Stirling Engine's for Power Generation

Do these help?

http://www.stirlingengine.com/

http://www.bekkoame.ne.jp/~khirata/

http://www.sesusa.org/

http://www.discoverthis.com/how-to-build-stirling.html

Reader and Hooper produced a very good book titled 'Stirling Engines' back in the late seventies or early eighties. They have heaps of info on all common drive types including detailed analysis. The book is a collection of conference proceedings in written form.

Mechanically speaking, standard crankshaft and pistons is awefully simple. Just remember they are 90 degrees out of phase not 180

You might want to consider steel concertina seals with oil transfer fluid on the cold side to reduce the dead space.

Christy,

Have you checked on what Winnebago used years ago? I seem to remember that one of the motor home companies, and I believe it was them, used a Stirling engine for a generator in thier units. I would start there to get a little history. Good Luck!!

mastrsmth

The question you pose is not that simple to answer.

First you need to decide on some other issues:

• What will be the heat source?
• What will be the cold source?
• Which Medium/gas do you want to use?
• At which pressure do you want to work?

The power you are looking for is quite low.

What will be the end result? a series product or a one unique model?

It is certainly the last question which will answer your question. For a unique model the production cost isn't that important. Series models allow more trials.

Thanks for all of the responses,

I realize I left out a lot of information about the project in my first post. Here are some more details of what I'm planning:

-air at atmospheric pressure as the working fluid

- using fire as the hot source (combustion chamber of a cooking stove)

- using aluminum cooling fins and room temp air for the cold source

- the design is more of an appropriate technology application so low cost is ideal

I know Beta engines have a higher compression ratio but I was concerned about the linkages for the piston. Since the power piston has to have a pass-through for the displacer piston rod which makes the power piston rod at an offset I was worried about the complication of constructing it and side forces of the power piston.

I've had a hard time finding any information about how much worse the efficiency is for a gamma engine. I'd also really like to find/buy a copy of engine plans (not a toy model) if anyone know where to find them. I did buy The Regenerator and the Stirling Engine though, which helps some.

That should clear up some of the questions,

Thanks,

Christina

Christina,

Just some thougths from this side of the globe:

You should really rethink the working fluid: atmospheric air is one of the worst choices to make.

I'm working on a unit for use with a solar dish.

We are aiming for 1 kW of power.

I decided to gor for air at 1 MPa (10 Bar) as this can be supplied by standard hand pumps for maintenance reasons. The filling out of the factory would be N₂.

The same unit could also be filled with He of H₂ which would almost quadruple it's performance.

The financing of my project is not complete yet but it could be that the units could have the same basic mechanics.

Regards,

Gwen

Hi Christina. I and a colleague are also planning to build an engine.

Hopefully we can compare notes through this forum.

If you haven't already, check out: http://www.sesusa.org/plans.htm

Frank

I live on a small island in the Philippines. Whilst we have mains power brown outs are so common I've rigged up a 12v lighting system. I'd like to expand this to provide all our electrical power using an inverter. a Stirling engine running on wood/rice husks/garbage producing 400watts+ would be ideal to reliably charge my battery bank. So if anyone knows of available plans the local machine shop is ready to build. (They have already assisted me in building a wind turbine, but there is just not enough wind here to provide the 4KW we use every 24hrs)

Are you close by the sea?

Wave ore tidal current electrical generation could be much easier:

Waves can make a floater go up and down. if you mount a magnet on the floater and make it move up and down in a coil you will generate electricity. now it is important to dimension the coil/magnet combination so that the generated voltage is sufficient to fill the battery.

A small stream can drive a wheel which drives an alternator = tidal movement of the water can be converted into electricity if you let water fill a reservoir at high tide and let it flow back at low tide.

You see: with simple techniques you can do much more than going for high tech apparatusses like Stirling Engines or dangerous situations like steam generators and turbines. The power you need is not that enormous.

The rice husks can be fermented and transformed into bio ethanol or methane, which you can sell to drive cars or as coocking fuel. The residue of the fermentation process can be used as fertilizer.

As a steam enthusiast I disagree with your statement "...dangerous situations like steam generators and turbines." Water tube boilers are safe, they do not explode, and if a tube bursts the pressure is released within the boiler container and goes out the exhaust. A turbine is high tech and can be expensive, but as for danger, you can also lose fingers in a Stirling engine or a waterwheel if you are not careful.

There is nothing wrong in using the ethanol or methane from rice husks to power a steam engine or even in using the dried rice husks as fuel directly. The ash is a fertilizer too. To keep it simple use a Lysholm expander or Tesla Turbine as a steam engine. The former is a type of auto turbocharger running backward and is easily available and the latter is not hard to build in a good machine shop.

Stirling's seem to be good for steady, low power, heavy, stationary engines. As Gwen suggests, anytime you can increase the density or expansion differential of the working medium you will gain efficiency. Using compressed air would help as would using a water bath for cooling. The greater the difference in temperature/density the more power and efficiency.

As a Stirling entousiast I don't agree with the statment that you can make steam systems safe.

When you want to go for a decent efficiency you will have to pressurize the steam circuit. As you are working with water you will face corrosion.

When I guide people towards other techniques than steam it is for their own safety: when they are decent educated and understand the potential dangers and need for maintenance they can take their own decisions and go ahead.

In all other cases: especially those where they ask for plans so that they can build it: please be carefull and contacts specialists.

I live in a region with the highest technical education level of the world, and a lot of energy production units using steam. Each year we get the news that somewhere a steam pipe bursted and boiled some workers until well done. (sorry for those who had to collect them) The accidents in less educated regions are uncountable.

And I have to admit, Stirlings tend to be bulky when compared to and equal power delivering ICE, and they are dangerous as well (they are pressured up to enormous levels with Hydrogen) but the idea behind their functionality is so nice.

Many thanks for all your constructive suggestions. Unfortunately I am 2k from the sea so any scheme to harness wave or tidal power is out of the question. Our land is flat with no flowing water so hydropower in any form is also out of the question.

I had been thinking about steam power but had rejected it, mainly for the reasons presented by Gwen. I may be competent to run the engine (Steam locos was one of my passions in UK), but inevitably othes would gain access to the engine. This was why i gravitated towards the stirling engine. It doesn't matter how bulky, heavy or large this engine is as long as I can produce 400w+ for around 8hrs to help charge the battery bank. What is useful here is the heat from the tropical sun.

All our hot water is piping hot & free..... Can I utilise this for electricity generation in some way?

There are different way's to use solar energy to generate electricity.

• Concentrated heat to boil water and drive a turbine: large scale installations typically. Cost is moderate when you look tot the total energy production.
• PV: from small scale to large scale the simplest solution. Low efficiency and high cost are the biggest problems.
• Concentrated solar on Stirling engine: reasonable cost

The concentrated techniques need to be pointed to the sun: a guidance systems is needed. but they give back efficiencies up to 30% (PV is no somewhere between 12 and 18% for direct perpendicular solar irradiation)

PV cells don't have to pointed to the sun but the efficiency goes even further down.

There are quite some idea's starting up to develop a small Stirling engine which can produce 500 to 1000W driven by concentrated solar heat or burning wood. The cold part could be domestic hot water generation. The only thing we need now is money to start up the prototype building and testing. Series production can start approx 2 years later.

Interested investors can always contact me.