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Forum Index : Solar : Solar Steam
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MacGyver Guru  Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I'm a newbie to this forum, so if this question has been asked and answered thousands of times, please excuse. Does anyone use sunlight to mechanically create electricity? I have perused as many of the "Solar" posts I can see, but don't see that anyone is using anything except perhaps solar film or PV to create electricity from sunlight. I'm a steam-engine nut (along with air-driven hybrid designs). Years ago I built a flat-plate solar collector that made steam, which I then used to turn a generator and was able to employ standard controls to maintain voltage while keeping up with current demand. The difference in my flat plate collector from any other is that it contained oil instead of water. The oil absorbed and held more heat than the water ever could. The oil circulated in a closed loop, driven by a magnetic-coupled pump welded into the system. I employed a simple conduction-type heat exchanger in my "boiler" and was able to produce an on-going supply of steam, enough to run a double-acting engine that turned a generator. I also developed a dandy way to make a concentrating collector, which produced as great a concentration as you could ever want. I made a 1,000-sun collector using a few sheets of 22 ga aluminum sheet, some aluminized mylar and a lot of thought. I put the collector together in a matter of hours. It had a fixed focus and melted a 23,000 degree pyrometer. To that end, I dis-manteled it and went back to using flat plate; too dangerous. But talk about flash steam!!! Anyone else had experience along these lines? 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 |
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| greendreamin Newbie  Joined: 02/02/2008 Location: AustraliaPosts: 20 |
you got photos, have you done it? this thread is alot like your other alot of yammering but no proof or technical details. or are you going to try and flog us a book on how to do it all?? (sorry just sounds like a bit of a sales pitch thats all)) |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
greendreamin: Photos: From 40 years ago? No. Recent photos (last 10 years)? Gobs; posted on another Website. Done it? Absolutely. Yammering: I'm 60; it's my right of passage. Book: None and none in the works. Pitch: None and none coming. Will I share my pictures and technical details? Doubtful. I was all set for that, but your attitude changed my mind! End of story. 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 |
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niall1 Senior Member  Joined: 20/11/2008 Location: IrelandPosts: 331 |
hi all as another newbie lately i,m just dipping my toe into solar water heating with very limited homemade results ...using oil as a heat collector sounds interesting ....... i rembember storing old engine oil (home service stuff) in a 5 gallen drum , this was left outside in a corner as i couldnt get rid of it 
one day during the winter (probabely sunny) i noticed the drum felt very slightly warm ...just struck me as one of those slightly odd things at the time .. if it had been full of water i doubt the heat would have been the same ... i,ve tried reading up on storing heat and it seems fluids with a higher boiling point can store more heat energy ..old engine oil is pretty dark i know this helps...is there any other advantage in using oil ? niall |
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| MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
I don't know that the oil's color has much to do with it, since it is trapped inside a continuous metal (copper in my case) tube. I just used it because it beat throwing it into the landfill! This was several years ago, so don't get crazy on my last statement; everybody did it. Eutectic salts are also used in some systems, but used oil seemed to me to be a way-easier way than something fancy. Just for a not-too- technical example, "French" fries are cooked in 520 F degree oil. Water "flashes" at 212 degrees F. Much hotter and in the presence of oxygen, oil will flash too, so it must be contained or it's an awful safety hazard. I'm going to post pictures eventually. I've got lots of plates in the air right now. Hide and watch, sooner or later I'll share all my goodies with the whole crew here. I've been at this so long and have so much to share, I'm contemplating cranking up a Web site for just that purpose "show-'n-tell". Like I said, hide and watch. 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 |
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| greendreamin Newbie Joined: 02/02/2008 Location: AustraliaPosts: 20 |
appologies to Macgyver sorry about the post the other night was in a A#@$hole mood and was one myself as it shows, 
hope it didnt put you off this great site Stu |
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| niall1 Senior Member Joined: 20/11/2008 Location: IrelandPosts: 331 |
