Mother's Super-simple Solar Tracker

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We can and do use this freon all the time (in refrigerators, air conditioning circuits, spray cans, etc.), however, and we do it quite easily ... merely by keeping it bottled up inside heavy coils of tubing, pressure containers, and other such "closed systems". When it is contained this way, the freon can build up a pretty good head of pressure (61.4 pounds/ square inch at 50°F, 131.9 psi at 100°F, 249.3 psi at 150°F, 430 psi at 200°F, etc.) but, as long as our closed system doesn't rupture, the freon is forced to stay right where we want it.

It is also interesting to note that not all the freon in a closed system has to boil (change from a liquid to a gas) in order for the pressure inside that sealed coil of tubing, pressure bottle, tank, or whatever to increase in the dramatic way just described. Frequently, in fact (depending on the size and shape of a freon container and the way in which heat is applied to it), the pressure inside a bottle or tank of the liquid can be raised 50 or more psi by the boiling away (the changing from a fluid to a gas) of only a few drops of the trapped freon.

Aha! Now we know why Steve Baer's tracking mechanism works. His two long tanks are filled with freon and laid perpendicular to the sun's rays so that Ole Sol's outpouring of heat energy will have the maximum effect on their contents. (The maximum possible surface of the tanks is directly exposed to the sun so that even the least amount of solar radiation will raise the temperature of the containers—and the freon inside them—as much as possible.)

In addition to that, Steve's two tanks are connected by a heavy-duty hose. Which means, when the two containers are equally exposed to the sun—and thus, equally heated—that the pressure inside one will exactly equal the pressure inside the other. And the two tanks will just sit there, getting warmer and warmer, with more and more of the liquid freon in each container boiling into a gas and forcing up the psi readings on the whole (two tanks and a hose) system. If the tanks were transparent, they'd look like Fig. 2... with more and more of the liquid freon in the bottom of each container boiling into the gas trapped in the upper portions of the tanks.

Likewise, when the two containers are equally exposed to less and less of the sun's rays, their contents cool equally. And more and more of the gas in each tank is converted back into a liquid—again, on an equal basis—and that's all that happens.

But what if one of the containers is heated more than the other? Well, not a whole lot would happen if that hose between the two tanks ran from the top of one to the top of the other tank. A little gas would siphon from the hot container over to the cool one ... and that would be that.

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