Stirling Engine Q&A Q151-Q200


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Q&A from December 24, 1998 to May 5, 1999.


Q200: I have been watching your site off and on for over a year and a half now. I am especially interested in your rotary displacer engine, since I have been attempting to come up with an idea for a completely rotary Stirling engine for a few years now.
The reason that I am writing is that ever since I've seen your plans for the rotary displacer Stirling engine, there was something about it that didn't seem right. Then, recently, it hit me. The rotary diplacer engine, as I understand your design, does not have a postive displacement of the air in the displacer cylinder. I'll try to clarify by comparing a typical piston displacer against your rotary displacer. In a piston diplacer engine, the displacer piston will push most of the air out of the displacer cylinder. In contrast, the rotary displacer in your design only moves the air around the displacer cylinder. It is only by heating the air in the displacer cylinder that the rise in air pressure causes it to perform work in the power cylinder. At least that's my impression, as I have studied your plans. Please correct me if I'm wrong. I belive, assuming I'm correct, that that is probably the reason for the mundane performance your have noticed in the engine.
My idea for, theoretically, improving it, would be to make the displacer look more like a cam and have spring loaded wipers (the wipers themselves being of a low friction, rigid material) set at 180 degrees apart. The wipers would ride on the displacer cam and seal against air leaking past. This way the displacer is not pushing the air around the cylinder, but instead forcing the air out of the working half of the displacer cylinder and into the power cylinder. The added benefit may be that the same displacer could use the other half of the cylinder as the working half for another power cylinder. The main obstacle to this is finding a low friction sealing material that can withstand high temperatures.
Do you think the idea would work? I, currently, can't build such an engine because I lack the machining equipment. If you would like, I could draw some pictures to show what I mean.
5 May, 1999
USA

A200: That is right. In the case of the rotary displacer type Stirling engine, the displacer moves the air around the displacer cylinder. My rotary engine cannot push out the air to heatexchangers compulsory, though the displacer of the typical piston engine does so. I seem that such rotary engine cannot get higher performance. I vaguely understand 'the spring loaded wipers'. But I can not imagine the engine structure with the wipers clearly. It is difficult to use two power cylinders for one displacer probably.


Q199: G. Walker says that stirling engines are not self starting. But I think the multiple-cylinder engines ( 3 or more cylinders, single action, or 2 or more cylinders, double action ) MUST be self-starting, like steam engine.
What's the truth?
29 April, 1999
Hungary

A199: I think that G. Walker is truth. When the multiple-cylinder engine has an enough temperature difference, there is not any cause of compression or expansion of the working gas by the piston. If the engine is self starting, it needs any other devices, I think.


Q198: I really enjoyed your page about stirling engines. I have a question about the simple engine built with a can and a balloon. Are both ends removed from the can or only the end with the balloon? If both ends are removed, what prevents the balsa wood piston from being burned by the candle? Thank you for a very interesting page.
28 April, 1999
USA

A198: It is only one end for the balloon. In the case of the Stirling engine, the air must be sealed, so it should not have any hole at the another end of the can.


Q197: I agree with nearly everyone that this is a well-done, informative, and thoroughly entertaining web site. Congratulations, and thank you!
I am just wondering if you know of Stirling Thermal Motors' STM 4-120 engine, for use in automobiles.
http://www.stmpower.com/
They claim 90 kW at 6000 rpm for an engine weighing 124 kg, which as far as I can gather is power-to-weight heretofore undreamed-of for Stirlings. ~.73kW/kg beats the specific power of any Stirling I have ever heard of by a factor of about 100, and if STM can be believed, constitutes a powerplant of roughly equivalent power/weight of the most efficient IC engine I have ever seen described: namely, the cutting-edge, high-performance, all-aluminum, multi-valve fuel-injected 3 cylinder, 1.5 liter IC engine used in GM's Ultralite prototype vehicle in 1992 or 1993.
http://www.gm.com/
If this claim is true, wouldn't you agree that Strlings are now very, very close to turning the automotive industry on its head? Give me their STM 4-120, scaled down to about 30 kW and 45 kg, and I will quickly build a series hybrid electric vehicle using flywheels as supplemental energy storage that will get 300 mpg, hold 4 people comfortably, and accelerate from 0-60 mph in under 4 seconds.
25 April, 1999
USA

