velocycle was equipped with a single-cylinder, four-stroke gasoline engine equipped with an ignition coil, carburetor, choke and liquid cooled... The engine developed a power of about 5 hp. with a volume of 600 cm3, and accelerated the car to 16 km / h.

Over the years, Butler improved the performance of his vehicle, but was unable to test it due to the "Law of the Red Flag" (published in 1865), Whereby vehicles should not exceed a speed over 3 km / h. In addition, three people had to be present in the car, one of whom had to walk in front of the car with the red flag. (such are the security measures) .

In the 1890 English Mechanic magazine, Butler wrote - "The authorities prohibit the use of the car on the road, as a result of which I refuse to further develop."

Due to a lack of public interest in the car, Butler took it apart for scrap and sold the patent rights to Harry J. Lawson. (bicycle manufacturer), which continued to manufacture the engine for use on boats.

Butler himself went on to create stationary and marine engines.

In 1891, Herbert Aykroyd Stewart, in collaboration with Richard Hornsby and Sons, built the Hornsby-Akroyd engine, in which fuel (kerosene) was injected under pressure into additional camera (because of its shape it was called "hot ball"), mounted on the cylinder head and connected to the combustion chamber by a narrow passage. The fuel was ignited by the hot walls of the additional chamber and rushed into the combustion chamber.

1. Additional camera (hot ball).
2. Cylinder.
3. Piston.
4. Carter.

To start the engine, a blowtorch was used, with which an additional chamber was heated. (after starting it was warmed up exhaust gases) ... Because of this, the Hornsby-Akroyd engine which was the predecessor of the diesel engine designed by Rudolf Diesel, often referred to as "semi-diesel". However, a year later Aykroyd improved his engine by adding a "water jacket" (patent dated 1892) to it, which increased the temperature in the combustion chamber by increasing the compression ratio, and now there was no need for an additional heating source.

In 1893, Rudolph Diesel received patents for a heat engine and a modified "Carnot cycle" called "Method and apparatus for converting high temperature into work."

In 1897, at the Augsburg machine-building plant» (since 1904 MAN), with the financial participation of the companies of Friedrich Krupp and the Sulzer brothers, the first functioning diesel engine of Rudolf Diesel was created
Engine power was 20 Horse power at 172 rpm, efficiency 26.2% with a weight of five tons.
This far outstripped existing 20% ​​efficiency Otto engines and 12% efficiency marine steam turbines, generating keen industry interest in different countries.

The Diesel engine was a four-stroke. The inventor has found that the efficiency of an internal combustion engine is increased by increasing the compression ratio of the combustible mixture. But it is impossible to strongly compress the combustible mixture, because then the pressure and temperature rise and it spontaneously ignites ahead of time. Therefore, Diesel decided to compress not the combustible mixture, but clean air and at the end of the compression inject fuel into the cylinder under strong pressure.
Since the temperature of the compressed air reached 600-650 ° C, the fuel ignited spontaneously, and the gases, expanding, moved the piston. Thus, the Diesel managed to significantly increase the efficiency of the engine, get rid of the ignition system, and instead of the carburetor use fuel pump high pressure
In 1933, Elling prophetically wrote: “When I started working on the gas turbine in 1882, I was firmly convinced that my invention would be in demand in the aircraft industry.”

Unfortunately, Elling died in 1949, never before the era of turbojet aviation.

The only photo that we managed to find.

Perhaps someone will find something about this man in the Norwegian Museum of Technology.

In 1903, Konstantin Eduardovich Tsiolkovsky, in the journal "Scientific Review" published an article "Exploration of world spaces with jet devices", where he first proved that a device capable of making a space flight is a rocket. The article also proposed the first project of a long-range missile. Its body was an elongated metal chamber, equipped with liquid jet engine (which is also an internal combustion engine)... He proposed using liquid hydrogen and oxygen as a fuel and oxidizer, respectively.

Probably on this rocket-space note it is worth finishing the historical part, since the 20th century has come and Internal Combustion Engines have begun to be produced everywhere.

Philosophical afterword ...

K.E. Tsiolkovsky believed that in the foreseeable future people will learn to live, if not forever, then at least for a very long time. In this regard, there will be little space (resources) on Earth and ships will be required to relocate to other planets. Unfortunately, something in this world went wrong, and with the help of the first missiles, people decided to simply destroy their own kind ...

Thanks to everyone who read it.

All rights reserved © 2016
Any use of materials is allowed only with an active link to the source.

