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neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 07:35am 23 May 2010
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I'd like to think you are correct. (It seems to be a reasonable proposition!)
I presume that was used in a situation where it had to support itself - not where is held firmly (glued?) in place?
Stop it! You're making mirror finish stainless steel look more reliable. Edited by neil0mac 2010-05-24
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 07:40am 23 May 2010
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Hi Mack
Ill be interested to see how your solar concentrator goes as I have plans along those lines to once I get this solar and wind project up and running. I am at present collecting various bits and pieces to make a 10 KW unit, doing research on gas charged Stirling cycle motors. Steam is an option as I have built one with a steam engine and it worked OK but problems with lube oil fouling the system.
Hi Bruce
The mention of the car costs is a good point as we tend to focus on home expenses, in the past I have converted a Morris Minor to a hybrid drive unit and look like going that way again, just keeping an eye out for a suitable motor 36 / 48 volt 20 Kw.
Batteries are a moot point at the moment but 60 volt Lipo pack at 500 amphr is the target. Car will likely be a small van like lite ace to be a utility vehicle, solar panels on the roof to supply a bit of float current and a 5 HP diesel with generator as a range extender.
All the best
BobFoolin Around
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 07:56am 23 May 2010
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Hi Neil
I went through the info from the Gov on solar and that is the way it reads to me, there are a couple of points on the time of the installation but no indication on specific parts such as a panel which may have gone faulty and need replacement it is aimed I think at the system as a whole not parts thereof.
On the stainless that is defiantly the best way to go but the most expensive, I think I would use cheaper option for proof of concept experiments, the very thin stainless sheet would need to be glued to a backing as well.
Your comment on the Mylar being glued to a base sheet may be OK but what I have seen is the Mylar dies even when glued to a structure so unless the mirror surface protects it 100 % I feel it would still have a short life span at most two years in a high temp situation with direct sunlight exposure 12/7
All the best
BobFoolin Around
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 04:05pm 23 May 2010
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[Quote=VK4AYQ]Steam is an . . . . lube oil fouling the system.
Using steam in a Rankin-cycle engine (or any engine for that matter) is a pain in the drain when it comes to lubrication. IMO if you're going to be making steam, why not just use destructive distillation to create methanol from wood chips and run an internal-combustion engine on it. Couple the engine to a generator and you're in business. Don't breathe the exhaust fumes and don't spill the ethanol on your skin, by the way!
The "usual" hard part with using a concentrator (necessary for the temps used in destructive distillation) is keeping the focus. I figured that one out long ago. What I did was use a fixed-focus mirror and bounced the moving sunlight onto the fixed mirror using a tracking, flat mirror I scrounged from a remodel. It was a mirrored closet door in a former life.
Seeing you live in Australia, I'm not sure how well my system would work for you. I'm at lat 38 or thereabouts, so the sun arcs in a southern path all year long. I mounted my fixed-focus mirror vertically in a stationary position facing north and the tracking mirror simply bisected the angle between the sun and the fence (where I had the other mirror mounted). If the sun's path is more directly overhead, perhaps you'd have to use a Fresnel lens instead of a mirror, I dunno.
Well, think twice before using steam as a motive force. Lots of lubrication problems, as you've found. IMO Sterling-cycle is not an option unless you're in a very cold climate. A Sterling-cycle engine is basically an atmospheric "sucker" engine. The motive force depends on the difference between how hot and how cold you can get the trapped slug of air inside the thing. As things heat up, things slow down, at least that's the way my Sterling works:
. . . . . Mac
Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 01:25am 24 May 2010
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Hi Mack
I know what you mean about the Stirling engine I restored one and it must of weighed a ton but only made 1 horsepower, but it was great to light a fire under it and a couple of minuets later see it chugging away.
I liked steam because of the energy gain with temp curve makes for a very efficient engine at around 300 C. which was achievable with solar energy and a trough collector.
The lube was a problem but an old steam guy gave me some tips on that, he used gum leaves in the feed water to extract the eucalyptus oil and sheep fat in the lubricator and made a fat trap on the condenser to reclaim the fat.
I tried it on my 5hp vertical engine and ut worked very well.
The steam is the best way to save the energy during the day to be used at night so thats the way I will go.
I also tried freon gas and that works well in a sealed system but not socially acceptable any more, could substitute LPG but in quantity could be a fire risk.
All the best
BobFoolin Around
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 03:39am 24 May 2010
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VK4AYQ
I think if I were to use steam, I'd build a contained "Pelton wheel contraption and just shoot the steam against the outside of the enclosed wheel, then run that through some sort of transmission and capture the energy with a generator.
Unless water (and noise!) is a problem, this would be by far the easiest build from scratch and NO lubrication problems unless you spin the thing at light speed. The airplane turbines spin on what is called an "air bearing" so I'm told. Apparently, the shaft is contained at a very close tolerance and compressed air bolsters it without adding heat from friction. With a steam engine acting as a Pelton wheel, too-high revs could be a problem.
I mentioned noise and this would be in the form of a high-pitched scream! Anyway, that's my take on it. A simple belt transmission could be used to tame the monster.
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539
Posted: 04:10am 24 May 2010
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Hi Mack
The problem with a pelton wheel on steam is that it only returns 1/3 rd the power of an-expansion steam engine so you would have the collectors 3 times bigger. The high RPM would require a transmission so that's more losses to contend with.
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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