4 Comparing concentrator to flat plate solar collector
In this test, both insulated collectors track the sun. The flat plate on the left and the concentrating parabolic reflector on the right are coupled to the solar tracker and motor drive on the far right. Although flat plate type collectors are not normally used in a tracking configuration, I wanted to see how the collectors compared when used in this way. All other aspects of the solar test jig were unchanged from the previous tests.
Unlike the previous tests, here the flat plate shows a slight advantage over the concentrator. The flat plate begins heating more quickly and cools less quickly. During the period around solar noon, the curves are virtually the same. Overall, the curves are pretty close, suggesting that the characteristics of the two collectors are very similar when used in this configuration.
Early in the test, I had a problem with the temperature sensor for the concentrator. Fortunately, I had a look at the data being logged at about 09:45 and was able to correct the sensor problem just in time as the sun hit both collectors. You can probably get an idea of the concentrator temperature during this period by joining the tops of the readings. After the sun hits, the data is clean.
This is an enlargement of the period around solar noon. The curves are virtually identical, usually within a degree F. As in the previous test, the tracker reaches it's western limit just after 16:00 and the concentrator collectors falls out of the beam about 30 minutes later. The flat plate does not fall in temperature as quickly since it is still picking up some heat until the sun sets.
The maximum for both is pretty hard to pick out. The actual peak for the flat plate of 131.939F occurs at 15:43 which is 51.4 degrees F above ambient. At that time, the concentrator is 131.107F, within one degree F or virtually the same.