电化学对SOFC平板电池堆燃料流均匀度的影响
首发时间:2016-06-02
摘要:固体氧化物燃料电池堆(SOFCs)中,电池与电池间通过内部连接体以串联方式连接。不同的电池输出等量的总电流,其等价于等量的燃料流消耗。因此,在所有电池中最小的燃料分配决定着整个电池堆的工作电流,进而制约整个堆的燃料利用率。为提高SOFC电池堆的工作效率,对燃料流分配问题的研究至关重要。本文主要着眼于研究SOFC平板电池堆的稳态过程中,电化学过程对燃料分配的影响--组分变化和电化学放热。为了准确探究电化学的影响,从启动到稳态的整个过程被分为三个阶段:启动,等温条件下的电化学反应,稳态。对这三个阶段进行相继的多物理场模拟,即流动计算,等温条件下的多物理场耦合计算,完全耦合的稳态计算。研究发现,电化学过程中的氢-水等摩尔互换将导致燃料分配均匀度相对启动阶段明显衰减,而电化学放热则对这一衰减有轻微的抑制。结果展示,为准确探究大型电池堆中燃料流分配特征,多物理场完全耦合的真实电池堆稳态模拟是非常必要的。
关键词: 凝聚态物理 电池堆燃料分配 多物理场耦合计算 均匀度 电化学
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Effect of electrochemistry on fuel gas uniformity within SOFC stack
Abstract:In solid oxide fuel cell stack, cells are connected in series via interconnectors. All cells export the same total current corresponding to the equivalent consume of fuel gas flux. As the result, the minimum assignment of fuel flux among cells determines the working current, and limits the fuel gas utilization rate of the whole stack. For the purpose of promoting the efficiency of SOFC stack, study of the fuel gas uniformity is very important. In this article, research is concentrated on the effect of electrochemistry on the fuel gas uniformity within SOFC stack. Equimolar gas exchange between H2 and H2O, and the heating process of electrochemical reaction form the total effect of electrochemistry. To study this effect, the whole process from start-up to steady state, is divided into 3 phases: phase 1 is the start-up, corresponding to pure flow condition, phase 2 is the electrochemical reaction process under isothermal condition, phase 3 is the steady state. Related multi-physics simulations are applied on these 3 phases. Results show that the Equimolar gas exchange between H2 and H2O can lead the series attenuation of uniformity which will be suppressed slightly by the heating process of electrochemistry. To explore the characteristic of fuel gas assignment within large scale stack, multi-physics coupled simulation based on true stack model is essential.
Keywords: Condensed matter physics Fuel gas assignment within stack Multi-physics coupled simulation Uniformity Electrochemistry
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