How the external combustion engine works. Power stations on Stirling Engine - Easy, efficiency and environmental safety. Additional details and options

In just about a hundred years ago, internal combustion engines had to conquer the place they occupy in modern automotive in a cruel competitive struggle. Then their superiority did not seem so obvious as today. Indeed, a steam engine is the main rival of a gasoline motor - possessed compared to it with huge advantages: silent, ease of power regulation, beautiful traction characteristics and striking "oku-binding", allowing to work on any form of fuel from firewood to gasoline. But ultimately, the economy, ease and reliability of internal combustion engines took over and forced to reconcile with their disadvantages, as inevitability.
In the 1950s, with the advent of gas turbines and rotary engines, the assault storming of the monopoly position occupyed by the engines of internal combustion in the automotive industry, the assault, which was still not crowned with success. At about the same years, attempts were made to bring to the scene new enginein which the cost-effectiveness and reliability of the gasoline engine with silent and the "omnivorous" of the steam plant is strikingly combined. This is the famous engine. external combustionThe Scottish Priest Robert Stirling patented on September 27, 1816 (English Patent No. 4081).

Process physics

The principle of action of all the thermal engines without exception is based on the expansion of the heated gas, a large mechanical work is performed than it is required to compress cold. To demonstrate this, enough bottles and two saucepans with hot and cold water. At first, the bottle is lowered into the ice water, and when the air is cooled in it, the neck is plugged with a plug and are rapid in hot water. After a few seconds, cotton is distributed and the gas heated in the bottle pushes the plug by making mechanical work. A bottle can be returned to ice water again - the cycle will repeat.
In the cylinders, pistons and intricate levers of the first stirling machine, this process was almost exactly reproduced, until the inventor realized that part of the heat was taken away from the gas during cooling, it can be used for partial heating. We need only some kind of container in which it would be possible to store heat taken from the gas during cooling, and again give it when heated.
But, alas, even this very important improvement was not saved by the stirling engine. By 1885, the results achieved here were very mediocre: 5-7 percent kp, 2 liters from. Power, 4 tons of weight and 21 cubic meters occupied space.
External combustion engines were not even saved by the success of another design developed by the Swedish Engineer Erickson. Unlike Stirling, he suggested heating and cooling the gas not at a constant volume, but at constant pressure. 8 1887 Several thousand small Ericson engines perfectly worked in printing houses, houses, in mines, on ships. They filled out water tanks, led the effect of elevators. Erickson tried to even adapt them to drive carriages, but they were too heavy. In Russia before the revolution, a large number of such engines were produced under the name "Heat and Strength".
However, attempts to increase power up to 250 liters. from. ended with a complete failure. The machine with a cylinder with a diameter of 4.2 meters developed less than 100 liters. e., Fire cameras burned out, and the ship on which engines were installed, died.
Unfortunately unfortunately spread up with these weak masteodons as soon as powerful, compact and light benzomotors and diesel engines appeared. And suddenly, in the 1960s, after almost 80 years old about "Stirling" and "Erixonakh" (we will conditionally call them so by analogy with Diesel) as the formidable rivals of internal combustion engines. These conversations do not subside and today. What explains such a steep turn in views?

Price of methodicity

When you learn about the old technical idea that has been revived in modern technology, the question immediately arises: what prevented its implementation earlier? What was the problem, that "hook", without a decision of which she could not make a way to life? And it almost always turns out that with his revival, the old idea is obliged to either a new technological method, or a new design, to which the predecessors or a new material did not think. The external combustion engine can be considered the rarest exception.
Theoretical calculations show that kp. "Stirling" and "Ericksons" can reach 70 percent - more than any other engine. And this means that the failures of the predecessors were explained secondary, in principle with eliminated factors. Right choice parameters and applications, a scrupulous study of the operation of each node, careful processing and finishing of each part allowed us to realize the advantages of the cycle. Already the first experimental samples were given by KPD 39 percent! (KPD Petrol engines and diesel engines, which were worked out for years, respectively, 28-30 and 32-35 percent.) What opportunities "viewed" in due time and stirling and ericson?
The very container in which alternately is inhibited, then heat is given. The calculation of the regenerator in those times was simply impossible: the science of heat transfer did not exist. Its sizes were taken on the eye, and how the calculations show, KPD engines External combustion depends very much on the quality of the regenerator. True, its poor work can be used to a certain extent to the increase in pressure.
The second reason for failure was that the first installations operated on air at atmospheric pressure: their dimensions were treated huge, and the power is small.
By bringing kpd. Regenerator up to 98 percent and filling a closed circuit with a compressed to 100 atmospheres with hydrogen or helium, the engineers of our days increased the cost-effectiveness and power of "stirlings", which even in this form showed by KPD. Higher than in internal combustion engines.
Already one would be enough to talk about installing external combustion engines on cars. But only a high economy is not yet exhausted the advantages of these regenerated from the oblivion of machines.

