Dynamic tank in series modeling of direct internal reforming SOFC

Abstract

Summary A dynamic tank in series reactor model of a direct internally reforming solid oxide fuel cell is presented and validated using experimental data as well as a computational fluid dynamics (CFD) model for the spatial profiles. The effect of the flow distribution pattern at the inlet manifold on the cell performance is studied with this model. The tank in series reactor model provides a reasonable understanding of the spatio‐temporal distribution of the key parameters at a much lesser computational cost when compared to CFD methods. The predicted V–I curves agree well with the experimental data at different inlet flows and temperatures, with a difference of less than ±1.5%. In addition, comparison of the steady‐state results with two‐dimensional contours from a CFD model demonstrates the success of the adopted approach of adjusting the flow distribution pattern at the inlet boundaries of different continuous stirred tank reactor compartments. The spatial variation of the temperature of the PEN structure is captured along with the distributions of the current density and the anode activation over‐potential that strongly related to the temperature as well as the species molar fractions. It is found that, under the influence of the flow distribution pattern and reaction rates, the dynamic responses to step changes in voltage (from 0.819 to 0.84 V), fuel flow (15%) and temperature changes (30 °C), on anode side and on cathode side, highly depend on the spatial locations in the cell. In general, the inlet points attain steady state rapidly compared to other regions. Copyright © 2017 John Wiley & Sons, Ltd.

CFD modeling and performance comparison of solid oxide fuel cell and electrolysis cell fueled with syngas

“…In addition, a higher overpotential is obtained due to the slow kinetics of the CO/CO 2 electrochemical reaction, but the experimental results show that the I‐V curves for pure H 2 O and syngas with low H 2 O and high CO 2 are almost identical. These results indicate that the WGS reaction is the preferred pathway for CO/CO 2 consumption in co‐redox reactions in SOFCs and SOECs . Hauck et al compared simulation results with experimental data and concluded that the best fit is obtained when CO/CO 2 is only considered in the WGS reaction when syngas is provided to an rSOFC.…”

“…39 In addition, dynamic switching is also modeled to investigate the switching performance between an SOFC and an SOEC. 38,39,[46][47][48][49] On the other hand, most of the dual-mode investigations presented above are focused on H 2 /H 2 O. The coredox reactions with syngas are mostly presented in a single FC or EC mode.…”

“…These results indicate that the WGS reaction is the preferred pathway for CO/CO 2 consumption in co-redox reactions in SOFCs and SOECs. [48][49][50][51] Hauck et al 31 compared simulation results with experimental data and concluded that the best fit is obtained when CO/CO 2 is only considered in the WGS reaction when syngas is provided to an rSOFC. Similar conclusions are cited in previous studies.…”

“…This model indicates that different electrochemical parameters are appropriate to fit dual‐mode operation, which depends on both gas compositions and material microstructures . In addition, dynamic switching is also modeled to investigate the switching performance between an SOFC and an SOEC …”

SOFC Stack and System Modeling, Fault Diagnosis and Control

“…However, this involves the trade-offs of reduced cell average temperature and reduced fuel utilisation, which are not desirable. A novel design for the planar SOFC interconnect was proposed by us in [18] to reduce the excessive thermal gradients. This design tackles the problem by introducing a secondary air stream in the counter direction and orifice based localised cooling to even out temperature differences and reduce hot spots.…”