Subject: Sterling Question

From: [email-masked] (Douglas S. Gonder)
Date: 28 Jun 1996 06:09:37 GMT

Does anybody know if a Sterling runs purely on the temperature
difference between the hot and cold sides?. Would a steam jacket
around same at a lower temperature but with a constant flow (<BTU's?)
have the same effect.

sneak preview: http://www.chatlink.com/~soltherm

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From: Michael Latcha <[email-masked]>
Date: Fri, 28 Jun 1996 08:45:22 -0400

Yes, a Stirling (correct spelling...) engine works due the temperature
difference between the hot and cold sections of the engine.  The heat can
be supplied any way you want - direct flame, steam, solar heat, etc. or
even removed by cooling the cold end.  It is not clear to me where your
steam jacket would go, but as long as there is a hot end and a cold end,
the engine should work.  How well it runs and how much power is available
is a function of many variables, the most important being the temperature
difference between the two extremes and the efficiency of the heat
transfer into and out of the working fluid... 

--------------------------------------------------------------------
Michael A. Latcha, PhD                     VOICE: (810) 370-2203
Associate Professor                        FAX:   (810) 370-4261
Department of Mechanical Engineering       Email: [email-masked]
Oakland University
Rochester MI 48309-4401

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From: PPIERCE <[email-masked]>
Date: Fri, 28 Jun 1996 08:32:09 -0700

> sneak preview: http://www.chatlink.com/~soltherm

Village Press has a  couple of books on Stirling Engines (See attached).
Also Bailey has books and videos onStirling and hot air engines.

Paul in AJ AZ
Metalworking Books and Videos

BAILEY CRAFTSMAN SUPPLY

How to videos - Lathe - Mill- Casting (Gingery)
	Stirling Engines
		(Not Hollywood quality but interesting - PP)

Books - Gingery's Charcoal Foundry and others.
	(Great series)

Listing $1 (refundable w/order - stick a buck in an envelope)

Phone:  1-314-642-5998
FAX:    1-314-642-2936

VILLAGE PRESS
	LIVE STEAM
	PROJECTS IN METAL
	HOME SHOP MACHINIST
	Also some Great Hardcover
	collections of reprints

http://members.aol.com/vpshop/index.html
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http://members.aol.com/vpshop/hsm.htm
http://members.aol.com/vpshop/steambook.htm

1-800-447-7367

Metalworking Books

LINDSAY PUBLICATIONS

[email-masked]

P. O. Box 538  HC2
BRADLEY IL 60915--0538

Phone:  1-815-935-5353
FAX:    1-815-935-5477

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From: [email-masked] (Doug White)
Date: Fri, 28 Jun 96 20:22:09 GMT

In article <[email-masked]>,
   [email-masked] (Douglas S. Gonder) wrote:
<Does anybody know if a Sterling runs purely on the temperature
<difference between the hot and cold sides?. Would a steam jacket
<around same at a lower temperature but with a constant flow (<BTU's?)
<have the same effect.
<
I'm not sure I understand your question, but as long as we are 
discussing Striling engines, I thought I'd throw out a query of my own.

Does anyone know if there are any particular problems in scaling a 
Stirling engine down in size?  I was thinking of building something on 
the order of a Cox .010 model airplane engine, but based on a Stirling 
cycle.

I have heard of people at the big model engineering show exhibiting 
really tiny, high-speed Stirling engines, and Stirling engines that 
would run off the heat of your hand.  Does anyone know of any magazine 
articles describing such designs?

I've checked out a variety of Stirling related Web sites, but none of 
them describe anything particularly small.

Thanks!

