Stirling engine power plants - simplicity, efficiency and environmental safety. DIY Stirling engine DIY Stirling engine with magnets

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. Optimal Height they pick it up after the Stirling engine is made with their own hands. Because on this stage length should allow for 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 the cylinder bigger size and connect the latter 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 home simple not powerful engine Stirling by hand. 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?

A Stirling engine is a kind of engine that starts to run on thermal energy. In this case, the source of energy is completely unimportant. The main thing is to make a difference temperature regime, in this case, such an engine will work. Now we will analyze how you can create a model of such a low-temperature engine from a can of Coca-Cola.

Materials and fixtures

Now we will analyze what we need to take to create an engine at home. What we need to take for stirling:

• Balloon.
• Three cans of cola.
• Special terminals, five pieces (for 5A).
• Nipples for fixing bicycle spokes (two things).
• Cotton wool.
• A piece of steel wire thirty cm long and 1 mm in cross section.
• A piece of large steel or copper wire with a diameter of 1.6 to 2 mm.
• Wooden pin with a diameter of twenty mm (length one cm).
• Bottle cap (plastic).
• Wiring (thirty cm).
• Special glue.
• Vulcanized rubber (about 2 centimeters).
• Fishing line (length thirty cm).
• Several weights for balancing (for example, nickel).
• CDs (three pieces).
• Special buttons.
• A tin can for creating a firebox.
• Heat resistant silicone and tin can for making water cooling.

Description of the creation process

Stage 1. Jars preparation.

First, you should take 2 cans and cut off the top of them. If the tops are cut off with scissors, the resulting notches will have to be ground off with a file.

Stage 2. Making the diaphragm.

As a diaphragm, you can take a balloon, which should be reinforced with vulcanized rubber. The ball must be cut and pulled onto a jar. Then glue a piece of special rubber on the central part of the diaphragm. After the glue has hardened, in the center of the diaphragm we will punch a hole for installing the wire. The easiest way to do this is with a special button that can be left in the hole until assembly.

Stage 3. Cutting and creating holes in the lid.

Two holes of two mm must be made in the walls of the cover, they are necessary to install the pivot axis of the levers. Another hole must be made in the bottom of the lid, a wire will go through it, which will be connected to the displacer.

On last step cover must be cut off. This is done so that the displacer wire does not catch on the edges of the cover. For such work, you can take household scissors.

Stage 4. Drilling.

In the jar, you need to drill two holes for the bearings. In our case, this was done with a 3.5 mm drill.

Stage 5. Making a viewing window.

cut into the engine housing special window. Now it will be possible to observe how all the nodes of the device work.

Stage 6. Terminal modification.

It is necessary to take the terminals and remove the plastic insulation from them. Then take a drill and do through holes at the ends of the terminals. In total, three terminals need to be drilled. Leave two terminals undrilled.

Stage 7. Creating leverage.

As a material for the manufacture of levers, copper wire is taken, the diameter of which is only 1.88 mm. How exactly to bend the knitting needles, it is worth looking on the Internet. You can take steel wire, just with copper wire, it is more convenient to work.

Stage 8. Manufacturing of bearings.

To make the bearings, you will need two bicycle nipples. The hole diameter needs to be checked. The author drilled them through with a 2 mm drill.

Stage 9. Installation of levers and bearings.

Levers can be placed directly through the viewing window. One end of the wire should be long, the flywheel will lie on it. Bearings should sit firmly in the right places. If there is a backlash, they can be glued.

Stage 10. Making the displacer.

The displacer is made of steel wool for polishing. For the manufacture of the displacer, a steel wire is taken, a hook is created on it, and then a certain amount of cotton wool is wound around the wire. The displacer must be the same size so that it moves smoothly in the bank. The entire height of the displacer should not exceed five centimeters.

At the end on one side of the cotton it is necessary to make a spiral of wire so that it does not come out of the wool, and on the second side we make a loop from the wire. Then we will tie a fishing line to this loop, which will subsequently be attracted through the central part of the diaphragm. Vulcanized rubber should be in the middle of the container.

Step 11. Making the pressure tank

It is necessary to cut the bottom of the jar in a certain way so that about 2.5 cm remains from its base. The displacer together with the diaphragm must be moved to the tank. After that, this whole mechanism is transferred to the end of the can. The diaphragm needs to be tightened a little. so that it does not sag.

