How to make a powerful stirling engine. Stirling engine made from tin cans. Stirling modification "Gamma"

The Stirling engine, once famous, was forgotten for a long time due to the widespread use of another engine ( internal combustion). But today we hear more and more about him. Maybe he has a chance to become more popular and find his place in the new modification in the modern world?

Story

The Stirling engine is a heat engine that was invented in the early nineteenth century. The author, as you know, was a certain Stirling named Robert, a priest from Scotland. The device is an external combustion engine, where the body moves in a closed container, constantly changing its temperature.

Due to the spread of another type of motor, it was almost forgotten. Nevertheless, thanks to its advantages, today the Stirling engine (many amateurs build it at home with their own hands) is back again.

The main difference from an internal combustion engine is that the heat energy comes from outside, and is not generated in the engine itself, as in an internal combustion engine.

Principle of operation

You can imagine a closed air volume enclosed in a housing having a membrane, that is, a piston. When the body is heated, the air expands and does work, thus arching the piston. Then cooling occurs, and it bends again. This is the cycle of the mechanism.

It is no wonder that many do-it-yourself thermoacoustic Stirling engines are made at home. The tools and materials for this require the very minimum that everyone has in their home. Consider two different ways how easy it is to create.

Work materials

To make a Stirling engine with your own hands, you will need the following materials:

tin;
steel spoke;
brass tube;
hacksaw;
file;
wooden stand;
metal scissors;
fastener details;
soldering iron;
soldering;
solder;
machine.

This is all. The rest is a matter of simple technique.

How to do

A firebox and two cylinders for the base are prepared from tin, of which the Stirling engine, made by hand, will consist. Dimensions are selected independently, taking into account the purposes for which this device is intended. Suppose the motor is being made for demonstration purposes. Then the sweep of the main cylinder will be from twenty to twenty-five centimeters, no more. The rest of the parts should fit in with it.

At the top of the cylinder for moving the piston, two protrusions and holes with a diameter of four to five millimeters are made. The elements will act as bearings for the location of the crank device.

Next, the working body of the motor is made (it will become ordinary water). Tin circles are soldered to the cylinder, which is rolled up into a pipe. Holes are made in them and brass tubes are inserted from twenty-five to thirty-five centimeters in length and with a diameter of four to five millimeters. At the end, they check how tight the chamber has become by filling it with water.

Next comes the turn of the displacer. For manufacturing, a blank is taken from wood. On the machine, they achieve that it takes the form of a regular cylinder. The displacer should be slightly smaller than the cylinder diameter. The optimal height is selected after the Stirling engine is made by hand. Therefore, at this stage, the length should assume some margin.

The spoke is turned into a cylinder rod. In the center of the wooden container, make a hole suitable for the stem, insert it. In the upper part of the rod, it is necessary to provide a place for the connecting rod device.

Then they take copper tubes four and a half centimeters long and two and a half centimeters in diameter. A circle of tin is soldered to the cylinder. On the sides on the walls, a hole is made to communicate the container with the cylinder.

The piston is also adjusted to lathe under the diameter of the large cylinder from the inside. At the top, the rod is connected in a hinged way.

The assembly is completed and the mechanism is adjusted. To do this, the piston is inserted into a larger cylinder and the latter is connected to another smaller cylinder.

A crank mechanism is built on a large cylinder. Fix part of the engine with a soldering iron. The main parts are fixed on a wooden base.

The cylinder is filled with water and a candle is placed under the bottom. The Stirling engine, made by hand from start to finish, is checked for performance.

Second way: materials

The engine can be made in another way. For this you will need the following materials:

tin;
foam rubber;
paperclips;
disks;
two bolts.

How to do

Foam rubber is very often used to make a simple, not powerful Stirling engine at home with your own hands. A displacer for the motor is prepared from it. Cut out the foam circle. The diameter should be slightly smaller than that of the tin can, and the height should be slightly more than half.

A hole is made in the center of the cover for the future connecting rod. To make it go smoothly, the paper clip is rolled into a spiral and soldered to the lid.

The foam circle in the middle is pierced with a thin wire with a screw and fixed on top with a washer. Then connect a piece of paper clip by soldering.

The displacer is pushed into the hole on the lid and the jar is connected to the lid by soldering to seal. A small loop is made on the paper clip, and another, larger hole is made in the lid.

The tin sheet is rolled into a cylinder and soldered, and then attached to the can so that there are no gaps at all.

The paper clip is turned into a crankshaft. The spacing should be exactly ninety degrees. The knee above the cylinder is made slightly larger than the other.

