Experimental Investigation of a SOFC/MGT Hybrid Power Plant Test Rig: Impact and Characterization of Coupling Elements

The main topic of the paper is the discussion of the operational behavior of the solid oxide fuel cell (SOFC)/micro gas turbine (MGT) hybrid power plant test rig with the pressure vessels of the SOFC emulator. In the first part a brief introduction to the test rig and its components is given. In the arrangement of the test rig the MGT is connected via an interface to the tubing system. Here, the preheated air after the recuperator can be led either to the emulator or via a bypass tube directly to the MGT. Furthermore, there is a direct connection between the compressor outlet and emulator for the startup and shutdown procedure. The facility is equipped with detailed instrumentation, including mass flow meters, thermocouples and pressure probes. In the second part of the paper the characterization of the hybrid power plant test rig is shown. To analyze the thermodynamic and fluid dynamic impact of the coupling elements various studies were carried out. Hereby, the influence of the coupling elements on the operational behavior, system stability and system performance of the micro gas turbine is shown for stationary load points, as well as during transient maneuvers like startup, load-change and shutdown. To avoid critical operating conditions limitations were defined and emergency maneuvers were developed and tested. Out of these investigations an operating concept for the hybrid power plant test rig can be derived.