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www.genoastirling.com

The designing and making of a Stirling engine at the DICHEP
Genoa

Images, movie and animation of our gamma type Stirling engine

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The Stirling engine

Silent, quiet, very little maintenance, easy to operate: the Stirling seems the ideal engine for hundreds of application. Excellent models have been produced in the past , every now and then some companies or some inventors announce the beginning in a short term of a mass production , yet, 200 years from its invention, the Stirling engine is even more a desire than a reality. It's a matter of materials ? Thermodynamics ? Manufacturing technology ?

The Stirling engine is a very attractive one. If it happens that you read a description of its cycle you will find yourself dreaming to have already built one and to see it working heated by the fire of your fireplace, so, while you are heating your isolated house in some distant and calm place, it produces enough electricity to keep working those electrical machines that make more comfortable your life. But it looks so simple to imagine as it is difficult to build one really able to develop some power.
In fact it is easy to find out perfectly working models as it is hard even to get information about engines that can develop 1 or 2 KW's.
The Nasa uses it in the spatial trips, some companies produce it for domestic use (at impossible prices) or for prototypes of solar plants but it seems far away the perspective to have Stirling engines available for "regular" users.
Stirling engine is a challenge. Not to build the most economic or the most efficient engine, just to build one that can be of some, real utility and at a reasonable cost.

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We are currently working on a Stirling engine gamma type

Better than words:
In this page you can easily follow what's going on. We plan to post a new movie every week or more depending on substantial progress in the construction or in testing the Stirling engine. The description below the movie will be a short resume of the action taken and of the work done.

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Actual configuration of the Stirling engine
2 pistons and 2 displacers in line
RPM : 935
Bore 53 mm
Stroke 36 mm
Displacer Dia. 52 mm
Disp. piston Dia. 48mm
Disp. stroke 50 mm
Type : Kinematic
Hot clearance 2mm
Cold clearance 2 mm
Side clearance 2 mm
Vmax/Vmin 1,68
T. cold 60 C°
T. hot 700 C°
Working gas : air
Pressurization : no
Regenerator : no
Cooling: water
Heating : gas

Engine specifications

Materials:
Heat exchanger tubes hot side : Inconel
Heat exchanger tubes cold side: Stainless steel AISI 316L
Regenerator: Stainless Steel mesh
Engine block: Aluminium
Con/rods: Aluminium
Crankshaft: Steel
Power piston: Aluminium. Molybdenum coated for perfect sealing and minimum friction
Displacer piston: Stainless steel AISI 316L
Displacer cylinder: Stainless steel AISI 316L and AISI 310
Crankcase: Steel.

Main characteristics
Volume 79 cc
Working gas : air (Nitrogen) or helium
Overpressure: up to 50 bars
Operating temperature ( hot side) 750 °C
Starting temperature( hot side) 500 °C
RPM ( on load) 600
Lubrication: no need
Permanent magnet generator
Maintenance: inspection every 5000 working hours
Overall dimensions:(approx) 520 mm x 550 mm x 320 mm

Performances
Electric output (DC) up to ½ HP
Can work 24 hour / 7 days continuously

The designing and making of a Stilrling engine at the DICHEP Genoa
200 watts electric output (DC) or more
Please download the pdf file for more technical informations and prices of the prototypes or contact us directly to have a fully detailed offer.

Forecast
improvements:
Connection to a permanent magnets generator by a magnet coupling, pressurization up to 3 atm, new lighter power pistons, new burning system
Target:
1/2 HP (0.370Kw)
power output by the end of 2003

11/07/2003
We rised the test speed of the Stirling engine to 935 RPM by increasing the hot temperature
04/07/2003
Test continues at 750 RPM 6 - 8 hours a day. Output of the Stiling engine measured with the help of a Prony brake : 23 W at 612 RPM
01/07/2003
Finally the Stirling engine re-started at the first attemp : we left it run at 750 RPM for about 6 hours
17/06/2003
All parts of the Stirling engine are ready and the assembly started : see photos on our "See more about ous Stirling" section.
27/05/2003
Most of the work is done. Two light aluminium pistons for motorbyke have been

Prony brake : 23 W at 612 RPM
01/07/2003
Finally the Stirling engine re-started at the first attemp : we left it run at 750 RPM for about 6 hours
17/06/2003
All parts of the Stirling engine are ready and the assembly started : see photos on our "See more about ous Stirling" section.
27/05/2003
Most of the work is done. Two light aluminium pistons for motorbyke have been acquired in order to replace the heavy previous one on the Stirling engine
08/04/2003
Drawings of the new crankshaft and support of the Stirling engine are ready ( see a 3D image following the link at the bottom right of this page - " See more about our Stirling")
14/02/2003
After a couple of week of continuous running of the Stirling engine the crankshaft showed some weakness so decision was taken to make a stronger one and to replace the existing support, the ball bearings and the conrods
07/02/2003
This week the Stirling engine has been tested in order to verify the stability of the crankshaft. We connected it to a permanent magnets alternator charging a 24 volts battery and kept it running at 550 rpm for the all week, 8 hours a day. As the crankshaft is made in several detached components the concern is the possibility of skew in some parts (that are not welded) with the consequent modification of the crank offset. So far we found no deviations. The test will continue at least for other 5 days next week

The Stirling engine was invented in 1816, before the gasoline and Diesel engines.

Are you interested in Stirling engines?
We offer a basic fully working engine prototype for educational and development purposes.

See more about our Stirling engine
Stirling The displacer cilinders are in superalloy The new crankshaft

How a Stirling engine does works

Stirling engine can use any type of fuel
In our machine we have coupled a pair of gamma type Stirling engines. Each one has two cylinders and two pistons: a working and a displacer piston. The cylinder left is constantly heated up at the lower part while it is cooled on the top. The displacer piston it is not sealed inside the cylinder to let the working gaseous fluid ( air ) to pass aside. If the displacer piston is now in the upper dead-center, air is strongly heated up and the pressure pushs up the working piston . The displacer piston gets now pulled downward by the coupling of the two pistons. Air is strongly cooled, and together with compression work from the flywheel the working piston is brought again to the bottom, the displace piston slides up and the air is heated up again.

The modern Stirling Engine is a clean and efficient engine. This is because the heat fueling the device is supplied from outside the engine. Thus creation of pollutants can be eliminated. The external combustion aspect enables a Stirling Engine to operate equally well on multiple types of fuel, such as natural gas, propane, gasoline, diesel, bio-fuels, or even heat from the sun.