Local Non‐Equilibrium Thermal Effects in Solid Oxide Fuel Cells with Various Fuels

Abstract

Local thermal equilibrium (LTE) is a common assumption used in thermal modeling of solid oxide fuel cells (SOFCs). However, its validity has not been fully verified. To examine the validity of the LTE assumption, a thermal model has been developed to evaluate the local thermal non‐equilibrium effect of SOFC electrodes with various fuels, considering methane internal reforming and ammonia thermal cracking in the anode. Although the local thermal non‐equilibrium effect for ammonia‐fed SOFCs was more pronounced than that for hydrogen‐fed SOFCs, the local thermal equilibrium assumption can be safely adopted for SOFC modeling for a wide range of operating/structural parameters and for various fuels, such as hydrogen, ammonia, and methane.

Generation of entropy and forced convection of heat in a conduit partially filled with porous media – Local thermal non-equilibrium and exothermicity effects

“…It should be noted that the constant heat sources in the solid and fluid phases of the porous media may represent various physical and chemical processes. These include, dissipation of electrical energy, absorption or radiation of infrared, gamma and beta waves and also nuclear and chemical reactions [23,[40][41][42][43][44][45].…”

The effect of electrolyte type on performance of solid oxide fuel cells running on hydrocarbon fuels

“…Therefore, the gas flow in SOFC is typically laminar. From heat transfer analysis, it is found that the temperature difference between the solid and the gas in the porous electrodes is negligibly small [28]. Thus local thermal equilibrium condition is adopted.…”

Influence of Lithium on the Sintering Behavior and Electrical Properties of Ce0.8Gd0.2O1.9 for Intermediate‐Temperature Solid Oxide Fuel Cells

“…In this study 1mol %o fl ithium is sufficient to improve the total conductivity.W ith an increase of the sintering temperature, 1 LiGDCh as amaximumvalue in ionic conductivity of 6.0 10 À2 Scm À2 . 2 LiGDC sintered at 1250 8Ch as at otal ionic conductivityl ower than that of 0 LiGDCs intered at 1500 8C.…”

“…High-purity cerium nitrate hexahydrate (Ce(NO 3 ) 3 ·6 H 2 O) and gadolinium nitrate hexahydrate (Gd(NO 3 ) 3 ·6 H 2 O) were used as precursors.D ifferent amounts of lithium nitrate (LiNO 3 )w ere added directly to the mixture.T he appropriate quantities of metal nitrate salts were calculated and weighed accurately to achieve the required stoichiometric ratio and to obtain af inal powder with al ithium content of 1a nd 2mol %. Thes amples with 1a nd 2mol %L iw ere denoted 1 LiGDC and 2 LiGDC,r espectively.M etal nitrates and the lithium aid were dissolved in distilled water and mixed at RT until full dissolution was observed. Ac ontrol sample without lithium nitrate was also prepared as ar eference (denoted 0 LiGDC).…”

“…Thes olid oxide fuel cell (SOFC) is considered to be the best energy technology for industriala pplication because of its versatility in fuel utilization (hydrogen, syngas,n atural gas, and light hydrocarbons) and operating temperature (500-1000 8C), and the mechanical stability of solid electrolytes. [1][2][3] Cerium oxide,p ure or doped, is the most studied solid conductor of oxygeni ons in SOFCst hat operate at intermediate temperatures (500-800 8C). [3,4] Gadolinium is the most effective dopantf or ceria solid solutions because of its ionic properties.…”