Design of a Test Rig and its Testing Methods for Rotation and Expansion Performing Assemblies in Parabolic Trough Collector Power Plants

Kurzfassung

The present master’s thesis deals with the design of a new test rig for the investigation of durability and failure mechanisms of flexible pipe connections – so called Rotation and Expansion Performing Assemblies (REPAs) –, which are utilized in Parabolic Trough Collector power plants. Said assemblies compensate for the motion of the absorber tubes relative to the fixed piping of the header connection. The work focusses on the test rig’s design in view of a realistic simulation of all loads a REPA is exposed to in commercial applications. To achieve this, all possible requirements of the components, which are supposed to endure a lifetime of up to 30 years in power plants, are depicted. A literature research is carried out in order to investigate and evaluate existing test rigs for REPAs or their single components. By means of the findings, a specification sheet is derived. The test rig is composed of two main assemblies. On the one hand, a Kinematics Unit is used to reproduce the cyclic rotational and translational motions of a Parabolic Trough Collector. On the other hand, an HTF cycle (Heat Transfer Fluid cycle) conduces to set up pressure, temperature and flow rate circulating through the test specimens. The main part of the thesis contributes to the integration of the externally designed Kinematics Unit into the HTF cycle – taking into consideration realistic operation conditions and a complete and precise measurement of all parameters. Special emphasis is put on an accurate acquisition of the mechanical loads the test objects have to cope with. As a result of this work, a test rig is erected enabling realistic endurance tests of two serially connected REPAs in less than three months. The hydraulic properties are adjustable in terms of mass flow (6−60 m3/h), pressure (up to 40 bars) and temperature (up to 450 °C). The investigations can be tailored to customized applications of the REPA concept (Ball Joint Assemblies or Rotary Flex Hose Assemblies) and the collector geometry (e.g. focal length).