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'[OT]:Sandia, Stirling to build solar dish engine p'
2006\08\25@062818 by Luis.Moreira

picon face
Hi Guys,

A friend as emailed this link to me so I thought I pass it on.

I absolutely love sterling Engines and I am planning on building one
from a few Cans just to see how difficult it is to getting them working.


I am very pleased to see that Stirling Engines are getting a bit more
main-Stream and if you have any more info about them, like calculations,
tips, practical ways of using them, please just let me know.

www.sandia.gov/news/resources/releases/2004/renew-energy-batt/Sti
rling.html

Best regards

                  Luis



Luis Moreira

spam_OUTluis.moreiraTakeThisOuTspamjet.uk

tel. 01235464615

JET PSU Department

UKAEA Culham Division

J20/1/55, Culham Science Centre

Abingdon

Oxfordshire

OX14 3DB



2006\08\25@134115 by James Newtons Massmind

face picon face
Notice the date. It didn't happen. Again, stirlings are not reliable. They
are either A) inefficient and long lasting or B) efficient and wear out
quickly. They don't even have a C) option with high cost and both efficiency
and long life as far as I can tell. And yet people keep throwing money into
them. I'm sorry, but at what point is that stupid? How much money do we need
to waste on something that has been around for just about forever and has
NEVER been cost effective?

Russell, et all, will now argue the point.

But what is most important to me is that there are viable options OTHER than
stirlings for turning heat into energy that are NOT developed due to the
continued "promise" of stirlings. And some of them are dirt cheap or will
within the means of the average home machinist. For example:

techref.massmind.org/techref/member/plp-actcom-f00/sun-turbo-1.htm
Possible quite efficient, long lasting, not terribly expensive.

http://techref.massmind.org/techref/idea/mc-heat-inject.htm Not efficient
but cheap as all heck.

http://www.flashsteam.com/ Not efficient, expensive, but probably long
lasting. If he would use solar, the efficiency doesn't matter so much.

http://www.redrok.com/engine.htm Lots of information on many alternatives.
Not many completed projects.

http://www.fieldlines.com/story/2003/6/26/10248/0825 Lots of crazy ideas
just waiting to be tried.

And in keeping with "money where mouth is" I am interested in providing
partial financial support for the attempted development of any of the above
or other reasonable heat engine ideas OTHER than stirling. In return I get
non-exclusive publishing rights. You just have to document what you do and
the outcome. Pictures, simple text descriptions, measurements of the result.
It doesn't have to actually work, in fact, failure is GREAT because it shows
what not to do in the future.

---
James.



> {Original Message removed}

2006\08\25@191242 by Russell McMahon

face
flavicon
face
> Russell, et all, will now argue the point.


No arguments.
I'll just point out  a few 'facts' and be on my way to the church AGM
:-)

> Notice the date. It didn't happen. Again, stirlings are not
> reliable.

That, of course, very much depends.
Their siameses twin, Stirling cycle coolers can be and are made as
reliable as all get out. When your are being designed to live in a
ComSat you have t be.

> They are either A) inefficient and long lasting or B) efficient and
> wear out
> quickly. ...

You seem to be, surprisingly, so I may still be asleep, which is
entirly possible, confusing efficiency with power density. Properly
designed and built built Stirling engines, ie not the numerous model
ones whose designers have no idea about the absolute need for a decent
regenerator for real purposes, are as about as efficint as anything
around. What they are generally not, and what you may mean, is that
they are not "power dense". ie they tend to be large in volume and
possibly in mass for their power output. There are reasons for this,
which is no excuse when comparing them against alternatives. But in an
"alternative energy" world and for non-nobile applications this is
often no big deal. Lifetime is an increasing issue as you attempt to
improve volumetric power density.

> They don't even have a C) option with high cost and both efficiency
> and long life as far as I can tell. And yet people keep throwing
> money into
> them. I'm sorry, but at what point is that stupid?

Something / one is stupid if you don't like its face. There are
several good reasons to keep trying. But I'll not expand at length
now, except to say that

> How much money do we need
> to waste on something that has been around for just about forever
> and has
> NEVER been cost effective?

*WHEN* the big boys (or the little girls) finally crack the problems
it will rule the world (tm) and replace many alternative systems
BECAUSE the external heating feature allows any heat sourcem use of
low grade and "waste" heat, better efificency in any give case than
any alternative and ... . The mighty Philips organisation threw in the
towel - but that was due to accountants and other issues. They
estimated it would cost (AFAIR) 60 BILLION dollars to get it truly
right. And that the payback period would be under 6 months once
someone did.

At that point nothing is stupid :-)

ie once you achieve this holy grail it will be the biggest cash cow
ever known.

Which is not why the little guys do it. They have other motivations.
Many are at least as sensible ones as James' drive to ride electric
bike/car thingies, grow chickens, use solar panels etc.
An interesting data point. NZ mborn and made Whispergen whose ad I
posted recently are THE most succesful Stirling maker ever (depending
on your metric) and in the process of gearing up to fill orders for
AFAIR 100,000 or so Stirling engines. Why doesn't that count? (special
circumstances notwithstanding)




       Russell.

2006\08\25@191445 by Russell McMahon

face
flavicon
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> But what is most important to me is that there are viable options
> OTHER than
> stirlings for turning heat into energy that are NOT developed due to
> the
> continued "promise" of stirlings.

I intend to attempt a niche Stirling investigation sometime in the
next year. If I am successful, and it just might happen, you will hear
more about it :-)


       Russell


2006\08\25@194543 by James Newtons Massmind
face picon face
> > But what is most important to me is that there are viable options
> > OTHER than stirlings for turning heat into energy that are NOT
> > developed due to the continued "promise" of stirlings.
>
> I intend to attempt a niche Stirling investigation sometime
> in the next year. If I am successful, and it just might
> happen, you will hear more about it :-)


Actually, I think this is part of the problem: "If I am successful... You
will hear about it"

The problem is that we DON'T hear about all the Unsuccessful stirling
projects. Documenting failure is important. I do it, for example, with my
server:
http://www.massmind.org/techref/servfail.htm and people hit that web page
all the time, referred from Google, searching for one of the error messages
that I have documented.

If all the stirling failures and eCar battery failures and community
designed programmer failures were documented, people would move on and try
some of the things that haven't failed a million times already.

Just my humble opinion, of course, and I would LOVE nothing more than for
Russell or anyone to prove me wrong and develop an efficient, long lasting,
low cost of operation stirling engine.

In the mean time...

there are viable options OTHER than stirlings for turning heat into energy
that are NOT developed due to the continued "promise" of stirlings. And some
of them are dirt cheap or will within the means of the average home
machinist. For example:

techref.massmind.org/techref/member/plp-actcom-f00/sun-turbo-1.htm
Possible quite efficient, long lasting, not terribly expensive.

http://techref.massmind.org/techref/idea/mc-heat-inject.htm Not efficient
but cheap as all heck.

http://www.flashsteam.com/ Not efficient, expensive, but probably long
lasting. If he would use solar, the efficiency doesn't matter so much.

http://www.redrok.com/engine.htm Lots of information on many alternatives.
Not many completed projects.

http://www.fieldlines.com/story/2003/6/26/10248/0825 Lots of crazy ideas
just waiting to be tried.