How Stirling works

External combustion engine circuit diagram:
1 - fuel nozzle;
2 - exhaust pipe;
3 - air heater elements;
4 - air heater;
5 - hot gases;
6 - hot cylinder space;
7 - regenerator;
8 - cylinder;
9 - cooler ribs;
10 - cold space;
11 - working piston;
12 - rhombic drive;
13 - the rod of the working piston;
14 - synchronizing gears;
15 - Camera combustion;
16 - heater tubes;
17 - hot air;
18 - piston-displacer;
19 - air actor;
20 - supply of cooling water;
21 - seal;
22 - buffer volume;
23 - seal;
24 - piston piston-displacer;
25 - piston pusher;
26 - yarm of the working piston;
27 - Finger of the Youth of the Work Piston;
28 - piston-oscillator rod;
29 - yarm of the piston-oscillator;
30 - crankshafts.
Red background - heating circuit;
dotted background - Cooling circuit

IN modern design "Stirling" operating on liquid fuel - three contours that have only heat contacts with each other. This is the outline of the working fluid (usually hydrogen or helium), the contour of heating and the cooling circuit. The main purpose of the heating contour is to maintain a high temperature at the top of the working circuit. Cooling circuit supports low temperature at the bottom of the working circuit. The outline of the working fluid itself is closed.
The contour of the working body. In the cylinder 8, two pistons are moving - working 11 and piston-oscillator 18. The movement of the working piston Up leads to the compression of the working fluid, its movement is caused by the expansion of the gas and is accompanied by the performance of useful work. The movement of the piston-displacer is squeezing the gas into the bottom, cooled cylinder cavity. The movement of it down corresponds to the heating of the gas. Rhombic drive 12 informs pistons moving corresponding to four cycle clocks ((these tacts are shown in the diagram).
Takt I. - cooling of the working fluid. The piston-oscillator 18 moves up, squeezing the working fluid through the regenerator 7, in which the heat of the heated gas is intensified, into the lower, cooled part of the cylinder. The working piston 11 is located in NMT.
Takt II. - Compression of the working body. The energy stored in the compressed buffer volume gas 22 reports the working piston 11 movement upwards accompanied by a cold working body compression.
Tact III. - Heating the working fluid. The piston-oscillator 18, almost stuck to the working piston 11, displaces the gas in the hot space through the regenerator 7, in which heat is returned to the gas, stored during cooling.
Tact IV. - Expansion of the working body - a worker. Heating in hot space, gas expands and makes a useful work. Some of it is inhibited in the compressed buffer volume gas for the subsequent compression of the cold working fluid. The rest is removed from the motor shafts.
Contour heating. Air fan is injected into the air 19, passes through the elements of the 3 heater, heats up and enters fuel injectors. The resulting hot gases heat the tube 16 of the heater of the working fluid, the elements 3 of the heater are streamlined and, by giving its heat to air to burn fuel, are thrown out through the outlet 2 into the atmosphere.
Cooling outline. Water through the nozzles 20 is fed to the lower part of the cylinder and, the flowing edges of the 9th cooler, continuously cools them.

"Stirling" instead of DVS

The first tests carried out by half a century ago showed that Stirling is almost perfectly infused. He has no carburetor, high pressure nozzles, ignition systems, valves, candles. The pressure in the cylinder, although it rises almost up to 200 atm, but not an explosion, as in an internal combustion engine, and smoothly. The engine does not need silencers. Rhomboid kinematic drive piston is completely balanced. No vibrations, no rattling.
It is said that, even by attaching a hand to the engine, it is not always possible to determine whether it works or not. These qualities car Engine Especially important, for in large cities, the problem of reducing noise is sharp.
But another quality is "omnory." In fact, there is no such source of heat that would not be suitable for the "Stirling" drive. The car with such an engine can work on firewood, on straw, on the corner, on kerosene, on the nuclear stuel, even on the sun's rays. It can work on the warmth, stored in the melt of some salt or oxide. For example, the melt of 7 liters of aluminum oxide replaces 1 liter of gasoline. Such universality will not only be able to always rescue the driver who fell into trouble. She will solve the sharply problem of the smoke of cities. Driving to the city, the driver turns on the burner and melts salt in the tank. In the city, the fuel does not burn: the engine runs on the melt.
And regulation? To slow down power, it is enough to release from a closed engine circuit into a steel cylinder the desired amount of gas. The automation immediately reduces the fuel supply so that the temperature remains constant regardless of the amount of gas. To increase power, the gas is injected from the balloon again into the contour.
But in terms of cost and by weight, "stirling" is still inferior to internal combustion engines. Per 1 liter from. they have 5 kg, which is much more than that of gasoline and diesel engines. But we should not forget that these are also the first not communicated to high degree Perfections of the model.
Theoretical calculations show that, with other things being equal, "Stirling" requires smaller pressures. This is an important dignity. And if they also have more constructive advantagesIt is possible that it is they who will be the most terrible rival of internal combustion engines in the automotive industry. And not a turbine at all.

"Stirling" from GM

Serious work on improving the external combustion engine, which began 150 years after its invention, has already brought its fruits. A variety of design options for the styling cycle are proposed. There are motor projects with an inclined washer to regulate the stroke of the pistons, a rotary engine is patented, in one of the rotary sections of which compression occurs, in the other - the expansion, and the supply and heat dissipation is carried out in the connecting 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 or more. Economitivity is brought to 150 g / hp / hour.
General Motors has reached the greatest progress, which in the 1970s built a V-shaped "stirling" with a conventional crank-connecting mechanism. One cylinder is working, the other is a compression. The worker is only a working piston, and the piston-displacer is in a compression cylinder. Between the cylinders there are heater, regenerator and cooler. The phase shift angle, in other words, the angle of the lag of one cylinder from the other, this "Stirling" is 90 °. The speed of one piston should be the maximum at the moment when the speed of another is zero (in the upper and lower dead points). The shift of the phases in the movement of the pistons is achieved by the location of the cylinders at an angle of 90 °. Constructively, this is the easiest "stirling". But it is inferior to the engine with a rhombic crank mechanism in equilibrium. For a complete balancing of inertia forces in the V-shaped engine, the number of its cylinders should be increased from two to eight.

