I created Stirling engine software (a design program) that will help designers and enthusiasts build high-power Stirling engines. The design program helps you design the various components of a Stirling engine for maximum power and efficiency. It’s practical and straightforward to use, and laid out in a format understandable to a layperson; meaning you don’t have to be an expert to use it. In addition, there’s a 144 page manual included that gives an in-depth description of Stirling engines. Every effort has been made to make the information as clear and accessible as possible. There is no confusing jargon or obscuring of detail. I created this program and manual with clarity in mind because I wanted to help bridge the knowledge gap between those who understand Stirling engines and those who don’t. There’s a lot of quality information out there, which unfortunately is scattered and hard to understand by the average person. So over the last year and a half I addressed this. I read all the information I could get my hands on. I also went through some serious design efforts of my own in order to gain a practical understanding of these engines. The end result is a practical information manual and design program.
What was my motivation for creating Stirling engine design software? It’s simple. I wanted to create something affordable and of value to someone who wants to design and build a high-power Stirling engine. Never mind all those cute little models you see on YouTube, which anyone can build. I wanted to put together a guide for building an engine that will put out serious power! That said, I did not create a fabrication manual that tells you how to machine the different parts, or how to join different metals together. Furthermore, I did not create a guide that tells you how big to make the linkages and crankshaft so that they can support the piston forces. However, what the program will do is give you the information you need to figure these things out, based on the dimensions and type of materials you are using in your design. For instance, the program will give you information such as pressure, temperature and speed, which you can use to calculate how strong to make the components. The program might also tell you why that engine you once built isn’t running. For example, the DIY Stirling engine I made last summer would not run, and I wasn’t really sure why at the time. So I entered the dimensions and other parameters of the engine into the program and found that it was capable of only 5-10 Watts of power, with a top speed of maybe 60 rpm. No wonder it wouldn’t run! It couldn’t overcome the frictional losses in the system. To get it to run I needed a much higher engine pressure and many more tubes for the heater and cooler.
Needless to say I am passionate about Stirling engines and want them to succeed. They are impressive machines deserving of serious attention. And this is especially true now given that demand for alternative energy sources is growing faster than ever.
This is what the Stirling engine design software does:
• Allows you to optimize the number of heater and cooler tubes, and regenerator volume for maximum power, given fixed swept volume
• Predicts engine power, torque and approximate pumping (flow) loss at different engine speeds. You can determine the speed at which maximum power occurs
• Gives you performance data at different engine speeds, such as temperature and pressure
• Gives you information to easily calculate the necessary size and mass of the flywheel
• Allows you to determine the necessary engine pressure to reach your desired power level
The manual gives information such as:
• How long to make the heater and cooler tubes relative to their diameter, to ensure sufficient heat transfer
• The size and range of porosity of the regenerator for optimal performance, based on a review of the literature
• The type of matrix material to use for the regenerator
• The type of seals to use for the pistons and displacers
• How pumping (flow) losses relate to the regenerator and number of tubes in the heater and cooler
• The importance of a pressurized buffer space for reducing the bulk and size of the linkages, crankshaft, and mass of flywheel
• How to design different mechanical drives for Stirling engines including the Ross Yoke and crank drive
• How to minimize thermal losses in the various engine components
• In-depth discussion of the heater, regenerator, and cooler
• Detailed information on the various functions of the program
• Detailed description of the mathematics and physics of the Stirling engine
• Pictures of the MOD II automotive Stirling engine produced in the 1980′s
• Pictures of the current SES engine (a Stirling dish that produces power using concentrated solar energy)
In addition:
• This Stirling engine software program is only for kinematic engines (with prescribed piston/displacer motion). It does not model Free-piston engines. However, its performance predictions can still be used for comparison purposes with existing free-piston engines.
• The program only models alpha engines with two pistons, and beta/gamma engines with a single piston and displacer. The three engine configurations (alpha, beta, gamma) modeled by the program are shown here. The program does not accommodate engine designs with multiple pistons/displacers operating in multiple cylinders (such as the Rinia configuration). This can be done with some extra programming effort, but as of right now this feature is not included.
