Posted by on September 17, 2003, 10:28 pm

Can microwave be focused on a droplet of water and turned to steam
in a fraction of a second? Just curious.
Mark

Posted by Dave McMahon on September 19, 2003, 6:44 pm

Probably if powerful enough requires lot of power though not practical for
electric I think

of course solar is a type of wave, efforts to concentrate this would be

Posted by on September 20, 2003, 1:43 am

Anybody try to make a microwave steam engine? I read somewhere
a single droplet of water will create 600 times it's size in steam.
Mark

Posted by daestrom on September 20, 2003, 4:24 pm

Well, the volume of the steam formed is a function of what pressure you have
it confined to.  If just atmospheric pressure, the expansion is 1603:1.  If
confined to a pressure of 200 psia, the expansion is about 127:1.  Of
course, to get 200 psia, you have to heat it to a higher temperature (about
380 degF instead of 212 degF).

But a 'microwave steam engine'??  Where would one get the microwaves?  Only
sources I can think of convert electricity to microwaves, at no better than
50%.  Wouldn't an electric boiler (100% efficient) be better?  But then, why
not just an electric motor ;-)

daestrom

Posted by on September 20, 2003, 5:49 pm

Ok. Forget microwave for the moment. Imagine a flat head piston with a
small upright cup, only large enough to hold a drop of water, welded to
the piston surface. A metered drop of water enters from beneath the cup.
When the piston reaches almost TDC, a focused beam of light originating
from the roof of a car and traveling to it's destination via large fiber
optic
cable zaps the droplet into steam. I see it as being efficient because
the energy is concentrated and therefore not lost throughout the
engine as would be a typical steam engine. Follow me?

OK back to microwave. I think you said using electricity to make
microwaves is only 50% efficient. But if it can be concentrated to where
it's needed the most, then maybe overall it's more efficient. Question is
can microwaves be channeled to a cylinder like the one I described
above?
I'm not thinking of a monster high horsepower machine. Just a simple
unit for demonstration purposes.