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'[OT] Vegetable oil in a diesel engine... Was: [EE]'
2005\09\12@124953 by James Newtons Massmind

face picon face
Make sure you can get the oil first. Supplies have totally dried up in my
area. Other people or companies have laid claim to all the available waste
oil.

---
James.



> {Original Message removed}

2005\09\14@153046 by Peter

picon face


On Mon, 12 Sep 2005, James Newtons Massmind wrote:

> Make sure you can get the oil first. Supplies have totally dried up in my
> area. Other people or companies have laid claim to all the available waste
> oil.

I think that I know where you could locate some extra supplies:

http://www.cnn.com/2005/WORLD/europe/09/14/germany.catfuel.reut/index.html

Peter

2005\09\14@210335 by William Chops Westfield

face picon face

> What I'd love to see is petroleum-based fuels (and other fossil fuels
> to a similar degree) going out of use. Run power stations off biomass
> (burn plants) and run cars off biodiesel (processed vegetable oil).

Alas, I don't think "used" vegetable oil scales nearly well enough, and
then you quickly run into "oh, so you think we should use land that
could
raise food for the hungry people in the world and use it to feed
american's
hunger for big cars instead?" sort of argument.

I saw someone claim (on piclist a long time ago?) that if you calculate
the delivered efficiency of biomass (So much solar flux per km^2 yields
so much energy in sugar, alcohol, or carbon), there is no way you can
even support the worlds current appetite for energy, much less projected
energy demand.  IIRC, I didn't buy all their assumptions, but it's a
sobering thought; one doesn't think of plant efficiency compared to
solar cell efficiency (for example), but the number is there somewhere
and apparently it's not all that impressive :-(

BillW

2005\09\15@044839 by Russell McMahon

face
flavicon
face
> I saw someone claim (on piclist a long time ago?) that if you
> calculate
> the delivered efficiency of biomass (So much solar flux per km^2
> yields
> so much energy in sugar, alcohol, or carbon), there is no way you
> can
> even support the worlds current appetite for energy, much less
> projected
> energy demand.  IIRC, I didn't buy all their assumptions, but it's a
> sobering thought; one doesn't think of plant efficiency compared to
> solar cell efficiency (for example), but the number is there
> somewhere
> and apparently it's not all that impressive :-(

I too disbelieve it in its more extreme forms, but the claim was in
fact that ALL terrestrial energy sources which may be considered to
replace finite lifetime hydrocarbons, failed to deliver a net energy
gain and that " we're all doomed". At the time I pointed out that
fusion, using lunar Helium strip-mined from the layer of dust on the
moon's surface has a very substantial net energy gain, even allowing
for the horrendous development costs and the large amount of energy
per mass required to obtain it. My argument was first misunderstood
and then ignored. The reason it works, where all other sources
notionally fail, is that it does not use conventional "old solar"
chemical energy sources or "new solar" sources such as wind / waves /
hydro/ biomass / ... but instead uses very-very-old solar-like nuclear
processes. ie All energy sources available to us have come (as far as
we can tell) from stars, but using nuclear processes gives you a leg
up.

At 19 megawatt-year/kg He3 fusion is well ahead of the typically 10
kWh/kg of fossil fuels. (By a factor of about 15,000,000:1).



       RM

2005\09\15@063048 by Howard Winter

face
flavicon
picon face
Russell,

On Thu, 15 Sep 2005 20:48:19 +1200, Russell McMahon
wrote:

> My argument was first misunderstood and then ignored.

Story of my life, mate!  :-)))

Cheers,


Howard Winter
St.Albans, England


2005\09\15@175533 by Peter

picon face

On Thu, 15 Sep 2005, Russell McMahon wrote:

>> I saw someone claim (on piclist a long time ago?) that if you calculate
>> the delivered efficiency of biomass (So much solar flux per km^2 yields
>> so much energy in sugar, alcohol, or carbon), there is no way you can
>> even support the worlds current appetite for energy, much less projected
>> energy demand.  IIRC, I didn't buy all their assumptions, but it's a
>> sobering thought; one doesn't think of plant efficiency compared to
>> solar cell efficiency (for example), but the number is there somewhere
>> and apparently it's not all that impressive :-(
>
> I too disbelieve it in its more extreme forms, but the claim was in fact that
> ALL terrestrial energy sources which may be considered to replace finite
> lifetime hydrocarbons, failed to deliver a net energy gain and that " we're

What is a 'net energy gain' ?! You can think in terms of man-energy
(paraphrasing LeCorbusier who got some flak for that at the time).
Estimate how much joe average needs and find a way to cover that. Of
course you can just about forget about street lighting and things like
immense billboards shining at night.

My probably incorrect calculations show that a man who has about 50m^2
of solar panels and a windmill in a temperate zone will make enough
power to sustain himself and to store some for maintenance and even some
development. Of course if the panels will be low tech (homemade) he will
need 500m^2. The large size comes from the need to run ovens and power
tools to make things with.

> solar" chemical energy sources or "new solar" sources such as wind / waves /
> hydro/ biomass / ... but instead uses very-very-old solar-like nuclear
> processes. ie All energy sources available to us have come (as far as we can
> tell) from stars, but using nuclear processes gives you a leg up.

Maybe we should wait until this is tested at least in a one-off trial ?

Peter

2005\09\16@141512 by James Newtons Massmind

face picon face
I would like to see a good engineering comparison of the following two
things:

A) A field of some size planted with some plant that grows over some time
and is then harvested, fermented to alcohol or oil extracted and that
resulting product burned to move a car down a road.

B) A field of the same size covered in solar panels or other means of
electric power generation and that power stored in batteries and used to
move a car down a road.

Which one:
1. is less costly to implement?
2. moves the car further over some set time (say 1 year)?
3. is more repeatable / renewable?

???

My guess is that A is cheap but doesn't move the car very far and that B is
more expensive both in terms of the generation field and the required
modifications to the car, but puts out more actual work.

So... We need either a GMO crop (more expensive seeds) that produces much
more oil or alcohol OR a less expensive method of generating electricity
from the sun even if it is a bit less efficient coupled with lighter, more
efficient batteries or even (shudder) hydrogen.

Russell will now assert that the GMO crop will end up killing us all.

I will now assert that we should chuck both issues and just build a nuke
plant. (that does still leave the need for better batteries)

Someone else will assert that Hydrogen is the answer and someone else will
assert that Hydrogen is a joke.

Now that the extremes have been preemptively addressed, maybe there are some
others who would like to comment on the mid ground?

---
James.



> {Original Message removed}

2005\09\16@143145 by David Van Horn

picon face

> Now that the extremes have been preemptively addressed, maybe there
are
> some others who would like to comment on the mid ground?

I think bush should release the area-51 alien technology, and the 100
MPG carburetor!

(you forgot one..) :)




2005\09\16@144942 by olin piclist

face picon face
James Newtons Massmind wrote:
> A) A field of some size planted with some plant that grows over some
> time and is then harvested, fermented to alcohol or oil extracted and
> that resulting product burned to move a car down a road.
>
> B) A field of the same size covered in solar panels or other means of
> electric power generation and that power stored in batteries and used to
> move a car down a road.
>
> ...
>
> My guess is that A is cheap but doesn't move the car very far and that
> B is more expensive both in terms of the generation field and the
> required modifications to the car, but puts out more actual work.

But these aren't the only ways to use the field to collect solar energy, nor
is it the only way to utilize electrical energy if that's what you have the
field produce.

For example it's not clear to me at all that the best artificial way to
collect solar energy over a large field is with solar panels.  At
efficiencies of 10-18%, there is a lot of room to do better.  A bunch of
mirrors for concentrating the radiation and a custom designed heat engine
for the task should be able to do considerably better.  The theoretical
maximum high temperature for the heat engine is the temperature at the
surface of the sun, and the low is ambient air.  The carnot efficiency
should be pretty good.  Even if only half of that is actually realized, it
should still beat solar cells handily.

Now what can you do with that energy?  A heat engine could run a generator
and then you can compare apples to apples with the solar cells.  However
there may be other ways to at least partially utilize the heat or the
mechanical energy that would have turned the generator.  I don't understand
all the processes, but there must be some way to produce chemical fuel, like
separating hydrogen and oxygen from water.  Carbon based fuels are more
convenient to our current infrastructure.  I've always been intrigued by the
idea of taking water and grabbing CO2 out of the air to make a carbon based
fuel, like methane or methanol for example.  I think the real problem is
that there is so little carbon in the air, that concentrating it will be
inefficient.  Still, there is nothing theoretical against this that I can
see, and the low fraction of carbon in the air makes it difficult but does
not require it to be theoretically inefficient, although you have to harness
the energy represented in the "waste" oxygen that will be produced.  I know
this is totally impractical today, but I wonder how feasible it could be if
there was a concerted effort to make it so.

> Someone else will assert that Hydrogen is the answer and someone else
> will assert that Hydrogen is a joke.

I think you need to separate what is theoretically feasible from what is
practical with today's existing infrastructure.  I think in this discussion
we are talking about what could be long term, so today's infrastructure
limitations aren't relevant.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\09\16@161333 by Alex Harford

face picon face
On 9/16/05, Olin Lathrop <spam_OUTolin_piclistTakeThisOuTspamembedinc.com> wrote:
>
> But these aren't the only ways to use the field to collect solar energy, nor
> is it the only way to utilize electrical energy if that's what you have the
> field produce.
>

Something like this?

http://pesn.com/2005/08/11/9600147_Edison_Stirling_largest_solar/

2005\09\16@171502 by James Newtons Massmind

face picon face
> But these aren't the only ways to use the field to collect solar
> energy, nor is it the only way to utilize electrical energy if that's
> what you have the field produce.

Very true. Perhaps I should have been more generic in my description.

> For example it's not clear to me at all that the best artificial way
> to collect solar energy over a large field is with solar panels.  At
> efficiencies of 10-18%, there is a lot of room to do better.  A bunch
> of mirrors for concentrating the radiation and a custom designed heat
> engine for the task should be able to do considerably better.  The
> theoretical maximum high temperature for the heat engine is the
> temperature at the surface of the sun, and the low is ambient air.  
> The carnot efficiency should be pretty good.  Even if only half of
> that is actually realized, it should still beat solar cells handily.

Now you have a few choices for heat engine. Stirlings have NOT caught on
well have they? Could it be the pricing? Or is it that to approach high
efficiencies they need working fluids that are caustic and expensive to
contain?

Is there a LOW cost heat engine? One that can be made from existing hardware
for example?

Steam engines are a possibility, but the boilers are unsafe and valving
modifications can be difficult. I personally have seen a 5hp Brigs and
Stratton gas engine that was modified by replacing the cam shaft to run as a
steam engine.

And there are other ideas.... <sly grin> Such as /internal/ boiler steam
engines:
http://www.massmind.org/techref/idea/mc-heat-inject.htm a version of this
with a much more expensive injector and an external (not quite) boiler has
been done using an existing (old) gasoline engine.
http://www.flashsteam.com/Steam_Engine_Project.htm He ran into the effect I
postulated in the first link there, but he thinks it is a bug and I think it
is a feature. He calls it "Heat of Rejection" and notes that if the engine
block isn't heated up, the steam expansion from his injector almost
instantly condenses back on the inside of the cylinder walls. I say to heck
with the preheated, high pressure injector, just heat the hell out of the
cylinder and/or head and inject cold water. When it hits the air / walls /
head inside the cylinder it will flash over into steam and the volume
expansion will push the piston down and the crank around.