Despite its high performance, modern engine internal combustion is starting to become obsolete. His efficiency has reached, perhaps, its limit. Noise, vibration, gases poisoning the air and other inherent disadvantages make scientists look for new solutions, reconsider the possibilities of long-forgotten cycles. Stirling is one of the "revived" engines.

Back in 1816, Scottish priest and scientist Robert Stirling patented an engine in which fuel and air entering the combustion zone never enter the cylinder. When they burn, they only heat up the working gas in it. This gave reason to call Stirling's invention an external combustion engine.

Robert Stirling built several engines; the last of them had a capacity of 45 liters. With. and worked in a mine in England for over three years (until 1847). These engines were very heavy, took up a lot of space and looked like steam engines.

For navigation, external combustion engines were first used in 1851 by the Swede John Erickson. The ship "Erickson" built by him safely crossed the Atlantic Ocean from America to England with a power plant, which consisted of four external combustion engines. In the age of steam engines, this was a sensation. but power point Erickson developed only 300 liters. c., not 1000 as expected. The engines were huge (bore 4.2 m, piston stroke 1.8 m). The coal consumption turned out to be no less than that of steam engines. When the ship arrived in England, it turned out that the engines were not suitable for further operation, as their cylinder bottoms had burned out. To return to America, the engines had to be replaced with a conventional steam engine. On the way back, the ship had an accident and sank with all the crew.

Low-power external combustion engines at the end of the last century were used in houses for pumping water, in printing houses, at industrial enterprises, including the St. Petersburg Nobel plant (now "Russian Diesel"). They were also installed on small ships. Stirlings were produced in many countries, including Russia, where they were called "warmth and strength". They were appreciated for their quietness and safety of work, which made them compare favorably with steam engines.

With the development of internal combustion engines, stirlings were forgotten. In the encyclopedic dictionary of Brockgaue and Efron, the following is written about them: “Explosion safety is the main advantage of caloric machines, thanks to which they can re-enter use if new materials are found for their construction and lubrication that better withstand high fever».

The point, however, was not only the lack of relevant materials. The modern principles of thermodynamics were still unknown, in particular the equivalence of heat and work, without which it was impossible to determine the most advantageous ratios of the main elements of the engine. Heat exchangers were made with a small surface, which caused the engines to operate at unreasonably high temperatures and quickly failed.

Attempts to improve Stirling were made after World War II. The most significant of them consisted in the fact that the working gas was used compressed up to 100 atm and not air, but hydrogen, which has a higher thermal conductivity coefficient, low viscosity and, moreover, does not oxidize lubricants.

The device of an external combustion engine in its modern form shown schematically in Fig. 1. A cylinder closed on one side contains two pistons. The upper one - the piston - in the s press l serves to accelerate the process of periodic heating and cooling of the working gas. It is a hollow, closed stainless steel cylinder that does not conduct heat well, and moves under the action of a rod associated with a crank mechanism.

The lower piston is a working piston (shown in the figure in section). It transfers the force to the crank mechanism through a hollow rod, inside which the displacer rod passes. The working piston is equipped with sealing rings.

There is a buffer tank under the working piston, which forms a cushion that acts as a flywheel - to smooth out the unevenness of the torque due to the selection of part of the energy during the working stroke and its return to the engine shaft during the compression stroke. To isolate the volume of the cylinder from the surrounding space, “wrap-around stocking” seals are used. These are rubber tubes attached at one end to the stem and the other to the body.

The top of the cylinder is in contact with the heater and the bottom is in contact with the cooler. Accordingly, "hot" and "cold" volumes are released in it, freely communicating with each other through a pipeline in which a regenerator (heat exchanger) is located. The regenerator is filled with a wire of small diameter (0.2 mm) and has a high heat capacity (for example, the efficiency of Filipe regenerators exceeds 95%).

The working process of a Stirling engine can be carried out without a displacer, based on the use of a spool valve working charge distributor.

In the lower part of the engine there is a crank mechanism, which serves to convert the reciprocating movement of the piston into rotational movement of the shaft. A feature of this mechanism is the presence of two crankshafts connected by two helical gears rotating towards each other. The displacer stem is connected to crankshafts by means of the lower rocker arm and trailed connecting rods. The working piston rod is connected to the crankshafts through the upper rocker arm and trailed connecting rods. The system of identical connecting rods forms a movable deformable rhombus, hence the name of this transmission - rhombic. The rhombic transmission provides the necessary phase shift during the movement of the pistons. It is completely balanced and does not exert lateral forces on the piston rods.

