A TRACKING SOLAR CONCENTRATOR
PIPING & CONTROLS
The piping to get the fluid into and out of the collector is routed along the top and bottom collector support rails (010). With insulation it is two inches wide and with the other one inch rails, only obstructs about 2% of the incident or unreflected energy. As you consider options to this rather circuitous routing, forget about the idea of running from the open center of the array to the collector. Such systems obstruct a significant portion of the energy reflected from every mirror, resulting in losses of 20 to 25%. Even if such piping is left uninsulated, most of the energy hitting the pipe would be reflected from it due to the low angle of incidence.
The top and bottom rails were chosen over the side rails as the top is always the high, in the morning or evening, and so it is the logical place to put the pressure release and recovery system figure 31.
The longer outdoor runs, on the collector system as well as the lines to your use/storage system are assembled from 1/2" rigid copper pipe wrapped with fiberglass and slid into a light gauge 2" downspout pipe to keep it dry. A doughnut cut from any convenient sheet material is cemented in the ends with silicon sealant to keep the pipe centered. figure 30.shows one end of one of these lines where it connects with the collector. Make sure that water that might seep into the fiberglass has a drain at the low end.
Flexible lines passing through the hub array are 5/8" automobile heater hoses. If you're using water/antifreeze mix, the pressure and temperature conditions are very much like the situation is in an automobile cooling system. The hose is wrapped with fiberglass tape that will get wet when it rains, but sure dries out fast when the sun comes out and the system starts working. An alternative would be to use the foam insulation used on air conditioning pipes, but it is rather expensive.
Your system must include provision for expansion if a closed loop is used as is done on the prototype. We circulate a 50/50 mix of automobile antifreeze and water. Because the operating conditions are so similar to conditions in the auto and there is simply not sense (cont pg 52)
