Harry,

Thanks, I think I have it now.

Tom

--- In sesusa@yahoogroups.com, "Harry Diers " <harrydiers@...> wrote:
>
> Hi Tom,
> Very sorry, I thought I had added some photos to my album but I
am thinking of another site I sent them to. I have loaded some photos to a
folder named, 4 cylinder outboard, these may help. There are 4 double acting
pistons in a square formation. The (expansion) top of one is connected via the
heat exchangers to the (compression) bottom of the next. The top of that one
likewise to the bottom of the next and so on for the four cylinders. There are
four gas circuits of 200cc effective swept volume each. The tops of the
cylinders are heated by four gas burners. The bottom of each cylinder is cooled
by 2 concentric coolers with the cooling gas flow path between them.
> The 4 cylinder assemblies are mounted by screw threads to a common 20mm thick
base plate. This plate houses the water flow divider, water cooling paths,
piston rod guides and seals and the working gas connecting ducts which connect
the bottom of each cooler to the underside of the next piston. A cover plate
encloses these items, adds strength to the assembly and forms the attachment for
the spun stainless, pin drive assembly cover, shown in the first picture. The
Siemens Pin drive is contained in this case and transfers the vertical movement
of the pistons to the vertical shaft. This pin drive swivels on a universal
cross assembly which allows it to nutate, (swing in a circle without rotating).
It has 4 radiating arms connecting to the 4 piston rods via 4 connecting rods
with ball ends. It also has a vertical pin which engages an off centre needle
bearing in a disc at the top end of the output shaft. This is shown in one
photo. The outer ends of the 4 radial arms follow a narrow figure 8 and have a
linear curve. This off line movement swings the connecting rods no more than
one degree each side of the cylinder centre line thus removing almost all piston
side loading. The connecting rods are fitted inside the hollow piston rods.
The cross sectional area of the piston rods reduces the area of the underside of
the piston by approximately one sixth. It therefore reduces the swept volume of
the compression space by the same amount. Having a compression space one sixth
less than the expansion space gave the best results in the previous V twin
engine. Only the gas circuits are to be pressurized. The pin drive case will
not.
> I hope this helps for a start.
> Regards, Harry.
>
>
>
>
> ----- Original Message -----
> From: Tom Gentry
> To: sesusa@yahoogroups.com
> Sent: Wednesday, June 10, 2009 5:22 AM
> Subject: [sesusa] Harry's outboard (was ST-5 etc.)
>
>
>
>
>
> Harry,
>
> Please forgive me for being a bit thick but does that mean that each PAIR (1
hot and 1 cold) have a swept volume of 200cc? That would be 800cc/4
pairs=200cc/pair.
>
> These are Siemens double acting cylinders correct?
>
> Or are there just 2 pairs of cylinders, making up 2 gas circuits?
>
> It is sort of important that I get this right. So please help me out here.
>
> Tom
>
> --- In sesusa@yahoogroups.com, "Harry Diers " <harrydiers@> wrote:
> >
> > Hello Tom,
> >
> > Sorry for the delay, I have been "off line" for a while. Here are some
specifications for the engine. Net swept volume of each cylinder is 207cc. 800,
(or 828cc) is the total effective swept volume of the 4 cylinders. The working
gas is air and the charge pressure is up to 3 bar cold (not running).
> >
> >
> >
> > SPECIFICATIONS for one cylinder.
> >
> > Bore 7cm, Stroke 4cm, Net swept volume 207cc, Max hot volume 147cc,
Working pressure (air) 3 bar, Max temp 600 deg C. Min temp 30deg C
> >
> > PISTON AREA; Top side ( expansion ) 38.5 cm2 Under side (compression) 33.6
cm2 Under side is less because of the cross sectional area of the piston rod.
> >
> > HEATER;
> >
> > Slot length 7cm Slot width .15cm, Cross sectional area 4.2cm2, Dead volume
29.4cc, Heat transfer area 261cm2.
> >
> >
> >
> > REGENERATOR;
> >
> > Length 5cm, Average width .6cm, Cross sectional area 16cm2, Total volume
80cc, Dead volume 70cc.
> >
> >
> >
> >
> > COOLER;
> >
> > Length 7cm, Slot Width .1cm, Cross sectional area 2.8cm2, Dead volume
19.7cc, Surface area 593cm2.
> >
> >
> > Transfer duct dead volume, 5cc.
> >
> > Totals;
> >
> > Swept Volume 207cc
> >
> > Dead Volume 124cc
> >
> > Regards, Harry.
> >
> >
> >
> > ----- Original Message -----
> > From: Tom Gentry
> > To: sesusa@yahoogroups.com
> > Sent: Sunday, June 07, 2009 2:20 AM
> > Subject: [sesusa] Re: ST- 5 and 4 DA 800
> >
> >
> >
> >
> >
> > Harry,
> >
> > Just a few comments before I start plugging in numbers.
> >
> > Due to the fact that the Nt ratio is less than 3.0, I calculate about
2.71, the Beal Equation is going to be off by 3.00-2.71/3.00%. To correct for