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

The operating cycle in such an engine proceeds as follows.
In the working cylinder 1 gas (hydrogen or helium) heated, in another, compression 7 - cooled. When the piston moves in the cylinder 7, the gas is compressed - compression tact. At this time, it starts to move down the piston 2 in the cylinder 1. The gas from the cold cylinder 7 flows into hot 1, passing sequentially through the cooler 6, the regenerator 4 and the heater 3 - heating tact. Hot gas expands in cylinder 1, making work, - expansion tact. When the piston 2 moves in the cylinder 1, the gas is pumped through the regenerator 4 and the cooler 6 to the cylinder 7 - cooling tact.
Such a scheme "Stirling" is most convenient for reversing. In the combined housing of the heater, the regenerator and the cooler (they will be discussed later) dampers are made for this). If you translate them from one extreme position to another, then the cold cylinder will become hot, and hot - cold, and the engine will rotate in the opposite direction.
The heater is a set of tubes from heat-resistant stainless steel, for which the working gas passes. The tubes are heated by the flame of the burner adapted for burning various liquid fuels. The heat from the heated gas is reserves in the regenerator. This node is of great importance for high efficiency. It will fulfill its purpose if it will be transmitted about three times more heat than in a heater, and the process will take less than 0.001 seconds. In a word, this is a high-speed heat battery, and the heat transfer speed between the regenerator and the gas is 30,000 degrees per second. The regenerator whose efficiency is 0.98 units, consists of a cylindrical housing, in which several washers made from a wire roller (wire diameter 0.2 mm) are sequentially located. To heat from it, the refrigerator is not transmitted, the thermal insulating coupling is installed between these units. Finally, the cooler. It is made in the form of a water shirt on the pipeline.
The power of "Stirling" is regulated by changing the pressure of the working gas. For this purpose, the engine is equipped with a gas cylinder and a special compressor.

Advantages and disadvantages

To evaluate the prospects for the use of "Stirling" on cars, analyze its advantages and disadvantages. Let's start with one of the most important for thermal Engine The parameters of the so-called theoretical efficiency for "Stirling" is determined by the following formula:

η \u003d 1 - TX / TG

Where η - efficiency, TX - the temperature of the cold volume and TG is the temperature of the "hot" volume. Quantify this parameter at "Stirling" - 0.50. This is much more than the best gas turbines, gasoline and diesel engines, in which theoretical efficiency is equal to 0.28; 0.30; 0.40.
As an external combustion engine. Stirling "can work on various fuels: gasoline, kerosene, diesel, gaseous, and even on solid. Such characteristics of fuel as cetane and octane number, ash, the dumping temperature when burning outside the engine cylinder, does not matter for stirling. So that he worked on different fuels, it is not necessary for large alterations - just replace the burner.
The external combustion engine in which the burning flows stably with a constant coefficient of excess air equal to 1.3. It highlights significantly less than the internal combustion engine, carbon monoxide, hydrocarbons and nitrogen oxides.
Small noise of "Stirling" is explained by a low degree of compression (from 1.3 to 1.5). The pressure in the cylinder rises smoothly, and not an explosion, as in a gasoline or diesel engine. The absence of fluctuations in the gases column in the graduation path determines the feasibility of the exhaust, which is confirmed by the tests of the engine developed by the company "Phillips" together with Ford for the bus.
Stirling is characterized by low oil consumption and high wear resistance due to the absence of active substances in the cylinder and relatively low working gas temperature, and its reliability is higher than that of internal combustion engines known to us, since it does not have a complex gas distribution mechanism.
The important advantage of "stirling" as a car engine is increased adaptability to load changes. It, for example, is 50 percent higher than that of a carburetor motor, due to which it is possible to reduce the number of steps in the gearbox. However, it is impossible to completely abandon the clutch and gearbox, as in a vapor car.
But why does the engine with such obvious advantages still have not found practical application? The reason is simple - he has a lot of confused flaws. The main among them is a great difficulty in management and regulation. There are also other "reefs", which are not so easy to get around and designers and production workers. - In particular, the pistons need very effective seals that must withstand high pressure (up to 200 kg / cm2) and prevent oil entering the working cavity. In any case, the 25-year work of the company "Phillips" on the finishing of its engine has not yet been able to make it suitable for mass applications on cars. Equally important is it characteristic feature "Stirling" is the need to divert a large amount of heat with cooling water. In internal combustion engines, a significant part of the heat is thrown into the atmosphere along with the spent gases. In Sterling, only 9 percent of the heat obtained during the combustion of fuel takes place in the exhaust. If in gasoline engine Cooling water internal combustion is given from 20 to 25 percent of heat, then in "Stirling" - up to 50 percent. This means that the car with such an engine must have a radiator about 2-2.5 times more than that of a similar gasoline motor. The lack of "Stirling" is its high proportion compared to the common internal combustion system. A rather significant minus is the difficulty of increasing the speed: already at 3600 rpm significantly increase the hydraulic losses and the heat exchange is worse. Finally. "Stirling" is inferior by the usual engine Internal combustion in the pickup.
Work on the creation and finishing of automotive "Stirling", including for passenger cars, continue. We can assume that currently fundamental issues have been solved. However, a lot of things on the finish. The use of light alloys can be reduced by the proportion of the engine, but it will still be higher. than at the motor internal combustion, because of more high pressure working gas. Probably the external combustion engine will be used primarily on trucks, especially military - thanks to their undepair to fuel.