In the space limited by the working piston, there is a working gas - hydrogen or helium. The total volume of gas in the cylinder is independent of the position of the displacer. The volume changes associated with the compression and expansion of the working gas occur due to the movement of the working piston.

When the engine is running, the top of the cylinder is constantly heated, for example from a combustion chamber into which liquid fuel is injected. The bottom of the cylinder is constantly cooled, for example by cold water pumped through a water jacket surrounding the cylinder. The closed Stirling cycle consists of four measures shown in Fig. 2.

Cycle I - cooling... The working piston is in the lowest position, the displacer moves up. In this case, the working gas flows from the “hot” volume above the displacer to the “cold” volume below it. Passing along the way through the regenerator, the working gas gives off part of its heat to it, and then it cools down in the "cold" volume.

Measure II - Compression... The displacer remains in the upper position, the working piston moves upward, compressing the working gas at a low temperature.

Step III - heating... The working piston is in the upper position, the displacer moves down. In this case, the compressed cold working gas rushes from under the displacer into the vacant space above it. On the way, the working gas passes through the regenerator, where it is preheated, enters the “hot” cavity of the cylinder and heats up even more.

Cycle IV - expansion (working stroke)... As the working gas heats up, it expands, moving the displacer and with it the working piston downward. Is done useful work.

Stirling has a closed cylinder. In fig. 3, a shows a diagram of the theoretical cycle (diagram V - P). The abscissa shows the volumes of the cylinder, and the ordinates show the pressure in the cylinder. The first cycle is isothermal I-II, the second occurs at a constant volume II-III, the third is isothermal III-IV, and the fourth is at a constant volume IV-I. Since the pressure during the expansion of the hot gas (III-IV) is greater than the pressure during the compression of the cold gas (I-II), the work of expansion is greater than the work of compression. The useful work of the cycle can be graphically depicted in the form of a curved quadrangle I-II-III-IV.

In the actual process, the piston and the displacer move continuously, since they are connected with the crank mechanism, therefore the diagram of the actual cycle is rounded (Fig. 3, b).

The theoretical efficiency of the stirling engine is 70%. Studies have shown that in practice, you can get an efficiency equal to 50%. This is significantly more than the very best gas turbines (28%), gasoline engines (30%) and diesels (40%).

Stirling can run on gasoline, kerosene, diesel, gaseous and even solid fuels. Compared to other motors, it has a smoother and quieter ride. This is explained by the low compression ratio (1.3 ÷ 1.5), moreover, the pressure in the cylinder rises smoothly, and not by an explosion. Combustion products are also discharged without Noise, since combustion occurs continuously. There are relatively few toxic components in them, because fuel combustion occurs continuously and with a constant excess of oxygen (α = 1.3).

Stirling with rhombic transmission is completely balanced and does not generate vibrations. This quality, in particular, was taken into account by American engineers who installed a single-cylinder styling on an artificial Earth satellite, where even a slight vibration and imbalance can lead to loss of orientation.

Cooling remains a problematic issue. Stirling with exhaust gases removes only 9% of the heat received from the fuel, so, for example, when installing it on a car, you would have to make a radiator about 2.5 times larger than when using a gasoline engine of the same power. The task is easier to solve in ship installations, where effective cooling is provided by an unlimited amount of seawater.

In fig. 4 shows a cross-section of a 115 hp Philips twin-cylinder boat engine. With. at 3000 rpm with horizontal cylinders. The total working volume of each cylinder is 263 cm 3. The pistons, located oppositely, are connected to two traverses, which made it possible to completely balance the gas forces and do without buffer volumes. The heater is made of tubes surrounding the combustion chamber through which the working gas flows. The cooler is a tubular cooler through which seawater is pumped. The engine has two crankshafts connected to the propeller shaft by means of worm gears. The engine height is only 500 mm, which allows it to be installed under the deck and thus to reduce the size of the engine compartment.

Stirling power is regulated mainly by changing the pressure of the working gas. At the same time, in order to keep the heater temperature constant, the fuel supply is also regulated. Almost any heat source is suitable for an external combustion engine. It is important that it can convert low-temperature energy into useful work, which internal combustion engines are not capable of. From the curve in Fig. 5, it can be seen that at a heater temperature of only 350 ° C, the efficiency of stirling is still ≈ 20%.

