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#Post#: 3007--------------------------------------------------
solar..flash..turbine..
By: tri-lobe Date: May 30, 2014, 5:27 am
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hello members...
this afternoon I took delivery of a 600mm dia Fresnel lens from
a US company and I want to have a go at making a small solar
fired flash boiler .......
with this solar boiler...I would like to spin a small
turbine....32mm dia rotor....that I purchased from another US
company.....
i have experimented bending up 3/16 dia tube into a 6"dia
form....
[img][/img]
it will take me a little while to get this happening.....i do
imagine a bit of trial and error in this project...so be it...
i will obtain some suitable timber this weekend to make a
mounting frame....
hopefully it will be a fruitful project....
#Post#: 3009--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: May 30, 2014, 6:09 am
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my first objective is to heat up a 4"dia 20mm thick piece of
aluminium......i need to find out the focal length to get say
250 degrees c ......
28 '' is the advertised focal length for the maximum
temp...which is at least 1200 f with a 1/2"spot .......900
degrees at nearly 2.5"dia spot....
i don't need the max temp.......i don't want a smallest hot
spot....i want 4-5"dia hotspot @ 250degrees c ......
i will follow flash steam model boat type approach.....small
size high performance type .....they just need a lot of
btu's....i want to use sunbeams.....
3/16" tube is what i'll try first....i do have 7m of 3mm ss tube
on hand...shoud i need to go that way...
like i said above...i envision a bit of trial and error.....
imagine a coil bundle encased in an aluminium block.....that
would be one hell of a heat sink.....aluminium can handle 700
c....before melting.....i only need 250 c....
this is another one of my gambles....
#Post#: 3011--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: May 30, 2014, 7:39 am
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during the 1930's when flash steam model boat racing in England
was very popular......
a documented test was done between
...5/16"...1/4"...3/16"....dia tubes.......3/16"was the winner
for efficiency....using the same burner,pressure...all things
being equal....
comparing apples to apples....
some of these boilers driving piston engines...could produce 1hp
and more......the speed record to-day for a model flash steamer
is around 125 mph.....it's on UTube...check it out...it's in
England....
i always wondered .....could i arrange a solar set-up.....as
long as a high temperature was maintained....that would give me
a output to compare too or match the same as what the model
boaters where getting.....these guy's are getting real work from
their steam.......
what I'm going to have a go at.... should tell me....
the above test were done at 500psi.......i don't intend to work
at this pressure.....100 to 125 psi is manageable ....with a
comparable performance...
#Post#: 3012--------------------------------------------------
Re: solar..flash..turbine..
By: lynx wind Date: May 30, 2014, 8:08 am
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Awesome.
BTUs are what you are concerned with. If you pull too much
power, pressure and temp will drop. A steam turbine does its
best work at high rpms. So, you are looking to load the steam
turbine only as much as your input allows.
I agree about the tubing size. Small diameter has far more
surface area. More surface area equals better more efficient
heat exchange.
How will you pump water into the tubing and control the water
level? That's always the big challenge. Some guys use flow
meters and electronics. One guy I know went super simple and
put the boiler on a sort of scale. When the weight of water
(maybe a few grams) was enough it closed a microswitch mounted
on the spring loaded frame. Getting the flow rate equal to
steam production is the key.
#Post#: 3013--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: May 30, 2014, 9:00 am
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Hello lynx and thanks for the reply....
I will aim to match the turbine performance with the boiler
out-put...and not go overboard with temps or pressures....I
think its the same as matching an alt to a windmill..
at the moment all of my figures are guesses.. 300 degrees c is
just an arbitrary max set by me...I could be satisfied with
250.....that's why I wish to build this set up to see what the
real life measurements say....a live and learn
exercise...hopefully fun..
the dc dynamo on my turbine is 25 w.......I'm personally not
trying to get 1hp.....the examples in the above post were just
examples of what others have done....
my turbine is suppose to do its work at 45psi.....
I think my project fits into the low power end of
things.....baby steps first.....
#Post#: 3014--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: May 30, 2014, 9:16 am
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Lynx...
I have an a water feed pump similar to what you have...mine is
rated at 55psi with 1.4 gal/min flow rate...
I don't know if this will be suitable....but I have to start
somewhere...if the flow rate is too much I might be able to slow
the rate down....
like I've said...a bit of trial and error with this project.
#Post#: 3019--------------------------------------------------
Re: solar..flash..turbine..
By: lynx wind Date: May 30, 2014, 10:31 am
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The first time I ran a monotube boiler I manually adjusted the
flow rate with a needle valve. That was with a wood fire and it
was tricky. Solar is going to be much steadier heat input on a
clear day. The nice thing about a steam turbine is if you flood
the boiler it wont harm the engine. The best gauge of proper
feed if you are doing it manually would be pressure or temp.
Keep the gauge reading in a zone. Record results at different
temps or pressures.
#Post#: 3312--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: June 14, 2014, 1:23 am
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hello members......
HTML an update for my backyard project.....[img]http://I've built
this timber frame to hold the Lenz and bits and pieces......I
can raise or lower the lenz to suit the focal point that I
need......I can swivel the lenz left or right to catch the
sun....
at the moment for us in Australia it is winter and the sun is
low on the horizon....not the best time for solar projects of
this nature....[/img]
#Post#: 3313--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: June 14, 2014, 1:39 am
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I'm still trying to learn the in's and out 's of posting on this
site....
for some reason the above post got cut in half.....something to
do with the pic...
anyway the above frame can be raised and lowered for the correct
focal point for my needs.....as well as swivelled left or right
to line up with the sun...
at the moment in Australia it's winter and the sun is low on the
horizon....not the best time for this sort of project....but
come summer I should have all items sorted and be ready to walk
the walk....
#Post#: 3314--------------------------------------------------
Re: solar..flash..turbine..
By: tri-lobe Date: June 14, 2014, 2:01 am
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I got some 3.5mm cord....and rolled 4meter into a 6inch
diameter....
now if I had 2 off these pancake coils made out of copper
tube.....one on top of the other.....I could perhaps have a
preheater on the bottom and a steamer coil on top....
seems like a good place to start.....
now if I contain these two coils in the 7 inch biscuit
tin....lined with rockwool...which is in the bag shown in
pic...I might be able to have a very contained coil bundle
insulated from the surrounding cooler air....it's very much a
suck and see approach...[img][/img]
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