Below are graphs taken from a sample simulation using the program. Note that the program does not directly create these graphs. The program creates an output file containing all the raw data calculated by the program. You can then copy and paste this data into a spreadsheet like Excel and graph it.
Click on the figures for a larger view.
The program is a simplified third-order model, based on the report by R. D. Banduric and N. C. J. Chen: Nonlinear Analysis of Stirling Engine Thermodynamics, Oak Ridge National Laboratory, June 1984.
Comments made by others about my Stirling engine software:
“For comparing Your program’s output with Urieli’s QSFM i made a spreadsheet, which shows for the basic values almost same results” — Bernhard, from Germany
Note: Professor Urieli is a well-recognized expert in Stirling engines. He teaches at Ohio University. The acronym QSFM stands for Quasi Steady Flow Model
“after much of questions and working days, I verified with your model-simulator the data shown by Mr. Dochat about a 5 kWe free piston Stirling engine (the report is: “design study of a 15 kW free piston stirling engine – linear alternator for dispersed solar electric power systems”; you can find it searching with Google!). I can ensure your program permits to obtain the results wrote in the report with absolute precision! That’s right! I hope this can be useful to you and for future improvements of your stirling engine simulator!” — Simone, from Italy
“I am extremely happy at having made the purchase and wanted to thank you for offering your work in this form. It is sound, well thought out, and is exactly the “bridge” between the purely academic and purely applied aspects of engine design that is so needed with respect to Stirling engine design.” — Jonathan
This program is also referenced in a paper by Francesco Miccio: “A mathematical model of a fluidized bed combustor coupled with a Stirling engine”, Istituto Ricerche sulla Combustione CNR, P.le Tecchio 80, 80125 Napoli, Italy.
The software program is written in Fortran. It captures all the essential physics in Stirling engines. It is easy to use and usually takes less than a minute to run. The input data is easy to enter. Every input parameter is clearly explained, with diagrams where necessary.
You don’t have to go through an installation procedure or change any settings on your computer, to use the program. You just download it and run it directly on your computer.
The cost of the Stirling engine design software plus manual is $89.95 CAD. It’s available as an instant download via PayPal and PayLoadz. To purchase go to the main page of http://newenergydirection.com. Click on the menu button “Stirling Engine”, and follow the instructions.
If you know where I can get stirling dish dimensions and schematics please contact me at the above address.
Does this program show CAD or similar animation of the designed engine?
No, there is no CAD or animation of the designed engine. On the post-processing side there is only a results file which contains all the raw performance data, which can be plotted if you wish.
Thanks for sharing. Interesting to see, how many people still are interested in this kind of engines. I still think they need development, there are new ways to go, new materials to use etc.
Why is it so difficult to find a ready made stirling engine for sale?
not the model ones!
do you know if there is a company that sell such an engine (1kw-50kw)?
thank you
A lot of people are asking the same thing! The problem is that they just can’t compete with ICE’s in terms of price, power/weight ratio, and ability to increase/decrease power output quickly.
It’s also a chicken and egg problem: The more you sell the better they get due to more development budget and the price comes down, but to sell them the price needs to come down and they need to perform at least as well as an ICE.
But the Stirlings have an ace card, they can use any hot temperature source, and it’s unavoidable that for this reason they will become major players as less fossil fuel is used and more energy is generated using solar heat, biomass, etc.
There are some companies that sell Stirlings. Here’s a page I made listing them:
http://newenergydirection.com/blog/2009/06/stirling-engine-generator/
If you are looking to install it in your car it cannot compete with ICE’s
anyhow,its a 100 years tech and not even a single manf??
the ones in your link ask 100,000 us dollars!!!
and doesn’t look like its made out of gold.. (-;
if someone know of a non home manufacture I’ll
be more then glade to hear from you (up to 20k)
even a prototype will do.
thanks
como conseguir desenhos e projetos de motores stirling
Hi
Since last year there is a company in Spain that is manufacturing and selling the 4 cilinder double acting Whispergen system in Europe through several distributors.