{Quote hidden}

Wow! Now that is interesting... Where does CO2 (as in fire extinguishers,
dry ice, etc... Come from now?) Pulling it out of the air could help to
reverse global warming as well, right?

> I think you need to separate what is theoretically feasible from what
> is practical with today's existing infrastructure.
> I think in this discussion we are talking about what could be long
> term, so today's infrastructure limitations aren't relevant.

The cost of development is a cost, so that has to be considered as a startup
cost in the system. I would love to know more about what could be done
today, and is perhaps not being done because it is not considered efficient
enough or is to costly to start. Then you can look for ways to get around
those problems.

>
> *****************************************************************
> Embed Inc, embedded system specialists in Littleton Massachusetts
> (978) 742-9014, http://www.embedinc.com
> -

2005\09\16@171521 by James Newtons Massmind

face picon face
> But these aren't the only ways to use the field to collect
> solar energy, nor is it the only way to utilize electrical
> energy if that's what you have the field produce.

Very true. Perhaps I should have been more generic in my description.

{Quote hidden}

Now you have a few choices for heat engine. Stirlings have NOT caught on
well have they? Could it be the pricing? Or is it that to approach high
efficiencies they need working fluids that are caustic and expensive to
contain?

Is there a LOW cost heat engine? One that can be made from existing hardware
for example?

Steam engines are a possibility, but the boilers are unsafe and valving
modifications can be difficult. I personally have seen a 5hp Brigs and
Stratton gas engine that was modified by replacing the cam shaft to run as a
steam engine.

And there are other ideas.... <sly grin> Such as /internal/ boiler steam
engines:
http://www.massmind.org/techref/idea/mc-heat-inject.htm a version of this
with a much more expensive injector and an external (not quite) boiler has
been done
http://www.flashsteam.com/Steam_Engine_Project.htm

{Quote hidden}

Wow! Now that is interesting... Where does CO2 (as in fire extinguishers,
dry ice, etc... Come from now?) Pulling it out of the air could help to
reverse global warming as well, right?

> I think you need to separate what is theoretically feasible
> from what is practical with today's existing infrastructure.  
> I think in this discussion we are talking about what could be
> long term, so today's infrastructure limitations aren't relevant.

The cost of development is a cost, so that has to be considered as a startup
cost in the system. I would love to know more about what could be done
today, and is perhaps not being done because it is not considered efficient
enough or is to costly to start. Then you can look for ways to get around
those problems.

>
> *****************************************************************
> Embed Inc, embedded system specialists in Littleton Massachusetts
> (978) 742-9014, http://www.embedinc.com
> -

2005\09\16@173038 by David Van Horn

picon face


I rather liked that one in California, like a flower.
A field of mirrors concentrates sun on a heat chamber. I think it's
metallic sodium or some such, maybe oil, but from there it's a steam
turbine.

The mirrors all need servos to track the sun, but that's not a huge
problem.



2005\09\16@175057 by James Newtons Massmind

face picon face
> Something like this?
>
> http://pesn.com/2005/08/11/9600147_Edison_Stirling_largest_solar/


Stirlings have issues. They wear out fast or are expensive as heck to make.

There is one design that I can't figure out why they haven't made, and I
can't figure out what is wrong with it...
http://www.qrmc.com/ View the three cylinder animation. But that is where
they were in 1999 and they haven't moved an inch. So something is wrong. I
just don't know what. And it isn't the rolling sleeve seal; those work just
fine in other areas.

---
James Newton, massmind.org Knowledge Archiver
.....jamesKILLspamspam@spam@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?


2005\09\16@192822 by William Chops Westfield

face picon face
>> But these aren't the only ways to use the field to collect solar
>> energy, nor is it the only way to utilize electrical energy if that's
>> what you have the field produce.
>>

Alas (I seem to be saying that a lot lately) alternative energy has
become a POLITICAL hotbed, and it's no easier to do real research
into the most efficient (really) way to use a given piece of land
than it is to do research into whether there are any racial components
of intelligence :-(

I find the current thrust into hydrogen fuel cells particularly
annoying,
since currently our only commercial scale source of hydrogen is ...
fossil
fuels.  (of course, the pollution issues are separate from the alternate
energy issues...)

BillW

2005\09\17@035058 by Roland

flavicon
face
..............


>> from water.  Carbon based fuels are more convenient to our current
>> infrastructure.  I've always been intrigued by the idea of taking
>> water and grabbing CO2 out of the air to make a carbon based fuel,
>> like methane or methanol for example.  I think the real problem is
>> that there is so little carbon in the air, that concentrating it will
>> be inefficient.  Still, there is nothing theoretical against this that
>> I can see, and the low fraction of carbon in the air makes it
>> difficult but does not require it to be theoretically inefficient,
>> although you have to harness the energy represented in the "waste"
>> oxygen that will be produced.  I know this is totally impractical
>> today, but I wonder how feasible it could be if there was a concerted
>> effort to make it so.
>
>Wow! Now that is interesting... Where does CO2 (as in fire extinguishers,
>dry ice, etc... Come from now?) Pulling it out of the air could help to
>reverse global warming as well, right?
>

I've thought about that too. The last I looked on the net, CO2 is a waste product in many industries, no need to go making it yourself.

"The Fischer-Tropsch process is a catalyzed chemical reaction in which carbon monoxide and hydrogen are converted into liquid hydrocarbons of various forms. Typical catalysts used are based on iron and cobalt. The principal purpose of this process is to produce a synthetic petroleum substitute."

Sasol in South Africa has been doing this for decades, using coal for the CO source. They are apparently negotiating with china to set up two plants there.

Also , from an article;
"A number of studies have attempted to estimate the global potential of biomass energy. Although the amount of sunlight reaching the earth's surface is substantial, less than a tenth of a percent of the total is actually captured and stored by plants. About half of it is reflected back to space. The rest serves to maintain global temperatures at life-sustaining levels.  ... "

To get the CO2 as you suggested, I suppose one would use heat exchangers; Cool the air to remove the water, then further cool to precipitate the CO2, then use the waste cooled air to pre-cool the incoming air. The CO2 ice is compressed into gas, into tanks.

If an 'air' to fuel process could run off a solar array, it would be quite neat to collect your free litre of fuel everday. The real difficult part is to quantify 'efficiency' See, even if you saved 50% of your current fuel costs, you'd probably spend that money on a holiday, or a new ICD3?, so where's the real saving in natural resources?

I think self-sufficiency and fun is the best motive for these endevours.


Regards
Roland Jollivet

2005\09\17@044323 by Lindy Mayfield

flavicon
face
part 1 866 bytes content-type:text/plain; (decoded base64)

There were articles going around (CNN, Yahoo, etc) about a German making fuel from dead cats.  Later he denied it, though.
www.cnn.com/2005/WORLD/europe/09/14/germany.catfuel.reut/

I'll refrain from any comments, but I'm sure Roland knows what I'm thinking.



Roland said:

       Also , from an article;
       "A number of studies have attempted to estimate the global potential of biomass energy. Although the amount of sunlight reaching the earth's surface is substantial, less than a tenth of a percent of the total is actually captured and stored by plants. About half of it is reflected back to space. The rest serves to maintain global temperatures at life-sustaining levels.  ... "
       
       ...
       
       I think self-sufficiency and fun is the best motive for these endevours.
       
       
       Regards
       Roland Jollivet
       


part 2 4983 bytes content-type:application/ms-tnef; (decode)

part 3 35 bytes content-type:text/plain; charset="us-ascii"
(decoded 7bit)

2005\09\17@093859 by Spehro Pefhany

picon face
At 11:42 AM 9/17/2005 +0300, you wrote:
>There were articles going around (CNN, Yahoo, etc) about a German making
>fuel from dead cats.  Later he denied it, though.
>http://www.cnn.com/2005/WORLD/europe/09/14/germany.catfuel.reut/
>
>I'll refrain from any comments, but I'm sure Roland knows what I'm thinking.

Put a tiger in your tank?

It seems to me that plants have essentially "poisoned" the atmosphere
over the eons (originally it reducing, not oxidizing) from their perspective
by emitting oxygen (when light is present) and consuming CO2, to the point
where
there is almost no free CO2 left. They have evolved to adapt to the harsh
conditions,
and other organisms like us have sprung up to take advantage of the free
oxygen,
but we can't tolerate very much CO2-- more than about 1000ppm and we start
experiencing problems. Modern plants are probably happy with lots of CO2 or
just
a whisper.

Calculations on biomass energy and solar must be very complex, depending
on the aim of the research. For example, fertilizer requires a fair bit
of natural gas to make, and oil products are used in mechanized harvesting
and planting operations. Similarly, the energy used to manufacture PV
cells is reportedly significant compared to the lifetime output of the
cells.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speffspamKILLspaminterlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff


2005\09\17@111915 by Mike Hord

picon face
> A) A field of some size planted with some plant that grows over some time
> and is then harvested, fermented to alcohol or oil extracted and that
> resulting product burned to move a car down a road.
>
> B) A field of the same size covered in solar panels or other means of
> electric power generation and that power stored in batteries and used to
> move a car down a road.
>
> Which one:
> 1. is less costly to implement?
> 2. moves the car further over some set time (say 1 year)?
> 3. is more repeatable / renewable?

I've wondered about this myself.  I've come to a few conclusions:

A has the advantage of little to no maintanence (some will disagree,
citing combines, tractors, irrigation, etc., but I maintain that working
smarter would allow us to reduce the technology involved to a
minimum), as well as producing useful O2 and reducing CO2.

B has the advantage of continuous output:  18-20% of the light
falling on it is captured and converted constantly, whereas the
plants capture sunlight over a growing season (or however long
the time between harvests), and probably not 18-20%.

Someone mentioned rafts of algae in the ocean.  TANSTAAFL-
That would probably unbalance the food chain in the ocean,
by reducing the amount of sun available to native organisms,
and would also reduce the surface temp of the ocean.  And
who can say what effect that would have?

Mike H.

2005\09\17@131042 by Peter

picon face

On Fri, 16 Sep 2005, David Van Horn wrote:

> I rather liked that one in California, like a flower. A field of
> mirrors concentrates sun on a heat chamber. I think it's metallic
> sodium or some such, maybe oil, but from there it's a steam turbine.
>
> The mirrors all need servos to track the sun, but that's not a huge
> problem.

Water is not an ideal fluid for use in small heat engines. Other liquids
and gases are better afaik. The highest efficiency Stirlings use Helium
as working gas afaik. Almost any gas can be used but most gases that
work very well are either very expensive, very explosive, or both. Plus
some are toxic (ammonia is one f.ex., ethyl ether another). Also high
efficiency heat engines either do not use phase change or use both phase
changes to recover latent heat. That can make them bulky and inefficient
if built small. Think about it: the most efficient known thermodynaic
machines are diesel engines, stirlings and turbines. Neither use phase
change internally.

So I do not think that it is simple. James could make a trial with a
stripped down model aircraft engine, just to see if it works. Imho, the
injector can be deleted and water can be injected at the 'intake' cycle.
The latent heat would keep it liquid until TDC is reached if this is
done right. Still, the latent heat will be lost unless the steam is
recirculated through a condenser and the heat recovered. As a 'hack'
such an engine could be interesting to make.

