Three‐dimensional nonisothermal modeling of solid oxide fuel cell coupling electrochemical kinetics and species transport

Abstract

Summary A three‐dimensional (3D) nonisothermal model is developed and applied for anode‐supported planar solid oxide fuel cell (SOFC). The mass and momentum, species, ion, electric, and heat transport equations are solved simultaneously by implementing the electrochemical kinetics and electrochemical reaction as volumetric source terms. The interconnect land limits the O2 transport under the land and lowers the local current density under the land. The effects of interconnect land width and cathode substrate thickness on SOFC cell performance are quantified in this study. Cathode stoichiometry is found to have a large effect on the SOFC cell temperature distribution. Under low‐cathode stoichiometry, significant temperature gradients are seen in the SOFC cell. Higher‐cathode stoichiometry is beneficial for lower temperature and more uniform current density distribution in SOFC cell. Co‐flow and counter‐flow arrangements are investigated and discussed with the model. Counter‐flow arrangement is found to induce a high temperature and high current density region near the H2 inlet. On the other hand, co‐flow arrangement leads high temperature and high current density to occur relatively downstream, a slightly lower maximum temperature on cell and considerably more uniform current density distribution. A 67.2‐cm2 SOFC cell is simulated considering the side cooling effect. The side cooling effectively lowers the cell temperature, at the same time, causes temperature, current density, and fuel utilization nonuniformity in the across multichannel direction. Because of the strong coupling of the in‐plane current density distribution and temperature distribution, limiting the locally high temperature and temperature gradient is critical for achieving a more uniform current density distribution in anode‐supported planar SOFC.

Effect of flow modes on operation characteristics of three‐dimensional non‐isothermal solid oxide fuel cell stack

“…It effectively reduces the thermal stress, solves the problem of poor durability of ceramic materials during the operation of variable load, extends the service life of SOFC, and contributes to the commercialization of SOFC. Yubai Li et al 32 studied the effect of side cooling on the operating performance of SOFC stack. The study provides a preliminary demonstration of a three‐dimensional fully coupled modeling approach for medium‐scale SOFC stack simulation, which is beneficial to further improvement and optimization of SOFC.…”

Temperature Gradient Analyses of a Tubular Solid Oxide Fuel Cell Fueled by Methanol

“…These two different trends in cell performance are reasonable since relevant phenomena are found in the available literature. With the increase in the air flow rate or air ratio, a decreased cell performance was frequently observed in several simulation studies from Xu et al (973 K) [56] and Li et al (973 K) [57], while enhanced power densities were also achieved with the rise of air flow rate in the research works by Colpan et al (1173 K) [58] and Raj et al (1073 K) [59]. The possible reason for these two opposite phenomena is because of different cell sensitivities to the temperature change.…”

Advanced modification of scandia‐stabilized zirconia electrolytes for solid oxide fuel cells application—A review

“…9,10 Besides, each component of the SOFC compartments will usually be exposed to interfacial problems such as mechanical stress and thermal stress due to different thermal expansion coefficients. 11 For example, high operating temperatures of SOFCs typically induce major reactions problems between cell compartments, resulting in compromised cell performance and life cycle. 12 Moreover, the power generation system based on high-temperature SOFCs has slow start-up times, which interfere with the activity of the operating management system.…”

“…High operating temperature conditions require the use of costly materials such as high‐temperature alloys as cellular components and ceramics as interconnectors, greatly increasing the cost of SOFCs 9,10 . Besides, each component of the SOFC compartments will usually be exposed to interfacial problems such as mechanical stress and thermal stress due to different thermal expansion coefficients 11 . For example, high operating temperatures of SOFCs typically induce major reactions problems between cell compartments, resulting in compromised cell performance and life cycle 12 .…”