Re: Cogeneration exercise...
-> You wrote a biggie, excuse me for chewing on the easier bits..
->
-> CH> But I would also need to calculate the value of the heating fuel
-> CH> would save.  It's not just for electricity, but residence heating
-> CH> the cold season.  Not even sure I would use it outside that time
-> of
->  CH> year.
->
-> Ahah. The sweet sound of reason. Cancel the engine option and move ho
-> hot water from your furnace in the usual proven way!!
But that's the fun/point of this particular exercise! 
-> My house was built in 1750, and does not lend itself to the
-> CH> mega-insulation that efficient homes have.
->
-> That is a big issue. Dress yourself to suit and make few mods to the
-> house.
I'd need to modify the family, too .  They're not so easily moved
off the "creature comfort" zone - particularly the wife...
-> CH> Cam profiles?  Yes.  I don't grind the cam myself, but I sure kno
-> CH> at least a dozen very qualified shops who can handle this.
->
-> I was taught that the cam curvature is not a simple arc of a circle,
-> very complex and the difficulty in making the best front and back cur
-> much more complicated than the mere grinding of those to the
-> required shape. The design is not a job for a shop, but for an
-> engine designer.
The people I'm referring to are racing camshaft designers.  They have
all the expertise and equipment to do the job.  At least as good as
the major automotive manufacturers.  These are *very* sharp folks,
not simply "build it from specifications" types.
-> And I know
-> CH> how to check the camshaft installation timing for maximum
-> compression.
-> Ideally you should do that at service rpm not while cranking. Is
-> that possible with your resources?
The difference between starter cranking speed and the projected
540-600 RPM isn't that great.  At that low speed there won't be
anywhere near the fluid dynamic differences as higher speeds would
have.
-> CH> My intent is to use a Vertex magneto with fixed advance.
->
-> Sounds wasteful of energy, unless you plan to run at constant power.
-> At
-> changing power doesn't the manifold pressure vary, hence the need for
-> vacuum advance in efficient gas engines
I am planning on running at a constant power/load.  Let the power
grid supply or absorb the difference.  It becomes the infinite
"flywheel".
-> As far as timing, what's wrong
-> CH> with putting a load on the engine, and adjusting timing for
-> maximum CH> RPM?  Same with fuel mixture.  Adjust for maximum RPM at
-> a fixed load, CH> then either increase load or drop RPM and repeat.
->
-> You are treating the load like a constant. As soon as you change the
-> load changes considerably. If you use a large fan load for example, t
-> speed change means 73% power change. The method you describe is
-> pretty rough. it is shooting at a moving target. Agricultural rather
-> than scientific.
I am planning on a constant power output.  I realize the problems
with a changing load, which is why I don't want to do that.  I have that
"moving target" with my current backup generator during power outages,
and have to be somewhat careful in keeping the house load constant.
-> -> CH> not proposing that .  I was thinking about a standard
-> -> synchronous CH> AC generator,
->
-> CH> I'm not sure I understand your objection.  As long as the generat
-> CH> large enough so it doesn't burn out, and small enough to be reali
-> CH> there shouldn't be a problem.  If the engine tries to run it at
-> 59 Hz,
->  CH> then it will supply no power to the grid.  As the engine tries t
-> CH> increase RPM over the 60 Hz grid, it will supply power in relatio
-> CH> to the amount of "push" up against the 60 Hz grid.  Heck, a large
-> CH> electric motor would work.
->
-> Have you changed the subject? A large electric motor would work yes B
-> said a synchronous AC generator. Elec motors are very rarely synchrom
-> are induction type and yes these are readily available.
But even an electric motor runs at a near-synchronous rate.  Close
enough for "fuzzy logic" anyhow.  The same push against the 60Hz
rate ends up with essentially the same effect.
-> Your reasoning re operation at 59Hz, 60 Hz is sound. But there are
-> serious risks, notably that the supply voltage is pulled down even
-> though you succeed in delivering energy into the grid. SO do not
-> consider a bigger induction motor than needed. Aim to run it at
-> close to the ratingplate amperes.
That's good advice, and would be a goal.  The absolute power out
would be determined by the point of maximum engine efficiency.
-> If you used [say] a 5HP machine and ran it for long periods each
-> day, the Utility would tolerate you. But if you use a 20HP for just
-> the odd hour or so they might hate you. Their substation on load-
-> tapchangers might become unduly exercised and you would soon be
-> discovered. Your neighbours would possibly have lamp flicker and
-> shrunken TV pictures.
In this part of the US, the substations cover a fairly large amount
of town.  I doubt they'd even notice my peanut whistle operation
The "flywheel" here is pretty big...  Hundreds of houses.
-c-
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