Thermal management oriented steady state analysis and optimization of a kW scale solid oxide fuel cell stand-alone system for maximum system efficiency

Abstract This research attempts to ensure system safety while to maximize system efficiency by addressing steady state analysis and optimization for solid oxide fuel cell (SOFC) systems. Firstly, a thermal management oriented kW scale SOFC stand-alone system (primarily comprising a planar SOFC stack, a burner, and two heat exchangers) is developed, in which a special consideration for stack spatial temperature management is conducted by introducing an air bypass manifold around heat exchangers. The dynamic model of the system is performed using transient energy, species, and mass conservation equations. Secondly, based on the system model, the effects of operating parameters including fuel utilization (FU), air excess ratio (AE), bypass ratio (BR), and stack voltage (SV) on the system steady-state performances (e.g. system efficiency, stack inlet, stack outlet, and burner temperatures) are revealed. Particularly, an optimal relationship between the system efficiency and the operating parameters is proposed; the maximum system efficiency can certainly be obtained at the inlet outlet temperature critical point of the BR-AE or FU-AE planes for all SV operating points. Finally, according to the optimal relationship, a traverse optimization process is designed, and the maximum system efficiency and safe operating parameters at any efficient SV operating point are calculated. The results provide an optimal reference trajectory for control design, where the system is safe and efficiency optimization. Moreover, the results reveal two important system characteristics: (1) the burner operates within safe temperature zone as long as the temperature of the upstream stack is well controlled; (2) the control design for the system is a nonlinear optimal control with switching structure, which is a challenging control issue.

[1]  Fabian Mueller,et al.  Transient Performance of Integrated SOFC System Including Spatial Temperature Control , 2010 .

[2]  Tao Zhang,et al.  Stress field and failure probability analysis for the single cell of planar solid oxide fuel cells , 2008 .

[3]  Jing Sun,et al.  Analysis and feedback control of planar SOFC systems for fast load following in APU applications , 2006 .

[4]  C. Adjiman,et al.  Anode-supported intermediate temperature direct internal reforming solid oxide fuel cell. I: model-based steady-state performance , 2004 .

[5]  Mohsen Assadi,et al.  Experimental investigation of temperature distribution over a planar solid oxide fuel cell , 2013 .

[6]  Lieh-Kwang Chiang,et al.  Thermal stress analysis of a planar SOFC stack , 2007 .

[7]  D. Favrat,et al.  The Effects of Dynamic Dispatch on the Degradation and Lifetime of Solid Oxide Fuel Cell Systems , 2019, ECS Transactions.

[8]  Handa Xi.  Dynamic modeling and control of planar SOFC power systems. , 2007 .

[9]  Anna G. Stefanopoulou,et al.  Control Oriented Analysis of a Hybrid Solid Oxide Fuel Cell and Gas Turbine System , 2009 .

[10]  Biao Huang,et al.  Estimation and control of solid oxide fuel cell system , 2010, Comput. Chem. Eng..

[11]  G. S. Samuelsen,et al.  Power and temperature control of fluctuating biomass gas fueled solid oxide fuel cell and micro gas turbine hybrid system , 2006 .

[12]  Biao Huang,et al.  Control relevant modeling of planer solid oxide fuel cell system , 2007 .

[13]  Prodromos Daoutidis,et al.  Design and control of energy integrated SOFC systems for in situ hydrogen production and power generation , 2011, Comput. Chem. Eng..

[14]  V. Dorer,et al.  Evaluation of hydrogen and methane-fuelled solid oxide fuel cell systems for residential applications: System design alternative and parameter study , 2009 .

[15]  F. Jabbari,et al.  Feedback control of solid oxide fuel cell spatial temperature variation , 2010 .

[16]  Tsung Leo Jiang,et al.  Thermal-stress analyses of an operating planar solid oxide fuel cell with the bonded compliant seal design , 2009 .

[17]  Faryar Jabbari,et al.  Novel solid oxide fuel cell system controller for rapid load following , 2007 .

[18]  Xi Li,et al.  Generalized predictive control for fractional order dynamic model of solid oxide fuel cell output power , 2010 .

[19]  Thomas F. Edgar,et al.  Dynamic modeling, simulation, and MIMO predictive control of a tubular solid oxide fuel cell , 2012 .

[20]  James Larminie,et al.  Fuel Cell Systems Explained , 2000 .

[21]  Zhonghua Deng,et al.  Dynamic modeling of electrical characteristics of solid oxide fuel cells using fractional derivatives , 2010 .

[22]  Miriam Kemm,et al.  Steady state and transient thermal stress analysis in planar solid oxide fuel cells , 2005 .

[23]  Xin Sun,et al.  The modeling of a standalone solid-oxide fuel cell auxiliary power unit , 2006 .

[24]  Xingjian Xue,et al.  Transient Modeling of Anode-Supported Solid Oxide Fuel Cells , 2009 .

[25]  James D. Maclay,et al.  Parametric Thermodynamic Analysis of a Solid Oxide Fuel Cell Gas Turbine System Design Space , 2010 .

[26]  Y. Inui,et al.  Analytical investigation on cell temperature control method of planar solid oxide fuel cell , 2006 .

[27]  Jing Sun,et al.  Dynamic Model of Planar Solid Oxide Fuel Cells for Both Steady State and Transient Performance Analysis , 2005 .

[28]  Xiongwen Zhang,et al.  Nonlinear model predictive control based on the moving horizon state estimation for the solid oxide fuel cell , 2008 .

[29]  Alex C. Hoffmann,et al.  Effects of heat sources on the performance of a planar solid oxide fuel cell , 2010 .