...  .....niall |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Mcguyver Im like you a bit of a dinasour these days with all the hi tech stuff they play with now. I was on a track like yours however I used freon 22 in a sealed system with a steam type engine in a sealed steel box containing oil and freon with the drive shaft coming out through a refrigeration face seal. seperate condenser unit with fan driven of the motor, all pumps and governor sealed in the box. Flat plate collectors sun tracking the sun 6 of total 24 meters approx and a trough reflector also tracking the sun it was 8 ft long with 1" hydrolic tube as rhe collector tube. It produced 5 -6 KW and I think a lot more as the gvenor used to hunt due to light loadibg, at 110 volt dc as that was the biggest generator I had at the time then into a transverter to 240 volt ac with battery bank made up of 3 old 32v packs 500ah I think big old glass cells. when I shifted to Queensland 30 years ago I dismantled it as I didnt want it floating around and killing somebody who didnt understand the danger of high volt dc. Could have been used to drive an alternator with a better design govenor but then no night backup. Also used propane as gass medium but more dangerous than freon. All the best Bob Foolin Around |
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Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi MacGyver The response from Bob indicates that both you and he are way way ahead of me in this, but I have been thinking about a steam powered solar project involving a tracking parabolic collector focussed on a pipe to generate flash steam. While you would need safety valves, there would be no attempt to store heated pressurised water (or heated anything), which sidesteps the problem of boiler safety to a large degree as the steam would be generated and transmitted only in small diameter pipes. Over temperature would be accommodated by shifting the collector tracking away from the sun. The steam engine would be a four stroke motor converted to steam (or compressed air) operation by disabling the cam followers, and using the spark plug hole to both inject steam via an injector, and exhaust it via a solenoid valve. These would be electronically controlled with the shaft position sensed by a rotary encoder. The electronics would also govern engine speed. A purpose built steam engine may well do a better, more reliable, and more efficient job, but I was thinking of things that I could most readily contrapt with my resources. The exhaust steam would be air cooled and condensed in a tank, then returned to the flash steam boiler via a separate pump. The condensor should provide a vacuum for the exhaust, hence making each stroke a power stroke. I was actually looking to use 3 single cylinder lawn mower motors for the engine, with the cranks set at 120 degrees to each other via couplings so that it could be self starting under any circumstance. As there is notionally about 1kW per sq metre of sun energy available, it would not take too many sq m to give a useful output. The mower engines that I have on hand are rated at 3 HP as (single power stroke) 4 strokes, so that I should have no trouble getting useful power output even at modest inlet pressures. I was particularly interested in MacGyver's description of his simply constructed solar collector, as my thinking to date had not progressed beyond using thin sheets of stainless for this. There are, of course, a number of practical problems in using steam as I am contemplating, not the least of which are maintaining adequate lubrication, avoiding rust, and how to live with entrained air, oil, and condensation. Bob's scheme of using a different medium like F22 could overcome some of these concerns, but I guess that everything has its own collection of problems. The set up that I have in mind could also pump up and store compressed air for limited operation when no sunlight is available. I might also add that I have not done any sums at all on this, so that there are probably glaring errors or misconceptions that would render it all completely impractical. This is therefore nothing more than a pipe dream of mine at the moment (if you will pardon the pun), but I hope that you can both contribute some comments to progress the direction of this thread as I am sure that it has merit. Regards Don B |
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KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
The good news is summer time its more like 5KW/m2 irradiance which is a helluva lot of power, hence why the evacuated tubes at 100 of kinda scary, could potentially capture 75KW/Day. use this as a preheater to 90 degrees then the concentrator for the final flash to steam.... Luck favours the well prepared |
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sPuDd Senior Member Joined: 10/07/2007 Location: AustraliaPosts: 251 |