On the other hand, imho, if some trick could be devised to inject
superheated water into the cylinder of a small engine, maybe compress it
further under a gas cushion (air, nitrogen), and trigger nucleation at
TDC, and repeat the process in a repeatable and stable way, then
something might come of it.

Peter

2005\09\18@075850 by Howard Winter

face
flavicon
picon face
Peter,

On Sat, 17 Sep 2005 20:10:39 +0300 (IDT), Peter wrote:

> On the other hand, imho, if some trick could be devised to inject
> superheated water into the cylinder of a small engine, maybe compress it
> further under a gas cushion (air, nitrogen), and trigger nucleation at
> TDC, and repeat the process in a repeatable and stable way, then
> something might come of it.

I don't quite follow what you mean here, but it sounds awfully like Newcomen's atmospheric steam engine!

Cheers,


Howard Winter
St.Albans, England


2005\09\18@140023 by James Newtons Massmind

face picon face
> So I do not think that it is simple. James could make a trial
> with a stripped down model aircraft engine, just to see if it
> works. Imho, the injector can be deleted and water can be
> injected at the 'intake' cycle.
> The latent heat would keep it liquid until TDC is reached if
> this is done right. Still, the latent heat will be lost
> unless the steam is recirculated through a condenser and the
> heat recovered. As a 'hack'
> such an engine could be interesting to make.

The point is that solar energy does not demand a high efficiency conversion.
It's "free" so a lower efficiency can be justified as long as the cost is
minimal.

> On the other hand, imho, if some trick could be devised to
> inject superheated water into the cylinder of a small engine,
> maybe compress it further under a gas cushion (air,
> nitrogen), and trigger nucleation at TDC, and repeat the
> process in a repeatable and stable way, then something might
> come of it.

Again, see:
http://www.flashsteam.com/Steam_Engine_Project.htm which is where that exact
thing is being done. But notice that he has to heat the cylinder to prevent
the super heated water from flashing to steam, then instantly flashing back
to water when it cools on the cylinder walls. Why incur the danger of
pre-super-heating the water under pressure when you can just heat the
cylinder and inject cold water?

The only reason I can think of is that it will wear out the engine faster,
but then we aren't talking about a mulit-million dollar sterling engine...
This is an old motorcycle engine or like that rescued from the junk yard. So
if it wears out, toss it and replace.
http://www.piclist.com/techref/idea/mc-heat-inject.htm

---
James Newton, massmind.org Knowledge Archiver
.....jamesKILLspamspam.....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?


2005\09\18@175813 by Peter

picon face


On Sun, 18 Sep 2005, Howard Winter wrote:

{Quote hidden}

No. Superheated water is liquid. It flashes into steam when triggered,
f.ex. chemically. I do not know how this can be done in a cylinder but
there should be a way. This would not require heating the cylinder !

Peter

2005\09\18@195255 by David Van Horn

picon face
> The point is that solar energy does not demand a high efficiency
> conversion.
> It's "free" so a lower efficiency can be justified as long as the cost
is
> minimal.

It's only "free" if the real estate to collect it is free.
Rooftop solar heaters work that way, because we were already using that
area for something, and the solar heater doesn't impact that use.

If you're trading farmable land, then efficiency matters.
It will be a diminishing returns curve of course, but it does matter.




2005\09\19@035008 by Russell McMahon

face
flavicon
face
> Russell will now assert that the GMO crop will end up killing us
> all.

It's unlikely that any individual GMO product will kill us all. Any
given one may destroy biodiversity, cause health problems and/or
assist transfer of genetic content into places where it could never
have got to without GE. Or not. But that's not killing us all.
Possibly just some of us :-). But it is likely that if we produce
enough unlikely candidates which we have no way of telling the effect
of in advance then we will in due course "get lucky".
and open the door onto one which will, without any way to tell what's
likely to happen before we actually try it out.

So far *almost all* of the opened doors have proved less than fully
lethal. At least one which has been publicised came close to
fulfilling the role for mice - its failing was that it was not very
infectious (as opposed to effective once transferred). That was
several years ago so by now those who work on such things to develop
weapons systems will almost certainly have overcome this "small
deficiency".


   RM



2005\09\19@071803 by Alan B. Pearce

face picon face
>On the other hand, imho, if some trick could be
>devised to inject superheated water into the
>cylinder of a small engine,

Hmm, this portion is essentially what any railway steam engine does, except
they do it as superheated steam. This is then used mostly twice, and
sometimes three times before being exhausted to the air.

2005\09\19@072613 by Alan B. Pearce

face picon face
>> The point is that solar energy does not demand a high
>> efficiency conversion. It's "free" so a lower
>> efficiency can be justified as long as the cost is
>> minimal.
>
>It's only "free" if the real estate to collect it is free.
>Rooftop solar heaters work that way, because we were already
>using that area for something, and the solar heater doesn't
>impact that use.

It is also a problem in that it needs to save money during the lifespan of
the system. It is not "free" if the end output cost is more than the output
cost of some alternative system, which is why we use petrol instead of
electrolysing water in oxygen and hydrogen to burn it.

2005\09\19@085312 by Xiaofan Chen

face picon face
I think fuel cell is one of the possibilities. I have been to NFCRC of UC Irvine
and indeed they are doing something interesting.

I have also been to the GM Advance Research Center in Torrece CA. They
have very interesting stuff as well (fuel cell drived car and hybride car).
Still it is very difficulty to promote electrical vehicle since the oil is still
too cheap in USA (California has one of the highest oil price in USA but
it is still cheaper than Europe). I guess oil price should be doubled so
that everyone will consider not to use oil any more and I hope that oil
price will really doubled within one year so that investment on alternaitve
energy really takes off. USA is the No 1 oil consumer and yet it blaims
China/India for the price of oil hike. This is really strange!

Regards,
Xiaofan

------------------------------------------

http://www.nfcrc.uci.edu/

National Fuel Cell Research Center
Mission
The mission of the NFCRC is to facilitate and accelerate the
development and deployment of fuel cell technology and fuel cell
systems; promote strategic alliances to address the market challenges
associated with the installation and integration of fuel cell systems;
and to educate and develop resources for the various stakeholders in
the fuel cell community.

2005\09\19@142627 by Peter

picon face

On Sun, 18 Sep 2005, James Newtons Massmind wrote:

> The point is that solar energy does not demand a high efficiency conversion.
> It's "free" so a lower efficiency can be justified as long as the cost is
> minimal.

Except high temperature = high efficiency. You may have to use a vacuum
chamber configured as a blackbody to put the heat where you want it. And
the first high wind is going to try out your structure.

> http://www.flashsteam.com/Steam_Engine_Project.htm which is where that exact
> thing is being done. But notice that he has to heat the cylinder to prevent
> the super heated water from flashing to steam, then instantly flashing back
> to water when it cools on the cylinder walls. Why incur the danger of
> pre-super-heating the water under pressure when you can just heat the
> cylinder and inject cold water?

Cold water in contact with a hot surface beyond a certain temparature
(about 200 degrees C) refuses to 'flash into steam'. This effect has a
name and I used to know it but I cannot find it now. All high throughput
applications that make steam either gradually heat water in a metal tube
with a high temperature gradient across it ('scottish' boiler etc) or
superheat water under pressure and flash it into steam by releasing it.
There is no way to transfer heat to water beyond its boiling point
without keeping it under pressure and because of the high specific heat
of evaporation this means that any boiler that does not use this
principle is limited in throughput. All useful 'flash' boilers use the
tube-with-a-gradient principle and then superheat the steam. The best
counter-example is your electric water kettle which sings and gurgles a
lot instead of efficiently heating the water that touches its well over
100 degree heating element. Cheap espresso machines have the same
problem (the ones without the pressurised water bomb, I mean reservoir).

Dropping a slug of water into a hot cylinder is the exact recipe for
inefficiency. The man who built that steam engine worked his way around
this problem in a neat way (using superheated water).

What I was trying to get at was to use an unmodified engine that is
charged with superheated water and gas (air, nitrogen) which it
pressurises further by compression, and triggers the steam flashing at
TDC using chemical means (contact with a catalyst or such). The exhaust
would be at high pressure and would be good to run a turbine off of.

> The only reason I can think of is that it will wear out the engine
> faster, but then we aren't talking about a mulit-million dollar
> sterling engine... This is an old motorcycle engine or like that
> rescued from the junk yard. So if it wears out, toss it and replace.
> http://www.piclist.com/techref/idea/mc-heat-inject.htm

Peter

2005\09\19@160128 by James Newtons Massmind

face picon face
> Cold water in contact with a hot surface beyond a certain
> temperature (about 200 degrees C) refuses to 'flash into
> steam'. This effect has a name and I used to know it but I
> cannot find it now. All high throughput applications that
> make steam either gradually heat water in a metal tube with a
> high temperature gradient across it ('scottish' boiler etc)
> or superheat water under pressure and flash it into steam by
> releasing it.

Very true. What happens is that the boiling water forms a barrier between
the heated plate and the unheated water and prevents the rest of the water
from boiling.

{Quote hidden}

Try this: (I did) take a skillet and heat it up nice and hot on your stove
then drop water on it. You will see the effect mentioned where the water
jumps about and doesn't all boil because it is on a layer of steam that
keeps it out of contact with the metal. It can take quite a long time for
all the water to boil off.

Next: Try again with a fine mist spray bottle. You can get a much nicer
blast of steam because the water is in very small packages and does not have
the mass required to form a shield. This is why I think the water injector
is necessary in the idea presented at
http://www.massmind.org/idea/mc-heat-inject.htm

Now: Find a screen or steel wool or any other metal object with a complex
surface. Heat it up in the pan making sure that it is contacting the pan
well and that it actually gets hot. Now drop the water on it or spray it.
Wear eye protection. I have personally blown steel wool all over my kitchen
doing this. What happens is that the water is divided up into fine parts and
each part has more surface area exposed so more of it flashes over.

So this problem is very certainly avoidable. Why aren't flash boilers made
this way? Because the flash over from water to steam removes a great deal of
the heat from the metal. Metal with enough mass to withstand the pressure
can not conduct enough heat to provide for a continuous flashing of water to
steam. But I see no reason why it can not be used for a periodic flashing as
would be the case in the link above.

Also, impurities in the water are deposited on the metal and again form an
insulative layer. This limits the complexity of the surface. It needs to be
fairly smooth to hopefully slag off the impurities between cycles. This is
probably the number one problem with the idea presented above, but running
distilled water or using nonstick surface materials or something like that
may overcome the problem.

> Dropping a slug of water into a hot cylinder is the exact
> recipe for inefficiency. The man who built that steam engine
> worked his way around this problem in a neat way (using
> superheated water).

All true, but his way is also very dangerous. Unlike internal combustion, a
large quantity of "combustible" (actually flashable water) must be
maintained under pressure. Who wants a pressurized boiler in their back
yard? Guess what happens if it ever runs out of water? Or if the pressure
exceeds the rating of the boiler? If the pop-off valve fails?

And we are not talking about a "slug" of water but rather a fine spray.
Exactly what a fuel injector is designed to provide. I think the spray will
flash over just from the air temperature in the cylinder. Especially with
compression. And the water will continue to boil off out of the spray as the
piston lowers and the pressure in the chamber is reduced.

Finally, keep in mind that it doesn't matter if ALL the water flashes over.
It is only necessary that enough steam is produced to do useful work.

