Stirling Engine Q&A Q51-Q100

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Q&A from June 13, 1997 to April 19, 1998.

Q100: Excellent site, i like it very much. Other than a few mis-spellings it was very easy to understand. Don't know much about these engines, but plan on visting your site again.
19 April, 1998

A100: Thank you very mach.

Q99: A fantastic site keep up the excellent work. I am interested in building a Fluidyne or liquid piston Stirling Engine would you have any plans for such a model or be able to inform me of a site that may contain a plan.
19 April, 1998

A99: Sorry, I have not built the fluidyne or liquid piston Stirling engine yet. You can view the photos and figures in following web sites.

Q98: My high school has started a synthetic practice related the Stirling engine since April 1997. Detail information is following web site.
15 April, 1998

A98: I connected your web site. I seem that your Stirling engine is very beautiful. I would like to see the real engine, if I have a chance.

Q97: I am looking to buy a stirling engine, that has 40% efficiency or higher and its power output is about 1/8 hp (93 watts) or higher. The cold side and hot side of the engine are clear, so that I can be able to install some heat exchanger and insulation devices on it. Please help me to find some company that make it. Thank you very much.
3 April, 1998

A97: It is difficult to help you for me. More 40 % efficiency is too high. I seem that you cannot fine such high performance engine.

25 March, 1998

A96: There are many kind of the beginner books. But, I recommend that you search the information on the internet.

Q95: I enjoy your work very much. This address could not be found. Is there an error in this address ?
A46: I answer this question in following web page.
I would like to study this information concerning overlape calculations.
25 March, 1998

A95: Yes, I had my mistake, and repaired it. Thanks.

Q94: I'm particularly interested in low temperature difference Stirlings to be used with a Solar Pond.
How well do you think that a low temperature difference Stirling will scale up from the very small engines that I've seen of this type? Any ideas on how to increase the heat transfer in the low temperature difference engine?
Like a previous questioner, I had wondered about using a series of holes in the displacer piston with regenerator material in the holes. I'm assuming that aluminum mesh would make a good regenerator material due to the high specific heat of aluminum.
21 March, 1998

A94: I think that one of the most important probrems for the low temperature difference Stirling engines is the heat exchangers with high heat transfer performance, as you said. When the heat exchangers with with high transfer performance are completed, the low temperature difference Stirling engine becomes small size and high engine speed. But I don't any good idea for the heat exchanger yet.
I think that the aluminum mesh is a good regenerator material, as you said. There are not a big probrem to locate in the displacer piston, because it is very light material.

Q93: Hi I am working on a modle stirling engine based on one that my brother has. it is made of tin cans, wood, brass rods, and some aluminum. I cannot get it to run though.
I have tryed several things to get it going but to no avail.
here is some what of a picture of what it looks like.I will really appreciate any info you can provide.


  (--)     3 |        |

  |  |       |        |5

   ||----    |        |

 1 ||----  --|------/-| \

  |  |       |  ^   \---/4

  |  |     2 |  5    

1 these are the tin cans two coffy cans and a spray can
there are two beer cans inside the spray can
2 this is a post to support 3
3 this is a waking beam
4 this is a wooden fly wheel
5 these are the brass rods
the top coffey can is filled with water the bottom has an opening for an alcohol burner there is a tube coming off spray can which has another piston in it I have set the timing at 90 degrees and there is almost no friction what else could be wrong? by the way his does run.
20 March, 1998

A93: I think that your engine is very interesting, though I cannot understand the structure of the engine enoughly. I wonder that the performance of the seal device is no good. Is not there the gas leakage between the beer can and the splay can?