Stirling is economical - its specific fuel consumption is only 150 g / l. With. hour. In the power plant "Stirling engine-heat accumulator" used on the American satellites of the Earth, the heat accumulator is lithium hydrite, which absorbs heat during the period of "illumination" and gives it to the stirling when the satellite is on the shadow side of the Earth. On the satellite, the engine is used to drive a 3 kW generator at 2400 rpm.

An experienced motor scooter with a Stirling and a heat accumulator has been created. The use of a heat accumulator and a stirling agent on a submarine allows it to go several times longer in a submerged position.

Literature

• 1. Smirnov GV External combustion engines. "Knowledge", M., 1967.
• 2. Dr. Ir. R. I. Meijer. Der Philips - Stirlingmotor, MTZ, N 7, 1968.
• 3. Curtis Anthony. Hot air and the wind of change. The Stirling engine and its revival. Motor (Engl.) 1969, (135) No. 3488.

Only about a hundred years ago, internal combustion engines had to conquer the place they occupy in the modern automotive industry in a fierce competitive struggle. Then their superiority was by no means as obvious as it is today. Indeed, the steam engine - the main rival of the gasoline engine - had enormous advantages in comparison with it: noiselessness, simplicity of power regulation, excellent traction characteristics and amazing "omnivorousness", allowing it to work on any type of fuel from wood to gasoline. But in the end, the efficiency, lightness and reliability of internal combustion engines prevailed and forced to come to terms with their shortcomings, as inevitable.
In the 1950s, with the advent of gas turbines and rotary engines, an assault on the monopoly position occupied by internal combustion engines in the automotive industry began, an assault that has not yet been crowned with success. At about the same years, attempts were made to bring to the stage new engine, which strikingly combines the efficiency and reliability of a gasoline engine with the quietness and "omnivorous" steam installation. This is the famous external combustion engine, which the Scottish priest Robert Stirling patented on September 27, 1816 (English patent no. 4081).

Process physics

The principle of operation of all heat engines, without exception, is based on the fact that when a heated gas expands, more mechanical work is performed than is required to compress a cold one. A bottle and two pots of hot and cold water are enough to demonstrate this. First, the bottle is immersed in ice water, and when the air in it cools down, the neck is plugged with a cork and quickly transferred to hot water. After a few seconds, cotton is dispensed and the gas heated in the bottle pushes out the cork, making mechanical work... The bottle can be returned to ice water - the cycle will repeat.
this process was almost exactly reproduced in the cylinders, pistons and intricate levers of the first Stirling machine, until the inventor realized that some of the heat taken from the gas during cooling could be used for partial heating. All that is needed is some kind of container in which it would be possible to store the heat taken from the gas during cooling and give it back to it when heated.
But alas, even this very important improvement did not save the Stirling engine. By 1885, the results achieved here were very mediocre: 5-7 percent efficiency, 2 liters. With. power, 4 tons of weight and 21 cubic meters of occupied space.
External combustion engines were not saved even by the success of another design developed by the Swedish engineer Erickson. Unlike Stirling, he proposed to heat and cool the gas not at a constant volume, but at a constant pressure. 8 In 1887, several thousand small Erickson engines worked perfectly in printing houses, in houses, in mines, on ships. They filled water tanks and operated elevators. Erickson even tried to adapt them for driving crews, but they turned out to be too heavy. In Russia, before the revolution, a large number of such engines were produced under the name "Heat and Power".
However, attempts to increase power to 250 hp. With. ended in complete failure. The machine with a cylinder with a diameter of 4.2 meters developed less than 100 liters. That is, the fire chambers burned out, and the vessel on which the engines were installed was lost.
Engineers without regret said goodbye to these weak mastodons as soon as powerful, compact and light gasoline engines and diesel engines appeared. And suddenly, in the 1960s, almost 80 years later, the Stirlings and Ericksons (we will conventionally call them that by analogy with a diesel engine) started talking about as formidable rivals of internal combustion engines. These conversations do not subside to this day. What explains such a sharp turn in views?