> What I was trying to get at was to use an unmodified engine
> that is charged with superheated water and gas (air,
> nitrogen) which it pressurises further by compression, and
> triggers the steam flashing at TDC using chemical means
> (contact with a catalyst or such). The exhaust would be at
> high pressure and would be good to run a turbine off of.


What chemical means would trigger this flashing? I've not heard of such a
thing but that part of it sounds very interesting.

2005\09\19@163630 by David Van Horn

picon face
> Also, impurities in the water are deposited on the metal and again
form an
> insulative layer. This limits the complexity of the surface. It needs
to
> be
> fairly smooth to hopefully slag off the impurities between cycles.
This is
> probably the number one problem with the idea presented above, but
running
> distilled water or using nonstick surface materials or something like
that
> may overcome the problem.

I would think that you could make a ribbon that was bi-metallic so it
would flex on each blast, and help shake off the flakes.

Still got to get them out of the boiler tho.




2005\09\19@221406 by Mike Hord

picon face
> > Cold water in contact with a hot surface beyond a certain
> > temperature (about 200 degrees C) refuses to 'flash into
> > steam'. This effect has a name and I used to know it but I
> > cannot find it now.

I believe this is the Leidenfrost effect.  Same thing that allows
the very brave or very stupid to dip a wet finger in molten lead.

Mike H.

2005\09\20@140404 by Peter

picon face


On Mon, 19 Sep 2005, Mike Hord wrote:

>>> Cold water in contact with a hot surface beyond a certain
>>> temperature (about 200 degrees C) refuses to 'flash into
>>> steam'. This effect has a name and I used to know it but I
>>> cannot find it now.
>
> I believe this is the Leidenfrost effect.  Same thing that allows
> the very brave or very stupid to dip a wet finger in molten lead.

That's the one.

Peter

2005\09\20@151624 by Peter

picon face

On Mon, 19 Sep 2005, James Newtons Massmind wrote:

> Next: Try again with a fine mist spray bottle. You can get a much nicer
> blast of steam because the water is in very small packages and does not have
> the mass required to form a shield. This is why I think the water injector
> is necessary in the idea presented at
> http://www.massmind.org/idea/mc-heat-inject.htm

You try it out. After a few dozen cycles the metal in the cylinder will
spall. Of course I hope you are right but I have some doubts. F.ex. the
clothesirons that use spray-on to make steam often have spalled,
weakened metal where the water hits the hot metal.

> surface. Heat it up in the pan making sure that it is contacting the pan
> well and that it actually gets hot. Now drop the water on it or spray it.
> Wear eye protection. I have personally blown steel wool all over my kitchen
> doing this. What happens is that the water is divided up into fine parts and
> each part has more surface area exposed so more of it flashes over.

Yes but not immediately. That allows it to first get under the wool/in
the hollow pattern. The time it takes to do this is essential. Unless
you make a huge machine with a couple of seconds per cycle you want it
fast. This is the same effect that causes molten metal or boiling oil to
explode if water gets into it. The water will not boil until it is
'under' the substance, and then it will blow. And also how good (not the
kind they sell by mail order) steam cleaners work. They are not steam
cleaners, they are superheated water cleaners.

> So this problem is very certainly avoidable. Why aren't flash boilers made
> this way? Because the flash over from water to steam removes a great deal of
> the heat from the metal. Metal with enough mass to withstand the pressure
> can not conduct enough heat to provide for a continuous flashing of water to
> steam. But I see no reason why it can not be used for a periodic flashing as
> would be the case in the link above.

Some special purpose flash boilers are made like that but they are not
for continuous use afaik.

> All true, but his way is also very dangerous. Unlike internal combustion, a
> large quantity of "combustible" (actually flashable water) must be
> maintained under pressure. Who wants a pressurized boiler in their back
> yard? Guess what happens if it ever runs out of water? Or if the pressure
> exceeds the rating of the boiler? If the pop-off valve fails?

If you have a good espresso machine then you already have a suitable
kettle, with safety valves and all that. One in a million occasionally
blows up. Usually it causes no damage (there is containment for it).

> Finally, keep in mind that it doesn't matter if ALL the water flashes over.
> It is only necessary that enough steam is produced to do useful work.

Since you inject the water into the cylinder and it becomes moving mass
and thermal inertia (and heat absorber i.e. cooler for the steam that
already flashed) you want it all flashed.

In fact, why not inject a gas ? Like CO2 ? Then you have 1/2 of a
stirling engine (well a hot air/gas engine). The only thing you want
from water is its pressure increase when heated. A gas can do better
here.

> What chemical means would trigger this flashing? I've not heard of such a
> thing but that part of it sounds very interesting.

There are several chemicals that will do it, any powder, a spark (which
causes a bubble to form), ultrasound that causes cavitation etc. I think
that it is hard to *prevent* it from happening while charging the
cylinder.

Here is another reason why your method will only work for *very* small
engines (which have high surface/volume ratio):

http://www.johnsboat.com/calcs-web.html

See the 'heating surface required'. You need 4-5 sq. feet of
conventional boiler surface per hp. By scaling this to the size of your
engine you will arrive at a very low power, probably much less than
100Watts for a motorcycle engine. See also his boiler design.

Peter

2005\09\20@171534 by James Newtons Massmind

face picon face
>
> If you have a good espresso machine then you already have a
> suitable kettle, with safety valves and all that. One in a
> million occasionally blows up. Usually it causes no damage
> (there is containment for it).

Yes, and I thought about building a concrete containment room for a steam
engine in my back yard... My wife loves me, but...

> > Finally, keep in mind that it doesn't matter if ALL the
> water flashes over.
> > It is only necessary that enough steam is produced to do
> useful work.
>
> Since you inject the water into the cylinder and it becomes
> moving mass and thermal inertia (and heat absorber i.e.
> cooler for the steam that already flashed) you want it all flashed.

Good point. Best to really "atomize" the water spray and get all of it
flashed. Or spray in less to match the available heat.

> In fact, why not inject a gas ? Like CO2 ? Then you have 1/2
> of a stirling engine (well a hot air/gas engine). The only
> thing you want from water is its pressure increase when
> heated. A gas can do better here.

Err... Are you sure? First, water is commonly available and therefore ideal
for use in a low cost system. Second, I thought the state change was what
really made the big difference in volume. Water to steam is approx 300 to
1... Or rather 1 to 300.

What sort of expansion can you get without phase change?

> > What chemical means would trigger this flashing? I've not heard of
> > such a thing but that part of it sounds very interesting.
>
> There are several chemicals that will do it, any powder, a
> spark (which causes a bubble to form), ultrasound that causes
> cavitation etc. I think that it is hard to *prevent* it from
> happening while charging the cylinder.

Sort of like pinging in a gas engine or detonation in a diesel? I can see
the point, but again, you have to pre-heat the working fluid and with that
comes all the issues of pressurized feed, safety, etc... Perhaps a
combination of heating the water to just below boiling without pressurizing
it and then injecting it as a fine spray, onto a somewhat convoluted surface
at top dead center.

Also note that the flashing of water to steam will not happen if the
cylinder is pressurized by the piston on the upstroke. The valving needs to
be such that there is no or little pressure in the cylinder when the water
spray is injected. As it is, the flash over will NOT happen instantly  for
all the water, no matter what you do. As the first, hottest, part of the
water flashes, it increases the pressure in the cylinder so that the
remaining water which happened to be a bit cooler will not reach the boiling
point until the piston has moved down and allowed the pressure to decrease.
There should be a smooth, long, power stroke.

{Quote hidden}

4 to 5 feet of surface area is attainable in a very small space, perhaps
even in a motorcycle cylinder head. The surface can be convoluted or
increased by a layer or several of wire mesh. There are lots of experiments
that can be done here. I would personally like to try making several
different types of heads to put on an old motor and try things with. One
with blades that form fins like a heat sink inside the cylinder head, one
with layers of wire screen, one with a fractal pattern, etc...

In any case getting even 100W of power out of an old motor cycle engine with
a batch of mirrors pointed at it would be a great start!

Thanks for the conversation, I'm really enjoying it. Does anyone think they
could find the time to do a few tests with something like this? I'd be
willing to pay for results, positive or negative, given some good
photographic and metric documentation.

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


2005\09\21@085656 by Russell McMahon

face
flavicon
face
>>> I saw someone claim (on piclist a long time ago?) that if you
>>> calculate
>>> the delivered efficiency of biomass (So much solar flux per km^2
>>> yields
>>> so much energy in sugar, alcohol, or carbon), there is no way you
>>> can
>>> even support the worlds current appetite for energy, much less
>>> projected
>>> energy demand.

>> I too disbelieve it in its more extreme forms, but the claim was in
>> fact that ALL terrestrial energy sources which may be considered to
>> replace finite lifetime hydrocarbons, failed to deliver a net
>> energy gain and that " we're

> What is a 'net energy gain' ?!

Assume you had NO energy resources whatsoever.
Your target is to ven "energy" to a customer.
Take every energy investment that you make as a debit and the amount
of energy that you can deliver as a credit.
Energy would be expended in prospecting, mining, processing,
delivering and handling.

The argument was that, after the higher grade hydrocarbon stores are
exhausted, there is no available terrestrial energy source available
that produces more energy than it consumes in its production. This
would (presumably) include shale oil, biomass, wind, wave, ... . To be
useful it would also have to include deep oceann methane and other
deposits. I didn't find the arguments as ut convincing BUT it was said
to be based on suitably detailed and authoritative research.

Regardless of whether the case is true r not for "conventional" energy
sources, nuclear fusion utterly romps home, IF you can do it and IF
you can fuel it. Lunar Helium (deposited from the sun via the solar
wind), while still not proven, would be a sustainable source of 'fuel'
(at least for the next billion years or two).

> Maybe we should wait until this is tested at least in a one-off
> trial ?

Trial of obtaining the 'fuel' or of getting fusion going :-) ?
On present planning NASA intends to be back on the moon by 2018 (and
about time too). If anyone cared enough tests could be done long
before then. Many expect to have achieved controlled fusion by then.



       RM

2005\09\21@092832 by olin piclist

face picon face
Russell McMahon wrote:
> Regardless of whether the case is true r not for "conventional" energy
> sources, nuclear fusion utterly romps home, IF you can do it and IF
> you can fuel it. Lunar Helium (deposited from the sun via the solar
> wind), while still not proven, would be a sustainable source of 'fuel'
> (at least for the next billion years or two).

We have plenty of fusion "fuel" right here on earth.  A surprisingly large
fraction (about 1/4500) of hydrogen atoms in naturally occurring surface
water is actually deuterium (an extra neutron).  This is the substance that
nuclear fusion reactor research is aiming to use.  A lot of oomph gets
released from making one helium from two deuteriums.  Refining water to
extract deuterium is not that difficult as such things go (a lot easier than
separating U235 from U238).  The Germans refined barrels of heavy water
during WWII.  In any case, the energy required to extract deuterium from
water is a small fraction of that released by turning the deuterium into
helium.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\09\21@094417 by Wouter van Ooijen

face picon face
> The argument was that, after the higher grade hydrocarbon stores are
> exhausted, there is no available terrestrial energy source available
> that produces more energy than it consumes in its production.