This article is devoted to one invention, patented in the nineteenth century by the Scottish one priest stirling. Like all predecessors, it was an external combustion engine. Only the difference between him from the rest is that it can work and gasoline, and on fuel oil, and even on corner and firewood.

In the XIX century, there was a need to replace steam engines to something more secure, since the boilers were often exploded due to the high pressure of steam and some serious constructive flaws.

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

True, "hot air engines" did before, even in the XVII century. But Stirling added a cleaner into the installation. In a modern understanding - regenerator.

It raised the installation performance, while maintaining heat in the warm zone of the car, at the moment when the working body was cooled. This significantly increased the efficiency of the system.

The invention has found wide practical application, there was a stage of lifting and development, but then stirlings were undeservedly forgotten.

They gave way to place steam machines and internal combustion engines, and in the twentieth century were reborn again.

Due to the fact that this principle of external combustion is very interesting in itself, today the best engineers and lovers in the USA, Japan, Sweden, are working to create new models.

External combustion engine. Principle of operation

"Stirling" - as we have already mentioned, the variety of external combustion engine. The basic principle of its work lies in the constant alternation of heating and cooling the working fluid in a closed space and energy obtaining, due to the change of the volume of the working flu.

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

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

Types of Stirling

There are three classic types of stirling engine:

Application

Stirling engine can be applied in cases if a simple, compact thermal energy converter is required or when the efficiency of other types of thermal vehicles is below: For example, if the temperature difference is insufficient for the use of gas or.

Here are specific examples of use:

• Already today there are autonomous generators for tourists. There are models that work from gas burner;

NASA ordered a variant of the "Stirling" generator, which works from nuclear and radioisotope heat sources. It will be used in space expeditions.

• "Stirling" to pump fluid is much easier to install the "engine-pump". As a working piston, it can use the pumped liquid, which will at the same time cooling the working fluid. The pump can be punished with water in irrigation channels using solar heat, feed hot water from the solar collector to the house, pump chemical reagents, since the system is completely sealed;
• Manufacturers of household refrigerators introduce models on "Stirling". They will be economted, and ordinary air is expected as refrigerant;
• Combined stirling with a thermal pump optimizes the heating system in the house. It will give a charm of the "cold" cylinder, and the resulting mechanical energy can be used to swap heat, which comes from the environment;
• Today, stirling engines are installed on all submarines of the Navy Sweden. They operate on liquid oxygen, which is further used for breathing. A very important factor for a boat, a low noise level, and the disadvantages of the type: "large size", "the need for cooling" - in submarine conditions are not significant. Similar installations are equipped with the latest Japanese submarines of the "Sori" type;
• Stirling engine is used to convert solar energy into electrical. For this, it is mounted in the focus of the parabolic mirror. Stirling Solar Energy builds solar collectors with a capacity of up to 150 kW per mirror. They are used on the world's largest solar power plant in southern California.

Advantages and disadvantages

The modern level of design and manufacturing technology allows you to increase the efficiency of "Stirling" up to 70 percent.

• What is surprising, the engine torque is practically independent of the rotation speed of the crankshaft;
• Power installation does not contain ignition systems, valve system and camshaft.
• Throughout the service life, you do not need adjustments and settings.
• The engine does not "stall", and the simplicity of the design allows it to operate it offline 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 hurrying and minimizing emissions of toxic substances.

• Since the fuel burns outside the engine, the heat removal goes through the radiator walls, and these are additional dimensions;
• Material consumption. To make a stirring machine compact and powerful, expensive heat-resistant steel are required, capable of withstanding high working pressure and having a low thermal conductivity;
• Need a special lubricant, the usual for "stirling" does not fit, as cocks when high temperatures;
• To obtain high specific power, the working fluid in the "stirlings" is used hydrogen and helium.

Hydrogen is distinguished by explosion hazard, and at high temperatures can be dissolved in metals, forming metalhydrites. In other words, the engine cylinders are destroyed.

And even hydrogen and helium have a high penetrating ability and easily seep through the seals, lowering the working pressure.

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

You understand themselves, those who are engaged in the improvement and implementation of this car hold their development secret and sell them only to solid buyers.

Watch this video and make it yourself.

Stirling engine, the principle of operation of which is qualitatively different from the usual for all of the Russian Federation, once amounted to the last worthy competition. However, for some time they forgot about him. As this motor is used today, what is the principle of its action (in the article you can also find the drawings of the Stirling engine, clearly demonstrating its work), and what are the prospects for use in the future, read below.