Methodical cost

When you learn about an old technical idea that has revived in modern technology, the question immediately arises: what prevented its implementation earlier? What was that problem, that "clue", without the solution of which she could not pave her way into life? And it almost always turns out that the old idea owes its revival either to a new technological method, or to a new design, which the predecessors did not think of, or to a new material. An external combustion engine can be considered the rarest exception.
Theoretical calculations show that the efficiency is Stirlings and Ericksons can reach 70 percent - more than any other engine. This means that the failures of their predecessors were explained by secondary, in principle removable factors. The correct choice of parameters and areas of application, a scrupulous study of the operation of each unit, careful processing and fine-tuning of each detail allowed to realize the advantages of the cycle. Already the first experimental samples gave an efficiency of 39 percent! (The efficiency of gasoline engines and diesels, which have been worked out over the years, is 28-30 and 32-35 percent, respectively.) What opportunities did Stirling and Erickson “overlook” in their time?
the very container in which heat is alternately stored and then given off. The calculation of the regenerator in those days was simply impossible: the science of heat transfer did not exist. Its dimensions were taken by eye, and as calculations show, the efficiency of external combustion engines depends very much on the quality of the regenerator. True, its poor performance can be compensated to a certain extent by an increase in pressure.
The second reason for the failure was that the first installations operated in air at atmospheric pressure: their dimensions were enormous, and their capacities were small.
Bringing efficiency regenerator up to 98 percent and filling the closed loop with hydrogen or helium compressed to 100 atmospheres, the engineers of our day increased the efficiency and power of the "styling", which even in this form showed efficiency. higher than that of internal combustion engines.
This alone would be enough to talk about the installation of external combustion engines on cars. But the advantages of these machines, revived from oblivion, are by no means exhausted only by high efficiency.

How Stirling works

Schematic diagram of an external combustion engine:
1 - fuel injector;
2 - outlet branch pipe;
3 - elements of the air heater;
4 - air heater;
5 - hot gases;
6 - hot space of the cylinder;
7 - regenerator;
8 - cylinder;
9 - cooler ribs;
10 - cold space;
11 - working piston;
12 - rhombic drive;
13 - connecting rod of the working piston;
14 - synchronizing gears;
15 - combustion chamber;
16 - heater tubes;
17 - hot air;
18 - displacement piston;
19 - air inlet;
20 - cooling water supply;
21 - seal;
22 - buffer volume;
23 - seal;
24 - pusher of the displacement piston;
25 - pusher of the working piston;
26 - yoke of the working piston;
27 - finger of the yoke of the working piston;
28 - connecting rod of the displacement piston;
29 - yoke of the displacement piston;
30 - crankshafts.
Red background - heating circuit;
dotted background - cooling circuit

V modern design"Stirling", operating on liquid fuel, - three circuits, having only thermal contact with each other. This is a working fluid circuit (usually hydrogen or helium), a heating circuit and a cooling circuit. The main purpose of the heating circuit is to maintain a high temperature at the top of the working circuit. The cooling circuit maintains a low temperature at the bottom of the working circuit. The contour of the working fluid itself is closed.
Working body contour... Two pistons move in the cylinder 8 - the working piston 11 and the displacing piston 18. The upward movement of the working piston leads to the compression of the working medium, its downward movement is caused by the expansion of the gas and is accompanied by the performance of useful work. The upward movement of the displacement piston squeezes the gas into the lower, cooled cavity of the cylinder. Its downward movement corresponds to the heating of the gas. The rhombic drive 12 imparts a movement to the pistons corresponding to four cycle strokes ((these strokes are shown in the diagram).
Measure I- cooling of the working fluid. The displacement piston 18 moves upward, squeezing the working fluid through the regenerator 7, in which the heat of the heated gas is stored, into the lower, cooled part of the cylinder. The working piston 11 is at BDC.
Measure II- compression of the working fluid. The energy stored in the compressed gas of the buffer volume 22 imparts upward movement to the working piston 11, accompanied by the compression of the cold working fluid.
Bar III- heating of the working fluid. The propellant piston 18, almost adjoining the working piston 11, displaces the gas into the hot space through the regenerator 7, in which the heat accumulated during cooling is returned to the gas.
Bar IV- expansion of the working fluid - working cycle. When heated in a hot space, the gas expands and does useful work. Part of it is stored in the compressed gas of the buffer volume 22 for subsequent compression of the cold working fluid. The rest is removed from the motor shafts.
Heating circuit... The air is blown into the air inlet 19 by the fan, passes through the elements 3 of the heater, heats up and enters the fuel injectors. The resulting hot gases heat the tubes 16 of the working fluid heater, flow around the elements 3 of the heater and, having given up their heat to the air going for fuel combustion, are thrown out through the outlet pipe 2 into the atmosphere.
Cooling circuit... Water through the pipes 20 is supplied to the lower part of the cylinder and, flowing around the cooler fins 9, continuously cools them.