I know they are producing hundreds per month but their production for this year is fully sold to germany, holland, UK and France.
They do not sell the engine solely but the complete micro-cogeneration unit.
Contact http://www.efficienthomenergy.eu/
Hmm stirlings not effective?, well they are used in submarines, the most quiet submarins which dont have an own nuclear powerplant.
http://en.wikipedia.org/wiki/Gotland_class_submarine
The next A26 will also utilize stirling engines.
I need to design a stirling cycle engine that use solar energy to supply at least 5kW of energy. And is limited to the roof area of a house. Do you think this program works to this design?
A stirling engine is independent of the heat source. So in your case you have to figure out how much solar power is falling on the roof, and then concentrate that energy to get a higher temperature, which in turn increases efficiency (Carnot efficiency). You can do this with parabolic mirrors. The program does not do this part of the design for you, since it uses heater side temperature as input. How you are able to generate that input temperature, is a separate matter.
Basically you need enough roof area to get 5 kW of engine power (after efficiency is accounted for). For example, for the most efficient solar-to-grid Stirling engine (The SunCatcher), the efficiency is 30%. So you need a solar incidence of (5 kW/0.3 = 16.7 kW). That’s a roof area of about 17 square meters, using a solar incidence of around 1000 W/m^2. However, your engine will likely be quite a bit less efficient than that, so you will need an area greater than 17 square meters to obtain the 5 kW engine power.
That’s scratching the surface though. There’s many other factors to consider in your design, such as the reflective efficiency of the mirrors, temperature reached at the focal point of the mirrors, actual solar incidence in W/m^2 in your geographic area, collector design at the focal point and heat transfer efficiency to the engine, tracking mechanism to use and associated losses, etc.
As a general rule, the fewer times you make heat move from one media to another the better. Each change in medum (collector to water, water to storage unit, storage unit to engine) takes a temp differential. You start with what you can and it goes downhill from there. SO, using the roof as the hot side would be ideal provided you have a) sufficient area and b) a sufficiently high temp.
I always though that putting a solar glass enclosure over the roof and using a steel roofing material and mounting the engine to the rafters with the hot side as the roofing material would be in keeping with the above. Use the cold side to heat your hot water or house. At night use the “icy blackness of space” to reverse the process so you can have 24 hour production. FWIW
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Can you suggest me some ways to design a solar sterling engine to generate about 1-5 kW power. From where can I find the helping material?
I am working on Solar Powered Stirling Engine nowadays. Is your software helpful in designing “Receiver” that receives heat from solar collector as you said your software provides sufficient information about heat exchangers as well. Furthermore, I am from Pakistan and our country is not included in the country list given on the paypal website. Without selecting country will it proceed?
There’s nothing specific in the software that will help you design a solar receiver. That has to be done separately.
I looked into it and PayPal is not set up to process payments from Pakistan. Now, some people work around that by asking relatives or friends from a PayPal supported country to send their online payments. Hopefully that is something you can do.
Is it possible to calculate Stirling Engine losses like fluid friction loss, mechanical friction loss, shuttle conduction, static heat conduction, pumping loss, temperature swing loss, internal temperature swing loss etc with your software.
With the software you can only explicitly calculate pumping losses from fluid friction (fluid friction loss and pumping loss are the same thing).
The other loss accounted for by the software is Adiabatic Loss. This loss results from a high compression ratio — (maximum-engine- volume)/(minimum-engine-volume), which forces the gas temperature in the expansion and compression space (during parts of the cycle) to exceed the heater and cooler temperature, respectively. This results in heat being pumped out of the heater and cooler due to the positive temperature difference. This lowers thermal efficiency. Note that the Adiabatic Loss is inherently captured by the equations of the program, and doesn’t need to be accounted for explicitly – so it isn’t accounted for explicitly.
The other losses such as mechanical friction are not accounted for since they can only be accurately calculated with experimentation.