Then you need to take the terminal that was not drilled, and pass the fishing line through it. The knot must be glued so that it does not move. The wire must be lubricated with high quality oil and at the same time make sure that the displacer can easily stretch the line behind it.

Stage 12. Making push rods.

These special links connect the diaphragm and levers. This is made from a piece of copper wire fifteen cm long.

Stage 13. Creating and installing a flywheel

For the manufacture of the flywheel, we take three old CDs. Take a wooden rod as the center. After installing the flywheel, bend the crankshaft rod, so the flywheel will no longer subside.

At the last stage, the entire mechanism is assembled completely.

The last step, creating a firebox

So we have reached the last step in the creation of the engine.

I have been looking for a working circuit for a long time. I found it, but it was always connected with the fact that there were problems either with equipment or with materials. I decided to make it like a crossbow. After looking at many options and wondering what I have available and what I can do on my own equipment. Those dimensions that I figured out right away, with assembled apparatus I didn't like it. It turned out too wide. I had to shorten the cylinder bed. And put the flywheel on one bearing (on one pylon). The materials flywheel, connecting rods, counterweight, sealing washer, lamp and working cylinder are bronze. Pylons, working piston, cylinder bed, cooler and washer with a thread from the flame chamber aluminum. steel. Stainless steel flame chamber. Graphite displacer. And what happened I put on display, you be the judge.

You can, of course, buy beautiful factory models of Stirling engines, such as in this Chinese online store. However, sometimes you want to create yourself and make a thing, even from improvised means. Our website already has several options for manufacturing these motors, and in this publication, read completely simple option manufacturing at home.

To make it, you will need improvised materials: a can of canned food, a small piece of foam rubber, a CD, two bolts and paper clips.

Foam rubber is one of the most common materials used in the manufacture of Stirling motors. An engine displacer is made from it. From a piece of our foam rubber we cut out a circle, we make its diameter two millimeters less than the inner diameter of the can, and the height is slightly more than half of it.

We drill a hole in the center of the cover, into which we then insert the connecting rod. For a smooth running of the connecting rod, we make a spiral from a paper clip and solder it to the cover.

We pierce the foam rubber circle from foam rubber in the middle with a screw and lock it with a washer from above and below with a washer and a nut. After that, we attach a piece of paper clip by soldering, having previously straightened it.

Now we stick the displacer into the hole made in advance in the lid and hermetically solder the lid and the jar together. We make a small loop at the end of the paper clip, and drill another hole in the lid, but a little more than the first one.

We make a cylinder from tin using soldering.

We attach the finished cylinder to the jar with a soldering iron, so that there are no gaps left at the place of soldering.

We make a crankshaft from a paper clip. Knee spacing should be done at 90 degrees. The knee, which will be above the cylinder in height, is 1-2 mm larger than the other.

We make racks for the shaft from paper clips. Making a membrane To do this, we put on the cylinder polyethylene film, push it inward a little and fix it on the cylinder with a thread.

The connecting rod that will need to be attached to the membrane is made from a paper clip and inserted into a piece of rubber. The length of the connecting rod must be made in such a way that at the bottom dead center of the shaft the membrane is drawn into the cylinder, and at the highest, on the contrary, it is extended. The second connecting rod is configured in the same way.

We glue the connecting rod with rubber to the membrane, and attach the other to the displacer.

We attach the legs from the paper clips to the jar with a soldering iron and attach the flywheel to the crank. For example, you can use a CD.

Stirling engine made at home. Now it remains to bring heat under the jar - light a candle. And after a few seconds, give a push to the flywheel.

How to Make a Simple Stirling Engine (with Photos and Video)

www.newphysicist.com

Let's make a Stirling engine.

A Stirling engine is a heat engine that works by cyclic compression and expansion of air or other gas (working fluid) at various temperatures, so that there is a net conversion of thermal energy into mechanical work. More specifically, the Stirling engine is a closed cycle regenerative heat engine with a constantly gaseous working fluid.

Stirling engines are more efficient than steam engines and can reach 50% efficiency. They are also able to operate silently and can use almost any heat source. The thermal energy source is generated outside the Stirling engine, and not by internal combustion, as is the case for Otto or diesel cycle engines.