"Stirlings" instead of ICE

The very first tests, carried out half a century ago, showed that the "styling" is almost perfectly silent. It does not have a carburetor, high pressure injectors, ignition system, valves, spark plugs. The pressure in the cylinder, although it rises to almost 200 atm, but not by an explosion, as in an internal combustion engine, but smoothly. The engine does not need mufflers. The diamond-shaped kinematic piston drive is fully balanced. No vibration, no rattling.
They say that even with a hand on the engine, it is not always possible to determine whether it is working or not. These qualities car engine especially important, because in large cities the problem of noise reduction is acute.
But another quality is "omnivorous". As a matter of fact, there is no heat source that is not suitable for a stirling drive. A car with such an engine can run on wood, on straw, on coal, on kerosene, on nuclear fuel, even on sunlight. It can work on the heat stored in the melt of some salt or oxide. For example, a melt of 7 liters of aluminum oxide replaces 1 liter of gasoline. Such versatility will not only be able to always help out a driver in trouble. It will solve the acute problem of smoke pollution in cities. Approaching the city, the driver turns on the burner and melts the salt in the tank. Fuel is not burned within the city limits: the engine runs on melt.
What about regulation? To reduce power, it is enough to release the required amount of gas from the closed loop of the engine into a steel cylinder. The automation immediately reduces the fuel supply so that the temperature remains constant regardless of the amount of gas. To increase the power, gas is pumped from the cylinder back into the circuit.
However, in terms of cost and weight, the Stirlings are still inferior to internal combustion engines. For 1 liter. With. they have 5 kg, which is much more than gasoline and diesel engines... But we should not forget that these are still the first, not brought to the high degree perfection of the model.
Theoretical calculations show that, other things being equal, "stirlings" require lower pressures. This is an important advantage. And if they also have constructive advantages, it is possible that it is they who will turn out to be the most formidable rival of internal combustion engines in the automotive industry. And not turbines at all.

Stirling from GM

Serious work on improving the external combustion engine, which began 150 years after its invention, has already borne fruit. Various design variants of the engine operating according to the Stirling cycle are proposed. There are projects of motors with a swash plate for regulating the stroke of pistons, a patented rotary engine, in one of the rotary sections of which compression occurs, in the other - expansion, and the supply and removal of heat is carried out in the channels connecting the cavities. The maximum pressure in the cylinders of individual samples reaches 220 kg / cm 2, and the average effective pressure- up to 22 and 27 kg / cm 2 and more. The efficiency has been increased to 150 g / hp / hour.
The greatest progress was made by General Motors, which in the 1970s built a V-shaped "styling" with a conventional crank mechanism. One cylinder is working, the other is compression. The working piston contains only the working piston, and the displacement piston is in the compression cylinder. A heater, a regenerator and a cooler are located between the cylinders. The phase shift angle, in other words, the angle of lag of one cylinder from another, for this "stirling" is equal to 90 °. The speed of one piston should be maximum at the moment when the speed of the other is zero (at the top and bottom dead center). The phase displacement in the movement of the pistons is achieved by positioning the cylinders at an angle of 90 °. Structurally, this is the simplest "styling". But it is inferior to the rhombic crank engine in poise. To fully balance the inertial forces in a V-shaped engine, the number of cylinders must be increased from two to eight.

Schematic diagram of a V-shaped "stirling":
1 - working cylinder;
2 - working piston;
3 - heater;
4 - regenerator;
5 - heat insulating sleeve;
6 - cooler;
7 - compression cylinder.