History

In 1816, in Scotland, Robert Stirling was patented today in honor of his inventor. The first hot air engines were invented before him. But Stirling added a cleaner into the device, which in the technical literature is called a regenerator, or a heat exchanger. Due to it, the engine performance increased when holding the unit in warmth.

The engine recognized the most sturdy steam machine from the at that time, since he never exploded. Before him, on other engines, such a problem occurred often. Despite the rapid success, at the beginning of the twentieth century, it was abandoned from its development, as it became less economical, compared with the other internal combustion engines that appeared then by other engines. However, stirling continued to be used in some industries.

Engine external combustion

The principle of operation of all thermal engines is that large mechanical efforts are needed to obtain gas in an extended state than when compressed cold. For a visual demonstration of this, you can spend experience with two saucepans filled with cold and hot water, as well as a bottle. The latter is lowered into cold water, plug through the plug, then transferred to hot. At the same time, the gas in the bottle will begin to perform mechanical work and pouches the plug. The first external combustion engine was based on this process completely. True, later the inventor understood that part of the heat can be used for heating. Thus, performance has increased significantly. But even this did not help the engine to become common.

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

PHILIPS external combustion engines

Such motors are the following types:

• steam;
• parroid turbine;
• Stirling.

The latter view did not develop because of the slight reliability and other not the highest rates compared to the other types of aggregates appeared. However, in 1938, Philips resumed work. Engines began to serve for drives of generators in inelectricated areas. In 1945, the company's engineers found them inverse use: if the shaft is uninstalled by an electric motor, then the cooling of the cylinder head comes to minus one hundred ninety degrees Celsius. Then it was decided to apply an improved stirling engine in refrigeration plants.

Principle of operation

The motor action lies in the thermodynamic cycles, in which compression and expansion occurs at different temperatures. At the same time, the regulation of the working fluid stream is implemented due to the varying volume (or pressure - depending on the model). This is the principle of operation of most such machines that can have different functions and constructive schemes. Engines can be piston or rotary. Machines with their installations work as heat pumps, refrigerators, pressure generators and so on.

In addition, there are motors with an open cycle, where the flow control is implemented by valve. It is them called Erikson engines, except for the overall name of the Schirling name. In DVS useful work It is carried out after prior compression of air, fuel injection, heating the mixture of the mixture with combustion and expansion.

Stirling engine The principle of operation is the same: at low temperatures, compression occurs, and with high expansion. But in different ways heating is carried out: heat is supplied through the cylinder wall from the outside. Therefore, he received the name of the engine of external combustion. Stirling used periodic change in temperature 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 - high. When the piston moves up, the gas moves from hot to the cold cavity, and down - returns to hot. First, the gas gives a lot of heat to the refrigerator, and then from the heater gets as much as I gave. A regenerator is placed between the heater and the refrigerator - the cavity filled with the material that gas gives heat. With reverse course, the regenerator returns it.

The displacement system is connected to a working piston compressing gas in the cold and allowing to expand warm. Due to the compression at a lower temperature, useful work occurs. The whole system passes four cycles during intermittent movements. The crank-connecting mechanism in this case provides continuity. Therefore, sharp boundaries between the stages of the cycle are not observed, and the stirling does not decrease.

Considering all of the above, it suggests that this engine is a piston machine with an external heat supply, where the working fluid does not leave the closed space and is not replaced. Stirling engine drawings well illustrate the device and the principle of its action.

Details of work

The sun, electricity, nuclear energy or any other heat source can supply energy into the stirling engine. The principle of its body is to use helium, hydrogen or air. The ideal cycle has the thermal maximum possible efficiency equal to thirty to forty percent. But with an effective regenerator, he will be able to work with more high efficiency. Regeneration, heating and cooling provide built-in heat exchangers working without oils. It should be noted that the engine lubricants need very little. The average pressure in the cylinder is usually from 10 to 20 MPa. Therefore, there is an excellent sealing system and the possibility of oil entering workers.

Comparative characteristics

Most of the engines of this kind are used today, liquid fuel is used. At the same time, continuous pressure is easy to control, which helps to reduce emissions. The absence of valves provides silent operation. Power with mass is comparable to turbocharged motors, and the specific power obtained at the output is equal to the indicator diesel aggregate. Speed \u200b\u200band torque do not depend on each other.

The cost of the engine production is much higher than on the engine. But when operating it turns out the reverse figure.

Benefits

Any model of stirling engine has many advantages:

• The efficiency in modern design can reach up to seventy interest.
• There is no system in the engine high voltage ignition, distribution Vala. and valves. It will not need to be adjusted throughout the service life.
• There is no explosion in stirlings, as in the internal combustion engine, which greatly loads the crankshaft, bearings and connecting rods.
• They do not have the effect when they say that the "engine stall".
• Due to the simplicity of the device, it can be operated for a long time.
• It can work both on firewood and with nuclear and any other fuel type.
• Combustion occurs outside the motor.

disadvantages

Application

Currently, the stirling engine with the generator is used in many areas. This is a universal source of electrical energy in refrigerators, pumps, submarines and solar electric stations. Thanks to the application of various types Fuel is available to its wide use.

