Research on Temperature Field and Stress Field of Prefabricate Block Electric Furnace Roof

This paper establishes the CAD/CAE model of high aluminum brick furnace cover and a precast furnace cover (casting three block, eight block, twelve block) based on a 30t electric furnace roof real model of a steel factory and simulates the temperature and stress field of the firebrick roof and prefabricate block roof with ANSYS. The calculation results have indicated that the contact stress between furnace cover and precast block will affect the performance of the furnace cover and the furnace cover which is assembled by three pieces of casting precast block obtains lower stress levels has a longer service life, providing a quantitative reference for selection of casting scheme

LBM prediction of effective thermal conductivity of lithium-ion battery graphite anode

Study of thermal characteristics of a lithium-ion battery plays a vital role in determining and enhancing the performance and safety of the battery. This paper predicts the effective thermal conductivity of a graphite anode having microstructure reconstructed by an ellipsoid based simulated annealing method. A lattice-Boltzmann (LB) model is established for simulating the thermal diffusion process in the computer-generated 3D microstructure of graphite anode. The effective thermal conductivities derived from LB simulation results indicate evident anisotropic feature of the graphite anode. The numerical results show that the particle size does have some effects on the effective thermal conductivity, but the effects are generally not significant. The real graphite may have particles with particle size following a certain statistical distribution, very probably the normal distribution, which is found to weaken the anisotropy of the electrode. Comparing the numerical data with the theoretical predictions by effective media theory (EMT) suggests that the suitable value of the empirical correction factor (I) for the effective thermal conductivity of graphite anode in the electrode through-plane direction is about 6.0 and in the other direction about 4.5. (C) 2017 Elsevier Ltd. All rights reserved

LBM prediction of effective electric and species transport properties of lithium-ion battery graphite anode

Numerical models play a vital role in the developing and performance optimization of lithium-ion batteries. The key factor to the prediction accuracy of macro-scale models is the specification of effective transport properties. This study, based on the anisotropic microstructure of graphite anode reconstructed by an ellipsoid-based simulated annealing method (SAM), established a mesoscopic model of diffusion process to predict the effective electric and species transport properties of lithium-ion battery graphite anode via lattice-Boltzmann (LB) method. The effect of particle size on the transport properties of graphite anode was discussed in detail. In the electrode through-plane direction, if the ellipsoidal particles are thinner and flatter, both the effective electric and species transport properties decrease; in the other two directions, the effective electronic charge transport properties barely change with the change of particle size while the effective species transport properties increase along with the increase of the size of particles. In addition, to get a more accurate replica of the real graphite anode, we assumed the sizes of solid particles follow a normal distribution and reconstructed the microstructure of electrode. The LB calculation results reveal that the normal distribution of particle size increases the electronic charge conductivity in the electrode through-plane direction and decreases in the other two directions, compared to the electrode of constant-sized particles; the effective species diffusivities (or ionic charge conductivities) in electrode through-plane direction for different microstructures are closer. (C) 2016 Elsevier B.V. All rights reserved

Direct Numerical Simulation Modeling of Multidisciplinary Transport during Li-Ion Battery Charge/Discharge Processes

We develop a direct numerical simulation (DNS) model of multidisciplinary transport coupled with electrochemical reactions during Li-ion battery charge/discharge processes based on the finite volume (FV) numerical technique. Different from macroscopic models, the DNS model is based on microstructure of composite electrodes and solves component-wise transport equations. During DNS, the input physical properties are intrinsic material properties, not effective physical properties for macroscopic models. Since the interface of solid and electrolyte phase is evidently differentiated in DNS, the occurrence of electrochemical reactions is prescribed exactly on the interface of solid and electrolyte phase. Therefore, the DNS model has the potential to unravel the underlying mesoscopic pore-scale mechanisms of multi-disciplinary transport coupled with electrochemical reactions and thus can provide insightful information of the involved processes, as well as enables the design and optimization of electrodes, including microstructures inside electrodes. One test case, in which the electrode microstructure is reconstructed with a purely random reconstruction method, is considered. Simulation results corroborate the validity of the DNS model

Direct Numerical Simulation Modeling of Multidisciplinary Transport during Li-Ion Battery Charge/Discharge Processes

We develop a direct numerical simulation (DNS) model of multidisciplinary transport coupled with electrochemical reactions during Li-ion battery charge/discharge processes based on the finite volume (FV) numerical technique. Different from macroscopic models, the DNS model is based on microstructure of composite electrodes and solves component-wise transport equations. During DNS, the input physical properties are intrinsic material properties, not effective physical properties for macroscopic models. Since the interface of solid and electrolyte phase is evidently differentiated in DNS, the occurrence of electrochemical reactions is prescribed exactly on the interface of solid and electrolyte phase. Therefore, the DNS model has the potential to unravel the underlying mesoscopic pore-scale mechanisms of multi-disciplinary transport coupled with electrochemical reactions and thus can provide insightful information of the involved processes, as well as enables the design and optimization of electrodes, including microstructures inside electrodes. One test case, in which the electrode microstructure is reconstructed with a purely random reconstruction method, is considered. Simulation results corroborate the validity of the DNS model

Numerical reconstruction of microstructure of graphite anode of lithium-ion battery

Due to the presence of graphite flake cascades, the real graphite anode of Li-ion battery shows non-isotropic characteristic. The present work developed an ellipsoid-based simulated annealing method and numerically reconstructed the three-dimensional microstructure of a graphite anode. The reconstructed anode is a composite of three clearly distinguished phases: pore (or electrolyte), graphite, and solid additives, well representing the non-isotropic heterogeneous characteristic of real graphite anode. Characterization analysis of the reconstructed electrode gives information such as the connectivity of individual phase, the specific interfacial area between solid and pore phase, and the pore size distribution. The effects of the ellipsoid size on the structural characteristics of graphite anode were particularly studied. As the size of the ellipsoidal particle slightly increases, the average pore diameter increases and as a result the specific interfacial area between the solid and pore phase in the reconstructed area decreases; compared with the equatorial radius, the polar radius of ellipsoidal graphite particles has more significant influence on the characteristics of electrode microstructure

Numerical reconstruction of microstructure of graphite anode of lithium-ion battery

Due to the presence of graphite flake cascades, the real graphite anode of Li-ion battery shows non-isotropic characteristic. The present work developed an ellipsoid-based simulated annealing method and numerically reconstructed the three-dimensional microstructure of a graphite anode. The reconstructed anode is a composite of three clearly distinguished phases: pore (or electrolyte), graphite, and solid additives, well representing the non-isotropic heterogeneous characteristic of real graphite anode. Characterization analysis of the reconstructed electrode gives information such as the connectivity of individual phase, the specific interfacial area between solid and pore phase, and the pore size distribution. The effects of the ellipsoid size on the structural characteristics of graphite anode were particularly studied. As the size of the ellipsoidal particle slightly increases, the average pore diameter increases and as a result the specific interfacial area between the solid and pore phase in the reconstructed area decreases; compared with the equatorial radius, the polar radius of ellipsoidal graphite particles has more significant influence on the characteristics of electrode microstructure