Q92: Surprisingly I found Your web-site, and this can probably help me to make a big stirling engine, on 5-10 KW, which I intend to run on wood waste and biogas from cow manure, as I live in a farm. I have seen the ST-5 from Madras factory, India, and from the pictures I have here, this must be about 3 KW when You see the waterpumping system fired by wood! The diameter of water tube is about 10 cm, and has quite good power; all from wood fired in a 200 litre oil can! See the pictures, I have them all here in my computer! And these pictures also gives a good idea what is the difference of a small and a big machine; this big machine has got an external air compressor(turbo?) monted at its side, even with a lever for hand, seems that You must help the air compressor a little by hand , till the engine really gives power. I a very pleased for Your comments of big engines and give You all the 10 pictures, detailed of crankcase, turbo, castings, diff. applications as attached file or I will make a home page.
20 March, 1998

A92: I have not seen the ST-5, though I have heard about it. In my feeling, it is a very good performance engine. As my comments for the big engine, I think that the big engine is said the high performance, when the engine has one of the follows good characteristics.
(1) High efficiency,
(2) Use a low emission fuel with pollution-free,
(3) Compact size and high power.
I seem that the characteristic (2) is very good in the ST-5.

Q91: I have been thinking of how to throttle a stirling engine. I can see a number of possible ways: varying the phase of the displacer, varying the stroke of the displacer, restricting the airflow between the displacer cylinder and the power piston. Are there any I've missed? Is any one method better than another; and if so,why?
9 March, 1998

A91: In the case of the model Stirling engines, there are above methods for the throttle as you said. They have each advantages and defects shown in follows, so I can not decide the best way.
(1) Varying the phase angle; It can be constituted an easy mechanism with some gears as my proposal on my web site. But, this mechanism is not suitable for a high power engine, because there is a problem for strength of the gears.
(2) Varying the stroke; It has a high responce of the engine speed. But, the mechanism receives a too big load for varying the stroke. The mechanism needs any inventions in order to hold the load.
(3) Restricting the airflow; I think that this is no good.
On the other hand, the high power Stirling engine has used varying the engine pressure for th ethrottle. This has had good results, and I recommend this way is aoolyed for the model Stirling engine.

Q90: This is an easy question. Why is the phase angle 90 degrees? Please explain theoretically, if you can.
23 February, 1998

A90: It is difficult to answer for me in this session. When you calculate an engine performance with an isothermal model or Schmidt theory, you see it.
But 90 degrees may not be the best phase angle, when the performance of the heat exchangers are considered.

Q89: Hello, we are a class from a technical highschool from Germany. We think that your websites are very good and interesting and we liked best the plans for the sterling engines. We would like to build the ESE10 but the plans aren't ready yet. Can you please tell us when the plans are ready or email us the complete plans for the ESE10.
We also had problems by building the LSE01, because we didn't know where to get the medical syringes. Is the declaration 3cc an international norm and can you tell us where we can get these syringes. Please offer more plans of such easy-to-build sterling engines.
Thanks for all.
20 February, 1998

A89: I have not prepared the plans of ESE10 yet. But the basic constaruction of the engine is the same of LSE01. So, I recommend that you build the LSE01 first, and you reform the engine under your consideration.
Please find the syringes of 10mm diametaer. I think that you can get the glass syringes on the science goods shop which is selling test-tubes, flask and etc.

Q88: Your site is very informative. I like the animations. I have several suggestions to make the animations still more clear.
1. put simulated pressure gages in the hot and cool sides of the displacer piston and above the power piston, to show the changes in pressure as the pistons move.
2. arrange the animation so that the viewer can change the speed (fast, slow, stop, single small steps) as desired.

Now an idea for regenerators. Why not make small holes in the displacer piston and put steel shaving regenerators in these holes, rather than have a separate by-passing channel for the regenerator? It would decrease the weight of the piston as well.
12 February, 1998

A88: Thank you for your suggestions. I will try to reform my animations when I have enough time.
We have developed the Stirling engine which have the regenerator in the displacer piston. I think that such type engine has follows probrems.
(1) types of heater and cooler,
(2) connection between heater and displacer piston (cylinder).
If you are interested in the engine, please conatct HERE.
I am interested in the steel shaving regenerator. I would like to try it.

11 February, 1998

A87: I have heard that the biomass Stirling engines have been developed and used in Southeast Asia, though 100 % not sure information. Sorry, I don't know more detail information about them.
On the other hand, a 40 kW Stirling engine for wood chips has been developed in Technical University of Denmark. Its reference is;
H. Carlsen, J. Bovin: Field Test of 40 kW Stirling Engine for Wood Chips, 8th International Stirling Engine Conference and Exhibition, p.525-530.