Revival

These engines began to develop again thanks to Philips. In the middle of the twentieth century, General Motors concluded with her. She led the development for the use of stirlings in space and underwater devices, on ships and cars. Following them, another company from Sweden, United Stirling, began to engage in their development, including possible use on

Today linear engine Stirling is applied on installations of underwater, cosmic and solar apparatuses. A great interest in it is caused by the relevance of the worsening environmental situation, as well as the fight against noise. In Canada and the USA, Germany and France, and Japan are active search for the development and improvement of its use.

Future

Explicit advantages that have piston and stirling, consisting in a large resource of work, the use of different fuel, silentness and low toxicity, make it very promising against the background of the internal combustion motor. However, taking into account the fact that ICE has been improved throughout the time, it cannot be easily displaced. One way or another, it is such an engine today occupies a leading position, and they do not intend to take them in the near future.

Engines of external combustion

An important element of the implementation of the energy saving program is to provide autonomous sources of electricity and heat of small residential entities and remote from centralized networks of consumers. To solve these tasks, innovative installations for generating electricity and heat based on external combustion engines are best suited. As a fuel, both traditional fuels can be used and associated petroleum gas, biogas obtained from wood chips, etc.

Over the past 10 years, increased prices for fossil fuels, increased attention to CO 2 emissions, as well as a growing desire to stop depending on fossil fuels and fully ensure itself with energy. This was the consequence of the development of a huge technology market capable of producing biomass energy.

External combustion engines were invented almost 200 years ago, in 1816. Together with the steam engine, a two-and four-stroke engine of internal combustion, external combustion engines are considered one of the main types of engines. They were designed to create engines that would be safer and more productive than the steam engine. At the very beginning of the 18th century, the lack of suitable materials led to numerous deaths due to the explosions of steam engines under pressure.

The significant market for external combustion engines was formed in the second half of the 18th century, in particular, due to smaller applications, where they could be safely operated without the need for skilled operators.

After the invention of the internal combustion engine at the end of the 18th century, the market for external combustion engines disappeared. The cost of producing an internal combustion engine in comparison with the cost of production of external combustion is lower. The main disadvantage of internal combustion engines is that for their work it is necessary to clean, fossil fuel, increasing CO2 emissions, fuel. However, until recently, the cost of fossil fuels was low, and CO2 emissions did not pay due attention.

Principle of External Combustion Engine

In contrast to the widely known process of internal combustion, in which the fuel is burned inside the engine, the external combustion engine is driven by an external heat source. Or, more precisely, it is powered by temperature differences created by external heating and cooling sources.

These external sources of heating and cooling can serve the exhaust gases of biomass and cooling water, respectively. The process leads to a rotation of the generator mounted on the engine, whereby energy is produced.

All internal combustion engines are powered by temperature differences. Gasoline, diesel engines and external combustion engines are based on the features that it is less effort to compress cold air than to compress hot air.

Gasoline and diesel engines suck the cold air and compress this air before it is heated in the process of internal combustion, which occurs inside the cylinder. After heating the air above the piston, the piston moves down, whereby the air expands. Since the air is hot, the force acting on the rod of the piston is great. When the piston comes to bottom, the valves open and hot exhausts are replaced with new, fresh, cold air. When the piston moves up the cold air is compressed, and the force acting on the piston rod is less than when it moves down.

External combustion engine works in accordance with a little different principle. It has no valves, it is hermetically sealed, and the air is heated and cooled with the help of heat exchangers of a hot and cold circuit. The built-in pump driven by the movement of the piston provides air movement there and back between these two heat exchangers. During the cooling of the air in the heat exchange apparatus of the cold circuit, the piston compresses the air.

After compression, the air is then heated in the heat exchange apparatus of the hot contour, before the piston begins to move in the opposite direction and use the extension of hot air to actuate the engine.

Pushed out the remaining types of power plants, however, work aimed at refusing to use these aggregates suggest the imminent change of leading positions.

Since the beginning of technical progress, when using motors burning fuel inside, it was not only obvious to their superiority. A steam engine, as a competitor, contains a lot of advantages: along with traction parameters, silent, omnivorous, easily controlled and configured. But lightness, reliability and efficiency allowed the internal combustion engine to take up the ferry.

Today, the head of the corner is issues of ecology, efficiency and security. It forces engineers to throw forces on serial units operating at the expense of renewable fuel sources. In the 16th year of the nineteenth century, Robert Stirling registered the engine operating from external sources Heat. Engineers believe that this unit is able to change the modern leader. Stirling engine combines economy, reliability, works quietly, on any fuel, it makes the product by a player in the automotive market.

Robert Stirling (1790-1878 years):

Stirling engine history

Initially, the installation was developed in order to replace the car operating at the expense of steam. The boilers of steam mechanisms exploded, with exceeding the permissible pressure standards. From this point of view, stirling is much safer, functions using the temperature difference.

The principle of operation of the stirling engine in alternate supply or selection of heat in a substance that work is performed. The substance itself is concluded in the volume of closed type. The role of the working substance is performed by gases or liquids. There are substances that perform the role of two components, the gas is transformed into a liquid and vice versa. Liquid stirling motor has: small dimensions, powerful, produces great pressure.

Reducing and increasing the volume of gas during cooling or heated, respectively, is confirmed by the law of thermodynamics, according to which all components: the degree of heating, the value of the space occupied by the substance, the force acting per unit area is associated and described by the formula:

P * V \u003d N * R * T

• P is the power of gas in the engine per unit area;
• V is a quantitative value occupied by gas in the engine space;
• n - molar amount of gas in the engine;
• R - permanent gas;
• T - the heating degree of gas in the engine to,

Stirling Engine Model:

Due to the unpretentiousness of the installations, the engines are divided: solid fuel, liquid fuel, solar energy, chemical reaction and other types of heating.