A197: Thank you for the valuable information. As you say, a high-performance Stirling engine can be used the power source of an automobile. However, it is wonder if the power, efficiency and weight of the Stirling engine can be reaced to the same or higher than the existing internal combustion engines. When the STM 4-120, whichi is one of the high-performance Stirling engine, works with biomass or solar energy, it operates with about 25 to 30 kW of the output power. It is the best operational condition, maybe.
Well, I describe my opinions about the STM 4-120 for the automobile in follows.
(1) Are the high-pressure and the high-temperature safety?
(2) Does the engine have enough endurance performance in the operation with the high-pressure, high-temperature and high-speed.
(3) There is a big diffrence in the same engines. So, is it difficult to scale-down? Is it the limit of the engine performance?


Q196: My name's Michele and I'm writing you from Cremona, Italy.
I'm an Engineering student and I found your interesting Web Site in the academic environment.
I would like to post you some simple question about Stirling motor but previously I wish check if you aren't too busy.
The questions refer to the possibility to use the machines you describe to cool if they are attached to an electric motor so using the inverse-cycle.
I'm looking forward to read news from you!
25 April, 1999
Italy

A196: In my opinion, the application of the inverse-cycle (the refrigerator) can put the characteristics of the Stirling cycle to practical use. Several ultra-low-temperature refrigerators are already practical used. And a practical used refrigerator or air-conditioner for home use will be come soon.


Q195: I know that a Stirling engine can work with the heat source of hot water or combustion gas. Well, in the opposite, can the Stirling engine work with the heat source of cold water? What type is the engine? Please tell me the detailed information.
20 April, 1999
Japan

A195: A low-temperature differential Stirling engine, which uses hot water as the heat source, can work using the cold water as the heat source essentially. However, the temperature difference is smaller than the hot water used engine. So, the cold water used engine must have a large heat transfer area.
The hot water used engine, which operates at 100 deg C water and 20 deg C room temperature, has 80 K of temperature difference. On the other hand, the cold water used engine, which operates at 0 deg C cold water and 20 deg C room temperature, has only 20 K of difference. So, you can know that the operation of the cold water used engine is too difficult.
In considerations of thermodynamics, Power and efficiency of the engine are decided by the ratio of absolute temperature. So, the hot water used engine has the temperature ratio of 293 K / 373 K = 0.79, the cold water used engine has the temperature ratio of 273 K / 293 K = 0.93. Efficiencies of Carnot Cycle are, respectively, 1 - 0.79 = 0.21, and 1 - 0.93 = 0.07. Here, power is lead from the next equation.

[Power] = [Heat input] x [Efficiency]

So, if the hot and cold water used engines have the same power, the heat input of the cold water used engine shoul be 3 times (= 0.21 / 0.07) of that of the hot water used engine. The heat input is lead from the next equation simply.

[Heat input] = [Heat transfer coefficient] x [Surface area] x [Temperature difference]

Therefore, in order to increase the heat input, the engine must have high heat transfer coefficient or large surface area. Of course, it is too difficult to get high temperature difference in the case of such low temperature differential engine.
When the power, described in above equation, is larger than the mechanical loss, the engine can work. The small power engine should have few mechanical loss.
As the first step, I recommend to calculate the ideal power with the Schmidt Theory, and to build a hot water used Stirling engine.


Q194: Does anyone know something about russian sirling or hot- air engines?
Please reply
18 April, 1999
Netherlands

A194: I don't have any information about it. Please tell us the information about the Russian Stirling technology.


Q193: Hello everyone,
I doesn't know a lot about the Stirlingmotor, and I'm looking for some information.
Please only send information in English and Dutch.
Thanks!
16 April, 1999
Belgium

A193: I regret that I cannot prepare the Dutch information. Please connect to Begginers page, or find other German web sites from my link page.