The remaining paper clips turn into racks for the shaft. The membrane is made as follows: the cylinder is wrapped in a polyethylene film, pressed through and fastened with a thread.

The connecting rod is made from a paper clip, which is inserted into a piece of rubber, and the finished part is attached to the membrane. The length of the connecting rod is made such that at the lower shaft point the membrane is drawn into the cylinder, and at the highest point it is extended. The second part of the connecting rod is made in the same way.

Then one is glued to the membrane, and the other to the displacer.

Can legs can also be made from paper clips and soldered. For the crank, a CD is used.

Here is the whole mechanism. It remains only to substitute and light a candle under it, and then give a push through the flywheel.

Conclusion

Such is the low-temperature Stirling engine (built with your own hands). Of course, on an industrial scale, such devices are manufactured in a completely different way. However, the principle remains the same: the air volume is heated and then cooled. And this is constantly repeated.

Finally, look at these drawings of the Stirling engine (you can do it yourself without any special skills). Maybe you are already on fire with the idea, and you want to do something similar?

Modern automotive industry has reached a level of development in which, without fundamental scientific research it is almost impossible to achieve dramatic improvements in the design of traditional internal combustion engines. This situation forces designers to pay attention to alternative power plant designs. Some engineering centers have focused their efforts on the creation and adaptation to serial production of hybrid and electrical models, other automakers are investing in the development of engines powered by renewable sources (for example, biodiesel with rapeseed oil). There are other projects of power units, which in the future may become the new standard propulsion for Vehicle.

Among the possible sources of mechanical energy for cars of the future is the external combustion engine, which was invented in the middle of the 19th century by the Scot Robert Stirling as a thermal expansion machine.

Scheme of work

The Stirling engine converts thermal energy supplied from the outside into useful mechanical work due to changes in the temperature of the working fluid(gas or liquid) circulating in a closed volume.

In general, the scheme of operation of the device is as follows: in the lower part of the engine, the working substance (for example, air) heats up and, increasing in volume, pushes the piston up. Hot air enters the top of the motor, where it is cooled by a radiator. The pressure of the working fluid is reduced, the piston is lowered for the next cycle. In this case, the system is sealed and the working substance is not consumed, but only moves inside the cylinder.

There are several design options for power units using the Stirling principle.

Stirling modification "Alpha"

The engine consists of two separate power pistons (hot and cold), each of which is located in its own cylinder. Heat is supplied to the cylinder with the hot piston, and the cold cylinder is located in the cooling heat exchanger.

Stirling modification "Beta"

The cylinder containing the piston is heated on one side and cooled on the opposite side. A power piston and a displacer move in the cylinder, designed to change the volume of the working gas. The return movement of the cooled working substance into the hot cavity of the engine is performed by the regenerator.

Stirling modification "Gamma"

The design consists of two cylinders. The first is completely cold, in which the power piston moves, and the second, hot on one side and cold on the other, serves to move the displacer. The regenerator for circulating cold gas can be common to both cylinders or be included in the design of the displacer.

Advantages of the Stirling engine

Like most external combustion engines, Stirling is inherent multi-fuel: the engine runs on a temperature difference, regardless of the reasons that caused it.

Interesting fact! Once, an installation was demonstrated that operated on twenty fuel options. Without stopping the engine, gasoline, diesel fuel, methane, crude oil and vegetable oil- the power unit continued to work steadily.

The engine has simplicity of design and does not require additional systems and attachments(timing, starter, gearbox).

Features of the device guarantee a long service life: more than one hundred thousand hours of continuous operation.

The Stirling engine is silent, since detonation does not occur in the cylinders and there is no need to remove exhaust gases. Modification "Beta", equipped with a rhombic crank mechanism, is a perfectly balanced system that does not have vibrations during operation.

There are no processes in the engine cylinders that can have a negative impact on the environment. By choosing a suitable heat source (e.g. solar power), Stirling can be absolutely environmentally friendly power unit.

Disadvantages of the Stirling design

With all set positive properties immediate mass use of Stirling engines is impossible for the following reasons:

The main problem lies in the material consumption of the structure. Cooling of the working fluid requires the presence of large volume radiators, which significantly increases the size and metal consumption of the installation.

The current technological level will allow the Stirling engine to compare in performance with modern gasoline engines only through the use of complex types working fluid (helium or hydrogen) under pressure of more than one hundred atmospheres. This fact raises serious questions both in the field of materials science and user safety.

An important operational problem is related to the issues of thermal conductivity and temperature resistance of metals. Heat is supplied to the working volume through heat exchangers, which leads to inevitable losses. In addition, the heat exchanger must be made of heat-resistant metals that are resistant to high pressure. Suitable materials are very expensive and difficult to process.