The working cycle in such an engine proceeds as follows.
In the working cylinder 1, the gas (hydrogen or helium) is heated, in the other, in the compression cylinder 7, it is cooled. When the piston moves up in the cylinder 7, the gas is compressed - the compression stroke. At this time, piston 2 in cylinder 1 begins to move downward. Gas from cold cylinder 7 flows into hot 1, passing sequentially through cooler 6, regenerator 4 and heater 3 - heating cycle. Hot gas expands in cylinder 1, doing work - expansion stroke. When piston 2 moves in cylinder 1 upward, gas is pumped through regenerator 4 and cooler 6 into cylinder 7 - cooling cycle.
This “stirling” scheme is most convenient for reversing. In the combined housing of the heater, regenerator and cooler (we will talk about their design later), dampers are made for this. If you move them from one extreme position to another, then the cold cylinder will become hot, and the hot - cold, and the engine will rotate in the opposite direction.
The heater is a set of heat-resistant stainless steel tubes through which the working gas flows. The tubes are heated by the flame of a burner adapted for burning various liquid fuels. Heat from the heated gas is stored in the regenerator. This unit is of great importance for obtaining high efficiency. It will fulfill its purpose if it transfers about three times more heat than in the heater, and the process takes less than 0.001 seconds. In short, it is a fast-acting heat accumulator, and the rate of heat transfer between the regenerator and the gas is 30,000 degrees per second. The regenerator, the efficiency of which is 0.98 units, consists of a cylindrical body, in which several washers are arranged in series, made of wire thread (wire diameter 0.2 mm). To prevent heat from being transferred to the refrigerator, a heat-insulating sleeve is installed between these units. Finally, there is a cooler. It is designed as a water jacket on the pipeline.
Stirling power is regulated by changing the working gas pressure. For this purpose, the engine is equipped with a gas cylinder and a special compressor.

Advantages and disadvantages

To assess the prospects for the application of "stirling" on cars, let's analyze its advantages and disadvantages. Let's start with one of the most important for heat engine parameters, the so-called theoretical efficiency For the "stirling", it is determined by the following formula:

η = 1 - Tx / Tg

Where η is the efficiency, Tx is the temperature of the “cold” volume and Tg is the temperature of the “hot” volume. Quantitatively, this parameter for the “stirling” is 0.50. This is significantly more than the best gas turbines, gasoline and diesel engines, which have a theoretical efficiency of 0.28, respectively; 0.30; 0.40.
As an external combustion engine. stirling "can work on various fuels: gasoline, kerosene, diesel, gaseous and even solid. Fuel characteristics such as cetane and octane number, ash content, boiling point during combustion outside the engine cylinder, do not matter for the “stirling”. To make it work on different fuels, no major alterations are required - you just need to replace the burner.
An external combustion engine in which combustion is stable with a constant excess air ratio of 1.3. emits significantly less than an internal combustion engine, carbon monoxide, hydrocarbons and nitrogen oxides.
The low noise of the “stirling” is explained by the low compression ratio (from 1.3 to 1.5). The pressure in the cylinder rises smoothly, and not by an explosion, as in a gasoline or diesel engine... The absence of fluctuations in the column of gases in the exhaust tract determines the noiselessness of the exhaust, which is confirmed by tests of the engine developed by Phillips in conjunction with Ford for the bus.
"Stirling" is distinguished by low oil consumption and high wear resistance due to the absence of active substances in the cylinder and the relatively low temperature of the working gas, and its reliability is higher than that of the internal combustion engines known to us, since it does not have a complex gas distribution mechanism.
An important advantage of the Stirling as an automobile engine is its increased adaptability to load changes. It is, for example, 50 percent higher than that of a carburetor engine, due to which the number of gears in the gearbox can be reduced. However, it is impossible to completely abandon the clutch and gearbox, as in a steam car.
But why has an engine with such obvious advantages still not found practical application? The reason is simple - it still has many unresolved shortcomings. Chief among them is the great complexity of control and regulation. There are other "reefs" that are not so easy to get around for both designers and production workers. In particular, pistons need very effective seals that must withstand high pressures (up to 200 kg / cm2) and prevent oil from entering the working cavity. In any case, Phillips' 25-year work on fine-tuning its engine has not yet been able to make it suitable for mass use in automobiles. Of no small importance is the characteristic feature of the “stirling” - the need to remove a large amount of heat with the cooling water. In internal combustion engines, a significant portion of the heat is emitted to the atmosphere along with the exhaust gases. In “sterling”, only 9 percent of the heat generated by the combustion of fuel goes into the exhaust. If in gasoline engine internal combustion with cooling water removes from 20 to 25 percent of the heat, then in the "stirling" - up to 50 percent. This means that a car with such an engine must have a radiator about 2-2.5 times larger than that of a similar gasoline engine. The disadvantage of "stirling" is its high specific gravity in comparison with the common internal combustion engine. Another rather significant disadvantage is the difficulty of increasing speed: already at 3600 rpm, hydraulic losses significantly increase and heat transfer deteriorates. And finally. "Styling" is inferior conventional engine internal combustion in throttle response.
Work on the creation and refinement of automobile "styling", including for passenger cars, continue. It can be considered that at present the fundamental issues have been resolved. However, there is still a lot of work to be done. The use of light alloys can reduce the specific gravity of the engine, but it will still be higher. than that of an internal combustion engine, due to the higher pressure of the working gas. Probably, the external combustion engine will find application primarily in trucks, especially the military - due to its low demand for fuel.

