A Model for the Configuration Design of a Tubular Solid Oxide Fuel Cell Stack

In this paper, a model of a tubular fuel cell is proposed. The model includes thermo-fluid dynamics, chemical reactions and electrochemistry. In order to formulate proper boundary conditions for the cell, a simplified model of the whole stack is proposed. This approach allows one to account for the position of the cell within the stack; this is particularly important for the formulation of the thermal problem. An application to a stack constituted of 24 tubular cells is shown. The temperature distribution, the concentration of species and the polarization curves in each single cell are obtained. The proposed approach is useful for investigating the stack performances and thus examine new configurations.

Measurement of the Velocity and Pressure Drop in a Tubular Type Fuel

We have developed a tubular type fuel assembly design as one of candidates for fuel to be used in the Advanced HANARO Reactor (AHR). The tubular type fuel has several merits over a rod type fuel with respect to the thermal-hydraulic and structural safety; the larger ratio of surface area to volume makes the surface temperature of a fuel element become lower, and curved plate is stronger against longitudinal bending and vibration. In the other side, a disadvantage is expected such that the flow velocity can be distributed unevenly channel by channel because the flow channels are isolated from each other in a tubular type fuel assembly. In addition to the design development, we also investigated the flow characteristics of the tubular fuel experimentally. To examine the flow velocity distribution and pressure drop, we made an experiment facility and a mockup of the tubular fuel assembly. The fuel assembly consists of 6 concentric fuel tubes so that 7 layers are made between fuel tubes. Since each layer is divided into three sections by stiffeners, 21 isolated flow channels are made in total. We employed pitot-tubes to measure the coolant velocity in each channel. The maximum velocity was measured as large as about 28% of the average velocity. It was observed in the innermost channel contrarily to the expectation from the hydraulic diameter. A change in the total flow rate did not affect the flow distribution. Meanwhile, the pressure drop was measured as about 70% of the drop in the rod type fuel assembly in use in HANARO.