Development of a Segmented Single SOFC Test Equipment to Simulate Stack-Like Operating Conditions

A common problem when it comes to stack CFD modelling is the lack of detailed local information about temperatures and gas compositions. For the calibration and validation of the CFD models local measurements of these parameters are required. However, it is fairly difficult implementing such measurements in commercial stacks without changing the stack design to allow for additional thermocouples or gas extraction channels. Furthermore, such implementations would automatically change the stack behavior compared to a stack without additional instrumentation due to heat and gas losses caused by the measurement itself. On the other hand standardized single cell tests do not represent stack like conditions due to typically very homogenous temperature distributions. Therefore, a new single cell test equipment based on a segmented single SOFC which enables an operation of the cell under stack like conditions was developed. The aim of this development is to provide a single cell test equipment which provides comprehensive data about temperature distribution, cell voltage distribution and local gas compositions to be used for the calibration of a commercial CFD code [1]. The complete test equipment was simulated by means of CFD and the results were compared with experimental data. The single cell consists of a commercial anode supported SOFC with 4 segmented cathodes (40.5x44 mm 2 each) and 1 anode (120x120 mm 2 ). The segmented cathode allows the measurement of local cell voltages. Furthermore, several gas extraction channels along the anode flow channels were implemented to measure the gas conversion with respect to the electrochemical and steam reforming reactions taking place. As the steam reforming reaction has a significant impact on the temperature profile, in real stacks it is important to consider the conversion rate properly along the anode to allow for a correct simulation of the temperature distribution. The temperature profile was measured with 34 thermocouples which were distributed along the anode flow field below the anode surface. Several test cases to calibrate the CFD model regarding the thermal behavior were carried out by placing the test equipment in an electric oven and heating it up to 600 °C. The cell test equipment was additionally equipped with 4 electrical heaters placed below the anode channels to produce temperature profiles similar to real stack operating conditions. Therefore, also inhomogeneous temperature profiles can be produced.