Direct internal reforming (DIR) of hydrocarbons like methane can help improve both economics and efficiency of solid oxide fuel cell (SOFC) systems. The endothermic reforming reaction yields chemical energy in form of hydrogen by directly utilizing waste heat from the cells, which is more efficient than other concepts like partial oxidation (POX) of the fuel gas. Furthermore, DIR cools the stack, reducing the need for excess air. The parasitic power consumption of the air blower is reduced, as well as investment costs for blowers and external reformers. However, DIR can potentially damage SOFC stacks due to thermal gradients and resulting stresses. Furthermore, in case of natural gas, usually some degree of external reforming is needed to convert heavy hydrocarbons like ethane, since these would cause carbon depositions on the SOFC anode. In this paper, we present experimental data from the operation of an anode supported short stack from Ningbo SOFCMAN Energy Technology. Natural gas was used as fuel, and the stack was operated under varying degrees of DIR. The reforming level was adjusted using an electrically heated reformer, and monitored with an online gas analysis. Up to 90 % internal reforming has been demonstrated without signs of carbon deposition or cell fracture. Increasing the degree of DIR had a moderate adverse effect on the stack performance. Possible reasons for this behavior are discussed. These results show that operation of stacks from Ningbo SOFCMAN Energy Technology under high degrees of DIR is feasible, while some performance decrease has to be expected.

The state-of-the-art alumina oxide housings used in single cell test rigs are fragile, inflexible and expensive. They are designed for a specific cell geometry, a change of the cell type - changing the cell thickness - or a change in the cell size is not intended and is thus associated with an immense expenditure of effort and time. In detail, the state-of-the-art ceramic frame concept is vulnerable to a fracturing of the frame or an insufficient contacting of the cell if a change in the cell thickness occurs. The connection of the ceramic housing with the typically metallic tubing of the gas supply is fragile, prone to develop leakages and is time consuming to replace and thereby prevents a change of the cell size. Gold wire seals used at the cathode side are a common source of leakage. Furthermore, the whole ceramic housing is sensitive to fracturing due thermal or load induced stress, and thus prevents fast thermal cycling of the specimen. This paper presents a modular, fully metallic housing concept which enables a fast and easy change of the cell size due to the utilization of a baseplate and a robustness towards different cell thicknesses due to the usage of a flexible metallic frame. The utilization of metal instead of alumina oxide reduces the manufacturing costs. Furthermore, an additional sealing on the cathode side enables a separation of the contacting pressure via a pneumatic piston from the sealing pressure applied via metallic screws. The force of the sealing pressure is not applied onto the cell and is thereby limited by the material constraints and not by the mechanical stability of the cell. For accurate voltage measurements, sense wires are separated from the current collection and are electrically isolated from the metallic housing. Thermocouples are used to measure the temperature distribution inside the anodic part of the housing, as close as possible to the cell. The chromium evaporation of the cathode part of the housing is reduced by a protective coating and the utilization of double layered tubes. In the end, the results of preliminary tests are presented.