Q192: I have read a lot about Stirling and other types of hot- air engines. i found that they were even made in Pakistan.
I never found anything about a Russian one. Does anybody know something about that or where to find information? The reason I want to know is combining two interests: Stirling and Russia.
15 April, 1999
Netherlands

A192: Thank you for your information. I regret that I don't know about Russian Stirling engines. If anyone have the information, please contact to us.


Q191: Hello !
I wonder where I can find a animation on a stirling engine done in the language C++.
13 April, 1999
Sweden

A191: I don't know. If anyone have the information, please contact to us.


Q190: Hello
Finally I found a site on which one can ask questions about Stirling engines.
I have read many years ago an article in Reader's Digest in which the author praised the Stirling engine for all its advantages (low pollution , low emission of heat which is very useful for the military use ...) so I wonder if there aren't yet any powerfull Stirling engines which can be used to power automobiles ?
12 April, 1999
Israel

A190: As you said, the Stirling engine can reach the low pollution and low emission. But in the case of the automotive engine, I wonder that the Stirling engine is better than other internal combustion engines, or not. Because the Stirling engine has a high cost and it does not have enough higher thermal efficiency. Please see Q197.


Q189: I look for a Stirling engine (15 kW) to install in a car.
12 April, 1999
Germany

A189: I think that you can find the 15 kW class Stirling engine from my link page, though it is too expensive.


Q188: On your drawing for the LSE-01 engine, you say to use a 3cc glass syringe. Have you tried it with a 2cc glass syringe? I have found that 3cc syringes are hard to come by and tend to be expensive. 2cc syringes are much easier to find.
31 March, 1999
USA

A188: I have not tried it with the 2cc glass syringe. But it is not problem for you. You can build the LSE-01 using it, with a little reform of the engine size.


Q187: I just finished a quick look at your gallery and I am most impressed with what I saw there. I wish that there was a bit of a discription of each display but maybe my computer being so old might not be able to bring it up in a timely manner.
29 March, 1999
USA

A187: Thank you for your suggestion. I will prepare a bit of the discription in near future.


Q186: Answer to Q152 is Yes, NASA has developed a free-piston engine for use in space. They also have a website.
25 March, 1999
USA

A186: Thank you very much!


Q185: I am student (at 12 Class in Bavaria Germany) and I am very interestet in Physics. So, I will make the "Facharbeit" (like Diplom work) in Physics.
My theme is: Build a Stirling Engine. Now I ask you if you can send me more details how to bild a Stirling Engine that is transparent (You can look inside the Cylinder). If you have plans and more Information about that, plese send it me. Thank you very much.
Our School Homepage: http://www.t-online.de/home/Lsh-ising.hml
21 March, 1999
Germany

A185: I don't know "Facharbeit" and "Diplom". Can you refer my "Let's build Stirling engines" page?


Q184: Have you had any experiance with moveing regenerator type stirling engines? Ive built one after reading about it in a modle enginering magazine from the 70's. It runs very nicely and seems very efficient. Would you like to see it I may be able to send a photo and some specs if you like.
see you
16 March, 1999
Australia

A184: Yes, I have. In the case of a 100 W class Stirling engine 'Ecoboy-SCM81' which we are developing, the regenerator is located in the displacer piston. Detail information is here.


Q183: I am looking for a low cost engine for use in my home-made solar concentrators (Scheffler collector), used at present for community kitchen units. It gives 2 to 4 kW thermal.
In fact I've been trying to trace the fluidyne engine. Please give as much info as you can!
15 March, 1999
Sudan

A183: It is difficult tofind the low cost engine with 2 to 4 kW output. Because, such powerful engine needs high efficient heat exchangers with high pressure. I think that it is too expensive.


Q182: I have realy learned from your site. Congratulations. You have done a wonderful job.
8 March, 1999
Colombia

A182: Thank you very much!


Q181: Stirling engines work well to convert delta T to E.
In reverse, they could convert mechanical energy to delta T.
Used as a heat pump, one could be used as part of an air conditioning / heating system. Has anyone got models or published how-to information using this configuration?
3 March, 1999
UK

A181: I have not heard the model of the air conditioning / heating system well. I think that a low-pressurized Stirling cooler cannot reach enough low temperature.