Q86: On an engine with both a displacer and single power piston, is the volume in the power piston considered to be part of the volume of the compression space?
If not, how do you calculuate volume ratios to be any different than 1???
9 February, 1998

A86: I think that the volume in the power piston can be included to the compression space, when we use an easy analysis method like an isothermal model. In detail, the volume in the power piston expands adiabaticly in the cycle, and decrease the gas temperature in the space. When we need to analyze the gas cycle in detail, the volume in the power piston must be considered as a separated space to the compression space.

Q85: We want to run stirling engine on producer gas. how to go about it. I am new to stirling engines, we have gasifiers to produce producer gas. How much theritical efficiency we can expect.
3 February, 1998

A85: First of all, I don,t know the producer gas. I think that it is a kind of combustibility gas.
The theoritical efficiency of the Stirling engine, n is calculated by a next equation.
Now, Th (Kelvin) is a temperature of hot heat source. And Tc (Kelvin) is a temperature of a cold sink.
If temperature of the combustion gas is 1200 K, and temperature of the cold side is 300 K, the theoritical efficiency becomes 75 %.
But there are many kind of thermal losses on the Stirling engine. Then a net efficiency of the high performance engine becomes about 20 - 30 %.

Q84: Various publications I have read refer to Alpha, Beta and Gamma type stirling engines.
What are the differences between Alpha, Beta and Gamma Stirling engines?
2 February, 1998

A84: Stirling engines can be cllasfyed two-piston-type and displacer-type. The two-piston-type equals the alpha-type generally. On the other hand, the displacer-type can be cllasfyed the beta-type and the gamma-type. On the beta-type, the displacer piston and the power piston are located in a single cylinder. On the gamma-type, these pistons are separated cylinders.

Q83: A friend of mine bought a set of plans for a Stirling designed by Rudy Kouhoupt...called the Sterling Cycle Hot Air Engine, and dated 1993. There is no text material with the plans, and he is trying to find out if any construction articles were written about the project that he might use.
I will pass any info to him. Thanks!
2 February, 1998

A83: You are welcome. I am happy if my web site is useful for you.

Q82: Hi, I am a second year student at the university of Calgary, faculty of Engineering, department of Electrical and computer Engineering.
Yes.... I know , if I am in electrical engineering then why am I interested in stirling engines.
Well , sometimes you like something but you wouldn't know the reason behind it. Anyway, I wanted to ask you if you can provide me with a schematic diagram of a practical stirling engine with dimensions on it.
The information I want are to be about the engine in its different cycles of operation. Kind of snapshots of the engine while it is at work.
I hope such info is possible to achieve with minimal effort. And I hope that I am not asking for too much.
Thank you for your concern in my message and hope to hear (or actually read !) from you soon.
29 January, 1998

A82: Sorry, I cannot answer your request soon.
Have you connected to Ecoboy-SCM81 page?
There are some information of a practical Stirling engine, though it is not enough.

Q81: I am a student, aiming at a junior high school teacher
I built the Can Stirling engine. But it cannot work.
Please tell me how to work it.
29 January, 1998

A81: You must decrease the gas leakage and the friction loss of the Can engine. Please make sure following points.
(1) Is the hole of the balloon too big?
(2) Have you putting on a drop of oil to the hole?
(3) Can the crank shaft work smoothly?
(4) Are holes of the frame and the connecting rods too small?
(5) Does not the mass weight touch the frame?
(6) Does not the displacer piston contact to the cylinder?
(7) Please adjust the weight in detail.

Q80: Your Web page is most interesting and very informative.
You helped me overcome many misconceptions about both stirling engines and even some thermo. I had my students construct your "Can Displacer-Type Stirling Engine" for extra credit in an AP Physics Class that I teach in Rockland County. Attempts by both me and some of my students has proved most successful.....It really works!! If you have any plans on how to construct a similar engine that might power a small vehicle, please send it to me. I think next year's class might enjoy such a project. Thanks!!
27 January, 1998

A80: I am veru happy that my web site was useful for you and your students.
Sorry, I cannot answer your request soon. Almost of my information of model Stirling engines are shown on my web site already. I will inform you the requested information on the web site, when I prepare it.