Doug White

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From: [email-masked] (Dave & Ellen Plumpe)
Date: Sun, 30 Jun 96 17:03:34 GMT

>articles describing such designs?
        I'd think it'd be extremely difficult to build a successful small 
bore, low temp Stirling engine.  Power piston pressures are very low at low 
temps.  Low pressures & small bore mean very low forces, so friction has to be 
vanishingly small.
        I have plans & some materials for Jerry Howell's "Miser" low-temp 
Stirling engine, which he says will run over 90rpm when hand-held.  Power 
piston is 5/8" bore and made of graphite for low friction.  Displacer piston 
is approx 6"dia.  C'shaft is supported on ball bearings.  The smallest 
Stirling engine listed in his catalog is the "Mini Stirling Fan" with 0.4" 
bore.  Says it runs 900rpm on alcohol lamp.

-Dave P.

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From: [email-masked] (Peter Brooks)
Date: 1 Jul 1996 18:16:28 GMT

One more variable in Stirling engines is the average pressure of the
working fluid.  To get the gory details, dig up a book like Colin West's
book on general stirlings (not the liquid piston book), or possibly a
primer like James Senft's book (you can get it from places like Coles
or Power Model supply.  I special ordered the West book.  There was also
a single copy in the San Jose public library system.

During the early '80s, there was a lot of research on using a stirling
to power a car.  The typical engines ran at pressures of 2000psi or so....

However, you can do pretty well at lower pressures.  Andy Ross got
about a half HP on a self-pressurizing engine.  I believe it was a
90cc that ran at about 2.7atm.  Also, low power applications like
cordless fans can run at atmosphere.

(wish I had a few of those fans handy right now.  The shop's too
hot to work in when it's 100F outside.....) 

Pete Brooks

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From: PPIERCE <[email-masked]>
Date: Tue, 02 Jul 1996 06:54:52 -0700

Peter Brooks wrote:
> 
> One more variable in Stirling engines is the average pressure of the...
> ........(wish I had a few of those fans handy right now.  The shop's too

Moved here last year...  I have a 10X20 shop that is now insulated and 
masonited (DON'T use 1/8).  Then I added a 7500 a/c.  That's living.  Just
like Jimmy and Tammy Bakkers dog house.
I usually start the a/c in the am (about 5:00) and quit by noon when the 
sun gets to the shop side.  7500 is marginal-were I doing it over the
unit would probably be 10,000.  It got down to about 89 last night
(but it's a dry heat).

Paul in AJ AZ

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From: Mike Rehmus <[email-masked]>
Date: 2 Jul 1996 17:11:40 GMT

I am not a Sterling engine expert but when you observe
the speed of a Sterling engine increase when the temp.
of the hot side is increased, it tends to make me believe
that the temperature differential is the driving force,
not available energy.

Of course if you increase the size of the engine, it
can use more of the available energy but for a given
size, temperature is the driving force, I think.

Best regards,

Mike Rehmus

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From: [email-masked] (Peter Brooks)
Date: 2 Jul 1996 22:53:33 GMT

Andy Ross tells of seeing (and later, building his own) airplane stirling engine.
At least as of the time of writing (1993), his own engine had not flown, but
it was supposed to have the power to do so.  

I suspect you can get 1/2A power levels from a suitable engine, but it might
be a lot bigger.  Perhaps 4-6" long and 2" or so in diameter.  The good news is
that such an engine can be made incredibly light.  Getting heat to the 
dispacer end is left as an exercise for the *very* interested student.  That
was the issue that stopped Andy Ross.  Boats, bikes, those were OK for him, but
he didn't like the prospect of mounting a burner on a plane.  Lends a whole new
meaning to the term flameout.

Pete Brooks

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From: [email-masked] (Ben)
Date: Wed, 3 Jul 1996 14:46:29 +1000

In article <[email-masked]> Mike Rehmus <[email-masked]> writes:
>From: Mike Rehmus <[email-masked]>
>Subject: Re: Sterling Question
>Date: 2 Jul 1996 17:11:40 GMT

>that the temperature differential is the driving force,

Increasing the temperature increases the heat transfer into the hot end.  
Therefore expansions will be greater, forces will be higher, and the speed 
will be greater.  Remember Q=UA(delta T)

Tom