Making steam and tracking questions

Tom wrote:

I just bought your doc and have skimmed over it quickly tonight. Very impressed. The ‘errata’ and the QandA links at the end don’t work however and I am interested in them…?

I am interested in using such an array (small initially, but scalable upwards) to generate steam, then a steam engine, then a generator etc. First of all, have you done any research on this? Secondly, what is your opinion of using oil and a closed loop system instead of water etc? And a heat exchanger etc.?

I was curious about trying to manipulate 2 axis instead of just one. Do you remember the game where you have a steel ball and 2 knobs that basically balance the entire wooden box on a point and slightly manipulate the balance to make the ball go around the maze? Do you see this concept as having any value in implementing it in this design compared to the gain you get in heat generated?

Hello Tom and thank you for your interest in my plans.

I have sold several hundred so far and you are the FIRST to point out that these links on the last page do not work! Thank you! Both pages are on the web and the text of the links is correct if you type them into your browser. Here are working ones for your convenience:

http://www.ffwdm.com/solar/errata.htm
http://www.ffwdm.com/solar/FAQ.htm

About making electricity from steam, this is indeed the "holy grail" project. I am working on this as are hundreds of other people. There is much on the web but after five years working on this and searching, I don't think that I have found a practical system detailed in such a way that it could be replicated easily by others. People talk about all sorts of things but as far as a robust, working, practical approach that can be built at an affordable cost and with simple tools, I have not seen it. It would have to be closed loop to be practical. Would it need a heat exchanger? Possibly not. Is high pressure steam dangerous? Certainly, especially if there is steam storage of any size included in the system.

About two axis tracking, one of the big advantages of a trough is that, if it is long enough, the effect of the other axis can be ignored. You can see that the larger commercial systems in the Mojave Desert make use of this principle.  A dish is another matter and all of those require two axis tracking.

Good luck with your project and let me know how you are doing with it.

Best regards,
George Plhak

Array orientation: N-S or E-W?

In your book, you mention N-S orientation vs E-W orientation.  Is it correct that with an E-W orientation, the tracking is not as critical as N-S and could be adjusted manually each morning to track the seasonal changes in the sun's angle?

Best regards,

John

I am not sure that I would agree that the tracking is less critical. I think that the main issue with orientation is the efficiency over an entire day.

Near solar noon it does not make much difference which way the array is oriented. The sun is highest in the sky at this time and it's rays fall very near perpendicular to the array in either orientation.

When it makes a difference is at higher latitudes (like mine) or if you have a wide unobstructed sky view and you want to get more out of the extremes of the day (morning and afternoon). In these cases, N-S orientation is better, more efficient.

Because home made collectors are not infinitely long (like the ones in the Mojave) we should expect a certain amount of "spill" at the ends if the array is not north-south. If you imagine an E-W array in the morning, the sunlight hitting the reflector at the end nearest the sun will focus some distance down the collector, not at the very end. The part of the collector that does not receive focused light is "wasted" during that time. At the other end of the collector, because of the sun low in the sky, the focused light at that far end does not hit the collector and is also "wasted".

Whether the controller and drive motor works less or not is to me a less important issue since I have adjusted the controller to a very low duty rate so it does not work very hard anyway, even though my array is mostly N-S.

In either case, the controller must accurately position the tilt of the array towards the sun.

I hope this makes sense?

George