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

圆盘状固体氧化物燃料电池（SOFC）具有比管状固体氧化物燃料电池更高的功率密度和更低的欧姆损耗，是一种很有前途的平面型燃料电池。对于盘状SOFC，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，空气从所述圆盘的外缘供给到所述上部空气通道，并到达所述内缘部分。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，实验研究了两个平行盘状板之间的径向流动，以模拟盘状SOFC中的流动。在平面型SOFC中，热应力的降低是一个重要问题。平面型SOFC的温度分布受气体流动行为的强烈影响，因此我们试图利用粒子图像测速（PIV）来澄清不同质量流量下的流动模式。实验结果表明，当雷诺数为7左右时，燃料通道内的流动分布较为均匀。在这种工况下，靠近阳极表面的流场也呈现均匀的速度分布。PIV测得的压力系数分布均匀，证实了这一结果。另一方面，在上层气流通道中，随着流量的增加，不均匀流动分布扩大，出现大规模涡。在下部风道中，以大流量存在局部高速区。对于目前的盘式流道，在雷诺数为30左右的空气流道内获得了最佳流场。这些结果表明了改进通道形状和空气注入方式的必要性。

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.