And in keeping with "money where mouth is" I am interested in providing
partial financial support for the attempted development of any of the above
or other reasonable heat engine ideas OTHER than stirling. In return I get
non-exclusive publishing rights. You just have to document what you do and
the outcome. Pictures, simple text descriptions, measurements of the result.

It doesn't have to actually work, in fact, failure is GREAT because it shows
what not to do in the future.

---
James.


2006\08\25@195126 by James Newtons Massmind

face picon face
> You seem to be, surprisingly, so I may still be asleep, which
> is entirly possible, confusing efficiency with power density.
> Properly designed and built built Stirling engines, ie not
> the numerous model ones whose designers have no idea about
> the absolute need for a decent regenerator for real purposes,
> are as about as efficint as anything around. What they are
> generally not, and what you may mean, is that they are not
> "power dense". ie they tend to be large in volume and
> possibly in mass for their power output. There are reasons
> for this, which is no excuse when comparing them against
> alternatives. But in an "alternative energy" world and for
> non-nobile applications this is often no big deal. Lifetime
> is an increasing issue as you attempt to improve volumetric
> power density.
>

Err... Where exactly are the large, heavy, fixed, long lasting striling
engines that are useful for alternative energy applications? 'Cause I don't
see those either. Is it that they are so huge that they cost a ton and never
recoup their initial investment despite running for years and years?

I challenge ANYONE to show me a sterling engine ANYWHERE in ANY application
that has EVER recouped what it cost.

*crickets*

---
James.


2006\08\25@201903 by Gus S Calabrese

face picon face
^ James
You are so right about failures not being documented.   This means that
they are repeated over and over.  The next step in human evolution  
will include
the propensity to document failed attempts.   Look for my novel  (1)  
to come
out in 2007.  I will be using this idea in it.
(1) The 60,000 Year Experiment

AGSC ^

On 2006-Aug 25, at 17:45hrs PM, James Newtons Massmind wrote:

>> But what is most important to me is that there are viable options
>> OTHER than stirlings for turning heat into energy that are NOT
>> developed due to the continued "promise" of stirlings.
>
> I intend to attempt a niche Stirling investigation sometime
> in the next year. If I am successful, and it just might
> happen, you will hear more about it :-)


Actually, I think this is part of the problem: "If I am successful...  
You
will hear about it"

The problem is that we DON'T hear about all the Unsuccessful stirling
projects. Documenting failure is important. I do it, for example,  
with my
server:
http://www.massmind.org/techref/servfail.htm and people hit that web  
page
all the time, referred from Google, searching for one of the error  
messages
that I have documented.

If all the stirling failures and eCar battery failures and community
designed programmer failures were documented, people would move on  
and try
some of the things that haven't failed a million times already.

Just my humble opinion, of course, and I would LOVE nothing more than  
for
Russell or anyone to prove me wrong and develop an efficient, long  
lasting,
low cost of operation stirling engine.

In the mean time...

there are viable options OTHER than stirlings for turning heat into  
energy
that are NOT developed due to the continued "promise" of stirlings.  
And some
of them are dirt cheap or will within the means of the average home
machinist. For example:

http://techref.massmind.org/techref/member/plp-actcom-f00/sun-
turbo-1.htm
Possible quite efficient, long lasting, not terribly expensive.

http://techref.massmind.org/techref/idea/mc-heat-inject.htm Not  
efficient
but cheap as all heck.

http://www.flashsteam.com/ Not efficient, expensive, but probably long
lasting. If he would use solar, the efficiency doesn't matter so much.

http://www.redrok.com/engine.htm Lots of information on many  
alternatives.
Not many completed projects.

http://www.fieldlines.com/story/2003/6/26/10248/0825 Lots of crazy ideas
just waiting to be tried.

And in keeping with "money where mouth is" I am interested in providing
partial financial support for the attempted development of any of the  
above
or other reasonable heat engine ideas OTHER than stirling. In return  
I get
non-exclusive publishing rights. You just have to document what you  
do and
the outcome. Pictures, simple text descriptions, measurements of the  
result.

It doesn't have to actually work, in fact, failure is GREAT because  
it shows
what not to do in the future.

---
James.


2006\08\27@050649 by Russell McMahon

face
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>> > But what is most important to me is that there are viable options
>> > OTHER than stirlings for turning heat into energy that are NOT
>> > developed due to the continued "promise" of stirlings.

I don't think you can significantly blame Stirlings for suppression of
other designs - that sounds like a severe case of special pleading and
regenerator envy.  Anyone is free to design anything they wish and
each concept must stand on it's own thermodynamic cycle / two feet.

The sad fact is that it's easy (enough) to draw pretty pictures of
something that sounds and looks extremely plausible, but all too often
the thermodynamic basis isn't really there.

Stirling is the wannabe king because

- It uses the Carnot cycle which is THE most efficient cycle possible.
- It uses external combustion.
- It SOUNDS easy to do :-)

It's easy enough to make a good engine using another cycle that's more
efficient than a poor Stirling design. But the top Stirling design is
about unbeatable. It's just that nobody's been able to build it and/or
make it stay together long enough yet :-).

Stirlings biggest problems revolve around the fact that you are using
hot gas as the energy transfer medium. Gas volume x delta-temperature
products must be large for large power. Gas volume size comes from
either big cylinders (so heavy and large) or high pressures. Next step
is to use a gas with higher specific heat and you're into Helium, or
king Hydrogen. Hydrogen has all sorts of advantages, but staying
inside our motor is not one of them. It will diffuse through steel if
it must, but it's even happier leaking through perfect seals and the
like. Steel that has had Hydrogen diffuse through it gets all anmd
tends to fall apart. Big delta temp comes from bigg hot end temp and
you have problems again.

IF you are happy to go for a low emperature, high volume, low pressure
design using air then you can make reasonably good Stirlings
reasonably easily. But big, heavy and gutless yends not to attract
people.

>> I intend to attempt a niche Stirling investigation sometime
>> in the next year. If I am successful, and it just might
>> happen, you will hear more about it :-)

> Actually, I think this is part of the problem: "If I am
> successful... You
> will hear about it"

If I'm successful you'll have to talk to te people I sell it to :-).
It's unlikely that I'd be able or willing to do what it took to bring
such a concept to market - I lack the 10's of millions in venture
capital for a start :-).

If I'm totally unsuccessful I'll tell you all about it.

> If all the stirling failures and eCar battery failures and community
> designed programmer failures were documented, people would move on
> and try
> some of the things that haven't failed a million times already.

Odds are the gutless Stirling (tm) is competitive with the designs
that James lists.

Rule of thumb. An air based low tech Stirling can deliver 1/3 Watt per
atmosphere of pressurisation per cc.
So a 1 litre unit operating at 150 psi or so would make about 3 kW.
Which explains why people don't put them in cars OR run them at 3000
psi and use Helium and very very very hot hot ends. And why they die.

>  Just my humble opinion, of course, and I would LOVE nothing more
> than for
> Russell or anyone to prove me wrong and develop an efficient, long
> lasting,
> low cost of operation stirling engine.

My niche target is lowish cost, OK efficiency, long lasting, far more
flexible than existing designs and very low power - probably about 100
Watt. For the power it won't be small. But given the low power it
won't be immense either. Think how many things YOU could do with a 100
Watt external combustion / heat power generator which also had 500 to
1000 Watt of heat output as well.