Cycle

The external combustion engine of stirling uses the same set of phenomena. The effect of the occurrence in the mechanism is high. Due to this, it is possible to construct an engine with good characteristics within normal dimensions.

It is necessary to take into account that in the design of the mechanism, the heater, refrigerator and regenerator, device, heat removal from the substance and heat return, at the right moment are provided.

The ideal cycle of Stirling, ("Temperature-volume" diagram):

Ideal circular phenomena:

• 1-2 change of linear dimensions of a substance with a constant temperature;
• 2-3 heat removal from the substance to the heat exchanger, the space occupied by the substance constantly;
• 3-4 Forced cutting of the space occupied by the substance, the temperature is constant, the heat is given to the cooler;
• 4-1 Forced increase in the temperature of the substance occupied by the space constantly, heat is summed from the heat exchanger.

The ideal cycle of Stirling, ("Pressure-volume" diagram):

From the calculation (mol) of the substance:

Favorite heat:

The cooling cooler is warm:

The heat exchanger gets heat (process 2-3), the heat exchanger gives the heat (process 4-1):

R is a universal permanent gas;

CV - the ability of the perfect gas to hold heat with the unchanic size of the occupied space.

Due to the use of the regenerator, part of the heat remains, as the energy of the mechanism that does not vary for passing circular phenomena. The refrigerator gets less heat, therefore, the heat exchanger saves heat heater. This increases the installation efficiency.

KPD circular phenomena:

ɳ =

It is noteworthy that without heat exchanger, the set of stirling processes is feasible, but its effectiveness will be significantly lower. The passage of the totality of the processes is backwards leads to the description of the cooling mechanism. In this case, the presence of a regenerator, a prerequisite, since when passing (3-2-2), it is impossible to heat the substance from the cooler, the temperature of which is significantly lower. It is also impossible to give heat to the heater (1-4), the temperature of which is higher.

Principle of engine operation

To understand how the stirling engine works, let's understand in the device and the frequency of the aggregate phenomena. The mechanism converts heat obtained from the heater, which is outside the product into force of force on the body. The whole process occurs due to the temperature difference, in the working substance located in the closed circuit.

The principle of operation of the mechanism is based on expansion by heat. Improved directly, the substance in the closed circuit heats up. Accordingly, before cooled, the substance is cooled. The cylinder (1) is enveloped by a water jacket (3), heat is served for the bottom. The piston, making a job (4) placed in the sleeve and is sealed with rings. Between the piston and the bottom there is a displacement mechanism (2), having significant gaps and fluently moving. The substance in the closed loop moves through the volume of the camera due to the displacer. Movement of the substance is limited to two directions: bottom of the piston, bottom of the cylinder. The movement of the displacer provides a rod (5), which passes through the piston and functions due to the eccentric with a 90 ° delay in comparison with the piston drive.

• Position "A":

The piston is located in the extreme lower position, the substance is cooled due to the walls.

• Position "B":

The displacer occupies the upper position, moving, passes the substance through the end slots to the bottom, is cooled itself. Piston stands motionless.

• Position "C":

The substance gets heat, under the action of heat increases in the volume and raises the extender with the piston up. Work is performed, after which the displacer falls on the bottom, pushing the substance and cooling.

• Position "D":

The piston lowers down, compresses the cooled substance, useful work. The flywheel serves in the design of the energy battery.

The model considered without a regenerator, so the efficiency of the mechanism is not large. The heat of substances after the operation is discharged into the coolant, using the walls. The temperature does not have time to decline on the desired value, so cooling time is extended, the speed of the motor is small.

Types of engines

Constructively, there are several options using the principle of stirling, the main types are considered:

The design applies two different pistons placed in various contours. The first circuit is used for heating, the second circuit is used for cooling. Accordingly, each piston owns its regenerator (hot and cold). The device has a good power ratio to volume. The disadvantage is that the temperature of the hot regenerator creates structural difficulties.

• Engine "β - Stirling":

The design uses one closed circuit, with different temperatures at the ends (cold, hot). The cavity is the piston with the displacer. The displacer divides the space on the cold and hot zone. The exchange of cold and warmth occurs by pumping the substance through the heat exchanger. Structurally, the heat exchanger is performed in two versions: external, combined with the displacer.

• Engine "Γ - Stirling":

The piston mechanism provides for the use of two closed circuits: cold and with the displacer. Power is removed from a cold piston. The piston with the displacer on one side is hot, on the other side is cold. The heat exchanger is located both inside and outside the design.

Some power plants Do not look like the main types of engines:

• Rotary stirling engine.

Constructively invention with two rotors on the shaft. The part performs rotational movements in the closed space of the cylindrical shape. The synergistic approach to the implementation of the cycle is laid. The housing contains radial slots. In the recess inserted blades with a certain profile. Plates are on the rotor and can move along the axis when the mechanism is rotated. All items create changing volumes with phenomena performed in them. Volumes of various rotors are associated with channels. The location of the channels have a shift of 90 ° to each other. Rotor shift relative to each other is 180 °.

