Posted by mike on May 4, 2013, 8:18 am
On 5/3/2013 10:35 PM, Morris Dovey wrote:
> On 5/3/13 9:40 PM, mike wrote:
>> On 5/3/2013 8:16 AM, Morris Dovey wrote:
>>> On 5/2/13 4:47 PM, mike wrote:
>>>
>>>> Would be interesting to see the theory.
>>>
>>> It?s a relatively straightforward Carnot cycle / Stirling / fluidyne
>>> engine. There?s an abundance of educational material on the web in
>>> addition to the specifics I provide in my web pages.
>>
>> I don't pretend to understand any of that except that temperature
>> differences and/or pressure differences are required to make it work.
>> And the upper bound of energy output is the energy you put thru it.
>
> Yes, the energy that goes in is the energy that comes out. :-)
>
> The upper bound on efficiency of thermal-to-mechanical energy conversion
> is determined solely by hot and cold side temperatures, and the goals
> are to maximize the operating ?P and the cycle frequency.
Correct me if I'm wrong...to maintain the superfluid, you have to keep
the end sections above 374F. If you don't use superfluid, you can keep
the cold ends at ambient. That almost doubles deltaT. What properties
do you gain from the superfluid that surpass that?
I can't support the argument, but my gut tells me that the mass of the
medium matters. For massive media, you have less physical movement.
F=MA. So, for the fluid "sloshing" back and forth in the engine,
the frequency is inversely proportional to the mass of the medium.
You want the path length of the "slosh" to be greater than the diameter
of the pipe. You want movement over the whole length of the magnetic
field. More heavy ions may not be better. For a fixed amount of energy
to accelerate 'em, maybe you want fewer, faster moving ions???
I have a second gut feeling. If you have two pressure waves in opposite
direction, what happens if you put an obstruction in the center of the
pipe? Does the pressure wave in the opposite direction differ from
a reflection off the obstruction in the middle? Stated another way,
can you run two half-pipes in parallel using the same magnetic
field for both constrictions?
Damn, I keep having gut feelings...
In a conventional MHD you start with a plasma and send it thru the magnet.
The ions do their thing and the whole mess gets sent out the exhaust.
In a closed system, you have to recreate the ions. Assuming that
takes energy, how much does that subtract from the total output?
>
>>>> Sounds like an evening project.
>>>
>>> With temperature above 705?F and pressure above 3200 PSIA, I?m inclined
>>> to proceed a bit more deliberately.
>>
>> Which begs the question, "why pick water with an exceedingly high
>> critical pressure?"
>
> The most obvious answers were listed together in my post before last.
>
>> Ethanol would reduce your pressures considerably.
>> And helium is supercritical at 2.24 atm at any temperature you'd
>> care to operate it.
>
> True, but at low pressures both are too compressible and provide
> inadequate dP/dT behavior - and you might want to consider the
> difficulty of inducing the high degree of ionization required.
I can understand that for Helium, but isn't Ethanol about the same
mass as water? Critical pressure is about 1/7th.
>
> Speaking of which, how would you go about ionizing Helium?
Pretty much the same way you ionize water...you don't.
You put something else in with it.
But I am thinking more in terms of plasma where you just supply
enough energy to make it come apart.
>
>> I'm doin' all this naysayin', but it's easy to put me in my place with
>> some simple theoretical/experimental results. And that's all I'm trying
>> to make visible. I don't wanna read websites or watch youtubes.
>
> I?m not interested in putting anyone in their place - and I can?t see
> publishig results before the experimentation is completed.
Standard development process is to start with a theory, propose an
implementation,
predict the results, then build it to verify results.
>
>> I wanna see YOUR analysis/plan/results...with real predicted/measured
>> numbers.
>
> Okay. When/if I have those online I?ll let you know - but then you?ll
> still need to read at least one web site. :-)
I have asked for links to sites that describe your working theory.
>
>> I'll even volunteer to help.
>
> If you had useful knowledge, your offer to offer would be appreciated,
> but without that I can?t see that you?d be able to help.
This has become polarized. Not my intention.
I've been probing you for information/understanding.
So far, I've got buzz words and generalization.