Q180: Thank you. I was looking for an interesting and scientific project for my students in Tech Ed. I have found some! I will keep you advised as how the students succeeded with them.
28 February, 1999
USA

A180: You are welcome!


Q179: As a total Stirling engine novice, I found your site extremely informative.
My feelings are that the Stirling engine, designed to operate with a low temperature differential, (Tropical sea water against a solar collector), would offer a maintenance -free part of a desalination plant for the hotter parts of the third world.
Is any research being done in this area ?
27 February, 1999
England

A179: I also think that the system with the high-performance low-temperature Stirling engine is very effective. We studied the low-temperature Stirling engines at Saitama University until March 1997. The reseaching results shows in this site.


Q178: Are there any stirling motors comercially available? If, what is their power?
What is the minimum temputure to let it work?
20 February, 1999
The Netherlands

A178: I know that there are some Stirling engines comercially, but I don't know that they are sold in reasonable price, or not. Please find them from my link page.


Q177: Now, I am building the LSE-01 type Stirling engine. But it does not work! What is the reason? I tried something in the followings.
(1) In order to decrease the friction, I cleaned the glass syringes.
(2) In order to get the high temperture difference, the cold side was in water. So, it could work slightly.
As additional information, the size of the glass syringes is 50 cc. And the piston of the hot side has been broken somewhat.
16 February, 1999
Japan

A177: The reason is that the engine has much gas leakage or big friction loss, maybe.
The gas leakage is caused by a broken gasket or defective gluing between a grass cylinder and a cover. Please check them. The friction loss becomes big, when the hot side piston touches a rubber gasket, or the crank mechanism has defective assembling. Please check them carefully.
Additionally, in the case of the engine used 50 cc glass syringes (25 mm of cylinder diameter), the engine needs enugh heat input, so it cannot work wit heating of an alcohol lamp or a small lighter.


Q176: Are stirling cycle engines available that will generate power in the 1 M.W. range at 60 Hz?
13 February, 1999
Canada

A176: It is diffucult to get 1 MW with one unit of a Stirling engine. It may be able to get the 1 MW power with plural Stirling engine units. If so, very higher technologies, than that of the present situation, are needed to development of the engine.


Q175: Hello and thankyou for a very useful site!!
I am interested in applying Stirling engines to generate electricity from solar power, using e.g. the concentrating solar collectors from http://www.suntherm.com/ (they use steam engines which are not as efficient and require the generation of steam). I have the following questions:
a) looking through your answers and questions and the Web, I have not found plans for a Stirling motor in ,say, the 3kW class (there are plenty of commercial sites, but no plans for hobbyists). Does anyone know of such plans ?
b) I came across a site (which I have lost, sorry) which suggested using two piston/cylinders from an VW IC engine to make a steam engine. Has anyone thought of using auto parts to make a Stirling engine, maybe an alpha type? Do you think such an engine could be made ?
c) As I am primarily interested in generating electricity, not mechanical energy, I am interested in hearing your opinion of the thermomechanical generator, which uses the Stirling cycle. Are these machines suitable for solar power generation? Has any hobbyist built one of these? It should be quite easy, as there is no piston, just a diaphragm and a displacer on a spring.
Any comments to walter.scott@acm.org are MOST welcome!
11 February, 1999
USA

A175: I cannot answer these questiosn.
a) I have not seen the plan of a 3 kW class Stirling engine. No one publish the plan on any web site, maybe.
b) What is the VW IC engine?
c) What is the thermomechanical generator? Is it a special generator?


Q174: I want to measure the shaft power of a Stirling engine. But I do not know to measure torque. What is the way to measure the torque? What parameters do have to measure for estimating the shaft power except engine speed and torque? What is the way to measure these parameters?
9 February, 1999
Japan

A174: The shaft power can be lead from the engine speed and the torque. I would like to prepare another web page for the measuring methods.


Q173: Do you know of anyone selling a 1 hp to 10 hp stirling cycle engine?
8 February, 1999
USA

A173: I know that there are some Stirling engines comercially, but I don't know that they are sold in reasonable price, or not. Please find them from my link page.