If you include sun energy into the equation this statement is an obvious
truth. If you exclude sun energy it is obviously false, otherwise no
life would exist on earth.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2005\09\21@123204 by Russell McMahon

face
flavicon
face
>> For example it's not clear to me at all that the best artificial
>> way
>> to collect solar energy over a large field is with solar panels.

Any method of collection solar input at the earth's surface has a
maximum possible output of only 4 or 5 times what is achievable now.
ie 20% versus 100%. Say 4 times as much would be "nice", but that's
not so vastly much more that it would make all the difference,
especially so if the cost was say twice as high per area.

{Quote hidden}

Carnot efficiency is (Thot-TCold) / Thot (= deltaT/Thot).
You don't need to get anywhere near solar radiation temperature to get
respectable efficiencies. call Tcold 300k (27Cish) for nice round
figures. At Thot = 1200 K =~ 930C you get 75% Carnot efficiency.
That's
enough to start with. Even at say 1000C collector temperatures you
have very nasty material problems.

> Now you have a few choices for heat engine. Stirlings have NOT
> caught on
> well have they? Could it be the pricing? Or is it that to approach
> high
> efficiencies they need working fluids that are caustic and expensive
> to
> contain?

Sort of, no, sort of.
Stirlings are doing very well thank you in niche applications. (cf eg
http://www.whispergen.com * ). Costs are higher partially because volumes are
low and applications tend to be specialist. WHEN someone gets some of
the more major problems sorted out the Stirling engine will rule. I
think Philips said something like a $US6 billion development effort
was needed and a payback period after success of under a year was
anticipated. Finding anyone who believes this enough to put up the
$US6B(now more) is the trick.

Greatest problems with Stirling engines is sealing a moving piston
with little or no lubrication at high temperatures and very large
pressures using a has that loves to diffuse through steel. Lower
temperature lower pressure Stirling engines using air as the working
fluid work just fine. but energy output per volume is "modest" making
them highly unsuited to portable/mobile applications. So people start
to do thinks to increase energy density. And the fun begins. First
swap the working 'fluid" to Helium or better still Hydrogen. Helium
will hold 5+ times as much energy as air all things being equal and
hydrogen about 14 times as much (!). Both also have other advantages
over air BUT are better escape artists. Hydrogen especially will
escape
through anything given time. At high temperatures and pressures it
will happily diffuse through steel. Small gaps in rotating seals etc
are even easier. Diffusion is not only not good for containment, it
leads to 'hydrogen embrittlement" of metals. Needless to say, high
temperature, high pressure Hydrogen is an exciting product to work
with.

Serious Stirling engine'ites try to run at pressures of 2000 - 4000
psi (15 - 30 MPa) and temperatures as high as materials so far won't
let them.

> Is there a LOW cost heat engine? One that can be made from existing
> hardware
> for example?

Absolutely. You can make a Stirling engine that runs on under 1 degree
C differential out of plastic and cardboard. Carnot efficiency is
"poor". You can also use eg an old (or new) Briggs and Stratton bottom
end as the basis for a modest medium temperature engine. Stirling
engines are not at all hard to make if you don't want a high energy
density. Something akin to the old Lister  single lunger run for ever
diesels is eminently doable. *AND*, because it is external combustion,
it will run on about anything that you can get to burn.

Here's one that was designed to run on rice husks! It's a 4.5 kW/6 HP
Stirling using air at 5 atmospheres. It was envisaged in the early
1980s. Some hundreds were built but some secondary problems and at
that stage falling oil prices killed them. (The main problems related
to linkage problems which were not the typical problems associated
with high performance Stirling engines).,
This one is HUGE  - a substantial reduction in size would be possible
for the same power level.

       http://www.stirling-tech.com/images/Madras4.htm

Information from the inventor here (1998 message)

       http://listserv.repp.org/pipermail/stoves/1998-November/004743.html

Their text:
       ... sub-contracted by the Asia Foundation to Sunpower, Inc. in
Athens, Ohio. The engine was completed in the first year of the
project and by 1982 a prototype rice husk fuelled Stirling engine had
been designed, built and demonstrated at Sunpower's facility in Ohio.
The engine had a bore of 300 mm, displacement of 7 litres and was
designed to operate at 5 bar air pressure at 600 rpm.

There are many enthusiasts worldwide building various engines.

Sunpower are still going and have built many wonderful and interesting
products, but their main income comes from Stirling cryo coolers. A
most interesting company.

       http://www.sunpower.com/

read "The sun, the Stirling engine, and the drive to save the world"
for a good picture of Sunpower and Stirling ins and outs.

> Steam engines are a possibility, but the boilers are unsafe and
> valving
> modifications can be difficult. I personally have seen a 5hp Brigs
> and
> Stratton gas engine that was modified by replacing the cam shaft to
> run as a
> steam engine.

The Stirling engine was originally invented by a Scottish clergyman
whose brother was a mine owner, in an attempt o make a safer engine
than the steam engines which at that stage tended to be rather
dangerous devices.

> And there are other ideas.... <sly grin> Such as /internal/ boiler
> steam
> engines:

All good stuff. But the basic cycles are inferior to the Carnot cycle.
A good eg Rankine or Otto etc engine will outperform a bad Carnot, but
sooner or later Carnot based cycles (eg Stirling) will win out due to
the inherent thermodynamic superiority. it just may take 'a while'
:-).


>> ... I've always been intrigued by the idea of taking
>> water and grabbing CO2 out of the air to make a carbon based fuel,
>> like methane or methanol for example.  I think the real problem is
>> that there is so little carbon in the air, that concentrating it
>> will
>> be inefficient.

The greatest problem is that if you "build a fuel" you must put energy
in from somewhere. it comes down to whether you have a suitably cheap
source of energy to "put into your fuel". In this case breaking the C
and O bonds is going to take energy which you will get back in due
course when you burn it back to CO2.


       RM

2005\09\21@140130 by Byron A Jeff

face picon face
On Mon, Sep 19, 2005 at 08:28:10PM +1200, Russell McMahon wrote:

Swapping energy sources is a project that I'm hot to work on right now.
With natural gas prices going through the roof here in the U.S. I'm
planning on adding solar to the package a kick NG out as my primary
heating fuel. So I've been doing a ton of research on solar.

> >>For example it's not clear to me at all that the best artificial
> >>way
> >>to collect solar energy over a large field is with solar panels.
>
> Any method of collection solar input at the earth's surface has a
> maximum possible output of only 4 or 5 times what is achievable now.
> ie 20% versus 100%. Say 4 times as much would be "nice", but that's
> not so vastly much more that it would make all the difference,
> especially so if the cost was say twice as high per area.

I also seems to me that it doesn't make a lot of sense to cover the
ground with extremely expensive panels that can only receive 1 sun's
worth of light. Concentrating solar would be a much better return on
your investment.

Of course with panels the efficiency is flat terrible as outlined
below.

{Quote hidden}

All true. But there's still the question of if efficiency is the critical
attribute. We're pretty sure that the Sun is going to be around for a few
billion years more. Collection systems don't necessarily need to be ultra
efficient. But they do need to be cost effective. Measurements in system
efficiency should be made in $/MJ or $/kWh.

{Quote hidden}

On the global scale it's chump change. There are energy companies that
could pay that out of pocket. It's not in their interest though.

{Quote hidden}

I'd trade some of that efficiency for reliability. As for rotating seals
part of the problem can be solved with free pistons which can be completely
encased in steel with the only outlet being for the electrical wiring.

> Serious Stirling engine'ites try to run at pressures of 2000 - 4000
> psi (15 - 30 MPa) and temperatures as high as materials so far won't
> let them.

What kind of power are we talking about in the 500C-900C range. Experiments
have shown that temp differentials in that range are pretty easily achievable
in using parabolic, Fresnell, or Curnutt style reflectors, even for the
do it yourselfer. Not real expensive either. Check out this parabolic solar
furnace that an be built with little more than an low airtight drum whos
mylar top is stretched by creating a partial vacuum behind it. Build one
with an 8 ft diameter and you can focus up to 50 Suns worth of energy into
a relatively tight spot. The question is there a homebrew Stirling setup
that can convert such energy into useful work?

{Quote hidden}

I'd like to see some pointers for a real moderate power engine that a DIY
with some scrap equipment and a bit of tooling could put together. Something
along the lines of what the Phoenix Turbine Builders Club is doing for
Tesla turbine technology: http://phoenixnavigation.com/ptbc/home.htm

The closest that I've seen so far is a demo engine built from a Briggs
and Stratton motor. You can find it here:

http://www.geocities.com/Yosemite/Rapids/2068/?200521

It's become clear to me that building small solar concentrating "cannons" are
in the realm of possibility. But how to capture the energy for useful work
cheaply is still elusive.

[Some snippage on the Madras and other topics]

Any further pointers for DIY collection of concentrated solar to convert
to electricity would be greatly appreciated.

James, I read your water injection into the engine page. I'm unclear on
how such a setup can be used to gain motive force for real work. Care
to add some addition explanation?

BAJ

2005\09\21@160420 by James Newtons Massmind

face picon face

> James, I read your water injection into the engine page. I'm
> unclear on how such a setup can be used to gain motive force
> for real work. Care to add some addition explanation?

I'm not sure how much more clear it can be... What doesn't make sense?
http://techref.massmind.org/techref/idea/mc-heat-inject.htm

1. You heat the engine, specifically the head and the top of the cylinder.

2. You spray unpressurized, unheated water into the unpressurized cylinder
at top dead center. Remember the valve timing has been changed. There is no
compression. There is no intake. Just the exhaust valve and that is changed
to close just before TDC.

3. The water spray flashes to steam due to the heat of the air and inside
metal surfaces in the cylinder. This is the most contentious part of the
idea. Lots of room for discussion and experimentation.

4. The steam pushes the piston down and is exhausted at the bottom.

Very simple. No?

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


2005\09\21@173008 by Peter

picon face

On Wed, 21 Sep 2005, Wouter van Ooijen wrote:

>> The argument was that, after the higher grade hydrocarbon stores are
>> exhausted, there is no available terrestrial energy source available
>> that produces more energy than it consumes in its production.
>
> If you include sun energy into the equation this statement is an obvious
> truth. If you exclude sun energy it is obviously false, otherwise no
> life would exist on earth.

I will have to ask my pet rock about that.

Seriously, people are a way for nature to increase entropy, from the
energy point of view. So the 'energy gain' problem's answer will always
be negative even if we bring in whatever fuel from wherever, because all
human activities have an efficiency lower than 1.

So as long as nobody tries to build a perpetuum mobile, and losses are
reasonable, anything goes, from burning camel dung to He3. As to gain, I
don't think that ever was the case. It all depends on how you set your
control volume. For example fossil fuel is considered to require less
energy for extraction than it produces *if* one disregards when it was
produced and how long it took, but energy quantity is scored by its
price, and that depends on human factors such as cost of labor, taxes,
and distances. Economics, and not physics or conservationism drive the
energy industry.

As long as one stops thinking about 'gain' and starts thinking about
'maintainable loss' things start to have solutions. Of course each
foreseable solution has an expiry time associated with it.

Peter

2005\09\21@212209 by Peter

picon face

On Tue, 20 Sep 2005, James Newtons Massmind wrote:

> Yes, and I thought about building a concrete containment room for a steam
> engine in my back yard... My wife loves me, but...

