> > No, it doesn't require high pressure injection: No 
> compression and the 
> > injected water is NOT boiling.
> 
> But here's where all the questions arise:
> 
> Without high pressure can you inject sufficient water to 
> generate a useful power stroke?
> Won't injecting cold water impact the efficiency of the 
> engine due to thermal cycling?

Yes, but that is offset by the reduction in cost of not needed an injector
that can managed high pressure. 
http://www.flashsteam.com/L912_Injector.htm is one such device. If memory
serves, he was selling them for $2,000.00

The incoming water can be heated as long as it isn't pressurized past what a
fuel injector can manage. That was why I suggested a heat exchanger with the
outgoing steam pre-heating the incoming water.

> > Yes, you probably have to increase the surface area inside the 
> > cylinder head to ensure a rapid transfer of heat.
> 
> Se we should be looking at larger displacement engines then?

Possibly. But keep in mind that larger surface area does not necessarily
mean larger displacement. A more convoluted surface can provide more surface
area in the same space. I personally think that the stack of razor blades
would be a good thing to try. Water sprayed down into that should flash
well. It might be possible to use a standard head and mill thin grooves into
the inside of it to approximate that razor blade stack.

> > Yes, it will turn over slowly, who cares? 
> 
> I do. If it's possible to double or triple the efficiency by 
> better equalizing the temp and pressure of the intake water, 
> then it's worth the effort to examine.

AFTER getting the thing working at all... Assuming that is possible. I don't
know that this idea will work... I just don't know that it will not work. 

But what I really meant by "who cares" was that while this engine may not
(probably will not) be as efficient as other designs, the efficiency isn't
the point. Cost, availability, and safety are. When you have a FREE source
of energy, you don't NEED to be efficient. WANT, sure, but not NEED.

> > No, preheating the injected water isn't a big deal, just bodge up a 
> > heat exchanger from copper tubing with the exhaust steam 
> and the intake water.
> 
> Actually I was thinking that since this is fact a solar 
> engine, why not simply use concentrated sunlight to preheat 
> the water. How hard can it be to construct a steel injection 
> chamber that takes in cool water and has focused sunlight on 
> it? Use a fresnel lens to concentrate a portion of the light 
> hitting the engine to preheat the water under pressure. It 
> lessens the thermal cycling of the engine and ensures that 
> sufficient water for a decent power stroke is injected.

My only concern would be OVER heating the water and boiling it.

> > No, it isn't supposed to be efficient, the sun is free: 
> trash 99% of 
> > it but get that 1% at very low cost without high pressure danger.
> 
> The problem I see is that though it's free there's only a 
> limited amount available every day to utilize. So if there 
> are ways that are still simple and low cost, and yet wastes 
> 95% of the sunlight instead of 99%, that's a vast efficiency 
> improvement.

Absolutely. But it seems like people don't want to do anything cheap and
simple if it isn't as good or better than the expensive, complex, caustic,
unsafe, high-pressure, pie in the sky crap that is out of reach. Baby steps.
Start simple.

> > Sure, a sterling engine would be better, but that isn't the 
> point... 
> 
> It's not better if it's inaccessible. Or if the efficiency of 
> an accessible engine is 10 times worse than your setup. 

Err... I think I agree?

> > ...this is cheap, simple, safe, and accessible to the little guy.
> 
> As a little guy in this I only have two questions:
> 
> How much is it going to cost?
> How much electricity can I get out of it?
> 
> Any ballpark figures on these?

I think both depend on how well stocked your local junk yard is. Old MC
about? Heat exchanger? Spare head? Milling machine? The mirrors are cheap in
any case. Needs something to keep the engine in the focal point. The point,
again, is to do SOMETHING and if it shows any promise at all, do more. If it
doesn't work in any way, scrap it and try something else.

> > Where can I buy a sterling engine right now? How much does it cost?
> > Sterlings are pipe dreams.
> 
> Any Sterling with useful power requires extemely high 
> pressure and difficult working fluids. So it's inaccessible.

Bingo!

> ICE's and water are extremely accessible. I have water. I 
> have a 3HP Briggs and Stratton engine from a scrap edger 
> that's been sitting in my basement for the last 3 years. Is 
> it possible to build a useful steam engine from it? It'd sure 
> like to know.

