Experimental Evaluation of SOFC System Exposed to Marine Inclination Conditions

Abstract

To comply with future emission regulations, the marine industry needs to reduce emissions. Marine actors are showing an increased interest in the application of Solid Oxide Fuel Cells (SOFCs) for ocean going ships, because of their high conversion efficiency, low pollutant emissions, and fuel flexibility. However, operation in ships is fundamentally different from stationary applications, since the installation rooms accelerate and incline due to wave-induced ship motions. This could lead to pressure variations in the fuel streams or detrimental mechanical stresses. So far it has not been extensively investigated what the consequences of inclinations and motions are on the operation of SOFCs. The goal of this research is to evaluate the influence of marine conditions in terms of static and dynamic inclinations on the operation, safety, and lifetime of SOFC systems. Ship motions are simulated with a one-axial oscillation platform. The inclination conditions the SOFC system is exposed to are derived from ship motion studies and marine regulations. The test campaign consists of two phases. In this paper, the results of the first test phase will be explained in detail. Moreover, the learned lessons and their implementation into the plan of the second test phase will also be shared.In the first phase of the test campaign, a 1.5kW SOFC system is inclined around two horizontal axes of rotation while producing power at nominal conditions. During the static experiments, the SOFC system is operated at fixed inclinations from -30 degrees to 30 degrees with steps of 5 degrees. In the dynamic experiment, the system is oscillated up to an angle of 30 degrees with frequencies of 0.025, 0.033, 0.05, and 0.1 Hz. The experiment showed no gas leakages or other significant safety risks during the experiment. However, for slow oscillations, relatively large deviations in several system parameters (e.g., fuel flow, stack voltage, and fuel utilisation) were found compared with the non-inclined operation. This indicates the natural frequency behaviour of particular components in the system. Although the deviations were much larger than in regular operation, the early stage indication was that these deviations do not result in safety issues or decreased system lifetime.The second phase of the test campaign was focused on including a larger range of possible ship motions and increasing test durations. An additional aim was to find the physical cause of the deviations in system parameters during oscillations. Additionally, a 100h test on one oscillation condition is included to evaluate whether the ship motions could cause increased cell degradation. Furthermore, several part-load conditions are included in the experiment.The results of the experiments are used to propose design improvements for SOFC systems that require to be inclined or accelerated. These proposals contribute to the marinization of SOFC systems. Furthermore, the results will be used to help class societies defining proper regulations for SOFC implementation in seagoing vessels. Figure 1