The Stirling engine, the principle of operation of which is qualitatively different from the usual for all internal combustion engines, once made up a worthy competition to the latter. However, they forgot about him 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 its use in the future, read below.

Story

In 1816 in Scotland, Robert Stirling patented the name today after its inventor. The first hot air engines were invented before him. But Stirling added a purifier to the device, which in 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 the time, as it never exploded. Before him, on other engines, this problem arose often. Despite its rapid success, at the beginning of the twentieth century, its development was abandoned, as it became less economical than other internal combustion engines and electric motors that appeared then. However, Stirling continued to be used in some industries.

External combustion engine

The principle of operation of all heat motors is that to obtain gas in an expanded state, greater mechanical forces are required than when compressing a cold one. To demonstrate this, an experiment can be carried out with two pots filled with hot and cold water, as well as a bottle. The latter is immersed in cold water, plugged, then transferred to hot water. This will cause the gas in the bottle to do mechanical work and push the cork out. The first external combustion engine relied entirely on this process. True, later the inventor realized that some of the heat could be used for heating. Thus, productivity has increased significantly. But even that did not help the engine become widespread.

Later, Erickson, an engineer from Sweden, improved the design by proposing to cool and heat the gas 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 turned out to be too heavy.

External combustion engines from Philips

Such motors are of the following types:

• steam;
• steam turbine;
• Stirling.

The latter type was not developed because of the low reliability and the rest are not the highest indicators in comparison with the other types of units that have appeared. However, Philips resumed operations in 1938. Engines began to serve to drive generators in non-electrified areas. In 1945, the company's engineers found the opposite application for them: if the shaft is rotated 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 in thermodynamic cycles, in which compression and expansion occur at different temperatures. In this case, the regulation of the flow of the working fluid is realized due to the changing volume (or pressure - depending on the model). This is the principle of operation of most of these machines, which can have different functions and design schemes. Engines can be reciprocating 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 realized by means of valves. They are called Erickson engines, except for the common name of the name Stirling. In an internal combustion engine, useful work is carried out after preliminary air compression, 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. 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 temperature change with a displacement piston. The latter moves gas from one cylinder cavity to another. On the one hand, the temperature is constantly low, and on the other hand, it is high. When the piston moves up, the gas moves from the hot to the cold cavity, and downward returns to the 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. A regenerator is placed between the heater and the refrigerator - a cavity filled with material to which the gas gives off heat. In case of reverse flow, the regenerator returns it.

The displacer system is connected to a working piston that compresses the gas in cold weather and allows expansion in warmth. Useful work is done by compression at a lower temperature. The entire system goes through four cycles with intermittent movements. The crank mechanism thus 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 piston machine with an external heat supply, where the working fluid does not leave the confined space and is not replaced. 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 energy to a Stirling engine. The principle 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 effective regenerator, it will be able to work with more high 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 cylinder pressure is usually 10 to 20 MPa. Therefore, an excellent sealing system and the ability to get oil into the working chambers is required here.

Comparative characteristics

Most engines of this kind in operation today use liquid fuels. The continuous pressure is easy to control, which helps to reduce emissions. The absence of valves ensures quiet operation. Power to weight is comparable to turbocharged engines, and the power-to-weight ratio is 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 indicator is obtained.

Advantages

Any model of Stirling engine has many advantages:

• Efficiency in modern design can reach up to seventy percent.
• There is no system in the engine high voltage ignition, camshaft and valves. It will not need to be adjusted during its entire service life.
• In Stirlings, there is no such explosion as in the 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 motor.

Flaws

Application

Currently, a Stirling engine with a generator is used in many areas. It is a versatile source of electrical energy in refrigerators, pumps, submarines and solar power plants. It is thanks to the application of various kinds fuel there is a possibility of its wide use.

Revival

Thanks to Philips, these motors have been developed again. In the middle of the twentieth century, General Motors entered into an agreement with her. She led the development for the application of Stirlings in space and underwater devices, ships and automobiles. Following them, another company from Sweden, United Stirling, began to deal with their development, including possible use in

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

Future

The clear advantages that piston and Stirling have, which consist 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 throughout the entire time, it cannot be easily displaced. One way or another, it is precisely such an engine that today occupies a leading position, and does not intend to hand it over in the near future.