Why I think I *may* be able to do this viably when everyone else fails
(according to James) is something I won't be able to tell you until
after I show I can't do it :-).


       Russell





2006\08\27@073308 by Howard Winter

face
flavicon
picon face
Russell,

On Sun, 27 Aug 2006 02:36:16 +1200, Russell McMahon wrote:
>...
> Think how many things YOU could do with a 100
> Watt external combustion / heat power generator which also had 500 to
> 1000 Watt of heat output as well.

I have!  :-)  These days solar heat collectors are getting very efficient - evacuated glass tube types are now coming down to a reasonable price, and
even in England it's reckoned that a 2m^2 "panel" will provide enough heat to supply an average house's hot water requirements for most of the
year.  But there's a problem:  when you go away for a while and don't use the hot water, what happens to the excess energy?  

The hot water storage tank can't be big enough to just absorb it indefinately (certainly not over a fortnight's summer holiday) and nobody wants to
build a radiator just to emit the extra, and covering up the collector is awkward mechanically , so it occurred to me that a Stirling engine could use
the excess heat to generate electricity, stored in batteries.  Which made me wonder how you'd get rid of the heat from the cold end of the engine -
and how much would there be?  Thermodynamics' laws say that some of the heat must be turned into kinetic energy, but how much do you "lose", I
wonder?  How do you calculate the heat output from the cold end?

Thinking around this lead me to a paradox, at least in my own mind!  The useful energy from a Stirling engine is represented by the heat "lost" that is
converted to kinetic.  But to work you have to keep the cold end cold, which means removing the heat energy that *isn't* turned into kinetic, so a
100% efficient Stirling would absorb all the heat and nothing would come out of the cold end - which is impossible!  Going on from that, the most
efficient Stirlings give off very little heat, so how does the cold end stay cold?  (My brain hurts! :-)

Anyway, what I'm talking about is a sort-of Whispergen with altered functional goals - instead of generating heat for hot water, and as a byproduct
generating a bit of electricity, I want to "use up" as much heat as possible to generate electricity, to minimise the amount of heat left to get rid of.  
This is starting to look like one of my Maths proofs at school, ending up with  1 = 1  and I never got any marks for those, so perhaps someone can
explain where my thinking is going wrong...

Cheers,


Howard Winter
St.Albans, England


2006\08\27@120720 by James Newtons Massmind

face picon face
> If I'm totally unsuccessful I'll tell you all about it.

Thank you. I'll hold you to that promise.

> Why I think I *may* be able to do this viably when everyone
> else fails (according to James) is something I won't be able
> to tell you until after I show I can't do it :-).

I genuinely hope you are able to pull it off.

If it doesn't work, would you be willing to look into trying one of the
other ideas next?

---
James.


2006\08\27@153433 by Peter Todd

picon face
On Sun, Aug 27, 2006 at 02:36:16AM +1200, Russell McMahon wrote:
> king Hydrogen. Hydrogen has all sorts of advantages, but staying
> inside our motor is not one of them. It will diffuse through steel if
> it must, but it's even happier leaking through perfect seals and the
> like. Steel that has had Hydrogen diffuse through it gets all anmd
> tends to fall apart. Big delta temp comes from bigg hot end temp and
> you have problems again.

Dumb idea time... Could I obtain hydrogen and helium by making a sealed
steel container, creating a good vacuum in it, and waiting for it to
fill up with hydrogen and helium from the atmosphere? How pure would it
be?

I'm sure it's not the most efficient method, but then again, I've been
known to run pic chips off AC rectified through vacuum tubes...

--
http://www.petertodd.ca

2006\08\28@014610 by Russell McMahon

face
flavicon
face
> Dumb idea time... Could I obtain hydrogen and helium by making a
> sealed
> steel container, creating a good vacuum in it, and waiting for it to
> fill up with hydrogen and helium from the atmosphere? How pure would
> it
> be?

Definitely impractical, but fun.

You'd get Hydrogen, not Helium.And, given the vanishingly small
(literally) amount in the atmosphere you'd get  about none over any
sensible time period. But a fun game :-).


       Russell


2006\08\28@014611 by Russell McMahon

face
flavicon
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> Err... Where exactly are the large, heavy, fixed, long lasting
> striling
> engines that are useful for alternative energy applications? 'Cause
> I don't
> see those either. Is it that they are so huge that they cost a ton
> and never
> recoup their initial investment despite running for years and years?

A problem is that nit many people have the glint in their eyes, the
fire in their bellie *AND* the money in their pockets to buy an
efficient and planet saving but large, heavy and low power density
Stirling (not Sterling) engine when there are many many nastier
alternatives. I suggest you ask all the people on their electric
commuter car-cycles (of the sort that you lust after) who zip past you
as you sit in traffic queues where to buy the stirlings. The answer
is, of course, the same place that they bought their (non existent)
car-cycles from. ie if you are a fanatic greenie alternate energyiser
and a century or so ahead of uour time and if your home  heat energy
comes from the Methane digester in your backyard, fuelled from your
families excrement and that of  your chickens and pigs, then you may
be willing to buy a car-cycle at the ridiculous prices they cost
nowadays. And a Stirling energy converter as well. The problem is,
without the volume you don't get the product and without the product
you don't get the volume.

> I challenge ANYONE to show me a sterling engine ANYWHERE in ANY
> application
> that has EVER recouped what it cost.

As an example of something that "should" have been commercial gargoyle
the Rice Husk Stirling. This was good enough that ex Sunpower stirling
(AFAIR) empolees actually spin it off and sought to commercialise it.
The problem was, even third world farmers didn't care enough to use
rice husks as an energy source. When you can run a nice little double
flying horse brand diesel to run your water pump, who wants to use
rice husks.

I'm surprised that someone as starry eyed in the eco sphgere as James
doesn't see that the Stirling is another car-cycle metaphor.

Just to spoil the picture there are people selling small and veruy
very very expensive stirling cycle devices to the military. Very niche
market.

An the Whispergen is going to spoil your day sometime soon, or that's
what the imvestors hop who are still putting big bucks into its
development. At present it fits our model BUT the orders they have
look set to spoil it. Forward sorders are AFAIR around 100,000 and
cost is thousands of dollars each ($4000?) AND the buyers intend
making a profit from them. Will that meet your challengs when/if it
happens?

And, I'll show you my idea working when I get it working :-)
I'm not at all "starry eyed" about it - just think that a fairly basic
design with a certain magical variation on what's usually done should
be commercially viable. I hope it may interest Whispergen :-)




       Russell


2006\08\28@100510 by Russell McMahon

face
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>> Think how many things YOU could do with a 100
>> Watt external combustion / heat power generator which also had 500
>> to
>> 1000 Watt of heat output as well.

> I have!  :-)  These days solar heat collectors are getting very
> efficient - evacuated glass tube types are now coming down to a
> reasonable price, and
> even in England it's reckoned that a 2m^2 "panel" will provide
> enough heat to supply an average house's hot water requirements for
> most of the
> year.  But there's a problem:  when you go away for a while and
> don't use the hot water, what happens to the excess energy?

Good question. Old style alcathene pipe systems just melted their
pipes :-).
Worst case you could boil water and recondense it. Boiling takes
rather more energy than heating all the way from 0C to 100C and the
steam can be recondensed more easily with air cooling than water
cooling.