Stirling engines are compatible with alternative and renewable energy sources, because they can become more significant as the price of traditional views fuel, as well as in light of such problems as the depletion of oil reserves and changing of the climate.

In this project we will give you simple instructions to create a very simple engine DIY Stirling using test tube and syringe .

How to Make a Simple Stirling Engine - Video

Components and steps to make a Stirling motor

1. Piece hardwood or plywood

This is the basis for your engine. Thus, it must be rigid enough to handle the movements of the engine. Then make three small holes as shown in the picture. You can also use plywood, wood, etc.

2. Marble or glass beads

In a Stirling engine, these balls perform an important function. In this project, the marble acts as a hot air displacer from the warm side of the test tube to the cold side. When marble displaces hot air, it cools down.

3. Sticks and screws

Studs and screws are used to hold the tube in a comfortable position for free movement in any direction without any interruption.

4. Rubber pieces

Buy an eraser and cut it into the following shapes. It is used to securely hold the tube and maintain its tightness. There should be no leakage at the mouth of the tube. If so, the project will not be successful.

5. Syringe

The syringe is one of the most important and moving parts in a simple Stirling engine. Add some lubricant to the inside of the syringe so that the plunger can move freely inside the barrel. As the air expands inside the test tube, it pushes the piston down. As a result, the syringe barrel moves up. At the same time, the marble rolls towards the hot side of the tube and pushes the hot air out and causes it to cool (reduce volume).

6. Test tube The test tube is the most important and working component of a simple Stirling engine. The test tube is made of a certain type of glass (such as borosilicate glass) that is highly heat resistant. So it can be heated to high temperatures.

How does a Stirling engine work?

Some people say Stirling engines are simple. If this is true, then just like the great equations of physics (e.g. E = mc2), they are simple: they are simple on the surface, but richer, more complex, and potentially very confusing until you realize them. I think it's safer to think of Stirling engines as complex: many very bad YouTube videos show how easy it is to "explain" them in a very incomplete and unsatisfactory way.

In my opinion, you can't understand a Stirling engine just by building it or watching it work from the outside: you need to seriously think about the cycle of steps it goes through, what happens to the gas inside, and how it differs from what happens in a conventional steam engine.

All that is required for the operation of the engine is the presence of a temperature difference between the hot and cold parts. gas chamber. Models have been built that can only operate with a temperature difference of 4 °C, although factory motors will likely operate with a difference of several hundred degrees. These engines may become the most efficient form of internal combustion engine.

Stirling engines and concentrated solar energy

Stirling engines provide a neat method of converting thermal energy into motion that can drive a generator. The most common scheme is to have the engine in the center parabolic mirror. The mirror will be mounted on the tracking device to Sun rays focused on the engine.

* Stirling engine as receiver

You may have played with convex lenses during your school days. Concentrating solar energy to burn a sheet of paper or a match, am I right? New technologies are developing day by day. Concentrated solar thermal energy is gaining more and more attention these days.

Above is a short video of a simple test tube motor using glass beads as a propellant and a glass syringe as a force piston.

This simple Stirling engine was built from materials that are available in most school science labs and can be used to demonstrate a simple heat engine.

Pressure-volume per cycle diagram

Process 1 → 2 Expansion of the working gas at the hot end of the tube, heat is transferred to the gas and the gas expands, increasing the volume and pushing the syringe plunger up.

Process 2 → 3 As the marble moves towards the hot end of the tube, the gas is forced from the hot end of the tube to the cold end, and as the gas moves, it gives off heat to the wall of the tube.

Process 3 → 4 Heat is removed from the working gas and the volume decreases, the syringe plunger moves down.

Process 4 → 1 Ends the cycle. The working gas moves from the cold end of the tube to the hot end as the marbles displace it, receiving heat from the wall of the tube as it moves, thus increasing the pressure of the gas.

Modern automotive industry has reached a level of development at which it is almost impossible to achieve cardinal improvements in the design of traditional internal combustion engines without fundamental scientific research. This situation forces designers to pay attention to alternative power plant designs. Some engineering centers have focused on creating and adapting hybrid and electric models for serial production, while 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

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 view 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 end. 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 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 the set of positive properties, the immediate mass use of Stirling engines is impossible due to 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 of 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 resistant to high pressure. Suitable materials 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 coolant (working fluid) options, limiting maximum temperature heating;
• 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 designs Stirling engines, such as those 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.