Let's say I wanted to duplicate what you're doing, but start small.
Ignoring the superfluid and the MHD for the moment and concentrating
on the heat engine.
I take my Bunsen burner and a chunk of glass tubing.
I heat the glass and stretch it to neck down a section.
I close up the ends. I heat the hot end and cool the cold end.
Should I be able to detect the acoustic wave created by the gas
oscillating back and forth? If not, what else do I need do?
What should be the relative lengths of the hot section, cold
section and reduced diameter section?
Telling me to google it won't help either of us. You should be
able to articulate in a few sentences what to do to make it oscillate,
cuz that's the basis of your project.
I'll go up in the attic to see if I can find the Bunsen.
I really am trying to learn and help.
Posted by Morris Dovey on May 4, 2013, 6:53 pm
On 5/4/13 3:18 AM, mike wrote:
> Correct me if I'm wrong...to maintain the superfluid, you have to keep
> the end sections above 374F. If you don't use superfluid, you can keep
> the cold ends at ambient. That almost doubles deltaT. What properties
> do you gain from the superfluid that surpass that?
Reduction of viscosity and greater ?P.
> I can't support the argument, but my gut tells me that the mass of the
> medium matters. For massive media, you have less physical movement.
> F=MA. So, for the fluid "sloshing" back and forth in the engine,
> the frequency is inversely proportional to the mass of the medium.
> You want the path length of the "slosh" to be greater than the diameter
> of the pipe. You want movement over the whole length of the magnetic
> field. More heavy ions may not be better. For a fixed amount of energy
> to accelerate 'em, maybe you want fewer, faster moving ions???
The frequency depends more on the rates of heat transfer and ?P. Note
that within the ionized working fluid, we may be dealing more with
charge migration than actual movement of the atoms themselves...
> I have a second gut feeling. If you have two pressure waves in opposite
> direction, what happens if you put an obstruction in the center of the
> pipe? Does the pressure wave in the opposite direction differ from
> a reflection off the obstruction in the middle? Stated another way,
> can you run two half-pipes in parallel using the same magnetic
> field for both constrictions?
I think this might be a really good question. I?ll guess that the
practical solution will be two distinct (synchronized) fields.
> Damn, I keep having gut feelings...
> In a conventional MHD you start with a plasma and send it thru the magnet.
> The ions do their thing and the whole mess gets sent out the exhaust.
> In a closed system, you have to recreate the ions. Assuming that
> takes energy, how much does that subtract from the total output?
You might be over-thinking here. In a closed system the radicals aren?t
destroyed, they just gain or lose electrons, and both the radicals and a
portion of the heat energy are recycled.
>> True, but at low pressures both are too compressible and provide
>> inadequate dP/dT behavior - and you might want to consider the
>> difficulty of inducing the high degree of ionization required.
> I can understand that for Helium, but isn't Ethanol about the same
> mass as water? Critical pressure is about 1/7th.
I don?t have good numbers for ethanol, but (intuitively, from the Ideal
Gas Law) ?P should then also be about 1/7th.
> Standard development process is to start with a theory, propose an
> implementation, predict the results, then build it to verify results.
Yeah, I?m probably approaching it all wrong - I have no theory and am
looking to discover whether observed results from other work can be used
to effect a pair of energy conversions simply and inexpensively.
>>> I wanna see YOUR analysis/plan/results...with real predicted/measured
>>> numbers.
>>
>> Okay. When/if I have those online I?ll let you know - but then you?ll
>> still need to read at least one web site. :-)
> I have asked for links to sites that describe your working theory.
>>
>>> I'll even volunteer to help.
>>
>> If you had useful knowledge, your offer to offer would be appreciated,
>> but without that I can?t see that you?d be able to help.
> This has become polarized. Not my intention.
> I've been probing you for information/understanding.
> So far, I've got buzz words and generalization.
The buzz words are search terms which lead to the specific information
you seemed to want. In blunt words, you aren?t entitled to spoon
feeding, and I have neither the time nor the energy to do so.
> Let's say I wanted to duplicate what you're doing, but start small.
> Ignoring the superfluid and the MHD for the moment and concentrating
> on the heat engine.