Evacuated glass tubes have got downright cheap here. Chinese heatpipe
in glass about $NZ20 retail - about 70 Watt in full sun. On my "buy
one and play with it" list. I want to see if you can air cool the hot
end at higher than usual temperatures.

{Quote hidden}

All "heat" = energy in must flow out as work or from the cold end
(assuming only hot and cold ends).
For Carnot cycle efficiency is (Thot-Tcold)/THot.
ie efficiency is delta-temperature/Absolute temperature in.
Makes sense.
A practicla Stirling may run at over 50% of Carnot efficiency but many
run lower or much lower.

If Tcold = 300K = ~ 27C (which is too low for practical purposes but
makes the arithmetic tidy for examples) then at 600 K = 327C hot end
Zcarnot = 50%   [ (600-300)/600]
At Thot = 900k = 627C
Zcarnot = (900-300)/900 ~= 66%

2:1 as above is easily done.
3:1 as above is pushing material limits in practice.
Higher and much higher is doable but things die easily.

So for practical "home" use Use 600K Thot = 50% max max.
At 50% of that practical you get 25% efficiency so 75% flows out the
cold end.
As an excellent rule of thumb starting point assume ALL the heat has
to flow out the cold end.
Overcooling never hurt a Stirling engine :-)

{Quote hidden}

100% efficincy can only occur when (Th-Tc)/Th = 1 so TC = 0 = absolute
zero.
AZ is impossile to achieve but vv close is achievable.
If you has a Stirling engine in a deep space craft and cooled the cold
end by radiating into dark space you'd have a 4.3K (AFAIR) sink which
is ~~~= 0 .
And it;'s very hard to heat up deep space.

The most efficient Stirlings we are liable to see with sinks at
ambient will seldom have efficiencies over 50% actual so at least half
the input emergy will exit via the cooling system.

Which is why using any engine system as a power plus heat cogeneration
system makes such good sense.

{Quote hidden}

Nothing wrong with logic - just with what can really be achieved.
Whispergen and any such systems try for as much energy out from SE as
possible. Heat is ALWAYS a by product. If you ever got "too much"
energy out it would be trivially easy to convert it to heat again. The
reason why Whispergen makes about 800 Watt electrical and far more as
heat is that's the best they can achieve in practice after having made
suitable compromise3s for lingevity, material limits etc.

Anything over 20% efficiency actual is doing OK. Far more is better.
(Th-Tc)/Th is the limit, but nobody will ever reach that.



           Russell






2006\08\28@124818 by James Newtons Massmind

face picon face
> A problem is that nit many people have the glint in their
> eyes, the fire in their bellie *AND* the money in their
> pockets to buy an efficient and planet saving but large,
> heavy and low power density Stirling (not Sterling) engine
> when there are many many nastier alternatives.

And yet there ARE people, however few, who DO have all that and a raging
hard on for Stirling engines.

Where is even ONE operating stirling engine that is actually doing its
promised job, generating power for someone, cost effectivly, even NOT
INCLUDING the development costs?

> I suggest you
> ask all the people on their electric commuter car-cycles (of
> the sort that you lust after) who zip past you as you sit in
> traffic queues where to buy the stirlings. The answer is, of
> course, the same place that they bought their (non existent)
> car-cycles from.

http://www.cyclecar.com/?id1:20593 Several solid models too choose from.
$3-$5K
http://www.rhoadescarshowroom.com/jumpshow.htm Satisfied customers.
http://www.sunvee.com/ Bike car from a Rhoades with electric motors and
solar panel. Doing it's job, moveing things from point a to b without
problems.
http://www.bikemania.biz/Quad_4_Wheel_Bicycle_p/palm_quadcycle.htm Quad 4
Wheel Roadster Bicycle by Palm $1780+
http://www.trimuter.com/Big-Wheel-Electric-Assist-C9.aspx Electric assist
recumbent trike $3,200.
http://www.cyclecar.com/ Sells a very well made Bicycle Car in several
models.
http://www.go-one.de/ukindex.shtml Go-One
http://www.velomobiel.nl Mango, Quest, etc.
http://www.cab-bike.com/english/ Cab-Bike
http://www.leitra.dk/  Leitra
http://www.velomobileusa.com/ Alleweder

If your commute is 10 miles or so, all of these are viable options.

{Quote hidden}

www.google.com/search?hl=en&lr=&safe=off&q=Rice+Husk+Stirling+Sunpowe
r%2C+Inc&btnG=Search shows 36 hits. None of them is the company that makes
it. None of them shows a currently running unit. Even the prototype broke
down and was removed.

www.stirlingengine.com/bboard/q-and-a-fetch-msg.tcl?msg_id=000019&top
ic_id=Power-producing%20Stirling%20engines&topic=
"During the next 4 years here in Bangladesh we went through three iterations
of design modification and fabrication in a facility we had set up near
Dhaka. In this process many snags in the prototype design were worked out
but we continued to have problems with lack of durability in the Ericsson
linkage which incorporated a bell crank system to drive the displacer."

Followed by the standard excuse of, e.g. "we fixed that but then our funding
ran out." Well, after 4 years, duh... How many years of funding will it take
to show that they aren't reliable?

"The compressor "fix" worked initially, but when the compressor itself wore
out the linkage again took the load and eventually the likleyhood of
mechanical failure increased. This and other problems, including increasing
costs, eventually put the engine into mothballs, though some are still being
nursed along by a few dedicated individuals."

> The problem was, even third world farmers didn't care enough
> to use rice husks as an energy source. When you can run a
> nice little double flying horse brand diesel to run your
> water pump, who wants to use rice husks.

And yet, these solar cooking ovens seem to be quite popular... Even very
technologically advanced versions are currently working in various places
all over the world...

http://techref.massmind.org/techref/other/solarovens.htm

It sure as heck looks like these people have the technical ability to couple
a solar collector with a stirling engine:
http://www.auroville.org/society/solarkitchen.htm

> I'm surprised that someone as starry eyed in the eco sphgere
> as James doesn't see that the Stirling is another car-cycle metaphor.

It isn't. As you can see from the links above, there are lots of people
using car-cycles. The /electric/ car cycles are questionable because if you
use the full range of the battery, they don't last long enough to justify
the expense. But short range, or non-electric (pedal only or small gas
engine) car-cycles are becoming popular. I can rent one for the day at a
local "village" to drive around and see the sites with my family.


> Just to spoil the picture there are people selling small and
> veruy very very expensive stirling cycle devices to the
> military. Very niche market.

The government will buy anything. <grin>

> An the Whispergen is going to spoil your day sometime soon,
> or that's what the imvestors hop who are still putting big
> bucks into its development. At present it fits our model BUT
> the orders they have look set to spoil it. Forward sorders
> are AFAIR around 100,000 and cost is thousands of dollars
> each ($4000?) AND the buyers intend making a profit from
> them. Will that meet your challengs when/if it happens?

Absolutly. I'll be happy to eat my words.

> And, I'll show you my idea working when I get it working :-)
> I'm not at all "starry eyed" about it - just think that a
> fairly basic design with a certain magical variation on
> what's usually done should be commercially viable. I hope it
> may interest Whispergen :-)

Best of luck.

