Then, we focus on the influence of hydrogen proportion in fuel on the temperature and current density distributions。 Chang- ing the hydrogen mass fraction in the fuel gas with 0。8, 0。9 and 1。0, reaction rate rise and more hydrogen is consumed, and then the more reaction heat is accumulated。 As a result, the temperature gradient and current density also rise, as shown in Fig。 5(b) and Fig。 6(a–c)。 Furthermore, as comparing Fig。 4 with Fig。 6, with higher delivery rate of hydrogen, current density distributions were less uniform, but with larger mass fraction of hydrogen in fuel gas, current density distributions are more uniform。

In order to decrease the temperature gradient, it is effective to increase delivery rate of air。 In the SOFC system, air not only provides oxygen ions but also has the cooling function。

Fig。 4。 Current density distributions on the interface of anode/electrolyte for the MOLB-type SOFC in the co-flow case under second working conditions。

Fig。 5。 PEN temperature distributions for MOLB-type SOFC under the second working conditions (a) and third working conditions (b)。

Fig。 6。 Current density distributions on the interface of anode/electrolyte for MOLB-type SOFC under third working conditions。

Increasing the delivery rate of air, the steep temperature gradient is mitigated in MOLB-type SOFCs, as shown in Fig。 7。 This is because more reaction heat is absorbed and then released by the air with the higher delivery rate, although the air utilization is dropped。

4。2。Advantage of MOLB-type SOFC compared with planar SOFC

On the basis of the preceding works about the simulating the planar SOFC system [26], the general trends of the temperature distributions in the planar and MOLB-type SOFCs are similar in essential。 Although the average temperatures in MOLB-type SOFC are higher than those in the planar, the temperature dif- ference (6T) is lower in MOLB-type SOFC。 This is because the electrochemical reaction area of MOLB-type SOFC is larger and

the more fuel is consumed in the active areas, as result, the more hydrogen is consumed and more reaction heat is accumulated。 However, due to the effect of corner formed by the inclined plane and the upper plane, the temperature and hydrogen mass fraction distributions in MOLB-type SOFC are less uniform than those in the planar。

As comparing the current density distribution in planar SOFC with that in the MOLB-type SOFC, some main characteristic features can be seen。 The first feature is that, in the two kinds of SOFCs, the current densities gradually decrease along the fuel flow direction because of the dropping of hydrogen mass fraction。 And the second is that, average current densities are higher than those in the planar SOFC due to the larger reaction areas in MOLB-type one, but the current density distributions are less uniform in the MOLB-type SOFC。 This is because, the current densities not only decrease along the fuel flow direction

摘要固体氧化物燃料电池（SOFC）是一种进行模拟的质量、动量和能量三维仿真工具。在单声道转换成分块分层（MOLB）型固体氧化物燃料电池系统。考虑到公司flow和反flow电池设计，温度分布，计算了不同工作条件下的反应物种和电流的单细胞密度变化。仿真结果表明，共flOW案例具有更均匀的温度和电流密度分布。类似于平面固体氧化物燃料电池，在共f1流的情况下，增加供油速率或氢的质量分数，燃料、平均温度（正/电解质/负）和电流密度上升，但平均温度都随空气输送率变化。特别是，本文型SOFC具有较高的氢的利用率，较低的温度差和更高的电流密度。然而在MOLB型固体氧化物燃料电池的电流密度分布是不均匀的，这是该型固体氧化物燃料电池的缺点。2007年由Elsevier公司出版。