Q172: How do you time between the hot piston to the cold piston & on a 1.5" bore moter what should be the clearance between the hot piston and the cyl. head , I build this sterling and I can not get it running, any help or trouble shooting info. Thank you for your web page
7 February, 1999
USA

A172: Sorry, I cannot answer this question adequately, because I don't know what the engine type, working temperature and other specifications. It is important that the engine has no gas leakage and no friction loss. The bore and the top clearance between the piston and cylinder wall are not important. However, the side clearance between the power piston and cylinder wall is very important. Because the side clearance affects to the gas leakage. You must decide the clearance under the consideration of the working temperature and materials of the piston and cylinder. Please find the suitable size through trial and error.


Q171: I have knowledge about the use of Stirling engines in space. (Question #152).
As far as I know, Stirling engines have not been space. The hydrogen/oxygen powered fuel cell puts out more power in a smaller and lighter space.
But as you know, a Stirling Engine spun in reverse acts as a refrigator.
And Stirling cycle refrigerators have been used on the U.S. Space shuttle. In fact the Sunpower Company (Athens, Ohio, USA) built them for NASA. I went to college in Athens, Ohio, USA and have met the engineers that designed the refridgerators for NASA and the space shuttle.
6 February, 1999
USA

A171: Thank you for your information.


Q170: I have a project going on about using a stirling engine in a green house for tomatoes wicht is the biggest inncome where I live.
I wonder if I can use a stirling engine to drive a generator then use that power too heat water (about 100 KW element), and use the cooling water,exhaust (Co2). We are now using oil heated water to warm up the greenhouses wicht is very expensive. Recomendet water is appr.350-500 L.
I wonder if this is possible today, and if it is where can I buy an engine and how big I need for this project.
I also want too buy a modell of a working stirling engine. Do you know where I can buy something like that.
I hope you like this idea and can help me out with this.
5 February, 1999
Norway

A170: I am very interested in your propject. But it is difficult to get the practical generator power using the heat water, though it is affected by power level. I think that you cannnot buy the Stirling engine for the application, today. On the other hand, you can buy the model Stirling engine soon. Please see to 'Link Page'.


Q169: I am looking for a simple way to measure the output power of a model Stirling engine, and necessary calculations.
1 February, 1999
UK

A169: I think that I will prepare another web page for the measuring. Sorry.


Q168: I'am trying to build one of your model (can sterling engine). My goal for the future is to build a sterling engine that is capable to run an alternator or generator to produce electricity. Whit this, I will be able to charge bateries and supply electricity for me house. What do you think of my project. Is it possible ?
I'am looking for plans and suggestions. Here in Canada, I can use wood as the heat source.
1 February, 1999
Canada

A168: It s good project, though it is difficult to build and realize the engine soon. Especially, wood is good heat source for a solution of environmental and energy probrems in the future. Also I think that it is difficult to find the plans recently.


Q167: I have observed your site for over 1 year and you are very dedicated. I live in an area outside of silicon valley and it gets very hot in the summer. I would like to experiment with a solar engine, one that maybe rotates from sun to shade or has a shield that slides back and forth over the cylender to allow heating by sun and cooling by shade, and then eventually connect to an air conditioner. since it would only be needed when it is sunny (and hot). I thought it would be a good aplication for a heat engine. Please return your thoughts.
30 January, 1998
USA

A167: I think that your idea is very good. The air conditioner must be driven with the natural energy like the solar energy. However, it is too difficult to develop the solar Stirling engine, which use solar and shade. The engine has too low efficiency, and does not have enough power for the application.


Q166: Hello Mr.Hirata, we shortly talked in Ancona at the 8th ISEC. I am interested in the Ericsson engine(caloric machine) and trying to build a new version of it. Anyway here my question: Why was the Ericsson engine not further developed yet ? It doesn˘t suffer from high turbulence losses through the regenerator, supplies isothermal heating, a very big heating surface and by that best eficiency. Can you give me an answer ?
29 January, 1999
Germany

A166: I am very interested in your new Ericsson engine. I think that a cause of the few development for the Ericsson engine is follows. In the case of the Ericsson engine, it is difficult to keep the high pressure in the working space by the some valves. As you know, the Stirling engine can get the high power and high efficiency by the high pressure. But I seem that the Ericsson engine has a bright future, when it is operated in a lower pressurized condition.
Sorry, I have not studied about the Ericsson engine yet. So I may have mistakes. Please keep up your project, and I hope to see you and discuss again.