---
James.


2006\08\28@214906 by Russell McMahon

face
flavicon
face
> Where is even ONE operating stirling engine that is actually doing
> its
> promised job, generating power for someone, cost effectivly, even
> NOT
> INCLUDING the development costs?

I think there must be a filter in your system that keeps taking out
the name I keep giving you :-)
So try one of these and remove the obvious fillers.

   http://www.whisperspamgen.com
   http://www.spamwhisp_ergen.co.nz

Or gargoyle for w_h_i_s_p_e_r_g_e_n

"Cost effective", of course, then becomes the bastion of the next
objection.
The best proof of cost effectiveness is that a big customer is
prepared to lay down big $ for a big order.
As is the case in the UK with Whisper_ge_n.
The reason that it is cost effective there is that it allows gas to be
turned into heat and electricity at point of use. Gas is superior for
peak load spreading and the power made this way is cheaper than power
made from some other sources and ... . The pricing distortions that
make this genuinely cost effective in this large and enabling
application may well not apply elsewhere. But they are real ones
nonetheless. Note that the electricity is made at 100% efficiency(tm)
as all the rest of the energy that would have ended up as heat if
you'd burnt the gas in a furnace ends up as heat anyway and is used to
heat the water or home. In fact the electricity is produced at ABOVE
100% efficiency (it's true I tell you) as after it has been used in
the home for non heating purposes (lighting, radio, tv,
refrigeration, doorbell, other no heating appliance ... it is then
turned into heat almost completely ans so "gets used twice". So a
Whispergen inside a home that makes say 800W of electricity and say
4200 W of heat directly actually adds 5000 Watt of heat to the home!
So the user gets 5800 Watt of energy use or ~115% efficiency :-)
compared to burning gas directly.

You can buy one now if you wish :-)

Note also that Whispe_gen has been selling at horrendous prices for
some years to the well heeled boating fraternity. These are "what the
market will bear" sales in direct competition with alternatives and
the fact that they have been selling, albeiy in small volume, shows
they are cost effective, all things considered. "All things
considered" is an important point, as cost effectiveness can only be
realistically measured in that environment. If someone is buying the
product in an open market then, stupidity and corruption aside, it's
cost effective for them.

I think your argument would be better changed to something like "Even
when development costs are ignored, Stirling engines have so far
proved themselves cost effective only in small or niche markets"
rather than attempting to filter eg W_hiSP_erGspamge_n out of
existence.



       Russell


PS - just reskimmed you answer and saw comment on WG at the bottom.
Doesn't really negate what's said above about large order and existing
niche market orders are a "nice little earner" along the way.

       RM





2006\08\29@013618 by Russell McMahon

face
flavicon
face
James and all,

Let's be realistic.

Set me the MINIMUM possible spec that you would find useful and I'll
see whether I can make a realistically realisable proposal for it.
This is an *absolute minimum* spec real device, not a toy, that would
be borderline acceptable as a demonstrator that Stirling had its
place.

Bear in mind the alternatives.

Bear in mind that peak *POSSIBLE* theoretical efficiency is
(Thot-Tcol)/Thot in absolute degrees. (ie Degrees in Kelvin, or
Centigrade plus 273, or
Fahrenheit plus 590 (if you must). A good working point is 600K
giving 50% Carnot efficiency. Actual will be lower, much lower or much
much lower than that. To be fair start with the best you can hope for
from the best diesel you know and halve it. That makes allowance for
100 years odd development and millions of dollars of production costs
to startup and more.

I'd say that 10% was commendable and 20% was frabjous.
I'd say that 5% was proof of concept reasonable.

Consider the *minimum* possible mechanical power out that would be
useful - more than just a toy. I'd say 10's of watts would be a fair
starting point. 50 Watts good. 100 Watts excellent. At 10% 100 Watts
out is 1 kW in. At that rate a 7 kg Propane bottle would last say 50
hours. And run a laptop and a radio and ... . Or charge an RV
accessories battery at 8A or so.  Useful.

Note that many hydrocarbons deliver AROUND 10 kWh/kg. Good wood and
coal similar. Hydrogen far more, but not what we are really looking at
here. Various not so good fuels still rate in the 5 kWh/kg range. So a
good burner MIGHT use say 200 grams of wood an hour. That's not a lot
of wood!

Whats the absolute largest you'd accept.
What's the absolute heaviest you'd accept.

Bear in mind that you need to cool this to 200 K = 27C at the cold
end.
Bear in mind that cooling source needs to be lowe rto allow for delta
t.
A stream would help.

BUT if you allowed cold end to rise about 100C you can use it for
boiling water source, thereby making it really useful. And steam
generation sets a rather practical cold end cooling method if desired.

For a 600K hot end with 100C = 400K cold end that takes Carnot
efficiency down to (600-400)/600 = 33%. To get back to 50% Carnot Z
you need 800 hot = about 500C hot end.

So. Lets hear people's reasonable specs for weight, size, power and
efficiency that THEY think would make a Stirling a viable small energy
converter. Bear in mind that you can make that hot end temperature any
way you like. Unlike an IC engine where you need just right diesel or
petrol or LPG or whatever, here you simply need to deliver 300C plus
via solar, petrol, biodiesel, used cooking oil, used sump oil, diesel,
wood, saw dust, fluidised bed garbage, coal, coke, dung, rice husks,
lp or other g or whatever. If you can burn it and make the temperature
and energy level required the Stirling will use it.

Let's negotiate this spec DOWN to a level that the majority would
grudgingly accept and then lets see if it looks like it can be done.
Cost hasn't bene mentioned. By all means suggest cost in 1 / 10 / 1000
/ 100,000,000 quantities. (Prototype, small trial, small group,
yeeha). 100 million of these could be rather useful.

Also suggest reasonable spec for reliability in whatever terms desired
and maintenance effort and cost. Be fair.



       Russell






2006\08\29@020741 by Peter Todd

picon face
On Mon, Aug 28, 2006 at 05:26:24PM +1200, Russell McMahon wrote:
> > Dumb idea time... Could I obtain hydrogen and helium by making a
> > sealed
> > steel container, creating a good vacuum in it, and waiting for it to
> > fill up with hydrogen and helium from the atmosphere? How pure would
> > it
> > be?
>
> Definitely impractical, but fun.
>
> You'd get Hydrogen, not Helium.And, given the vanishingly small
> (literally) amount in the atmosphere you'd get  about none over any
> sensible time period. But a fun game :-).

Hmm... could make for a neat toy. Think a balance beam, one side a solid
weight, the other side my evacuated and hermetically sealed cylinder.
Eventually they won't balance...

Good enough for a canada council for the arts grant application I think!

--
http://www.petertodd.ca

2006\08\29@022710 by Russell McMahon

face
flavicon
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> Hmm... could make for a neat toy. Think a balance beam, one side a
> solid
> weight, the other side my evacuated and hermetically sealed
> cylinder.
> Eventually they won't balance...
>
> Good enough for a canada council for the arts grant application I
> think!

Hang two similar containers on balance beam.
Place on in sunlight.
Expanding container displaces more air and loses "weight".
Beam moves.

You could use it to move a sun shield between containers to promote
oscillation.
Over centre or similar "snap" action needed to stop it assuming an
equilibrium stable position.
Without the shield it's a solar tracker  - see other thread :-)

I'm sure similar engines have already been built.