The principles of changing the modes of the Stirling engine are also fundamentally different from the traditional ones, which requires the development of special control devices. So, to change the power, it is necessary to change the pressure in the cylinders, the phase angle between the displacer and the power piston, or to affect the capacity of the cavity with the working fluid.

One way to control the shaft speed on a Stirling engine model can be seen in the following video:

Efficiency

In theoretical calculations, the efficiency of the Stirling engine depends on the temperature difference of the working fluid and can reach 70% or more in accordance with the Carnot cycle.

However, the first samples realized in metal had an extremely low efficiency for the following reasons:

inefficient variants of the coolant (working fluid), limiting the maximum heating temperature;
energy losses due to friction of parts and thermal conductivity of the engine housing;
lack of structural materials resistant to high pressure.

Engineering solutions have constantly improved the design of the power unit. So, in the second half of the 20th century, a four-cylinder automobile Stirling engine with a rhombic drive showed an efficiency equal to 35% in tests on a water coolant with a temperature of 55 ° C. Careful study of the design, the use of new materials and fine-tuning of the working units ensured the efficiency of the experimental samples at 39%.

Note! Modern gasoline engines of similar power have a coefficient useful action at the level of 28-30%, and turbocharged diesel engines within 32-35%.

Modern examples of the Stirling engine, such as the one built by the American company Mechanical Technology Inc, show efficiency up to 43.5%. And with the development of the production of heat-resistant ceramics and similar innovative materials, it will be possible to significantly increase the temperature of the working environment and achieve an efficiency of 60%.

Examples of successful implementation of automotive Stirlings

Despite all the difficulties, there are many workable models of the Stirling engine applicable to the automotive industry.

Interest in Stirling, suitable for installation in a car, appeared in the 50s of the XX century. Work in this direction was carried out by such concerns as Ford Motor Company, Volkswagen Group and others.

UNITED STIRLING (Sweden) developed Stirling, which made maximum use of serial components and assemblies produced by automakers (crankshaft, connecting rods). The resulting four-cylinder V-shaped engine had a specific gravity of 2.4 kg / kW, which is comparable to the characteristics of a compact diesel engine. This unit was successfully tested as a power plant for a seven-ton cargo van.

One of the successful examples is the four-cylinder Stirling engine of the Dutch production model "Philips 4-125DA", intended for installation on a car. The motor had a working power of 173 liters. With. in dimensions similar to the classic gasoline unit.

General Motors engineers achieved significant results by building an eight-cylinder (4 working and 4 compression cylinders) V-shaped Stirling engine with a standard crank mechanism in the 70s.

Similar power plant in 1972 equipped with a limited series of Ford Torino cars, whose fuel consumption has decreased by 25% compared to the classic gasoline V-shaped eight.

Currently, more than fifty foreign companies are working to improve the design of the Stirling engine in order to adapt it to mass production for the needs of the automotive industry. And if it is possible to eliminate the shortcomings of this type of engine, while at the same time retaining its advantages, then it is Stirling, and not turbines and electric motors, that will replace gasoline internal combustion engines.

Stirling engine - a heat engine in which the working fluid, in the form of a gas or liquid, moves in a closed volume, a kind of external combustion engine. It is based on periodic heating and cooling of the working fluid with the extraction of energy from the resulting change in the volume of the working fluid. It can work not only from fuel combustion, but also from any heat source.

A heat engine in which the working fluid, in the form gas or liquid, moves in a closed volume, a kind of external combustion engine.

is based on periodic heating and cooling of the working fluid with the extraction of energy from the resulting change in the volume of the working fluid. It can work not only from fuel combustion, but also from any heat source.

Rice. 1. Stirling engine

@ https://dvigyn.com/?p=1032

In the 19th century, engineers wanted to create a safe replacement for the steam engines of the time, whose boilers often exploded due to high steam pressures and unsuitable materials for their construction. A good option appeared with the creation Stirling engine, which could convert any temperature difference into work.

It was first patented by the Scottish priest Robert Stirling on September 27, 1816 (English Patent No. 4081). However, the first elementary engines hot air" were known back in late XVII century, long before Stirling. Stirling's achievement is the addition of a node, which he called "economy". In modern scientific literature, this node is called the "regenerator". It increases engine performance by keeping heat in the warm part of the engine while the working fluid is cooled. This process greatly improves the efficiency of the system. Most often, the regenerator is a chamber filled with wire, granules, corrugated foil (the corrugations go along the direction of the gas flow).

The principle of operation of the Stirling engine:

Basic working principle Stirling engine consists in constantly alternating heating and cooling of the working fluid, for example, gas, in a closed cylinder.