That was my starting point and, from experience, it?s a good one.
> I take my Bunsen burner and a chunk of glass tubing.
> I heat the glass and stretch it to neck down a section.
> I close up the ends. I heat the hot end and cool the cold end.
> Should I be able to detect the acoustic wave created by the gas
> oscillating back and forth? If not, what else do I need do?
> What should be the relative lengths of the hot section, cold
> section and reduced diameter section?
You?ve made an incorrect (but unfortunately common) assumption - the
engine parameters do NOT scale in linear fashion.
> Telling me to google it won't help either of us. You should be
> able to articulate in a few sentences what to do to make it oscillate,
> cuz that's the basis of your project.
Okay, a few sentences of intro: It is a thermodynamic state machine with
exactly four distinct states, none of which are stable, and it is
constrained to transition between these states in strict sequential
order. The independent variables which determine the states and the
transitions between them are energy, pressure, volume, and time. It?s
useful to think of temperature as another independent variable. The
relationships which describe at least two of the transitions are non-linear.
The (ugly) answer to your request: You make it oscillate by choosing the
coordinates for the four states and building a mechanical (plumbing)
construct which supports those states and the transitions between them,
and then applying (and removing) thermal energy as per your design. If
your design and construction are good, the damn thing will cycle.
> I'll go up in the attic to see if I can find the Bunsen.
> I really am trying to learn and help.
It?s not as simple as either of us would like, and I?m really not the
right guy to teach anyone thermodynamics, heat transfer, or fluid
dynamics (all of which come into play). What I have learned has been the
result of focusing very narrowly on those portions of needed disciplines
which seem to apply - and most of what I learned I organized as best I
was able, added photographs and data plots, and put on web pages to share.
Having done that, I find myself unwilling to re-type it all into usenet
posts. I?m leaving those footprints behind and trying to move forward.
Simply put, I don?t have time to rehash old stuff while I?m struggling
with the stuff that?s still undone.
Something that might help if you decide to build: It seems easier to get
larger engines working than smaller ones, especially for those just
getting started.
--
Morris Dovey
http://www.iedu.com/Solar/Engines
Posted by Pete C. on May 1, 2013, 8:27 pm
amdx wrote:
>
> Not much happening here!
> Morris do you have anything to brighten up this group?
> Mikek
Unfortunately, given current economic conditions many who would like to
experiment with AE/RE are not able to to any meaningful extent.
Posted by Morris Dovey on May 1, 2013, 8:49 pm
On 5/1/13 3:27 PM, Pete C. wrote:
>
> amdx wrote:
>>
>> Not much happening here!
>> Morris do you have anything to brighten up this group?
>> Mikek
>
> Unfortunately, given current economic conditions many who would like to
> experiment with AE/RE are not able to to any meaningful extent.
It is tough, but that?s not really new. Let share a favorite old quotation:
?We the willing, led by the unknowing, are doing the impossible for the
ungrateful. We have done so much, for so long, with so little, we are
now qualified to do anything with nothing.?
...Mother Teresa
I think I know how she felt when she said that. :-)
Posted by Vaughn on May 1, 2013, 8:52 pm
On 4/30/2013 7:38 PM, amdx wrote:
> Not much happening here!
> Morris do you have anything to brighten up this group?
> Mikek
FYI: I'm still here on a daily basis, and chime in when I have
something to add to a conversation.
Vaughn
>> On 5/3/2013 8:16 AM, Morris Dovey wrote:
>>> On 5/2/13 4:47 PM, mike wrote:
>>>
>>>> Would be interesting to see the theory.
>>>
>>> It?s a relatively straightforward Carnot cycle / Stirling / fluidyne
>>> engine. There?s an abundance of educational material on the web in
>>> addition to the specifics I provide in my web pages.
>>
>> I don't pretend to understand any of that except that temperature
>> differences and/or pressure differences are required to make it work.
>> And the upper bound of energy output is the energy you put thru it.
>
> Yes, the energy that goes in is the energy that comes out. :-)
>
> The upper bound on efficiency of thermal-to-mechanical energy conversion
> is determined solely by hot and cold side temperatures, and the goals
> are to maximize the operating ?P and the cycle frequency.