基于流动均匀性的SOFC单元的热电特性分析

Analysis of the thermoelectric characteristics of solid oxide fuel cell stack using flow uniformity

建立了平板式固体氧化物燃料电池堆的耦合电化学动力学与流体动力学的三维模型,据此揭示电池堆内部传热传质过程.基于空气与燃料气流动均匀性分析,结合Fluent软件与外部VC++子程序计算了不同工作条件下电池堆的热电特性参数.与同向流条件下模拟结果相比较,在逆向流条件下,电池堆沿电池宽度方向具有较均匀的核心部件PEN(阳极/电解质/阴极)温度与电流分布,更高的功率输出、燃料利用率及发电效率;降低燃料供给速率,PEN温度梯度减小,而功率输出、燃料利用率以及发电效率提高;提高空气供给速率,PEN温度梯度减小.

A three-dimensional mathematical model coupling the electrochemical kinetics with fluid dynamics was developed to simulate the heat and mass transfer in the stack of planar solid oxide fuel cell （SOFC）. The thermoelectric characteristics of the stack in various operating conditions were obtained by Fluent software and external VC＋ ＋ sub-routine, after the flow uniformity of air and fuel flow rates was analyzed. Results show that the stacks in counter-flow case have the advantages in better uniform current density and temperature distributions of PEN （positive/electrolyte/negative） in the width direction, higher power output, fuel utilization factor and fuel efficiency than those in co-flow case. For counter-flow ease, lower temperature gradient of PEN, higher power output, fuel utilization factor and power generation efficiency are observed with the decrease of the fuel inlet flow rate. Moreover, the air inlet flow rate can be increased to reduces the temperature gradient of PEN.