It is known that when a gas is heated, its volume increases, and when it is cooled, it decreases. This property of gases underlies the work Stirling engine.

It uses the Stirling cycle, which is not inferior to the Carnot cycle in terms of thermodynamic efficiency, and even has an advantage. The fact is that the Carnot cycle consists of isotherms and adiabats that differ little from each other. The practical implementation of this cycle is unpromising. The Stirling cycle made it possible to obtain an engine that works in practice in an acceptable size.

Rice. 2. Diagram "pressure-volume" of the idealized Stirling cycle

The Stirling cycle consists of four phases and is separated by two transitional phases:

– heat,

– extension,

– transition to source of cold,

– cooling,

– compression

– and transition to a heat source.

Thus, when moving from a warm source to a cold source, the gas in the cylinder expands and contracts. In this case, the pressure changes, due to which useful work can be obtained.

Heating and cooling of the working fluid (sections 4 and 2) is performed by the displacer. Ideally, the amount of heat given off and taken away by the displacer is the same. useful work is produced only due to isotherms, that is, it depends on the temperature difference between the heater and cooler, as in the Carnot cycle.

Working cycle Stirling engine beta type (the most common) looks like this:

Rice. 2. Stirling engine duty cycle

@ https://ru.wikipedia.org/wiki/Stirling_Engine

where: a - displacement piston; b - working piston; c - flywheel; d - fire (heating area); e - cooling fins (cooling area).

1. An external heat source heats the gas at the bottom of the heat exchange cylinder. The pressure generated pushes the working piston up (note that the expelling piston does not fit snugly against the walls).

2. The flywheel pushes the displacement piston down, thereby moving the heated air from the bottom to the cooling chamber.

3. The air cools and contracts, the working piston goes down.

4. The displacement piston rises, thereby moving the cooled air to the bottom. And the cycle repeats.

IN Stirling machine the movement of the working piston is shifted by 90° relative to the movement of the displacing piston. Depending on the sign of this shift, the machine can be an engine or a heat pump. With a shift of 0°, the machine does not produce any work (except for friction losses) and does not produce it.

Advantages of the Stirling engine:

- "omnivorous" engine. The Stirling engine can run on almost any temperature difference: for example, between different layers of water in the ocean, from the sun, from a nuclear or isotope heater, coal or wood stove etc.,

– simplicity of design - design engine very simple, it does not require additional systems such as a gas distribution mechanism. It starts on its own and does not need a starter,

- increased resource - simplicity of design, the absence of many "delicate" nodes allows the Stirling engine to provide an unprecedented performance margin for other engines of tens and hundreds of thousands of hours of continuous operation,

– profitability - for the utilization of certain types of thermal energy, especially at a small temperature difference, engines Stirling are often the most effective types engines. For example, in the case of converting solar energy into electricity, "stirlings" sometimes give greater efficiency (up to 31.25%) than steam engines,

- environmental friendliness - "stirling" has no exhaust, which means that its noise level is much less than that of piston engines internal combustion. Beta stirling with rhombic mechanism is a perfectly balanced device and, with enough high quality manufacturing, has limit low level vibrations (vibration amplitude less than 0.0038 mm). Stirling itself does not have any parts or processes that can contribute to pollution. environment. It does not consume the working fluid. The environmental friendliness of the engine is primarily due to the environmental friendliness of the heat source,

– efficiency engine Stirling is up to 45%.

Stirling engine configuration and design:

There are several configurations engine Stirling:

– alpha Stirling- contains two separate power pistons in separate cylinders, one is hot, the other is cold. A cylinder with a hot piston is in a heat exchanger with a higher temperature, with a cold piston - in a colder one.

Rice. 3. α-Stirling

@ https://ru.wikipedia.org/wiki/Stirling_Engine

In this species engine the ratio of power to volume is quite large, but, unfortunately, heat"hot" piston creates certain technical difficulties. The regenerator is located between the hot part of the connecting tube and cold

– beta-stirling- there is only one cylinder, hot at one end and cold at the other. A piston (from which power is removed) and a displacer move inside the cylinder, separating the hot and cold cavities.

Rice. 4. β-Stirling

@ https://ru.wikipedia.org/wiki/Stirling_Engine

The gas is pumped from the cold part of the cylinder to the hot part through the regenerator. The regenerator can be external, as part of a heat exchanger, or can be combined with a displacing piston,

– Gamma Stirling- there is also a piston and a displacer, but at the same time there are two cylinders - one cold (the piston moves there, from which power is removed), and the second is hot from one end and cold from the other (the displacer moves there).

