Chapter 3.2 - Measurements of Environmental Stress Conditions and Evaluation for Service Life Prediction

Abstract

This chapter describes some measurement techniques and methods that can be employed in the characterization of environmental stress for the durability assessment of components and materials. For service life prediction the knowledge of the environmental stress conditions is of essential importance. In recent years, a lot of research on durability assessment of absorber coatings for solar thermal collectors was made within the framework of the Solar Heating and Cooling Program (SHCP) of the International Energy Agency (IEA). In the case of solar absorbers, the environmental factors that may result in loss in optical performance are of principal interest. These are identified as high temperature, high humidity and moisture, and airborne pollutants. Measurement techniques adapted to these factors will be discussed in detail. The form of data acquisition is not restricted to time-dependent data only. Sometimes the acquisition of extreme values or dose functions is much more appropriate. Even well-defined standard specimens may be used as a sensor.