A significant level of power conversion may be possible if expanding
metal was used with suitable heating and cooling applied. Someone made
a "Sterling" (not Stirling) engine using this basic principle.



       Russell

2006\08\29@103342 by Howard Winter

face
flavicon
picon face
Russell,

On Tue, 29 Aug 2006 13:48:59 +1200, Russell McMahon wrote:

>...
> So a
> Whispergen inside a home that makes say 800W of electricity and say
> 4200 W of heat directly actually adds 5000 Watt of heat to the home!
> So the user gets 5800 Watt of energy use or ~115% efficiency :-)
> compared to burning gas directly.
>
> You can buy one now if you wish :-)

Powergen, one of the biggest UK electricity suppliers, have Whispergen on their web site, but with no information except a number to call for more
information (most of their web site is like that!).

I just called them, and they said they're not selling them at the moment (they used to) but they are hoping to resume next year.  When I asked why,
he said "Well it's a production thing - they're handmade in New Zealand, then they have to be brought here... you get the idea?"  I didn't disappoint
him by pointing out that ships have been travelling that route for several hundred years...

I asked about the cost, and he said "If it's anything like when we were selling them before, about £3000 installed."  Which makes the US$4000 price
you mentioned look a bit light... or it's just the Rip-off Britain effect in action again.

Ah well, back to Solar.  At least they will now pay for bought-back electricity at something approaching the same rate that they sell it!  But as it's
currently raining, my experimental panels are generating about 1/40 of the peak power I've seen from them.  I wonder if that's a function of the type
they are (amorphous silicon, I think) or are they all like that?

Cheers,


Howard Winter
St.Albans, England


2006\08\29@122134 by James Newtons Massmind

face picon face
> > Where is even ONE operating stirling engine that is
> actually doing its
> > promised job, generating power for someone, cost
> effectively, even NOT
> > INCLUDING the development costs?
>
>     http://www.whispergen.com
>     http://www.whisp_ergen.co.nz
>

I've seen the whispergen system. But I was not aware that they were actually
shipping units. As to buying one... Well, there are no dealers for the AC
unit, and my dealer for the DC unit is:
http://www.boatswainslocker.com/ which does not exactly inspire confidence.

I've added the email address to this post; Let's see if they actually
respond.

{Quote hidden}

No, the AC unit is not available in the USA. I'll be curious to see if the
DC unit is really available to me here.

{Quote hidden}

Or they have been promised that it will be cost effective and are not
prepared for the repair, replacement, and warranty costs.

> I think your argument would be better changed to something
> like "Even when development costs are ignored, Stirling
> engines have so far proved themselves cost effective only in
> small or niche markets"
> rather than attempting to filter eg whispergen out of
> existence.

I'm not convinced that they are cost effective. I'm not seeing any satisfied
customer letters, or even statements of how long one has run without
breaking down. But I must admit, if there is hope for Stirlings, it lays
with whispergen, and I am very interested to watch as see what they make of
it. My prediction, sadly, is that the units will start failing in the field
and the company will fold. I hope to be wrong.

Now, in the mean time, there are other things that need to be tried. For
example:

techref.massmind.org/techref/member/plp-actcom-f00/sun-turbo-1.htm
Possible quite efficient, long lasting, not terribly expensive.

http://techref.massmind.org/techref/idea/mc-heat-inject.htm Not efficient
but cheap as all heck.

http://www.flashsteam.com/ Not efficient, expensive, but probably long
lasting. If he would use solar, the efficiency doesn't matter so much.

http://www.redrok.com/engine.htm Lots of information on many alternatives.
Not many completed projects.

http://www.fieldlines.com/story/2003/6/26/10248/0825 Lots of crazy ideas
just waiting to be tried.

And in keeping with "money where mouth is" I am interested in providing
partial financial support for the attempted development of any of the above
or other reasonable heat engine ideas OTHER than stirling. In return I get
non-exclusive publishing rights. You just have to document what you do and
the outcome. Pictures, simple text descriptions, measurements of the result.

It doesn't have to actually work, in fact, failure is GREAT because it shows
what not to do in the future; IF it is documented and available to direct
future efforts. And that is my main point: Probably thousands of hobby level
mechanics have attempted to build Stirling engines with the goal of solving
the worlds energy needs. Not one has succeeded. People who are interested in
this area would not be throwing bad hours after good, IF they had proof of
that assertion.


---
James Newton, massmind.org Knowledge Archiver
.....jamesKILLspamspam@spam@massmind.org 1-619-652-0593 fax:1-208-279-8767
http://www.massmind.org Saving what YOU know.

2006\08\29@140558 by James Newtons Massmind

face picon face

> James and all,
>
> Let's be realistic.
>
> Set me the MINIMUM possible spec that you would find useful
> and I'll see whether I can make a realistically realizable
> proposal for it.
> This is an *absolute minimum* spec real device, not a toy,
> that would be borderline acceptable as a demonstrator that
> Stirling had its place.

Ok, this I can deal with...

Lets make it easy for you: No need for you to justify fuel costs, let's use
solar power and limit operation to when the sun is high in the sky. I'll pay
for the concentration of the sunlight into several hundred 'F heat.

Harbor Freight has a 40" by 60" parabolic reflector for $99. It will hit
350'F in open air. That is about 180'C or 453K.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94171

If you want to bury one end of the engine in the ground for cooling, or in a
pool of water, I'm sure it could be adapted to a trough type reflector. That
should get you ~90F, ~30C, ~303K on the cold end or 150K delta.
(450-300)/300 = ~50%

I pay 8-10 cents per KWh for electricity and the only time I have a need for
more than what my PV system provides is when it is hot and I'm running the
AC.

>From what I can see of available, useful AC units, we are looking for about
1KW while operating, or 700KWh per year to cool a few rooms. Check under
"Product Spec" on these pages:
http://www.sears.com/sr/javasr/product.do?pid=08066026000 or
http://www.sears.com/sr/javasr/product.do?pid=04275121000 10 amps at 115V
~1000W

I will buy any system that can run an AC from a few of those reflectors
given the promise that it will eventually pay for itself. E.g. if it will
last for 1 year and produce enough energy to turn over the pump in a
standard window AC when the sun is up, I would pay $70 for it (heck, call it
$100). If it will last for 5 years, I'll pay $500. If it will last 10 years,
I'll pay $1000. If it fails before it pays for itself, you have to fix it;
your dime.

Looking over your numbers below, this offer looks iffy. I'm sure a good
solar collector can get you your 50% temperatures, but 1000 watts out is
2000 watts in and that is a pretty big collector, huh? Or no?

---
James Newton, massmind.org Knowledge Archiver
jamesspamKILLspammassmind.org 1-619-652-0593 fax:1-208-279-8767
http://www.massmind.org Saving what YOU know.



2006\08\29@173603 by Russell McMahon

face
flavicon
face
>> Set me the MINIMUM possible spec that you would find useful
>> and I'll see whether I can make a realistically realizable
>> proposal for it.
>> This is an *absolute minimum* spec real device, not a toy,
>> that would be borderline acceptable as a demonstrator that
>> Stirling had its place.

> Ok, this I can deal with...

Apparently not :-)
Read the above again.
Your unit is about 2 generations on from there.

