Curnutt Style Furnace Project
by Sean Capogreco
(July 9) I have a Curnutt Style Solar furnace coming online
within the next few weeks. Like many inventors I am proud of what I
have done and have hurdled many stall points.
The reflector frame is 7 x 9 feet and will accommodate 160
square flat mirrors. I have 120 that are mount ready and will order
the other 40 to be cut once the existing set is installed. An 8 ft.
cross arm that is a 4" I beam with pivot mounts is finished,
along with the polar alignment post ready to be set in concrete. All
these parts are made from steel.
Now I am coming to the step where I mount the heat exchanger.
However, I have yet to fabricate it. I looked at heater cores today
-- Advanced auto Parts and Auto Zone -- and they are comprised of aluminum
and copper, not suitable for the temperatures and pressures I am
shooting for (1000 f. and 100 PSI).
Is there an off the shelf solution for a STEEL heat exchanger? I
have an idea about how to build it but as always would love to know
of a shortcut.
To start with I have a 3.5 inch Tesla turbine standing by with a
7 disk pack. I hope I burn it up as the casing is 1 inch thick home
cast aluminum. (thanx Steve Redmond!) I've taken up aluminum
foundry too. Runners are built of stainless.
I don't care If I smoke my prototype turbine, as that would mean
that I could plug in a bigger one. Next one will be better anyway.
I've seen it run on 100 PSI compressed air at length and am
satisfied that it will be fine for a while.
so.... enough bragging about progress... where can I find an off
the shelf heat exchanger that will sustain pressures of 100 PSI and
temperatures of 1000 degrees?
Sean - There are companies that sell stainless steel tubing and
will fabricate it into the shape you require, but you can probably
do that yourself with an automotive brake line bender. Since your
target area is on 6 inches square, I would opt for a narrow slot
flat plate design 8 inches by 8 inches square and about a 0.25
inch to 0.5 inch gap. - Ken Rieli
(July 23) Thank you. Heat exchanger is already being fabricated.
Should be done by Wednesday next week at the latest.
I have a 12 inch by 12 inch 12 gauge steel plate to mount on top
of my stainless plumbing that will serve as a target to sight in the
mirrors (hopefully this weekend.)
Right now I'm finishing the upright structure that leads to the
heat exchanger (cross members) for the vertical plumbing. ALL
I have to admit I was floored at the end of February 04 when I
saw your composite with the dish and the turbine concept because I already
had it on paper and had been working with it for some time. Common
Here is where I'm at right now.
Wow this sucker was a LOT OF WORK... Whufff.. Sunburnt, bruised
and cut up hands, blisters etc. But I'm on the home stretch now. We
hit my Tesla Turbine with 100 PSI compressed air yesterday and she
screamed like a router. Plenty of torque to drive 2, maybe even 3
alternators. First version prototype. Likely out of balance.
I was already deep into this concept when I discovered your
website this past winter. I am including last year's project in
Storyboard format. Last year's aluminum frame was too flimsy.
PS: mirrors are computer generated. To correct myself the
heliostat dimensions are 7 x 10... Sorry. heavy sucker too.
Ohh yeah, I may require guidance as to what to do with all this
power. My electrical background is very limited. But I've spent a
lifetime building and flying model Airplanes and jumping out of
Sean - Great job! Thanks for sharing your project!