Q79: I build a Stirling engine. But it cannot work. It has a small friction loss. What kind of the causes are considered?
24 January, 1998

A79: If your engine has a small friction loss, next causes are considered.
(1) Large gas leakage.
The seal device between the piston and cylinder needs high quality.
(2) Small temperature difference.
In the case of the engine which the distance between the high and low temperature space is too short, the low temperature increase too high. Then the engine cannot work.

Q78: Thanks for this great site! I finally understood how it works!
My question: Is it mandatory that hot and cold cylinder have different volumes, and why? In other terms, is the difference of bore/stroke between both cylinder that help the engine to produce power thru temp difference?
17 January, 1998

A78: You can decide the volume freely. But you must consider the capacity of heat exchangers. Please see Q6 and A6.

Q77: I want to draw a p-v diagram of theoretical Stirling cycle on the MS-Excel. What terms is it need?
14 January, 1998

A77: You need to use Hot temperature, cold temperature, minimum volume and maximum volume, maybe.

Q76: Hi I have only visited this site once and it looks great.
I am in the process (very long process) of building a 5hp steam engine. The boiler makes this an expensive exercise. I was wondering if there are any plans or ideas on making a useable hot air engine say 300-500 watt or bigger. I read about a 1000 watt engine in a book produced by phillips. Is this possible or am i wasting my time and will continue with my steam project. also any info on how they work would be appreciated as they seem more complicated than steam. Thanks in advance for any info to follow.. Mark.
9 January, 1998

A76: I have not build the steam engine yet. And I don't know the steam engine well. In my opinion, the maximum highest temperature of such 1000 watt class Stirling engine is very higher than that of the 5hp steam engine. So, nickel steel like stainless steel is needed as the heater material. If you can use welding work for the steel, you can build the large scale Stirling engine (in the very long process).
Sorry, my answer is not enough.

Q75: Please tell me who will sell me a 1-10kw Stirling engine/generator set which can use both solar and natural gas. I have my own high-powered solar collector/concentrator (3072:1) but I need a target other than the occasional unfortunate bird.
8 January, 1998

A75: I don't know if the 1-10kW Stirling engine is selling now. Follows comanies have been developping the engines. Please contact them.
(1) Stirling Thermal Mortors, Inc., USA
(2) TEM Stirling engines, Sweden
(3) Sigma Elektroteknisk A.S, Norway
(4) Whisper Gen, New Zealand

Q74: I am a battle-scarred Stirling developer from the pre-Internet days. In 1991 I began constructing the first of my four failed designs! The reasons for the failure were,
a-the designs tried to be too ambitious, clever and 'original'
b-the friction was too high
c-the problems were under-estimated and the expectations were too high
d-the test-beds were too ill-designed
e-personal problems intruded!!!
I put away the whole thing in 1996 thinking Stirlings were in my past. But are they ever?....A VISIT TO YOUR SITE HAS CONVINCED ME THAT STIRLING LIVES ON AIDED BY ENTHUSIASTIC DEVOTEES LIKE YOU. Who knows I might even resume my work.
I live on a farm about 20kM out of Madras city. I have a good work-shop with a lathe and a milling machine (now moth-balled!) and through the years of experimenting I had a wonderful machinist Venu, who worked with me. YOUR SITE HAS INSPIRED ME TO GET IN TOUCH WITH HIM AGAIN SO THAT MY SHOP IS BACK TO WORK! Somehow, all the correspondence in your site and the magic of Internet makes me feel its not going to be so lonely as I felt in my last spell with Stirlings!!
One of the major fabrication defects in my approach was to weld heater tubes instead of brazing. Can someone help me build a small brazing furnace; tell me about the technology involved? I'd like to talk to anyone with experience in this.
29 December, 1997

A74: I am happy that I accepted your hot message. I hope that you build the 'ambitious' Stirling engine.
I seem your failure will be useful for me and other Stirling developers.
I don't know about the brazing furnace. If someone know about it, please contact him or me.

22 December, 1997

A73: I seem it very interesting idea. I think that the Stirling engine can work using the temperature difference between the hot room and the cold air, as you said. In my opinion, it is difficult that the engine gets an effective power using such low temperature difference.