What I had in mind and was trying to explain the specs of was
something that *some* people would buy now because it met a need
effectively, and that produced power at an exorbitant cost by normal
standards but which would be cost effective if extended to the
millions per month category BUT which showed that Stirling had real
promise. ie something which looked as impractical to Joe average as eg
the early innovator Segway purchases. Or Benz's 2nd car. or the first
Motorola flip cellphones ($US3000 when introduced)(people bought them)
Or ... .

ie NOT a toy per se and undeniably useful, but not liable to be in any
way competitive with grid power at this stage. I don't think that this
is an unrealistic target to demonstrate viability as some people will
buy such and they serve as harbingers of the halcyon years to come
:-).

Something which produces around 1 kW is a big energy converter by
these standards. Once you have the technology sorted that would be run
of the mill, BUT for small workshop & prototype production the torques
and stresses involved at those power levels make turning out something
like that an extreme challenge. If you asked most people to make a
diesel motor from absolute scratch based on those requirements there
would be major problems in doing so. And that's simply trying to
emulate known technology.

Also, I'd rather *start* with eg an LPG energy source. This is because
it is a well known, consistent, readily and accurately variable and
scaleable and available energy source to deal with which eliminates
developing that aspect of the design. Getting eg 1 kW or even 100 W of
consistent solar energy input is a challenge in its own right which
distracts from the main development AND even measuring energy input
adds to the fun. Once you have it running on LPG you can extend it to
solar, cow dung, gasified garbage and more.

> Lets make it easy for you: No need for you to justify fuel costs,
> let's use
> solar power and limit operation to when the sun is high in the sky.
> I'll pay
> for the concentration of the sunlight into several hundred 'F heat.

Far too hard :-). And too cold as well.
What I said was serious but it had to be seriously limited in power
output and general expectation. This is not an attempt to back down
from the original intention, just pointing out that it wasn't a
suggestion that one start by making a grid power air-conditioning
driver replacement. (And for that you are probably better off driving
eg an absorption refrigerator directly and eliminating the middle
stages).

I'll give here the most basic of straw men specs for you or others to
knock down and modify.

Hot end temperature:
Mentioned first as it impacts the whole design, how easy it will be to
convert to other fuels, reliability, materials, more.
300 degrees C- excellent.
400 C - OK.
500 C - pretty marginal.
600 C - really too high.

Cold end temperature:    Around and up to 100 degrees C coolant
temperature. ie hot or just boiling water is the aim. Actual cold end
will necessarily be slightly to somewhat above this BUT not too much
higher as efficiency is impacted by this. Aim is to use the hot water
as the other (and larger quantity) output after electrical power.

Fuel:    LPG or Propane initially. Reasons as above.

Power output:    Up to 100 Watt electrical constantly as required.
More is good if readily achieved.

Electrical efficiency: 10% electrical compared to the thermal power
achievable in a representatively good burner using  the same input gas
flow. ie if you can get 1 kW thermal output from the gas in the
reference burner you can get 100 Watt electrical power from the
Stirling energy converter. Higher is good if achievable reliably.

Balance of power:    Good concept. Remaining gas energy to be
converted to thermal, mainly as boiling or near boiling water. Output
water to be potable and usable for domestic purposes.

ie so far, this looks like a 1 kW LPG water heater that produces 100 W
electricity and slightly less thermal output as a consequence.

Size:    Smaller than a bread basket. Much smaller is good.

Mass:    Average woman can carry it from the car to the picnic table
without too much difficulty (without water inside). Lighter better.
Much lighter much better.

Selling cost in small run production:    $US1000. Less is better. Much
less is much much better. $US100 target in zillions but not any time
soon.

Reliability:    Reliable :-). TBD, but essentially "just goes" for a
period of time consistent with consumer expectations based on other
vaguely comparable equipment. 10,000 hours to full overhaul would be a
commendable and probably too high target. (By comparison the average
automobile engine probably lasts 2000 - 4000 hours, many much less.

Noise:    Distressingly quiet compared to alternatives. Running in
your RV in a trailer park it wont disturb the neighbours. I could
sleep
with it running in the RV. My wife couldn't. ie it's not totally
silent but it's quiet enough that some people would hardly notice it.

SO:    This is horrendously expensive and incapable compared to
existing alternatives. It won't run a sensible air conditioning unit.
It won't run power tools etc directly. It will maybe run a TV or a
single PC. Power cost is substantial wrt grid power. eg even if it had
a lifetime of 10,000 hours operating cost per unit of electricity
would be    ($1000/10,000hours) / 0.1 kW  = $1 / kWh !!!!
BUT that's ignoring the thermal output.
Adding thermal output brings that to 10 cents / kWH.
That's just for capital cost without fuel costs. Fuel costs  depend on
burner efficiency and fuel cost/kg but are probably in the $US0.10 -
0.20 / kWh range. Wood chips, solar, rice husks or cow dung may cost
differently depending where you are. .

What this will do is run a laptop or two. It will charge a 12v battery
at about 7 amps and indirectly operate battery powered power tools.
Use
for anything whose main aim is to make heat or even light would be
less useful than alternatives. But it will run specialist equipment
that demands electrical power rather than thermal or optical. This is
probably mainly electronic or electrical items. Where there is a
specialist requirement for such there could be a place for it. For
example, it may be a Wifi link and supporting computer equipment in
any number of places. Or a satellite terminal. Or a TV or radio. Or a
weather station, or coms node or ... . There would have to be reasons
why this should be used rather than a diesel or petrol genset. Or
solar panels, or wind power, or water turbine, or Peltier or ... .
There will be niches for each of these.

Now, if they would only deregulate the supply of nuclear waste, cast 1
to 10 kW heat output hunks of it in LARGE blocks of concrete and bury
these in everyone's back gardens then one of these units per home
could prove very useful. With a 10 kW waste source and a 1 kW version
of this converter James could even run his air conditioner.


.
       Russell


> Harbor Freight has a 40" by 60" parabolic reflector for $99. It will
> hit
> 350'F in open air. That is about 180'C or 453K.
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94171

A bit over 1 kW IN at full sun. Enough for the above unit if it worked
rather better than per spec. Two would be better. Don't forget to cost
the liquid sodium heat pipe to deliver the heat to the hot end :-).

> should get you ~90F, ~30C, ~303K on the cold end or 150K delta.
> (450-300)/300 = ~50%

Alas it's  (Th-Tc)/Th  (not /Tc) = (450 - 300)/450 = 33%
And that's Carnot efficiency.
Real world efficiency is less to much less of that.
50% of Carnot is usually doing rather well.

>>From what I can see of available, useful AC units, we are looking
>>for about
> 1KW while operating, or 700 KWh per year to cool a few rooms. Check
> under

You arguably want to look at using an ammonia (or other) absorption
cooler heated directly by the sun. One Albert Einstein long ago
patented a new improved version of such.

> If it fails before it pays for itself, you have to fix it;
> your dime.

Almost nothing gets sold on that basis.
Domestic anythings (including cars) get sold on a typically 12 month
warranty and commercial tools etc often on far less. Few cars "pay for
themselves" (quaint concept) within warranty and vanishingly few power
tools.