Take a look at Ausra.com.au - it should give you some ideas on making a simple robust solar thermal collector. sPuDd.. It should work ...in theory |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Don Sounds like you are going to have some fun with this project. Just a few comments to help you not make some of the mistakes I made, using a normal 4 stroke motor sounds simple but has a problem with oil dilution as the water drops out of the steam. If you use the bottom end and the piston as the base of the steam engine and make dedicated steam cylinders mounted on top of the block you can isolate the condensate from the oil and have a double action piston returning twice the power on the same conrod. Flash steam as you propose will deliver a scary amount of power as pressure and would be hard to control without a buffer pressue chamber to store BTU energy this is important if you use a controlled expansion governer as I feel you are proposing from your description of the electronics. you would need a set of special balanced valves as the pressure from what you propose could be around 1000 psi A flat plate labyrinth boiler about 18 " square would do made from mild steel or aluminium if you keep the temp down stainless has a poor heat conduction and is prone to high temp fatigue. A good starting point would be a 10 ft dia parabolic reflector for initial experiment bathroom mirror tiles work ok but wont stand the elements for a long time polished SS segments are better there. You will need a oil extractor fron feed water to reduce carbonation in the High temp side I used with some success euycaliptus oil in the feed water and beef fat for high temp cylinder oil got that from an old steam plant opperater not my idea, Big condenser is essential with at least three seperation chambers to grt most of the oil out. A friend of mine used HD soluible oil in his machine but it breaks down quicker than fat. I used an old oxy cylinder as my buffer chamber as they have a high test pressure but make sure you water test to 1000 psi before using it as you have a bomb if it blows. I would recommend you start off with a low pressure unit 20 to 25 psi for safety unless you are aware of the dangers present. 6" bore X 3" stroke at 500 rpm is a good size to play with to get srarted, Compressed air is a very inifficient way to store energy unless you go to very high pressure. beter a car alternator and a couple of batteries to avoid double conversion losses. Freon and LPG are good toplay with when you are comfortable with the medium. I feel steam has a lot of potential for small sufficiency power units. I had the plans for a small plant that produced 700 watts, it run off a fireplace built into a low pressure boiler and condensing engine opperating at 30 lb differential. On a 24 hour opperation it provided all the power needed and hot water for a family home 32 volt system thereare much more efficient devices available now so it would be a real goer in a cold climate. Best of luck with your project All the best Bob Foolin Around |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi There Just mention a heat absorbsion plant several of my friends where working on a basic design it was a hot storage tank containimg superheated medium from solar collectors one was oil and the other one was mercury opperating temp in excess of 500Deg C the mercury one was very efficient but opperated at high pressure and had a mercury vapor collector to prevent loss to atmosphere. High tech and dangerous. The oil one worked at low pressure and didnt cause enviro pollution. The boiler was a steam tube coil like a stanley steamer boiler but immersed in the heated medium with a variable displacement pump injecting water into the tube in line with the power requirements of the engine the large boiler well insulated gave a good storage of energy for light loadings, I dont think they ever got beyond experimenting but from what I saw it had potential for development. All the best Bob Foolin Around |
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| petanque don Senior Member Joined: 02/08/2006 Location: AustraliaPosts: 212 |
Am I using the wrong book but isn’t the problem with solar heating that you need heating in the cool months Almost by design it seems that the cool months are when there is little solar energy available to harvest? |
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| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
yep, house heating in summer and a 200KW steam engine for summer, sound great Luck favours the well prepared |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi don House heating is a differenc coloured cow, to heat you need an absorbsion bank to store BTU for a longer term. In saying that it is surprising how much energy can be harvested in the winter by well designed passive units providing the sun shines a bit. The only one that I have seen that worked from summer heat was a absorbsion bank made of a hundred tonnes of old bricks and concrete slab pieces under the house with fan circulated warm air not practical in existing building. I used two water tanks well insulated with a VSWM driving an air compressor with the first tank absorbing the heat out of the compessed air, the second tank had a radiator in it in which the pressure of the now cooled air was released this cooled the water so you have hot tank and a cool tank to circulate as required. Not as nice as looking at a nice fire in winter, you could also use peltier plates if you have excess power from PV cells or a windmill. All the best Bob Foolin Around |