20 December, 1997

A72: Please contact to the link page on my web site. I have informed about many model and commercial companies.
The Stirling engine can work using the solar or spring water. I hope that the engine is developed using such natural energy in near future.
I sure that the practical engine for the generator is developed soon.

Q71: Great Page! thanks for all the information, please add more.
I have recently finished the LSE-01 engine, it runs great!
I made a few changes during construction:
-The cylinders are horizontal for compactness.
-Glass syringes are too hard to find, so I made the pistons and cylinder liners from A2 tool
-steel tool steel doesnt change size mush when heated and i ground them to size after heat-treating for a great fit
-I increased the bore to 13mm.
-A regenerator of rolled up brass screen was inserted in the passage between the cylinders. This increased the run-on time after the heat is removed, from 30 seconds to more than a minute and a half.
-I lightened the flywheel, after reading another question about the LSE-01, but this seems to have slowed down the engine.
-The cold cylinder jacket has fins added, and a light coat of flat black paint, both to aid heat radiation
-The hot cylinder is wrapped in fiberglass cloth and aluminum tape to hold heat
-I tried lowering the compression ratio to run it on less heat, by milling the head plate to add spave above the working piston. This caused the engine not to run at all.
Bearings are also available at hobby shops that carry parts for R.C. cars, and they're fairly cheap, and high quality.
Thanks for the plans, they were a big help!
10 December, 1997

A71: You are welcome. Your information is very useful for me and other persons who will build the model Stirling engine. Thank you.

Q70: I have a question,your drawings of the rotary displacer type are different than of the one in the picture.
I think the one in the drawings has tomuch dead space between the displacer and the powerpiston
Also i`am not sure about all the holes in the flywheel.Please explane.
1 December, 1997

A70: My drawings are no good, then you may misunderstand the structure of the rotary displacer type engine. The minimum clearance of the real engine between the displacer and the power piston is 0.5 mm. Also, the flywheel does not have any holes. The holes, you said are located between the displacer space and the power piston space, maybe.

5 November, 1997

A69: Sorry, I cannot understand this question.

Q68: I love this site! I have been looking for such a site for a while now! I found it off of an electronic enthuthiast's site, of all places! Such is the web! Anyhow, I do have one question:
Does the simple Sterling engine you describe to build (the one with the rubber balloon and can, etc.) run fast? In other words, what kind of RPM can I expect? As for the Tailor engine - I have a copy of that article - It came out in an issue of Scientific American - I am not sure which one, but sometime in the '80's I believe. Anyhow, when I have the info in front of me, I will send you the information (or if I can get the article scanned, I will send it to you). Interestingly enough, I saw in an antique store here a little car that was powered by such a device. I didn't have the money to buy it at the time, and the owner of the store said he got it at a steam engine convention. Someone bought it later - but I don't thing they know what they have. I only wish I had bought it when I saw it... The date on the car was 1926, and it must have run slow, cause the Tailor engine only runs at about 6 RPM (!), and the builder geared it down using a belt drive. It looked to be a possible school science project...
9 October, 1997

A68: Thank you for your veri interesting information. I cannot compare the Can Stirling engine and the Tailor engine, because I don't know the Tailor engine at all. The Can engine is able to run about 60 rpm.

Q67: You have a great website, very informative!
I have never built an MSE, but I would like to, at this time is I am gathering infomation about the engine.
I would like to build a sturdy engine with metal cylinders and pistons, I don't want to use glass.
I have found two very nice piston and cylinders in a junk yard made of brass,the pistons are of iron.
Can you give me any information on how to get a good seal around the piston, as the seals on them are not very tight.
The engine I want to build will be a two piston alpha with regenerator and water cooled, propane fueled.
5 October, 1997

A67: I think that you can use the metal piston and cylinder, when the piston is not too hot temperature. If so, I recommend that Teflon material is used as its piston rings. Generally, an expansion piston of the two piston alpha type Stirling engine is located near the heater. But it is not good for the piston seal, it lead to a lot of friction loss or much gas leakage. When the metal piston is used, the displacer type engine is better. Because the piston seal of the displacer piston does not need few gas leakage.

Q66: I'm a student of last year of Mechanical Engineering.
I'm trying to do a Stirling dispalcer type simulation, but I've got too many problems with the thermodynamic cycle. How can I develop this cycle in mathematical way.
3 October, 1997

A66: It is difficult to answer this question for me. I cannot answer soon, sorry.