I have seen a 5HP Briggs converted to steam by my father. Now, this was a
conventional steam engine, not the type we have been talking about here. He
took out the cam shaft, removed the hardening by heating and slowly cooling
it several times. Then he welded or silver soldered extra metal to one side
of the existing lobes and ground the results into the timing he needed for
the valves. I don't have the details on that.

If I had a spare unit like that, I would just vice it, take the spark plug
out, put a torch to the head and spray water from a bottle into the spark
plug hole to see what happens. Err... Wearing a heavy glove of course. If it
makes a nice puff of steam, I'd move on.

Then I might go and buy a fuel injector from the local auto parts place and
see about finding a way to screw it in place of the plug and feed it with
some water from a tank and hose. Then disable the intake valve, move the
engine to just past TDC, heat the head up and spark the injector.

If it turned the crank, even a little, I would work on changing the exhaust
valve timing so that it prevented any compression. And figure out a trigger
for the injector based on TDC. 

Somewhere in there, if I had a mill, I would try to increase the surface
area inside the head. Maybe build a shroud to keep more of the torch heat
focused on the head.

It might actually start to run... Or not... Either way, it would be good to
know.

> [Snipped the ICE/water discussion]
> 
> A Curnutt solar furnace. I can't figure out why 25 years 
> later why every backyard/ rooftop doesn't have one.

A) Safety. Both from the amount of weight that needs to be moving through
the air and from the need to use a high pressure boiler to generate steam.

B) Cost. That is a lot of metal to weld up. If you aren't a welder yourself
and you don't have access to scrap metal, it costs $10k or more and
generates about 4KWh if I remember correctly.

> I'm still thinking that this XenoTech Research idea of using 
> flexible Mylar may simplify many of those issues:
> 
> http://xenotechresearch.com/solvari1.htm
> 
> It's little more than an airtight drum with a mylar cover and 
> a vacuum pump to form a collector. Light, cheap (very cheap), 
> and no mirrors involved.

It's a very interesting idea. My only concern, and one that has been voiced
by others as well, is the ability to resist wind.

> > Here is another idea: Put the mirrors on the ground. You 
> can prop them 
> > up with rocks if you want. Align them at night with a laser pointer 
> > and a target in the center. Hang the pointer on a string 
> from a tripod 
> > which is placed over each mirror like a plumb bob then move 
> the mirror 
> > until the beam hits the target. Next day, you have a small 
> copy of the 
> > sun tracking through the air over the mirror field.
> > 
> > Then, put the engine and generator in the air on a post and 
> move them 
> > to match the focal point of the mirrors. Since there is no high 
> > pressure feed to run to the motor and no hot exhaust to run 
> out, the 
> > only thing that needs to follow them is a water hose going 
> in, and an electrical cable going out.
> > I would probably use two arms and a pole between them with 
> the motor / 
> > generator mounted in the middle.
> 
> My gut keeps telling me its better to put the engine on a 
> base below the collector.
> Find attached a rough sketch of the idea.

Good idea. My only concerns would be with the extra work involved in
focusing it and with the possibility of heat losses through 2 mirrors. But
if enough heat gets through, who cares?

I really think the thing to do is put the mirrors on the ground. They won't
flex, they won't move, they won't loose focus. Even 1,000 1' square mirrors
can be focused to a 1' square area if they are on stable enough mounts.
Otherwise, you get 1,000 1' square mirrors focused on a 2' area and that
is.... Think about it.... HALF as good. 500 focused to 1 is as good as 1000
focused to 2. So the stability of the mirror mount and the alignment of the
mirrors is more critical than all the existing designs take into account. I
know from experience: You can't get even 144 mirrors focused dead on when
they are mounted to a metal frame that is light enough to move through the
air. It flexes. It bends. It melts very slowly over time. Things happen. The
best thing would be a huge concrete pad poured right on bedrock formed to a
perfect parabola with the mirrors glued in place after adding a little sand
or something to adjust each one to be dead on to the target.

Failing that, a nice hard dirt lot with one edge stuck in the ground and a
good sized, roughly triangular rock to prop them up at the right angle. 

Why make it complex? I swear people do that just so they don't have to try.

---
James Newton, massmind.org Knowledge Archiver 
james@massmind.org 1-619-652-0593 fax:1-208-279-8767 
All the engineering secrets worth knowing:
http://techref.massmind.org What do YOU know?




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