Global Aging and Lifetime Prediction of Polymeric Materials for Solar Thermal Systems – Part 1: Polypropylene Absorbers for Pumped Systems
Abstract
Part 1 of the paper series deals with the lifetime estimation of black-pigmented polypropylene (PP) absorber grades for pumped solar thermal hot water systems at different sites (Antalya, Mumbai, Phoenix). Absorber temperature loading profiles were calculated using the simulation tool SHW. Furthermore, global aging experiments in hot air or heat carrier fluid were carried out on specimen level for a commercial black- pigmented PP grade. The aging indicator strain-at-break was measured and endurance times at elevated temperatures (up to 135°C) were extrapolated to service relevant temperatures (maximum 105°C). The lifetime was assessed by weighting the temperature dependent endurance times with the loading profiles assuming cumulative damages. Depending on the extrapolation method, system specific parameters (i.e., collector size and storage tank volume) and installation site, lifetimes ranging from 20 to 45 years were obtained.
Keywords
Polypropylene, solar thermal collector, absorber, lifetime