Study on Preheating Techniques for Start-up of Tubular Solid Oxide Fuel Cells

Abstract

For start-up of tubular solid oxide fuel cells preheating concepts of gas heating, induction heating, sequential hybrid of gas and induction heating and concurrent hybrid of gas and induction heating were experimented. Due to impossibility of heating-up of porous electric conductive layers in electromagnetic field, stainless steel material was adopted for the gas distributor tube, which is readily heated by induction method and transfers heat to adjacent layers. Start-up times of 95, 31, 49 and 20 seconds were attained for gas heating, induction heating, hybrid of sequential gas and inductive heating and hybrid of concurrent gas and induction heating methods respectively. Axial distribution of temperature in the course of start-up was steadier in hybrid methods which resulted in diminished axial temperature gradient and reduced performance degradation of the cell. A numerical model was developed and calibrated to predict the preheating phenomenon. Analytical results implied the positive effect of layers porosity on the heating rate, concerning mainly the gas heating methods.

Coke-Tolerant Ni/BaCe1–xYxO3−δ Anodes for Solid Oxide Fuel Cells: DFT+U Study

“…Thus, we are using a simplified form for evaluation of adsorption rates, which does not require the sticking coefficients, but allows a generic evaluation of all rates using the values of k + and k − . For surface reactions, the respective rates are evaluated as ∏ ∏ (7) where θ i + and θ i − are the coverages of reactant and product, respectively, and n is the number of surface species involved in the reaction step. The time-dependent concentrations of gaseous species as well as surface coverages of intermediate products can be evaluated by solving the system of coupled differential equations:…”

“…These include low anode stability to redox cycling, 2,3 adverse reactions between adjacent cell components, 4,5 and temperature gradients in the cell parts occurring during the start-up and shut-down phase. 6,7 Moreover, if hydrocarbon fuel is used, the metallic (i.e., Ni) part of the SOFC anode is also rapidly covered by a carbon film (coke formation) at elevated temperatures (most severely at T > 800 °C), which results in chemical deactivation of the anode. 8 Numerous attempts have been made by researchers worldwide to either diminish or fully eliminate coke formation on the anode surface.…”

“…Unfortunately, the high operating temperatures of SOFC lead to a number of complications that can be detrimental for the cell performance. These include low anode stability to redox cycling, , adverse reactions between adjacent cell components, , and temperature gradients in the cell parts occurring during the start-up and shut-down phase. , Moreover, if hydrocarbon fuel is used, the metallic (i.e., Ni) part of the SOFC anode is also rapidly covered by a carbon film (coke formation) at elevated temperatures (most severely at T > 800 °C), which results in chemical deactivation of the anode …”

Simulation‐based multiobjective management of transient heating process of solid oxide fuel cell

“…In many applications (such as in vehicles), the heat-up duration should be as short as possible. However, the high operating temperature of SOFCs makes this goal hard to achieve [9][10][11]. The brittle nature of SOFC structure adds to this difficulty because a rapid heat-up process can cause high temperature gradients and, consequently, high thermal stresses, which in turn results in a greater risk of SOFC delamination and cracking [12,13].…”