Test Method for the Determination of the Long-Term Stability of Absorber Welding Seams in Flat Plate Solar Thermal Collectors
Abstract
A rapid test method for the long-term stability of absorber welding seams of solar collectors using thermal shocks is being developed within the framework of the SpeedColl2 project. Annual simulations of solar thermal systems show that the number of thermal shocks decreases with increasing irradiation sum and decreasing heat demand, while the magnitude (temperature difference) of the thermal shocks and the temperature level increase. The amount, magnitude and temperature level of thermal shocks was determined for four different locations representing different climate conditions. Comparisons using different temporal resolutions of weather data showed that thermal cycles can be determine with good accuracy using hourly data for system simulations. The good availability of hourly weather data therefore enables the determination of the thermal shocks from system simulations for different climate conditions and thermal loads and thus a test method which is adapted to the location (and purpose) of the solar thermal collector. This is the basis for the rapid test method which is being developed.