> Looking over your numbers below, this offer looks iffy. I'm sure a
> good
> solar collector can get you your 50% temperatures, but 1000 watts
> out is
> 2000 watts in and that is a pretty big collector, huh? Or no?

At full sun you get about 1 kW/m^2 input to a panel. Working on half
that out would be safe.
You can get insolation tables for your location online. Where I am its
about 8 kWh/m^2/day in summer and about 2.5 in winter.





2006\08\29@191204 by James Newtons Massmind

face picon face

> Now, if they would only deregulate the supply of nuclear
> waste, cast 1 to 10 kW heat output hunks of it in LARGE
> blocks of concrete and bury these in everyone's back gardens
> then one of these units per home could prove very useful.

Now, that is the first thing you've said that makes sense...

...perfect way to solve the nuke waste problem and the energy crisis.

:D

---
James.


2006\08\29@193917 by Russell McMahon

face
flavicon
face
> Now, that is the first thing you've said that makes sense...

It's sad when so little that's sensible makes no sense to some people
:-)

> ...perfect way to solve the nuke waste problem and the energy
> crisis.

I've thought for many many decades that this would be a neat idea. The
intractable problem is human nature. Stupidity, greed and malevolence
make it a non-starter. As you'll be aware. People would cut corners in
the design, construction and inspection. People would decide to look
inside, no matter how many warnings. And the opportunity for misuse is
extreme. They also would need to be 'reclaimed' after a given time as
their mechanical longevity would be limited by both radiation and
thermal issues.

But, it should be possible to make a large enough block that radiation
externally is minimal, heat losses to ambient when untapped are such
that cooling occurs at acceptable surface temperature rises BUT by eg
running water through the perfect pipe (tm) through the interior you
get either hot water or steam out depending on flow rate.


       Russell


2006\08\30@035919 by Robert Ammerman

picon face
>> Now, if they would only deregulate the supply of nuclear
>> waste, cast 1 to 10 kW heat output hunks of it in LARGE
>> blocks of concrete and bury these in everyone's back gardens
>> then one of these units per home could prove very useful.
>
> Now, that is the first thing you've said that makes sense...
>
> ...perfect way to solve the nuke waste problem and the energy crisis.
>
> :D
>
> ---
> James.

And the terrorism crisis after they kill us all with dirty bombs made with
the stuff :-)


Bob Ammerman
RAm Systems

2006\08\31@104002 by Luis.Moreira

picon face
Hi Russell,
When you talk of a regenerator on the Stirling Engine, what kind of
thing are you talking about? What materials do you use?
Best regards
               Luis



{Original Message removed}

2006\08\31@120123 by Russell McMahon

face
flavicon
face
> When you talk of a regenerator on the Stirling Engine, what kind of
> thing are you talking about? What materials do you use?


The "Regenerator", which is arguably the heart of any serious Stirling
Engine, is a thermal store interposed between the hot and cold spaces.
Gas flows through it from cold to hot and expands thereby raising
overall system pressure in all spaces, or from hot to cold and
contracts and thereby lowers the overall system pressure in all
spaces.

The regenerator is ideally a matrix with high thermal capacity per
volume, high to infinite resistance to thermal "heat" flow in the
longitudinal direction (ie in the direction of gas flow) and high
thermal conductivity in the transverse direction. It has ideally zero
dead space and no pneumatic resistance. The best material is
nonexisteum.

Practical alternatives are wire screens packed together under
pressure. These can be sintered together to make a rigid block with
appropriate properties. . At low temperatures (more for Stirling
coolers) material such as lead shot has been used. With wire screens
heat can flow across each screen through the wires but less easily
from screen to screen as they are not in total contact at all points
and points of contact are not necessarily optimum for heat transfer.
Lead shot is used in Stirling cryo coolers as lead retains more
thermal capacity at cryogenic temperatures than almost any other
substance. Other unlikely substances such as cotton wool have been
used successfully in some regenerators.

Imagine a cylinder filled with hundreds of circular screens each a
good fit to the circular cross section. These are pressed in tightly
and end caps fitted. Place a "hot space" at one end and a "cold space"
at the other. Blow gas from hot to cold via the holes in the screens.
The first screen will be heated to the temperature of the hot gas and
there gas will be slightly cooled. The next screen will be slightly
cooler and this effect will progress with the temperature of each
dropping and the gas being cooled. If properly designed the gas will
enter the cool end totally cooled to the cool end temperature. Now
reverse the flow. Cold gas entering the screen pack will encounter
increasingly warm screens and will get hotter as it flows towards the
hot end. If an equal quantity of gas flows from cold to hot as flowed
from hot to cold then it will enter the hot space at about the same
temperature as the other gas left. The screen temperatures will be
decreased. If the thermal capacity of the screens is several ties or
more of the thermal content of one charge of gas then the screen
temperatures will not vary too widely during each cycle.

If work is done at the cold end by expanding he gas to drive a piston
then a net flow of "coolth" will flow up the regenerator and the hot
end must supply a net downwards flow of heat energy to balance this.
But overall the energy stored in the regenerator is several times at
least the energy flow per piston cycle.

If the regenerator has "dead space" in it then system pressure
increases which are intended to drive the piston will instead go to
increasing the pressure in these dead spaces. So a R will ideally have
zero dead space. However, as R "dead space" falls the air passages get
smaller and pneumatic resistances rise and losses increase. As with
most aspects of Stirling engines, actual dead space is a compromise.
Dead space also occurs in the hot and cold ends when the "displacer"
which sweeps the gas into or out of the space, is not a perfect fit.
The displacer also needs some wall clearance and this is also dead
space. Also, large gaps around the displacer encourage gas to flow to
and from past it and bypass the regenerator. Some systems actually use
the walls of he displacer tube as the regenerator, while others have
the regenerator inside the displacer with the gas flowing through the
inside of the displacer as it goes from hot to cold and back.

Heat which flows from hot to cold or coolth which flows the other way
(same thing) via the regenerator structure, and not carried by gas, is
waste energy which will increase overall system energy consumption
without benefits.



           Russell




'[OT]:Sandia, Stirling to build solar dish engine p'
2006\09\01@104427 by Luis.Moreira
picon face
Hi Russell,
Do you have any drawings or photographs that can illustrate this kind of
regenerator?
Best regards
               Luis



{Original Message removed}

2006\09\01@174638 by Russell McMahon

face
flavicon
face
> Do you have any drawings or photographs that can illustrate this
> kind of regenerator?

Gargoyling

       stirling regenerator

gives both a range of images and a number of related diagrams and
operating
charts

Diagrammatic view of some regenerators

       http://www.nasatech.com/Briefs/Jan99/GIFS/LEW16581_FIG_1.jpg

Page showing both actual regenerator matrix plus some Stirling heat
exchange structures.

       http://www.nmri.go.jp/eng/khirata/stirling/ecoboy/hx/indexe.html

Photos of some NASA "microregenerators"
These are from a cryocooler but the concept and principle of operation
is the same.The regenerator does not "know" which it is in - it does
an identical
task in each case.

       http://www.grc.nasa.gov/WWW/RT/2003/5000/5490moran.html

NASA flocked carbon fibre (!!!) as regenerator component

       http://sbir.nasa.gov/SBIR/successes/ss/041text.html

Step by step

       http://www.steamengine.com.au/stirling/operation/old/index.html


Many more listed.


       Russell




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