this, I believe we can perhaps use the West Equation which has a term for the
temperatures albeit in the form of efficiency a la Carnot.
> >
> > I will look at the scaling functions to see if the efficiency is used
anywhere.
> >
> > Questions:is 800cc = Vswept ot displacement of each cylinder?
> > is gas Nitogen (air)?
> > What is the charged pressure (nor running, cold)?
> >
> > Thanks,
> >
> > Tom
> >
> > --- In sesusa@yahoogroups.com, "bernhard" <baernibaer@> wrote:
> > >
> > > Hello Harry,
> > >
> > > --- In sesusa@yahoogroups.com, "Harry Diers " <harrydiers@> wrote:
> > > >
> > > > Hello Tom,
> > > > Thanks for the compliment it is very much appreciated.
> > > > The strength of the arms was designed to take 1.5 Kw. At this power I
calculated about 70 Kg max load on each piston. That meant that if I locked the
mechanism so it could not move each arm would need to support my weight if I
stood on it. It did that easily. The tops of the arms are reinforced with a thin
steel plate under tension. The rest is aluminum accept for the pin (shown in one
photo), which is steel. A large amount of work went into this mechanism. The
universal cross in the centre of the arms still has the original needle races on
it. They do not like the end loading they get for part of the cycle and so need
to be replaced with deep groove ball races. Because of the work involved in
fitting this type of bearings I used the needle races just to get the engine
going in the time available. This is a first time for this layout and I just
wanted to see how it would work. It is very good and could be built to take
whatever power you like. And I don't need a pressurized crankcase! The piston
rod seals have to hold the pressurization and there are 4 of them instead of one
shaft seal so leakage might be up a bit. When I first tried them they held
pressure for quite a while and they had not been run in.
> > > > I am happy to consider other gas circuit configurations. Getting the
gas circuit right is the hardest part. The original design parameters were;
Light weight, simple unfinned heat exchangers, (unfinned for simplicity and to
avoid the plenun and its dead volume at the base of the cooler, I would like to
copy Andy Ross' furnace brazed internal heater fining but have not found anyone
to help with that).
> > > > Also lots of cooling as I have found just how much difference this
makes. The Rinia was chosen for smooth torque at low revs hopefully reducing
noise as well and giving larger heating and cooling surface area for the same
size engine. I would like the design to be as simple as possible so other people
might be interested in building one. The pin drive may not look simple but it is
really once you figure it out. ( A 4 cylinder engine with only 6 moving parts).
> > > > The design also had to allow pressurization. Not having a pressurized
crankcase greatly reduces the weight. For a couple of years I had been designing
around a pressurized crankcase until I read Bob Sier's article in Stirling News
where he said his reason for his choice of design was to avoid this. Thinking
about this I realized I didn't need one either. What a wonderful realization
that was. It means that the pin drive arms have to cope with more load but I can
get rid of the heavy case. At this stage I am planning not to have a flywheel.
The pin drive box is the support for the engine and so the only way a flywheel
could be fitted would be to use a long small diameter tube around the drive
shaft in the outboard leg.
> > > > For my application the engine must not weigh more than 15Kg complete.
It is close to that already without the auxiliaries. A new burner is almost
finished saving half a Kilogram and hopefully giving a better fire.
> > > > There is one experience I must tell you about. when the engine was
first run you could hear the water sloshing inside. After a very short run I
turned off the heater, the engine stopped and I went outside to turn off the
cooling water. I was surprised to hear the engine start and run a few turns. I
came back in and as I was looking at it it started again for 2 or 3 turns.
Perhaps part steam and part stirling, very strange.
> > >
> > > Strange, but interesting - maybe combinations You like?
> > >
> > > Partly Stirling/Rankine system:
> > >
http://www.sae.org/servlets/productDetail?PROD_TYP=PAPER&PROD_CD=1999-01-2502
> > >
> > > seperate systems for higher overall efficiency:
> > > http://www.rgpsystems.com/solutions.html
> > >
> > > Thanks for the hint about the possibility for the unpressurized
crankcase (no buffer space losses also - yeah that's great!).
> > > You are inspiring my research, Regards,
> > > bernhard
> > >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
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