The containment is the steel casing of the machine. Don't worry too much
about it, there is not that much energy in that small reservoir. An old
book about steam engines gone bad showed extensive damage from ... an
exploding flywheel (overrevved). As long as you are not standing
directly next to the exploding espresso machine you should be fine. The
biggest danger is the big cloud of steam that could cause burns.

>> Since you inject the water into the cylinder and it becomes
>> moving mass and thermal inertia (and heat absorber i.e.
>> cooler for the steam that already flashed) you want it all flashed.
>
> Good point. Best to really "atomize" the water spray and get all of it
> flashed. Or spray in less to match the available heat.

First the available heat in the air in the cylinder will not be much.
The heat capacity of air compared to water is negligible. Second very
small droplets as you would like to make do not travel far, they
decelerate very fast and form a 'cloud'. They may not hit the wall.
Third, you are talking about injection pressures on par with those in a
Diesel engine to make fine mist. The price of such a pump will likely
kill your project very dead, at least financially, even before it
starts having problems due to impurities in water and corrosion.

>> In fact, why not inject a gas ? Like CO2 ? Then you have 1/2
>> of a stirling engine (well a hot air/gas engine). The only
>> thing you want from water is its pressure increase when
>> heated. A gas can do better here.
>
> Err... Are you sure? First, water is commonly available and therefore ideal
> for use in a low cost system. Second, I thought the state change was what
> really made the big difference in volume. Water to steam is approx 300 to
> 1... Or rather 1 to 300.

The point is you want work done. Volume does not do work, pressure +
swept volume does. If you look at a steam calculator you will see that
the pressure rises fast *but* the heat input required to achieve it is
very high! Taintstaafl! Example:

http://www.efunda.com/materials/water/steamtable_sat.cfm

A normal gas will increase pressure according to pV/T = CvR (per Mole
and standard Mole volume). Water is a 'normal' gas once it is steam, but
its Cv*R is large so the pressure increase is large (but hard to bring
by). Nitrogen (air with the oxygen reduced out of it) should do as well
when compressed sufficiently.

The difference lies in the energy density. Steam has a lot of it because
of its high density. If you compress a gas to similar density then it
should also work as well or better. Helium is a good choice because it
has very high heat conductivity so it is easy to heat and cool in heat
exchangers. The energy density of a gas under pressure is rho*P.
Obviously high rho will give a high energy density for a given pressure.

> What sort of expansion can you get without phase change?

More than enough. The Carnot cycle, which represents the most efficient
heat engine cycle does not use a phase change. Again, the best Stirling
engines use Helium as it is the closest known to an ideal gas and has
high thermal conductivity and low flow resistance even at high pressure.

> Also note that the flashing of water to steam will not happen if the
> cylinder is pressurized by the piston on the upstroke. The valving needs to

Not true. The flashing is caused by the temperatue and pressure
difference. You can flash 370 degree C pressurised water (at 210 bar) in
a 350 degree C container by just dropping the pressure (to 160 bar). I
think that you are confusing the *delayed* flashing of superheated water
with normal evaporation by boiling. Superheated water will not boil
before it is given a nucleation point even if it should have been steam
already at that pressure. This is a way to transport energy in a compact
form to where it is needed, nothing else.

> In any case getting even 100W of power out of an old motor cycle engine with
> a batch of mirrors pointed at it would be a great start!

I think that you underestimate the losses. A small IC engine is only
about 70% efficient mechanically. A small motorcycle engine may not even
turn over with 100W input. Typical starter power for such a motor is
30A@12V (~360W or ~1/2hp).

By scaling some numbers from:

http://www.johnsboat.com/calcs-web.html

350W = ~0.5hp is made from ~0.65lb H2O/minute which requires a heating
power of about 11000 Watts, just to boil it (disregarding the heat
needed for superheating, which is considerable). This is the output of a
11m^2 high efficiency (>>95%) mirror in full sunlight (3.8 meter
diameter parabolic dish). So your efficiency will be less than 3% before
energy conversion losses. Remember the Victorians who liked steam so
much had plenty of coal and wood.

If you find a reproduction of that solar driven printing press from the
Paris exhibition in the pre-previous century you will see that they used
a mirror about as large.

Back to 350 Watts that's about one man-power on a bicycle, at least at
the beginning of the ride ;-)

> Thanks for the conversation, I'm really enjoying it. Does anyone think they
> could find the time to do a few tests with something like this? I'd be
> willing to pay for results, positive or negative, given some good
> photographic and metric documentation.

I could suggest that you convert a small air-powered tool into a
generator and try to power it with steam to see what happens. That would
be the shortest way to get it going somehow. A handheld grinder would be
a good start imho (high rpm and low losses, also cheap, you can get
one for $30 and it will run fine on 28psi (2bar) pressure).

Peter

2005\09\22@080458 by Russell McMahon

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flavicon
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>> Regardless of whether the case is true r not for "conventional"
>> energy
>> sources, nuclear fusion utterly romps home, IF you can do it and IF
>> you can fuel it. Lunar Helium (deposited from the sun via the solar
>> wind), while still not proven, would be a sustainable source of
>> 'fuel'
>> (at least for the next billion years or two).

> We have plenty of fusion "fuel" right here on earth.  A surprisingly
> large
> fraction (about 1/4500) of hydrogen atoms in naturally occurring
> surface
> water is actually deuterium (an extra neutron).  This is the
> substance that
> nuclear fusion reactor research is aiming to use.

Deuterium is indeed is one of the several components that can be used
in fusion reactions, but has it's problems. Abundance is not one of
them :-). As you note, it is freely available in all water. Water
electrolysis will not break down deuterium based "heavy water"
molecules and it accumulates in the cell as a byproduct. The WW2
Germans obtained theirs from Norway where they had large hydroelectric
resources and used electrolysis for gas generation. BUT the intended
German use was as a moderator (neutron absorber) in a "conventioal"
fission reactor.

HOWEVER, the other component in the most workable (for us at this
stage) form of fusion is tritium This is a radioactive substance which
does not occur naturally and has a half life of 10 years. It is
commonly used in H bombs and (surprise) some luminous watch faces. It
is in extremely short supply. It can be bred from Deuterium by slow
neutrons so a fusion reactor could breed its own tritium in due
course. However, while this is one of the more doable versions for a
startup, about 80% of the energy output is as neutrons which must be
managed by absorbtion or secondary reactions.

All fusion reactions except one produce nasty by-products which must
be dealt with. The exception is Deuterium - He3 fusion which produces
no undesired byproducts and whose output is able to be handled
"easily" (relatively speaking).

       Deuterium + He3 -> He4 + a 14.7 MeV Proton.

As He4 is not radioactive and the Proton can be managed with electric
or magnetic fields this is the gold standard for controllable
containable fusion. But it requires far higher temperatures than some
of the other options. Many of these produce really energetic gamma
rays (light on steroids) which are not keen on being contained or
directed.

Deuterium-He3 is liable to be the method of choice for space use and
ultimately for terrestrial use. He3 is very rare on earth, being
obtained only from nuclear reactors (or H bombs if you can run very
very very fast). Production at present is only 10 to 20 kg/year and
total reserves around 300 kg. However, it is believed (hoped
earnestly, prayed that, ...) the top layer of the lunar surface is He3
rich which has been deposited by the solar wind. (Don't you just love
it when a plan comes together). Once we exhaust that source the
gas-giant planets are believed to contain vast amounts of He3 from the
(believed) original nebula that our system (is believed to have)
condensed from. There seems to be a staged progression here :-).

Real men (and stars) use Proton-Proton fusion (or the carbon cycle for
real heavyweights), but these are liable to be out of our class for
the forseeable future.

Read all about Lunar He3 - The Artemis Project
Immense amounts of information.
Excellent.

       http://www.asi.org/adb/02/09/

1 kg of He3 + 2/3 kg of Deuterium yield 19 megawatt years of energy.
A He3-D reactor is inherently fail safe (as long as you are not
standing tooooo close). No radioactivity release. No cleanup (just
pick up the (very small) pieces). Earth's current energy needs could
be supplied by about 50 to 100 tons/tonnes of He3/year. An entirely
achievable amount from lunar resources IF it really exists. If the
estimated 1,000,000 odd tons are really there that should be enough
for 10,000 years at present energy use. If we get that long (highly
moot) we should be very well into being able to mine the gas giants by
then.


       RM

_______________

Desert Storm VI
Where your power may come from.
Lunar He3
Lunar solar power farms.
Material for Hydrogen fuel cells
More ...

       www.finetuning.com/articles/p2-970-the-moon-the-persian-gulf-of-the-21st-century.html

2005\09\22@174625 by Howard Winter

face
flavicon
picon face
James,

On Tue, 20 Sep 2005 14:15:32 -0700, James Newtons Massmind wrote:

> >
> > If you have a good espresso machine then you already have a
> > suitable kettle, with safety valves and all that. One in a
> > million occasionally blows up. Usually it causes no damage
> > (there is containment for it).
>
> Yes, and I thought about building a concrete containment room for a steam
> engine in my back yard... My wife loves me, but...

Tell her it's a hurricane shelter...

{Quote hidden}

I seem to remember it's actually 1:1500 - one of the reasons that steam is so widely used as a medium to
convert heat into mechanical energy is this huge expansion (plus the huge latent heat of vapourisation, 640
times water's specific heat).

> What sort of expansion can you get without phase change?

See Boyles' Law.  Not much, but enough for Stirling engines to work.

> > > What chemical means would trigger this flashing? I've not heard of
> > > such a thing but that part of it sounds very interesting.
> >
> > There are several chemicals that will do it, any powder, a
> > spark (which causes a bubble to form), ultrasound that causes
> > cavitation etc. I think that it is hard to *prevent* it from
> > happening while charging the cylinder.
>
> Sort of like pinging in a gas engine or detonation in a diesel?

No, they are both detonation, a localised explosion reaction rather than a change of phase, caused by such
things as too high a compression, the shape of the combustion chamber causing uneven flame-front spread, and
so on.

Personally I think the whole idea of flashing to steam inside the cylinder is doomed - the temperature cycling
of the material making up the chamber is a killer for efficiency (see Newcomen's engine, and the vast
improvements in efficiency that Watt brought about by having the condenser seperate, so keeping the cylinder
hot).

>I can see
> the point, but again, you have to pre-heat the working fluid and with that
> comes all the issues of pressurized feed, safety, etc... Perhaps a
> combination of heating the water to just below boiling without pressurizing
> it and then injecting it as a fine spray, onto a somewhat convoluted surface
> at top dead center.

It's all getting terribly complicated!  You now have two locations to heat (the pressurised water storage and
the cylinder) plus a high pressure injection pump (timed), and valves, and then what do you do with the "wet
steam" exhaust?  Compare this with a Stirling engine, with one heat location, only a couple of moving parts,
and no danger of explosions, and I really thing you're on a dead-end path.  Sorry!  :-)

Cheers,


Howard Winter
St.Albans, England


2005\09\22@183248 by Richard Prosser

picon face
But the difference is that the heating block/head  would not require
cooling - it would remain substantially at the same temperature and
just be used to flash the water spray to steam. The hot steam would
then be ejsvted in the exhust cycle ready for the next injection. I
like the idea but think that the running speed would be limited.