Q165: In our university, we are building a two-piston type Stirling engine using glass siringes. Two siringes are conected with a silicone rubber tube. As the siringe is heated directly, the rubber tube is extended and has a gas leakage. Is there any solutions? We use an alcohol lamp as a heat source. Does it have enough heat? Also, the engine cannot work till cool down after heating (the piston may be expanded). How should we heat the engine? Is it better to have much air in the cylinder? Finaly, how is the best phase angle between the pistons? Sorry, too many fundamental questions.
27 January, 1999
Japan

A165: I have not built such type Stilring engine, and answer the questions as far as I know.
I recommend to fix the silicone rubber tube and the grass syringe with a stainless wire. Few gas leakage is kept while short time.
If the engine has few gas leakage and friction loss, it can work using the alcohol lamp.
The expansion of the piston is caused by lacked cooling heat. Please consider to cool the cold cylinder.
It is not better to have much air in the cylinder. You must decrease the dead space in the cylinder. General high performance Stirling engines get high power by pressurized working gas. In such case, in order to keep the balance to piston force, a buffer space, which is behind space of the piston, must be pressurized.
Generally, a Stirling engine has the highest power when the phase angle is set to 90 degrees. However, more larger phase angle (about 120 to 150 degrees) is better, when the heat input is small or heat transfer of the engine is low. It caused that the engine, which has the larger phase angle, increases the exchanged heat in the engine. Please try to operate with various phase angles.
I hope your success.


Q164: What is the formula for determining h.p. output in relation to temperature gradiant used to run the engine?
Are there any suppliers of manufatured stirling engines (not models)?
Are detailed plans available for home building?
25 January, 1999
USA

A164:


Q163: POWERFUL STIRLING ENGINE.Now I finally got some drawings on a 4 KW Stirling engine. This is built around a hot water boiler as cylinder. The cranchshaft is from a compressor, and the flywheel is about 200 kilos ! a whel form train. As a gasket is used a tyre from a bicycle or You can use a gasket from big cement tubes for waste water.
Copys and explanation of this LEHMAN type stirling engine costs usd 10. - I havent tried to build it yet, but will very soon.
25 January, 1999
Norway

A163:


Q162: Is there a vendor for Sterling cyle engines?
24 January, 1999
USA

A162: The model Stirling engines are sold in the world. But, I think that more practical Stirling engines are not sold generally. They are only experimental or developing used, and very expensive.


Q161: Where can I purchase a Stirling engine powered generator suitable for recreation camping?
Would look for perhaps 650 watts into 240 volts or 8to10 amps at 12 volts. Propane gas powered.
24 January, 1999
England

A161: I think that the PPS16 engine of Whisper GEN is the best for your request. The url is;
http://www.whispertech.co.nz/index.htm.
But I don't know if it has been sold now.


Q160: Are you aware of anyone working on a stirling engine design that could use wood as a fuel source for remote home power supply? Thanks for a great web site!
21 January, 1999
USA

A160: Biomass fuel Stirling enegines are dedveloped at a technical university in Denmark. The engine has 40 kW of output power, and it is being made an experiment by a reference of a conference.


Q159: I have downloaded the source for Schmidt analyse program, but I can not make it run - can you explain how I can compile the progra.
18 January, 1999
Denmark

A159: The source is used in Microsoft Quick Basic 4.5 (QB45). I have made sure that the source run in QB45. But I could not compile the program today. I don't know the cause yet. If you don't have the QB45, you cannot make it run.
Do you have Microsoft Visual Basic 4.0 or higher viersion? If so, I can prepare another program for Schmidt analysis for it.