Q65: Can you tell me if there any stirling engines for cogeneration application that run on natural gas which are commercial or available for testing?
2 October, 1997

A65: Recentry, I don't know what company is developing the Stirling engines for the cogeneration. A few years ago, several companies had developed the engine for such application in Japan. But I don't know that they have been developing it now.

Q64: Has anyone tried increasing the mass of the working fluid by any means other than higher pressure? Perhaps by increasing humidity, or even adding water to introduce some steam? It would seem to me that steam would be an excellent working fluid, because it would have more mass at lower pressures than some commercial stirling engines currently use. Or is there something I'm missing?
1 October, 1997

A64: I have heard that the Stirling engine using the steam as the working fluid was developed. The power of the engine was increased. But, I seem that it is difficult to keep the steam in the engine. Also, I wonder that the pressure loss in th eheat exchanger is increased.

Q63: How soon are we going to be able to use stirling engines on a world wide, or national level? How feasible are they to implement on a nationwide level for the majority of energy use? How efficient is it now compared to gasoline engines or electrice cars, and in the future? We are team debaters and would like anyones input on these questions or any other comments people would care to share with us.
25 September, 1997

A63: It is difficult to answer this question. I am one of the Stirling enthusiasts, then I believe the Stirling engine will be used on the world wide in near future.

Q62: Just completed your can engine today. I really was just doing a sort of quickie job to get some practice bending the crankshaft. I really did not expect my first engine to run. But after some minor tinkering and adjusting on the counterbalance, IT RAN! Thanks for your very helpful Web sight. Can't wait to get started on another engine. Thanks, again.
8 September, 1997

A62: I am very happy that I can hear your message. I hope that your engine will be pleased your family and friends.

Q61: Can you tell me in what markets/applications I could introduce a working, efficient, competitively priced stirling engine power source in the 300W to 5KW range? I see much written about models, technology discussions and history but very little about markets and marketing.
29 August, 1997

A61: Sorry, I don't know about the markets in detail. I cannot answer this question well.

Q60: I would like to share a quote from R.J. Meijer, Past president of Stirling Thermal Moters "The 90's is the decade of Stirling technology commercialization. Co-generation of heat and powerand solar-powered Stirling engines offer promising prospects. Multi-fulled generator sets for decentralized power supply in developing countries is anouther prospect.
However, under the renewed worldwide interest in the enviroment and pending strict legislation on pollution, other Stirling applications also emerge as very promising for the future. These include non-CFC heat pumps driven by electricity or by gas-fired Stirling engines, and Stirling-electric propulsion systems for mass transportation.
New enviromental concern and legislation has induced industry, especially in Europe and Japan, to refine and clean up existing internal-combustion technology. In the 90's, billions of dollars will be spent to develope engines with cleaner and quieter combustion. It needs only a fraction of this investment for the Stirling engine to conquer a stable position in the commercial market place.
It is up to industry and the financial world to give Stirling technology its support. Stirling technology is available: its time has finally come."
Thank you for helping some of us understand these principals!
28 August, 1997<

A60: Thank you for your information. I would like to descrive suce philosophy(?) related the Stirling technology.

Q59: My congratulations! Your web site is very good. I discovered my interest in Stirling Engines in your home page.
I finished construct your Can Stirling, but it didnīt work.
So I have some questions:
1) I used a cylinder with diammeter of 66 mm and 100 mm hiegh. This will cause any problem?
2) What is the correct position of the mass in relation to the piston?
13 August, 1997

(1) Your cylinder does not cause any problem. Please make sure that the displacer piston does not contact to the cylinder, and keep the clearance between the displacer piston and the cylinder to about 3~5 mm.
(2) The mass must be located to opposite of the engine stopping position. ( Sorry, I cannot explain well.)

Q58: I think that the Stirling engine has following problems.
(1) The engine has a lot of pressure leakage under the high temperature and high pressure.
(2) It is difficult to start the engine, because the engine torque is large.
How is solved these problem?
From Japan
6 August, 1997

(1) The piston ring of the Stirling engine is used 3-piece-type or 4-piece-type generally. The material is Teflon based. They are high seal performance thatn that of the internal combustion engines.
(2) As you said, the torque of the pressurized engine is large. But I think that it is not a big problem, because the compression ratio of the Stirling engine is very lower than that of the internal combustion engine.