I've actually been thinking of a similar effect by injecting water
into a petrol engine. Similar effect except that the burning petrol is
used to vapourise the water. It is a recognised technique for
efficiency improvement.
The benifits are quoted as reducing engine operating temperature while
increasing mpgs. Most benifit is obtained if the timing is advanced
somewhat.  Apparently the optimum mix is about 1/20 to 1/10 of the
fuel so the effect is not massive. (maybe 5% improvement)
I just have to be able to measure the fuel usage on the fly and meter
the water appropriately. And not care too much if I damage the engine,
which is a sticking point at the moment.
RP

On 23/09/05, Howard Winter <@spam@HDRWKILLspamspamh2org.demon.co.uk> wrote:
> James,
>
> On Tue, 20 Sep 2005 14:15:32 -0700, James Newtons Massmind wrote:
>
> > >snipped

2005\09\22@194326 by Byron A Jeff

face picon face
On Thu, Sep 22, 2005 at 10:46:24PM +0100, Howard Winter wrote:
> James,
>
> On Tue, 20 Sep 2005 14:15:32 -0700, James Newtons Massmind wrote:
>
> > >
> > > If you have a good espresso machine then you already have a
> > > suitable kettle, with safety valves and all that. One in a
> > > million occasionally blows up. Usually it causes no damage
> > > (there is containment for it).
> >
> > Yes, and I thought about building a concrete containment room for a steam
> > engine in my back yard... My wife loves me, but...
>
> Tell her it's a hurricane shelter...

Funny. I did have a thought. I realized that instead of putting the engine in
the focal point of the collector, that instead use another mirror to beam the
concentrated sunlight down onto the engine. So the focal point will have a lot less
sun blockage. The next thing is that the engine itself is going to have to track with
the collector. Imagine the whole setup on a beam that swings from east to west each
day.

{Quote hidden}

But medium to high efficiency Stirling engines have their problems too. Air isn't
a real good gas to use, and good Stirling engines need a good working gas and
high pressure to be effective.

I think that steam can be usable in this setup. I'll take a crack at some of the
issue you raise below.

{Quote hidden}

Since we're talking about external heat engines, I'll let this one go by the wayside.

> Personally I think the whole idea of flashing to steam inside the cylinder is doomed
> - the temperature cycling
> of the material making up the chamber is a killer for efficiency
> (see Newcomen's engine, and the vast improvements in efficiency that Watt
> brought about by having the condenser seperate, so keeping the cylinder
> hot).

What would be the temp cycling for superheated water injected into the cylinder?
What pressure would superheated water need to be in order to get in the ballpark
temp of a 600-700C steam chamber?

> >I can see
> > the point, but again, you have to pre-heat the working fluid and with that
> > comes all the issues of pressurized feed, safety, etc... Perhaps a
> > combination of heating the water to just below boiling without pressurizing
> > it and then injecting it as a fine spray, onto a somewhat convoluted surface
> > at top dead center.
>
> It's all getting terribly complicated!  You now have two locations to heat
> (the pressurised water storage and the cylinder)

In James' suggestion the water isn't pressurized. However it would be better if
the water slug to be injected could be superheated under pressure. More on this
in a minute.

> plus a high pressure injection pump (timed),
> and valves,

We're talking about an engine that already has valves in it right? We would set the
timing so that the exhaust valve would be open for the return stroke moving the
wet steam out of the cylinder. I think that's what James' original proposal states.

I'll come back to my idea in a later post...

BAJ
{Quote hidden}

> --

2005\09\22@202934 by James Newtons Massmind

face picon face
> But the difference is that the heating block/head  would not
> require cooling - it would remain substantially at the same
> temperature and just be used to flash the water spray to
> steam. The hot steam would then be ejsvted in the exhust
> cycle ready for the next injection. I like the idea but think
> that the running speed would be limited.

I'm glad someone gets it. I'm amazed at the number of replies that show a
complete misunderstanding of the idea.

No, it doesn't require cooling.

No, it doesn't require high pressure injection: No compression and the
injected water is NOT boiling.

Yes, you probably have to increase the surface area inside the cylinder head
to ensure a rapid transfer of heat.

Yes, it will turn over slowly, who cares?

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.

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.

Sure, a sterling engine would be better, but that isn't the point...

...this is cheap, simple, safe, and accessible to the little guy.

Where can I buy a sterling engine right now? How much does it cost?
Starlings are pipe dreams.

http://techref.massmind.org/techref/idea/mc-heat-inject.htm

{Quote hidden}

That is about what my dad found. He ran water injection on his 1968 E-type
Jag for many years. It gave him 2 mpg more for a total of 26, allowed more
advanced timing without pinging and kept the engine exhaust system quite a
bit cooler which is what he was worried about. He used it as a sort of
variable compression system. More water was injected when the engine was not
under load. The timing was advanced a tad. When he floored it, the water cut
out and the timing was retarded.

Water injection into a petrol engine is limited by the amount of heat
produced by the explosion which really isn't that much. The sun can provide
much more heat at little or no cost. Just the cost of a batch of old 1'
decorator mirrors and something to mount them on.

Another thing my dad made was a solar powered boiler for energy generation.
The mirrors were each held by a scrap of sheet metal with the ends bent up
at the tip and then bent at the center into a V. The mirror was held at the
top of the V by the bent tips and the bottom was welded to a bit of narrow
rebar which was then welded to a frame and bent to align the mirror. The
frame was 12'x12' made from electrical conduit and strengthened by guy wires
to posts along the central axis.

This entire frame was suspended in the air in a cradle that allowed it to
track the sun. It flexed like all heck, was very heavy and we never did put
all the mirrors on it.

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.

For safety and to help concentrate the heat on the head of the engine, a
second "collar" mirror of metal could be made and placed around the head
facing down.

And yes, I did see the episode of Myth busters where they tried to light up
the boat. But that rig was so floppy that they had no focus at all. It was
probably multiplying the sun by a factor of 5, if that, on any given point.
And the heat had a nice shiny coated surface to bounce off of.

Try this: Take a stack of razor blades about an inch thick and hold them
together pointed edge on at the sun. See how long you can hold on. The
radiation goes down in-between the blades and bounces around in the cracks
about a million times until all the heat is absorbed. It's been a lot of
years since my dad showed me that, but I seem to remember I couldn't hold it
more than a few seconds.

What if you made a head for an engine like that? Blades sticking up on top
and down inside as well. Hit that with some sunlight on the outside and
spray water onto it from the inside.

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


2005\09\22@220001 by Russell McMahon

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Experiments (mind or hands-on) in this area should be preceded by at
least a working knowledge of the thermodynamics involved.

Here's an interesting and possibly even useful presentation of
Carnot's original work. Fascinating as a historical glimpse even if
one isn't intending to attempt to break the laws of physics :-)

   http://www.history.rochester.edu/steam/carnot/1943/



       RM

Ref from Ken Mardle.

2005\09\22@222157 by Richard Prosser

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part 1 1170 bytes content-type:text/plain; charset=ISO-8859-1 (decoded quoted-printable)

And from the PIC files
I have a very rough spreadsheet of the engine.
It appears to indicate that a solar mirror of about 1m2 "could" be
used to produce about 130W of power from a modified 160cc motormower
engine operation at 300C.
Maybe. There are all sorts of effects that are not taken into account
and other posibilities that could improve performance (using exhaust
steam to preheat the water for example).
And some figures are pure guesswork (e.g initial pressure).

But it may give someone who knows about these things a bit of a laugh

Richard P


On 23/09/05, Russell McMahon <RemoveMEapptechTakeThisOuTspamparadise.net.nz> wrote:
{Quote hidden}

> -

2005\09\23@004704 by Richard Prosser

picon face
Er,
Sorry. There are a couple of errors in the spreadsheet but I'm not
sure the attachment got through anyway.
If anyone's interested I'll send an updated version.
The errors are in the use of mechanical efficiency and the water usage
calculation but don't change things too much if you use sensible
figures.

Richard P

On 23/09/05, Richard Prosser <spamBeGonerhprosserspamBeGonespamgmail.com> wrote:
{Quote hidden}

2005\09\23@042034 by Alan B. Pearce

face picon face
>I've actually been thinking of a similar effect by
>injecting water into a petrol engine. Similar effect
>except that the burning petrol is used to vapourise the
>water. It is a recognised technique for efficiency improvement.
>
>The benifits are quoted as reducing engine operating
>temperature while increasing mpgs. Most benifit is
>obtained if the timing is advanced somewhat.  Apparently
>the optimum mix is about 1/20 to 1/10 of the fuel so the
>effect is not massive. (maybe 5% improvement) I just have
>to be able to measure the fuel usage on the fly and meter
>the water appropriately.

The effect is similar to driving on a cool night, where you get two
effects - a greater intake of oxygen because the air is cooler, and
therefore denser, and also the possibility of some moisture in the air.

>And not care too much if I damage
>the engine, which is a sticking point at the moment.

The trick is probably not to have much water injected at all. You talk of 5%
to 10% of the fuel volume as water, but I have a feeling it is lower than
that.

My understanding is that part of the way it acts is the water is turned to
steam by the cylinder heat, and then the molecule is split up by the flame
making more oxygen available to burn, and then at the end of the burn any
free hydrogen and oxygen recombines to water.

2005\09\23@134216 by Peter

picon face

On Thu, 22 Sep 2005, Byron A Jeff wrote:

> Funny. I did have a thought. I realized that instead of putting the engine in
> the focal point of the collector, that instead use another mirror to beam the
> concentrated sunlight down onto the engine. So the focal point will have a lot less
> sun blockage. The next thing is that the engine itself is going to have to track with
> the collector. Imagine the whole setup on a beam that swings from east to west each
> day.

Look at how a Newton or Coude setup works. You do not need to move
the engine at all.

> What would be the temp cycling for superheated water injected into the cylinder?
> What pressure would superheated water need to be in order to get in the ballpark
> temp of a 600-700C steam chamber?

Most steam tables stop at 370 deg. C. At 370 deg. C it's 210 bar. Here
is a calculator:

http://www.efunda.com/materials/water/steamtable_sat.cfm

Now a 210 bar steam generator would be interesting to build in your
garage ... I think that the Shuttle's main engines operate at such
pressures. Maybe the design could be adapted ... <g>

I don't think that the combustion pressure reaches 210 bar in a normal
(Otto) engine.

Peter

2005\09\23@135524 by Michael Rigby-Jones

picon face


>-----Original Message-----
>From: RemoveMEpiclist-bouncesspamTakeThisOuTmit.edu [piclist-bouncesEraseMEspam.....mit.edu]
>Sent: 23 September 2005 18:42
>To: Microcontroller discussion list - Public.
>Subject: Re: [OT] Vegetable oil in a diesel engine... Was:
>[EE] ROHS ~ lead free soldering - reality strikes.
>
>
>I don't think that the combustion pressure reaches 210 bar in a normal
>(Otto) engine.

Nothing like that high, googling found some typical numbers:

Four stroke diesel engine: 50 Bar

Two stroke petrol engine: 15 Bar

Four stroke petrol engine: 20 Bar

Regards

Mike

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2005\09\23@135913 by Peter

picon face

On Thu, 22 Sep 2005, James Newtons Massmind wrote:

> 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.

http://www.answers.com/topic/heliostat

I don't know where Barstow is, but it says it's in California. Here are
two pdf documents that show what has been realised:

http://www.iaec.gov.il/docs/IAEC11.pdf

This has an optical scheme that may be scaled for smaller installations.
The focal point is on the ground.

http://www.docrenewableenergy.info/en_path-en%5Crenewable+energy%2Fthermal+solar~id-10337~action-download~url-http:%2F%2F66.102.9.99%2Furl%3Fsa%3DU&start%3D138&q%3Dhttp:%2F%2Fhttp://www.solarpaces.org%2FEUREC-Position_Paper_STPP.pdf&e%3D747~title-Solar+Thermal+Power+Plants

The Almeria plant also has Stirling motors mounted directly at the focal
point of parabolic mirrors (big ones).