Here’s a section from the software manual which explains engine losses:
In a real engine there are friction losses, such as in the mechanical drive, linkages,
and between the piston/displacer seals and cylinder wall. This directly reduces
engine power. These friction losses can only be accurately calculated with
experimental measurements. They are not accounted for in the program.
• There are also thermodynamic losses such as from hysteresis effects, due to compression of the working gas in the expansion and compression space, causing it to heat up to a temperature higher than that of the cylinder wall, during parts of the cycle. As a result, heat is lost to the environment. This loss mechanism can be minimized, by insulating the outside walls of the expansion and compression space. In the program it is assumed that the expansion and compression space are adiabatic, which means that the working gas does not lose heat through the cylinder walls. This is a good assumption for large high-pressure engines.
• Other losses include: working gas leaking out of the engine, heat transfer inefficiency from heat source to heater tubes, and other thermodynamic inefficiencies due to heat loss in other parts of the engine. For instance, there are heat transfer losses that occur as a result of heat flowing along the engine wall from the hot side to the cold side. There are heating losses that occur between the gap of the displacer and the cylinder wall, due to the temperature difference between the expansion and compression space. No provision is made in the program to account for these losses. For the most part they can only be accurately calculated by experimental measurements, and then minimized by proper material selection and design.
• As mentioned, regenerator inefficiency is one of the major sources of thermal loss. But the other thermal losses mentioned above can (in combination) further reduce thermal efficiency by several percent.
• This program is meant to optimize the design based on the intrinsic engine thermodynamics, which models the main physical phenomenon occurring inside the engine. For the most part, the losses mentioned in the previous paragraph affect the thermal efficiency only (i.e. by reducing it). This means that extra heat energy input is required to compensate for these losses. In other words, the engine power itself is not affected, provided there is sufficient heat energy available to compensate for the thermal losses.
• It is very important to know that (with the exception of hysteresis losses and leakage of working gas), accounting for all the above-mentioned losses would not affect the thermodynamics and physics inside the engine. So for optimization purposes they can be excluded from the model. In other words, their exclusion will not affect the number of tubes and (proportional) regenerator volume required for maximum power.
• One way to significantly improve thermal efficiency in the design is to improve the heat transfer efficiency from heat source to heater tubes. A common loss mechanism in this regard is heat loss to the surrounding environment (e.g. warm exhaust from a burner). A way to minimize this loss is with an air Preheater. Using the exhaust stream, a Preheater heats the air before it enters the combustion chamber, and more of the heat energy of the fuel is used. This is also more economical since it reduces fuel consumption. In addition, you can also minimize heat loss by placing an insulated enclosure around the heat source.
• A well-designed heat source, such as burner with air Preheater, can have a heat transfer efficiency of 90%. This means that 10% of the heat is lost to the environment. This loss further reduces thermal efficiency by several percent. For example, an engine operating at 40% thermal efficiency with (theoretically) perfect heat transfer from the heat source, would run at 36% efficiency with 90% heat transfer efficiency (0.90×0.40).
Hello, I am interested in your program to try to build a stirling engine that is multi-kw power has emerged and I doubt the graphics shown above noted, the term “speed Hz” Are revolutions per second? I found too many to so it can withstand an engine of this type.
Yes, Hz is “revolutions per second”. The speed shown in the graphs is for hydrogen which has low density and low viscosity, which results in higher engine speeds (since pumping losses are lower). The MOD II Stirling engine, developed in the 1980s, used hydrogen as the working gas, and it reached comparable speeds. At peak power it ran at about 4500 rpm which is 75 Hz. Also, note that predicting engine speed is among the biggest uncertainties, which is why in the design manual that comes with the program I give a speed tolerance of +25/-30% from the nominal value predicted by the program (as shown in the graph), which means that you can easily expect an actual running speed quite a bit lower than that.
wer to download dis software?
I explained it at the bottom of this page. But in any case, to download it you go to the main page http://newenergydirection.com. You then click on the menu button “Stirling Engine”, and then follow the instructions.