Durability and reliability testing
In addition to the equipment required for thermal performance testing, the test facility is delivered with the complete equipment required for durability and reliability testing of solar thermal collectors according to EN 12975-2. This comprises test facilities for outdoor exposure, external and internal thermal shock, rain penetration, mechanical load test and internal pressure test.
Like for thermal performance testing, it is also possible to combine test facilities required for several durability and reliability tests into a single test facility. Figure 5 shows the test facility for the rain penetration which can also be used for performing external thermal shock tests.
For carrying out exposure tests, high-temperature resistance tests and internal thermal shock tests, the same test facility can be used since only the frame with the spray nozzles has to be moved sidewards.
Furthermore, the collector test procedures related to the positive and negative mechanical load test, the internal pressure test, and the impact resistance test can be performed using only one single test facility. For this purpose, the collector is mounted on the mechanical load test facility; see figure 6.
Obviously, the mechanical load tests (negative and positive pressure) may be performed subsequently.
After connecting the equipment for the internal pressure test of the collector, the corresponding test can be performed on the mounted collector without any changes on the test facility.
According to EN 12975-2 two methods for performing the impact resistance test are specified. One method is using a steel ball and the other one ice balls.
For performing the impact resistance test by means of a steel ball, the collector does not need to be remounted since the collector is mounted stiff enough on the test facility. The supporting frame of the mechanical load test facility was designed by IAO as a push loading drawer. Due to this it is possible to pull out the support frame including the mounted collector underneath of the frame simulating the mechanical load; see figure 7.
For performing the impact resistance test with ice balls, it becomes necessary to utilize a complete different test facility. Since the ice balls must have a certain speed at the time of the impact on the collector cover the application of a certain kind of acceleration mechanism (“ice ball gun”) is essential. Such an acceleration mechanism is shown in figure 8.
The performing of an impact resistance test according to this method makes it necessary to mount the collector vertically.
The mobile, stand-alone solar thermal test facility has been registered by SWT for patenting under the number AZ 102007018251.3 at the German Patent Office. Major issues of this patent are the mobile and stand-alone characteristics of the test facility combined with the possibility to perform tests according to three different standards with one single test facility.