Rice. 5. γ-Stirling

@ https://ru.wikipedia.org/wiki/Stirling_Engine

The regenerator can be external, in which case it connects the hot part of the second cylinder with the cold one and simultaneously with the first (cold) cylinder. The internal regenerator is part of the displacer.

Stirling engine application:

Applicable in cases where a small converter is needed thermal energy, simple in design, or when the effectiveness of other thermal engines turns out to be lower, for example, if the temperature difference is not enough to operate a steam or gas turbine:

– universal sources of electricity,

– pumps,

– heat pumps,

– refrigeration technology.

The well-known Stirling engine can be created independently from improvised materials. Any heat source in this design is able to give you energy at the exit of the device.

materials

To make a Stirling engine with your own hands you will need:

CD - disk;
plastic holder from under CDs;
aluminum sheet measuring 25 x 13 cm;
epoxy resin;
wire;
7" PVC pipe;
Styrofoam;
copper pipe ¾ inch;
adhesive tape;
thermal gun and hot glue;
hacksaw for metal;
drill;
wire cutters;
jigsaw;
compass.

Step 1. It is necessary to cut off part of the structure from the CD holder. The result should be a circle without a bottom and top with smooth edges. Height - about 4 cm.

Step 2. Use a compass to measure the diameter of the resulting circle. Transfer it to the foam. Make two circles. Be sure to mark the center. Sand the circles with a jigsaw. Glue them. For a clear fit in the circle, glue the outer edge with duct tape.

Step 3. Cut out circles with a diameter of the circumference of a CD holder from aluminum sheets. There should be two.

Step 4. Exactly in the middle of the top aluminum sheet, drill a hole into which the wire will enter. To make the wire move straight, as we need it, weld a piece of an angled pipe, as shown in the photo. In his top hat, make another hole for the wire. Take the wire itself that will hold the piston, check that it can move through these holes, but at the same time there is also a tightness.

Closer to the edge of the top cover, drill another hole with a diameter equal to a piece of the existing metal pipe.

Step 5. Now you need to make a piston. To do this, take a piece of metal pipe, which will then go into this design. Rinse it and place it on a lid lined with a piece of plastic bag. Lubricate the inside of the tube and the bag itself with oil. After that, pour into the resulting mold, heated epoxy. It should be warm, not hot. As it solidifies with force, you will have to push out the learned piston. Form a hook from the wire. Drill in a piece epoxy resin hole and insert this wire into it. The piston is ready.

Step 6. Part of the structure needs to be assembled. Glue the bottom of the structure with hot glue. Also make a few more wire hooks. Cut the hook, which will be located in the middle of the whole structure. Seal the ends of the hooks with epoxy.

Step 7. Fasten the pipe to the aluminum top sheet. Lubricate it, insert the piston. Make a layout of the moving part of the structure. To do this, simply attach paper and make basic markings. Bend the wire according to the drawn layout.

Step 8. Drill a hole in the hooks, slightly larger than the main wire.

Step 9. pvc pipe cut in half attach to the aluminum base with hot glue. Make holes in the pipe into which you put the wire crankshaft. Attach the cap to the other end of the shaft. plastic jar or CD. They must rotate.

The Stirling engine, once famous, was forgotten for a long time due to the widespread use of another engine (internal combustion). But today we hear more and more about him. Maybe he has a chance to become more popular and find his place in the new modification in the modern world?

Story

The main difference from an internal combustion engine is that the heat energy comes from outside, and is not generated in the engine itself, as in an internal combustion engine.

Principle of operation

It is no wonder that many do-it-yourself thermoacoustic Stirling engines are made at home. The tools and materials for this require the very minimum that everyone has in their home. Let's look at two different ways how easy it is to create.

Work materials

To make a Stirling engine with your own hands, you will need the following materials:

tin;
steel spoke;
brass tube;
hacksaw;
file;
wooden stand;
metal scissors;
fastener details;
soldering iron;
soldering;
solder;
machine.

This is all. The rest is a matter of simple technique.

How to do

The piston is also adjusted on a lathe to the diameter of the large cylinder from the inside. At the top, the rod is connected in a hinged way.

The assembly is completed and the mechanism is adjusted. To do this, the piston is inserted into a larger cylinder and the latter is connected to another smaller cylinder.

A crank mechanism is built on a large cylinder. Fix part of the engine with a soldering iron. The main parts are fixed on a wooden base.

The cylinder is filled with water and a candle is placed under the bottom. The Stirling engine, made by hand from start to finish, is checked for performance.

Second way: materials

The engine can be made in another way. For this you will need the following materials:

tin;
foam rubber;
paperclips;
disks;
two bolts.