Commissioning and optimization of a test bench for life cycle Analysis of Rotation and Expansion performing assemblies (REPAs) in parabolic trough collector power plants

Kurzfassung

Rotation and Expansion Performing Assemblies (REPAs) are used in Parabolic Trough Collector (PTC) power plants to connect the moving absorber tubes to the fixed piping of the rest of the power plant. They are one of the most stressed and critical components of a PTC power plant. During their service life they have to withstand approx. 10.000 daily load cycles. A failure can lead to HTF leakages which are often flammable and environmentally hazardous. That’s why a leak free and reliable operation is crucial for safe power plant operation. The main focus of this thesis is the optimization of the kinematics unit (KU) of a life cycle assessment test rig in regards to reproducibility and overall test time. The test facility can subject the REPA to typical pressures, temperatures and mass flows of Heat Transfer Fluids while simulating the daily motions of a PTC. The rotation can be mimicked with a continuous rotation or a step-by-step motion for a more realistic suntracking simulation. At the same time the KU simulates thermal expansions of the absorber tube with a lateral translation. A full REPA life cycle test with reproducible loads can be achieved within 17 days for a continuous or 63 days for a step-by-step motion. In order to ensure operational safety, issues regarding the mechanical stability of the KU have been investigated and solution approaches are proposed and partially tested. At the conclusion of this work the step-by-step motion causes critical oscillations which need to be dealt with in future work. While these oscillations prohibit a 10.000 cycle test with step-by-step motion at this point, a life cycle test with continuous rotation is feasible.