Q57: This Q&A-Site is very helpful for me. Often is Styropor used for Low-temperatur-Displacer-Stirlings.
I tested stone and wood in form of wool. The best results I had with wood. Wood has 2,5 kJ/kg*K, better than all other materials!
Now I'm looking for a table, where I can find out the (spec.) surface of wood-wool and stone-wool for evaluation the optimum. Helpful is also a table with the current-resistance to find out the optimum.
Can someone help me? Is there anyone, who testet water as regenarator for low-temp-Stirling? It's only an idea, but what happens, when just a little steam is in the Stirling?
Thanks for the best over Stirling ever published!
4 August, 1997

A57: I don't have any information about the table. Please contact him or me, if anyone have the information.

Q56: I heard that there is a stirling-engine, built out of very cheap and easy-to-get materials: test-tube, marbles etc.
The inventor's name is said to be Schlagenhauf (I found some information about the machine in 'Stirling World'). Do you know more about it?
4 August, 1997

A56: Yes, I do. I have seen the test tube engine and it is veru interesting. There is more information on a following web site.
Omniscience Futureneering

Q55: I am interested in making a model low temperature solar stirling engine similar to the Bomin sunpulse.
What material do you recommend for the displacer/regenerator?
2 August, 1997

A55: It is difficult to answer this question. The displacer must be light weight. On the low temperature Stirling engine of Saitama university, the material of the displacer is polyurethane. The regenerator material is piled mesh made by brass. I think that more beter regenerator material is found after more consideration.

Q54: Concerning the Schmidt Theory, I believe there is an error in the calculations for the example. The indicated power, Li, appears to be in error. Believe it should be calculated using Wi. It appears that the calculation as given made a sign error on Wc.
26 June, 1997

A54: Thank you for your suggestion. I will find my error and reform it.

Q53: i liked the web site and found it very interesting. I have seen the drawing of Roy Darlington's marble engine with fly wheel are there any pictures of it anywhere.
20 June, 1997

A53: I don't know about the marble engine. Sorry.

Q52: Hi, i am just a beginner on Stirling engine and i am doing a research on it at the moment.
I just wonder, that the Stirling engine you shown on the page "Stirling engines Structure" does it use the Steam Cycle?
If not, what is the different between Stirling Steam cycle engine and the Two Piston Type of Stirling engines?? (well, is there any differences)
19 July, 1997

A52: The Stirling engine and the steam engine are the same internal combustion engine. But they are diffrent type engines at all. The Stirling engine has no valves, and is a closed cycle. The steam engine has some valves, and is a open cycle.

Q51: I wrote you last in question 13. I was wondering if you have uncovered any information on the Bomin "selfstarting" process yet.
In any event, I have information for you on the Tailer engine. An excellent paper by Peter Tailer and Jonathan West appears in Vol 4 of the Proceedings of the 22nd Intersociety Energy Conversion Engineering Conference, IECEC '87, Vol 4, Pages 1914-1919. The title is "Plunging Cylinder Liquid Piston Stirling Engine." There are many other interesting articles in that volume (and others of the 4-volume set) as well on regenerators, novel mechanical linkages, and different engine types, including a novel single cylinder valveless engine with no displacer. The 87 proceedings are the only set that I've been able to get and it has provided many hours of thought provoking enjoyment. If you can't get the whole set or Volume 4, try to get the paper, "Rotary Liquid Piston Stirling Engine," by Stephen C. Baer on pages 1920-1923.
Thanks for your continuing dedication to your Stirling site.
13 June, 1997

A51: I cannot understand a construction of the Bomin's HEATPULSE enough. I think that it is a free piston or liquid piston type engine. If so, it is possible to "self starting", maybe. In my opinion, the engine with the self starting mechanism cannot keep a high engine speed. Because the engine must have a low compression.
Thanks again for your information of the papers of IECEC. I will be able to get the papers, though I need enough time.

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Koichi Hirata

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