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nweeks Newbie Joined: 22/01/2007 Location: AustraliaPosts: 36 |
Just regarding solar steam, I've had ideas recently to use an old AusStar dish (1m diameter), plated with a reflective material, then to produce steam to run one of Liney's 5 cylinder machines: http://sites.google.com/site/lineymachine/l5 It's be a glorious sight to see it chugging away, turning a small generator instead of a prop... N. Nigel Weeks nweeks at karbonit dot com |
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| nweeks Newbie Joined: 22/01/2007 Location: AustraliaPosts: 36 |
But then, upscale one of these, and drive a decently built alternator with it, with the two changes in energy type (Solar to Mechanical, mechanical to electrical), is it better than the ~20% efficiency of photovoltaics we can go out and buy? http://www.pmresearchinc.com/store/product.php?productid=309 6&cat=5&page=1 Nigel Weeks nweeks at karbonit dot com |
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| VK4AYQ Guru Joined: 02/12/2009 Location: AustraliaPosts: 2539 |
Hi Nigel Great idea the only thing is that the design dosnt lend itself to steam efficiency and is very complicated a real show piece. I like the idea of the Sat dish you could extend it a bit as well and get a bit more power try and get some stainless sheet as it polishes up well. All the best Bob Foolin Around |
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| Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
Hi Bob and others that responded to my previous post. I was astonished at the number of responses on this thread in such a short time. With regard Bob's comment re the oil dilution with condensate using a modified 4 stroke engine, I agree that this would be a problem, and my only thought at present is to dry sump the engine with an external oil/water separation tank. Still thinking about that, although the suggestion to use something like eucalyptus oil could have merit. With eucalyptus, at least I should be able to avoid colds while working around it. Alternatively. if I used beef fat, then at least I should always have a cup of soup available. As I remember, the model aeroplane engines that I fiddled with as a kid used castor oil for a lubricant, so maybe something non-mineral is the way to go for a lubricant (though I don't think that I would ever be tempted to drink that one). Then there is sperm whale oil, which is apparently a very good lubricant, though I guess that I would have to import that from Japan. I guess that it all comes down to finding a lubricant which minimises contamination in the boiler tube if it can't be adequately separated from the condensate. Food for thought (although probably not drink). While it would be ideal to replace the piston and cylinder with a double acting sealed piston and cylinder, it would probably take me longer than my remaining years to set something like that up. With the condensor operating at a vacuum though, I would still get a power stroke from each stroke of the piston in my modified 4 stroke motor. With regard to a buffer pressure chamber for the steam, my inclination is to avoid having any large volume (or diameter) of steam storage for safety reasons. I had thought to pump the condensate up to working (steam) pressure (probably fairly low, as you suggest) incorporating a small air backed storage tank such as you might find on an automatic pressure water system. Admission of water to the boiler tube would be by an electronic controlled injector (like used on modern common rail diesels), which would control steam pressure. Not sure yet how to quickly control the boiler tube temperature if it starts to exceed safe limits, but I guess that part of the key is either to flood it and let the safety's lift, and/or not to have too big a solar collector area in the first place As far as the governor is concerned, I was imagining that I would be controlling engine speed by limiting the number of rotational degrees during which steam is admitted by each cylinder injector. My pipe dream envisages using the steam engine to drive an alternator arrangement which outputs 48V DC to a grid connect inverter, so that I would not have to worry about energy storage (or intermittent output)to any extent. With regard to the comment by one other poster about possibly using a dish as a solar collector, the problem with a dish is that it focusses the solar energy to a point, meaning that you have an almost impossibly small "boiler" area to handle the energy involved. Better to stick with a part cylindrical (parabolic) trough shape. Regards to all and a happy new year Don B |
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