Peter

2005\09\23@142149 by James Newtons Massmind

face picon face
Yes, but again, why move the mirrors?

---
James.



{Quote hidden}

gy%2Fthermal+solar~id-10337~action-download~url-http:%2F%>
2F66.102.9.99%2Furl%3Fsa%3DU&start%3D138&q%3Dhttp:%2F%2Fwww.so
larpaces.org%2FEUREC-Position_Paper_STPP.pdf&e%3D747~title->
Solar+Thermal+Power+Plants
>
> The Almeria plant also has Stirling motors mounted directly
> at the focal point of parabolic mirrors (big ones).
>
> Peter
> -

2005\09\23@154145 by Byron A Jeff

face picon face
On Fri, Sep 23, 2005 at 11:21:47AM -0700, James Newtons Massmind wrote:
> Yes, but again, why move the mirrors?

Upwards of 40% more available solar energy simply by tracking the Sun.

BAJ

2005\09\23@161323 by James Newtons Massmind

face picon face
> > Yes, but again, why move the mirrors?
>
> Upwards of 40% more available solar energy simply by tracking the Sun.
>


Arrrggghhh....


No, no, no...


I'm sorry...


I mean, why move the mirrors when you could move the target instead?

---
James.


2005\09\23@163231 by Howard Winter

face
flavicon
picon face
James,

On Fri, 23 Sep 2005 13:13:19 -0700, James Newtons Massmind wrote:

>...<
> I mean, why move the mirrors when you could move the target instead?

Because the Sun "moves" more than that - any given angle of mirror would be completely out of sunshine for
part of the day, and at unfavourable angles for a lot of the time.  Unless you have them horizontal, facing
upwards, in which case you can't focus them, and you'd need a large clear area around them to make
low-Sun-angles usable.

I'm not clear whether you are talking about trading efficiency for ease of construction?

Cheers,


Howard Winter
St.Albans, England


2005\09\23@173031 by James Newtons Massmind

face picon face
I'm thinking about an array of mirrors, each perhaps 1 foot square (these
are sold at low cost for decorating in homes), all laying on a flat surface,
and each tilted at some angle so that sunlight shining on that mirror is
reflected back to a central point.

Yes, the angle may be somewhat more limited.

Yes, I'm talking about trading efficiency for ease of construction.

My contention is that for the cost of moving some number of mirror on
heliostats, you could build a field of unmoving mirrors some factor larger.

In the end, I believe the "efficiency with respect to cost" would be higher
than with moving mirrors. In other words, for X dollars, you could generate
more total power with non-moving mirrors and a moving target than with
moving mirrors and a non-moving target. The loss due to angle is offset by
the increased area of the mirror field.

The exceptions are probably due to a very high cost of moving the target.
Such as when there are high pressure or caustic materials involved.

I don't think very large, and therefore difficult to move targets count
against this idea because in most cases, the target could be split into many
smaller targets, each moveable.

---
James.



> {Original Message removed}

2005\09\23@233022 by Byron A Jeff

face picon face
On Fri, Sep 23, 2005 at 01:13:19PM -0700, James Newtons Massmind wrote:
> > > Yes, but again, why move the mirrors?
> >
> > Upwards of 40% more available solar energy simply by tracking the Sun.
> >
>
>
> Arrrggghhh....
>
>
> No, no, no...
>
>
> I'm sorry...
>
>
> I mean, why move the mirrors when you could move the target instead?

Angle of incidence. If the mirrors are fixed at true south then it'll be
nearly midday before they can concentrate full sun. It narrows the window
of useful sun significantly.

Tracking isn't about the target of the concentration. It's about the source.

BAJ

2005\09\23@234806 by Byron A Jeff

face picon face
On Fri, Sep 23, 2005 at 02:30:29PM -0700, James Newtons Massmind wrote:
> I'm thinking about an array of mirrors, each perhaps 1 foot square (these
> are sold at low cost for decorating in homes), all laying on a flat surface,
> and each tilted at some angle so that sunlight shining on that mirror is
> reflected back to a central point.

Fresnel mirror array. Curnutt solar furnace. The Phoenix Turbine Builders Club
(PTBC) has a description here:

http://phoenixnavigation.com/ptbc/articles/ptbc36.htm

>
> Yes, the angle may be somewhat more limited.
>
> Yes, I'm talking about trading efficiency for ease of construction.

But if you keep making such tradeoffs, your efficency will be so low as
to not be useful.

> My contention is that for the cost of moving some number of mirror on
> heliostats, you could build a field of unmoving mirrors some factor larger.
>
> In the end, I believe the "efficiency with respect to cost" would be higher
> than with moving mirrors. In other words, for X dollars, you could generate
> more total power with non-moving mirrors and a moving target than with
> moving mirrors and a non-moving target. The loss due to angle is offset by
> the increased area of the mirror field.

If you use a larger field, then maybe you can fix different parts of the field
to point at the sun at different times of the day. So you can have an East, South,
and West Field.

But the PTCB is looking at a tracking system that's little more than a couple
of sensors, a PIC (16F84: how quaint!), and a stepper motor. That combo is
a heck of a lot cheaper than enlarging the mirror array.

>
> The exceptions are probably due to a very high cost of moving the target.
> Such as when there are high pressure or caustic materials involved.

The target isn't the problem here, the sun is. I was arguing that moving the
target along with the mirror(s) would simplify tracking the mirror box at the
focal point. Simply mount everything on a big boom that swings east to west
during the day. Since the target would be directly below the focal mirror box
on the boom, no additional adjustments from the mirror array to the target would
need to be done except for a weekly or bi-weekly elevation adjustment.

> I don't think very large, and therefore difficult to move targets count
> against this idea because in most cases, the target could be split into many
> smaller targets, each moveable.

But what I can't figure out here is why there is an additional cost of moving the
mirror if you're moving the target anyway? I know that you're thinking about the
stability of the mirror array. But enclosing it in a clear top enclosure should
mitigate virtually all of the wind effects.

BAJ

2005\09\25@231451 by Russell McMahon

face
flavicon
face
Comments on various past comments:

> Cooling is the worst thing in the world for a heat engine yes?

> > No, it doesn't require high pressure injection: No compression and
> > the
> > injected water is NOT boiling.

But there has to be "cooling" somewhere.
All heat engines work by transferring energy across a temperature
drop.

> > Yes, it will turn over slowly, who cares?

Speed is not important of itself. But work done is force x distance.
That is, average piston force x distance travelled x pistonj strokes
per unit time = work done. For a given power and piston force power
output is proportional to speed.

> > 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.

That's acceptable if overall cost per power out is lower. but cost is
related to material used, size of installation, land used and more.
Making large low power per size units has a point below which it will
be less cost effective to do. The same applies to very large power per
size units due to technology and engineering costs.

> > 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.

It's Stirling, with an "i".
It's not that Stirlings need high pressure and special fluids for high
power - they need these for high power density. If you don't mind
making an engine that is larger than you may be used to a Stirling
engine may be a very good solutionm. Low prssure Stirling engines
using modest temperatures are easier for a home constructor to build
than an internal combustion engine.

> 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.

Yes. But it's also possible to build a Stirling engine from it.



       RM

2005\09\26@013855 by James Newtons Massmind

face picon face
> But the PTCB is looking at a tracking system that's little
> more than a couple of sensors, a PIC (16F84: how quaint!),
> and a stepper motor. That combo is a heck of a lot cheaper
> than enlarging the mirror array.

You left out the cost of the mount, frame, and drive. All significant costs.


>
> The target isn't the problem here, the sun is. I was arguing
> that moving the target along with the mirror(s) would
> simplify tracking the mirror box at the focal point. Simply
> mount everything on a big boom that swings east to west
> during the day. Since the target would be directly below the
> focal mirror box on the boom, no additional adjustments from
> the mirror array to the target would need to be done except
> for a weekly or bi-weekly elevation adjustment.

I see your points and I understand your idea.

What I'm saying is actually sit down and figure out the total cost of a
stable frame that will actually keep the mirrors or whatever focused tightly
on the target and that will move the target or not and then compare that
total cost against a fixed field of mirrors and moving the target only.
Compensate for the losses due to morning and evening angles and then see
which one works better.

Don't get tied up in one design without actually looking at what works
better, when all is said and done.

Let me give you an example. We do a little gardening around the house and I
had purchased a wheelbarrow. I also had an electric lawn mower. At some
point (about a day after the warranty ran out on each, I'm sure) the wood
beams on the bottom of the wheelbarrow rotted out and the wheel fell off and
the motor imploded on the lawn mower. They sat around for a while and then
one day, my little boy said, "dad, why don't we put the bucket of the
wheelbarrow on the carriage of the lawn mower?" So we did. The result is the
best wheelbarrow I've ever had.
http://techref.massmind.org/images/member/jmn-efp-786/Garden/0123.JPG It
turns, fully loaded, with a single finger (if you balance the load right)
and it pulls easy on level ground. Simple to dump. Low to the ground.
Stable. Better. Period. Invented by a mind that didn't know that
wheelbarrows are always built the way wheelbarrows are built.

I have a feeling that for systems where the target isn't terribly difficult
to move, the fixed mirrors will come out ahead. But I could certainly be
wrong.

What I do know is that building a frame that will hold all those mirrors
just so and still swing through the air is a bloody pain.

> But what I can't figure out here is why there is an
> additional cost of moving the mirror if you're moving the
> target anyway? I know that you're thinking about the
> stability of the mirror array. But enclosing it in a clear
> top enclosure should mitigate virtually all of the wind effects.

Because that mirror array is heavy and if it isn't, you have to add in the
cost of shielding the entire thing. And I think a lot of people don't take
into account the loss of focus from a movable frame flexing.

And I like the simplicity of just putting the mirrors on the ground.

---
James.


2005\09\26@075811 by Gerhard Fiedler

picon face
James Newtons Massmind wrote:

>> But the PTCB is looking at a tracking system that's little more than a
>> couple of sensors, a PIC (16F84: how quaint!), and a stepper motor.
>> That combo is a heck of a lot cheaper than enlarging the mirror array.
>
> You left out the cost of the mount, frame, and drive. All significant
> costs.
[...]
> And I like the simplicity of just putting the mirrors on the ground.

If that is done in large numbers, a tracking system for a single mirror
could possibly be simple and cheap. You wouldn't move a large frame with a
heavy drive, you'd move every individual mirror -- placed on the ground.

Gerhard

2005\09\27@023139 by Russell McMahon

face
flavicon
face
>>> But the PTCB is looking at a tracking system that's little more
>>> than a
>>> couple of sensors, a PIC (16F84: how quaint!), and a stepper
>>> motor.

The (arguably) simplest tracker I've seen was a solar receiver
floating in a tank. As the sun moved off centre the incident radiation
caused heating of a flotation bag thereby increasing flotation on that
side and caused the receiver to reorient towards the sun. A tank full
of "eyeballs" tracked the sun in any direction so no adjustment was
needed for time of day or season.



       RM


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