Optimization of the Gas Flow in the Model Channel of a Disk shape SOFC

盘状固体氧化物燃料电池(SOFC)比管式SOFC具有更高的功率密度和更低的欧姆损耗，是一种很有前途的平板型燃料电池。对于盘状SOFC的情况，燃料从盘的中心孔供应并在燃料通道中向外流动。另一方面，空气从盘的外缘供应到上部空气通道并到达内缘部分。之后，空气返回其流动方向，并在较低的空气通道中向外流动。在本研究中，对平行盘形平板间的径向流动进行了实验研究，模拟了盘状SOFC中的流动。在平面型SOFC中，降低热应力是一个重要的问题。平板型SOFC内的温度分布受气体流动行为的影响很大，因此我们尝试用粒子图像测速仪(PIV)来研究不同质量流量下的流动形态。实验发现，在雷诺数为7左右的情况下，燃料通道内的流动分布是均匀的。在这种工作条件下，阳极表面附近的流场也呈现均匀的速度分布。由PIV测量得到的压力系数的均匀分布证实了这一结果。另一方面，在高空流道中，随着流量的增加，不均匀的流量分布被放大，出现大尺度的涡流。在较低的风道内，存在高风速的局部高速区。对于目前的圆盘流道，空气流道内的最佳流场在雷诺数为30左右。这些结果表明，有必要改进通道形状和空气的注入方式。

A disk shape solid oxide fuel cell (SOFC) is a prospective planar-type fuel cell, because it provides higher power density and keeps lower ohmic loss than tubular-type SOFC. For the case of disk shape SOFC, fuel is supplied from the center hole of the disk and flows outward in the fuel channel. On the other hand, air is supplied to the upper air channel from the outer rim of the disk and reaches at the inner rim part. After that air returns its flow direction and flows outward in the lower air channel. In the present study, a radial flow between two parallel disk-shape plates, which simulates a flow in the disk shape SOFC, was experimentally investigated. In the planar-type SOFC, a reduction of thermal stress is one of the important issues. A temperature distribution in the planar-type SOFC is strongly affected by the gas flow behavior, and hence we tried to clarify flow pattern at various mass flow rate by using particle image velocimetry (PIV).It was found from this experiment that a uniform flow distribution in the fuel channel was attained in the case of the Reynolds number of about 7. For this operating condition, a flow field near the anode surface also shows uniform velocity distribution. This result was confirmed by the uniform distribution of pressure coefficient estimated from PIV measurements.On the other hand, in the upper air channel, non-uniform flow distribution was enlarged and large-scale vortex appears with increase of flow rate. In the lower air channel, local high velocity region exist at a high flow rate. For the present disk channel the optimum flow field in the air channel was obtained around the Reynolds number of 30. These results suggest the necessity of improvement of the channel shape and injection method of air.