• Thermoacoustic stirling engine.

The engine uses acoustic resonance for processes. The principle is based on moving a substance between hot and cold cavity. The scheme reduces the number of moving parts, the complexity in removing the resulting power and maintain resonance. The design refers to free motor.

Stirling engine with his own hands

Today, quite often in the online store you can meet souvenir productsmade in the form of the engine under consideration. Constructively and technologically, the mechanisms are quite simple, if desired, the stirling engine is easy to construct with their own hands from the remedies. On the Internet you can find a large amount of materials: video, drawings, calculations and other information on this topic.

Low-tempered stirling engine:

• Consider the easiest option of the wave engine, to execute the canning bank, soft polyurethane foam, disc, bolts and stationery clips. All these materials are easy to find at home, the following actions remain:
• Take a soft polyurethane foam, cut two millimeters with a smaller diameter from the inner diameter of the conservation circle. The height of foam is two millimeters more than half the height of the jar. Foolon plays the role of the seizer in the engine;
• Take the lid of the bank, in the middle do the hole, the diameter is two millimeters. Squash to the hole hollow rod, which will perform the role of the engine rod guide;
• Take the circle cut out of the foam, insert into the middle of the circle of the screw and stroke on both sides. To the washer, solder the pre-straightened clip;
• In two centimeters from the center, drill holes, a diameter of three millimeters, the threads of the outstruder through the central hole of the cover, solder the lid to the bank;
• Make a small cylinder from a tin, a diameter of a centimeter one and a half, solder it to the lid of the cans in such a way that the side opening of the cover turned out to be clearly in the center inside the engine cylinder;
• Make crankshaft Engine from paper clips. The calculation is performed in such a way that the knee variation was 90 °;
• Make the stack under the engine crankshaft. From the polyethylene film, make an elastic membrane, put on the film on the cylinder, sell it, lock;

• Independently make the engine connecting rod, one end of the straightened product will be in the form of a mug, insert the second end into the slice of the eraser. Length is adjusted in such a way that in the extreme lower point The mucker shaft was drawn, at the extreme top point, the membrane is pulled as much as possible. Set the other connecting rod for the same principle;
• Rubber tip rolling rod ride. Shutun without a rubber tip fasten on the displacer;
• Put on the crank mechanism of the engine flywheel from the disk. At the bank, make legs to keep the product in your hands. The height of the legs allows you to place a candle under the can.

After you managed to make the stirling engine at home, the motor is started. To do this, a lit candle is placed under the jar, and after the bank warmed up, give a push to the flywheel.

The considered installation option can be quickly collected at home as a visual allowance. If the goal and desire to make the stirling engine as close as possible to the factory analogues, there are drawings of all parts in free access. Step-by-step execution of each node will create a working layout of anything no worse than commercial versions.

Benefits

For the stirling engine, such advantages are characteristic:

• To work the engine, a temperature difference is needed, which fuel causes the heating is not important;
• No need to use attachments and accessories, the engine design is simple and reliable;
• The engine resource, due to the design features, is 100,000 hours of operation;
• The operation of the engine does not create extraneous noise, because there is no detonation;
• The process of operation of the engine is not accompanied by emissions of spent substances;
• Engine operation is accompanied by minimal vibration;
• The processes in the installation cylinders are environmentally friendly. The use of the correct heat source allows you to make the engine "clean".

disadvantages

The disadvantages of the stirling engine belong:

• It is difficult to establish mass production, since a structurally engine requires the use of a large number of materials;
• High weight and large engine dimensions, because for efficient cooling it is necessary to use a large radiator;
• To increase efficiency, the engine is forced, applying complex substances (hydrogen, helium) as a working fluid, which makes the operation of the unit dangerous;
• The high-temperature resistance of steel alloys and their thermal conductivity complicates the engine manufacturing process. Significant heat losses in the heat exchanger reduce the efficiency of the unit, and the use of specific materials make the manufacture of the engine expensive;
• To adjust and transition of the engine from the mode to mode, you need to apply special control devices.

Using

Stirling engine found his niche and actively applied where dimensions and omnivores are important criterion:

• Engine stirling electric generator.

The heat transformation mechanism into electrical energy. It is often found products used as portable tourist generators, installations for the use of solar energy.

• Engine, like a pump (electrician).

The engine is used for installation in the contour of heating systems, saving on electrical energy.

• Engine as a pump (heater).

In countries with a warm climate, the engine is used as a premises heater.

Stirling engine on a submarine:

• Engine as a pump (cooler).

Almost all refrigerators in their design use heat pumps, installing the stirling engine, save resources.

• Engine, as a pump that creates ultra-low degrees of heating.

The device is used as a refrigerator. For this, the process is launched in the opposite direction. The aggregates liquefit gas, cooled measuring elements in accurate mechanisms.

• Engine for underwater technology.

Summer ships of Sweden and Japan work through the engine.

Stirling engine as solar installation:

• Engine as energy battery.

Fuel in such aggregates, salt melts, the engine is used as a source of energy. Motor in power reserves is ahead of chemical elements.

• Solar engine.

Transform the energy of the sun into electricity. Substance in this case, hydrogen or helium. The engine is placed in the focus of the maximum concentration of the energy of the Sun, created using a parabolic antenna.