Transient electrochemical characteristics of solid oxide fuel cells under adiabatic conditions

doi:10.3969/j.issn.1674-1951.2021.07.005

Abstract

Abstract:

Coupling energy storage equipment into energy systems can effectively improve the utilization efficiency and technical level of renewable energy.To obtain the internal thermoelectric coupling characteristics of a solid oxide fuel cell （SOFC） during the transient process switching from electrolysis mode to power generation mode, we established a dynamic model for the SOFC stack based on thermodynamics and electrochemical mechanisms. Based on the dynamic model, the stack temperature, the Nernst EMF, activation polarization voltage loss, ohmic voltage loss, the concentration polarization voltage loss and the output voltage of the cell during the switching from electrolysis mode to power generation mode were calculated. The electrochemical performances of the SOFC under isothermal and adiabatic conditions are compared. The results show if the stack operates in electrolysis mode and then in power-supply mode for 20 000 seconds each, the stack temperature will vary by 45.8 K and 101.1 K by modifying current density in step and ramp format, respectively. When the current density is identical, the maximum output voltage difference of a single cell is 0.015 V if the stack operates in adiabatic and isothermal environment.

Key words: renewable energy, energy storage, SOFC, thermoelectric coupling characteristics, mode switching, transient process, dynamic model

CLC Number:

TK91

WANG Chaoyang, LIU Ming, ZHAO Yongliang, CHONG Daotong, YAN Junjie. Transient electrochemical characteristics of solid oxide fuel cells under adiabatic conditions[J]. Huadian Technology, 2021, 43(7): 30-36.

Figures/Tables 17

Fig.1

Tab.1

Governing equations for the stack dynamic model

名称	表达式
质量守恒	$d M i d t = q ˙ n, i, in - q ˙ n, i, out + ϕ q ˙ n, i, react$
动量守恒	$R r q ˙ n, i, total 2 = p in - p out$
动量守恒	$q ˙ n, i, total = ∑ q ˙ n, i, out$
能量守恒	$c s m s d T s d t = ∑ q ˙ n, i, in h i, in - q ˙ n, i, out h i, out - W ˙ s + Q ˙ s, react + P ˙ ext + P ˙ s, int W ˙ s = N V cell J A cell$ $Q ˙ s, react = JN A cell 2 F Q ˙ react$ $P ˙ ext = σ T f 4 - T s 4 A sur$ $P ˙ s, int = J V act + V ohm A cell - J A cell T s Δ S 0 2 F$ $Δ S 0 = Δ S H 2 O 0 - (Δ S H 2 0 + 0.5 Δ S O 2 0)$
电化学控制	$V cell = E Nernst - V act - V ohm - V conc$ $V s = N V cell$ $E Nernst = - Δ G 0 2 F + - R T s 2 F ln p O 2 p H 2 p H 2 O$ $V act = R T s 2 αnF sin h - 1 J 2 J 0$ $V ohm = J R as$ $V conc, fuel = R T s 2 F ln p H 2 O, tpb p H 2 p H 2 O p H 2, tpb$ $V conc, oxygen = R T s 2 F ln p O 2 p O 2, tpb$ $V conc = V conc, fuel + V conc, oxygen$

Tab.1

Tab.2

Fig.2

Fig.3

Fig.4

Fig.5

Fig.6

Fig.7

Fig.8

Fig.9

Fig.10

Fig.11

Fig.12

Fig.13

Fig.14

Fig.15

References 16

[1]	习近平在第七十五届联合国大会一般性辩论上的讲话[EB/OL]. ( 2020-09-22) [2021-05-13]. http://m.xinhuanet.com/2020-09/22/c_1126527652.htm.
[2]	继往开来,开启全球应对气候变化新征程[EB/OL]. ( 2020-12-12) [2021-05-13]. http://www.gov.cn/gongbao/content/2020/content_5570055.htm.
[3]	《新时代的中国能源发展》白皮书[EB/OL]. ( 2020-12-21)[2021-05-13]. http://www.scio.gov.cn/zfbps/32832/Document/1695117/1695117.htm.
[4]	MALLAPATY S. How China could be carbon neutral by mid-century[J]. Nature, 2020, 586(7830):482-483. doi: 10.1038/d41586-020-02927-9
[5]	BOTTA G, ROMEO M, FERNANDES A, et al. Dynamic modeling of reversible solid oxide cell stack and control strategy development[J]. Energy Conversion and Management, 2019, 185:636-653. doi: 10.1016/j.enconman.2019.01.082
[6]	SRIKANTH S, HEDDRICH M P, GUPTA S, et al. Transient reversible solid oxide cell reactor operation——Experimentally validated modeling and analysis[J]. Applied Energy, 2018, 232:473-488. doi: 10.1016/j.apenergy.2018.09.186
[7]	胡小夫, 汪洋, 田立, 等. 中高温SOFC/MGT联合发电技术研究进展[J]. 华电技术, 2019, 41(8):1-5.
	HU Xiaofu, WANG Yang, TIAN Li, et al. Progress in intermediate and high temperature SOFC/MGT combined power generation technology[J]. Huadian Technology, 2019, 41(8):1-5.
[8]	史翊翔, 蔡宁生, 王雨晴. 固体氧化物燃料电池能量转化与储存[M]. 北京: 科学出版社, 2019.
[9]	LI Zheng, ZHANG Hao, XU Haoran, et al. Advancing the multiscale understanding on solid oxide electrolysis cells via modelling approaches: A review[J]. Renewable and Sustainable Energy Reviews, 2021, 141:110863. doi: 10.1016/j.rser.2021.110863
[10]	SHAO Z P, HAILE S M. A high-performance cathode for the next generation of solid-oxide fuel cells[J]. Nature, 2004, 431(7005):170-173. doi: 10.1038/nature02863
[11]	HAUCH A, KUNGAS R, BLENNOW P, et al. Recent advances in solid oxide cell technology for electrolysis[J]. Science, 2020, 370(6513):186.
[12]	蒋先锋. 固体氧化物燃料电池的热力学及电化学应用基础[J]. 化工时刊, 2012, 26(7):54-58.
	JIANG Xianfeng. Thermodynamic and electrochemistry foundation of solid oxide fuel cell[J]. Chemical Industry Times, 2012, 26(7):54-58.
[13]	TIKIZ I, TAYMAZ I, PEHLIVAN H. CFD modelling and experimental validation of cell performance in a 3-D planar SOFC[J]. International Journal of Hydrogen Energy, 2019, 44(29):15441-15455. doi: 10.1016/j.ijhydene.2019.04.152
[14]	楚迪. 板式固体氧化物燃料电池电化学性能数值模拟研究[D]. 郑州:郑州大学, 2020.
[15]	WU Xiaojuan, YANG Danan, WANG Junhao, et al. Temperature gradient control of a solid oxide fuel cell stack[J]. Journal of Power Sources, 2019, 414:345-353. doi: 10.1016/j.jpowsour.2018.12.058
[16]	WANG Chaoyang, CHEN Ming, LIU Ming, et al. Dynamic modeling and parameter analysis study on reversible solid oxide cells during mode switching transient processes[J]. Applied Energy, 2020, 263:114601. doi: 10.1016/j.apenergy.2020.114601

项目	参数
单电池有效面积/cm²	87.7
单电池个数N	8
工质	H₂/H₂O/O₂
工作压力/MPa	0.1
H₂/H₂O摩尔流量/(mol·s^-1)	0.006 50
O₂摩尔流量/(mol·s^-1)	0.002 98
工质入口温度/K	1 073.0