Q158: A few years again I purchased a book on the Sterling Engine which I have read more than once. I find the engine fasinating and would like to build one around the 5hp and probably the twin piston would be most suitable. I have a few questions which I hop you can help me with:
1. Where can I get to scale plans
2. How do you lubricate the piston.
3. How do seal the piston to the cylinder wall.
If you can steer me in the right direction I would be grateful.
18 January, 1999
Australia

A158: It is difficult to answer your question for me. I have never seen the available scale plans for 5hp Stirling engine. I seem that you must design the engine by yourself. First, you decide the engine size and mean pressure. Next a structure of the heat exchangers are decided by the kind of fuel. They are not so easy.
In the case of the general high temperature Stirling engine, the piston cannot be lubricated. Because performance of the heater and regenerator becomes low, when the oil sticks to the heat exchangers. So, the piston rings made by Teflon based are used, and do not lubricate. They are general information. If you have special idea, please adopt it.
Sorry, my lacked answer.


Q157: Has anyone coverted a gas motor 2cyl or 4cyl to operate on this principle? Hot air / cold air compressor. Getting heat from solar pannels.
11 January, 1999
USA

A157:


Q156: I would like to obtain Stirling engines plans, such as those developped by Ford, Philips or any other firm, and information about it, to expose its principle and advantages to a board of examiners.
10 January, 1999
France

A156:


Q155: Hi and congratulations on your efforts with this site.
I am new to this innovative engine, and wondered about the methods used to produce high output generators etc.
Do they use large quantities of smaller pistons, or aim to get higher efficiency and differentiation to achieve higher power? Also, why is it not possible to utilise a liquid to affect the movement of pistons, in a way like a hybrid steam engine crossed with a hydraulic motor,, but utilising the principle of differentiation as the Stirling concept does.
I hope this makes sense, and is not too naive.
9 January, 1999
Australia

A155:


Q154: I am interested in building a Stirling Engine to run a generator from 500 watt to 3 kva.
As I live in an isolated area and am fully self sufficient as regards to power, and I find the Stirling Engine concept extremely interesting and think it would be of enormous benefit to me as I could run it on wood and the idea of it being very quiet appeals to me.
Can you recommend any good sites showing diagrams, photographs and information?
I have started building a model but would appreciate any advice you can give me and different sizes available.
9 January, 1999
Australia

A154:


Q153: As a graduation thesis, I try to develop the small Stirling engine, which has 300 ml of volume and uses exhaust gas of an automobile as a heat source. I built a kit of coffee cul Stirling engine. I think that I almost understand the structure. But follows are not understood yet.
(1üjHow is the atmosphere pressure Stirling engine?
(2) Is there a relation between the volume of a cylinder and heat surface area of a heat exchanger?
(3) I have a plan that the engine has a heat exhanger in a displacer piston. What is a problem for it?
Please tell me them.
5 January, 1999

A153: It is difficult that your Stilring engine kit is applied to the exhaust gas used engine. Because the engine kit operates with low temperature difference.
(1) High pressurized Stirling engine can be compact size, and have high power. A practical used Stirling engine needs high pressurized working gas. But if you want to know a basic performance of an engine, you can use an atmosphere pressure engine for your project.
(2) There is an impotant relation between the volume of a cylinder and heat surface area of a heat exchanger. In order to discuss in detail, you should calcilate the heat transfer of the heat exchangers.
(3) Is the heat exchanger, which is in the displacer piston, a regenerator? I seem that the engine has no problem. But if the displacer piston has low seal performance, the working gas does not flow in the regenerator.


Q152: I wonder why the don't use stirling engines in space. The sun is always available and cooling is also possible. Or is some country already using stirling engines in space.
27 December, 1998
The Netherlands

A152: I think that the Stirling engine has not used in the space yet. But the space Stirling engines are studying in USA, Japan and other countries. I hope that they are practical used in near future. In my opinion, there are several problems on the cost and life time compared with a solar cell, and vibration for the space.


Q151: I don't know the way to draw a P-V diagram of a Beta-type Stirling engine. Please tell me any program of a Schmidt analysis.
24 December, 1998
Japan

A151: I offer a program source of the Schmidt analysis. This is written by Quick Basic 4.5. I have not prepared any explanation about it.


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Koichi Hirata

e-mail: khirata@gem.bekkoame.ne.jp (Home)
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