scholarly journals A mathematical model for determining and analyzing temperature regimes in a battery pack of electric trucks

2020 ◽  
Vol 30 (1) ◽  
pp. 132-135
Author(s):  
В. І. Гавриш ◽  
В. Б. Лоїк ◽  
О. С. Король ◽  
О. Д. Синельніков
Keyword(s):  
Thermal Conductivity ◽  
Mathematical Model ◽  
Temperature Field ◽  
Lithium Ion Batteries ◽  
Internal Heat ◽  
Lithium Ion ◽  
Discontinuous Coefficients ◽  
Generalized Functions ◽  
Temperature Regimes ◽  
Mathematical Relation

A mathematical model for the determination of the temperature field and the analysis of temperature regimes in lithium-ion batteries have been developed. Using the theory of generalized functions, the thermophysical parameters of the structural components of a battery are represented by a single mathematical relation. A function in the form of the product of the generalized thermal conductivity coefficient for temperature was introduced, which avoided the differentiation of the product of two generalized functions as a result of constructing the initial differential equation of thermal conductivity, which was obtained with discontinuous coefficients. An analytical solution of this equation is determined, which is expressed by the temperature value at the conjugation surfaces of the layers of the structure. A relation was obtained to determine these values ​​and expressions for constant integration. To determine the numerical values ​​of the temperature in the design of the battery nodes, as well as to analyze the temperature gradients in its environment caused by the heterogeneity of the components due to heating, an algorithm and computational programs have been developed that allow to analyze lithium-ion batteries for their normal functioning. Using numerical programs, numerical values ​​of the temperature were obtained for given values ​​of the power of the internal heat sources, which made it possible to construct curves that reflect the behavior of the temperature field depending on the spatial coordinate. The angular points on the curve are revealed, which indicate the presence of a phase transition in the design of lithium-ion battery assemblies. As a consequence, it becomes possible to determine the permissible temperature values ​​for the fire safety of these batteries.

Distributed Optical Fiber In-Situ Monitoring Technology for a Healthy Temperature Field in Lithium Ion Batteries

2020 ◽  
Vol 47 (12) ◽  
pp. 1204002
Author(s):  
周炜航 Zhou Weihang ◽  
叶青 Ye Qing ◽  
叶蕾 Ye Lei ◽  
李璇 Li Xuan ◽  
曾朝智 Zeng Chaozhi ◽  
...  
Keyword(s):  
Temperature Field ◽  
Optical Fiber ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
In Situ Monitoring ◽  
Monitoring Technology ◽  
Distributed Optical Fiber

Analysis of Li-Ion Battery Characteristics and Thermal Behavior

2013 ◽  
Author(s):  
Krishnashis Chatterjee ◽  
Pradip Majumdar ◽  
David Schroeder ◽  
S. Rao Kilaparti
Keyword(s):  
Thermal Behavior ◽  
Lithium Ion Batteries ◽  
Electric Vehicles ◽  
Hybrid Electric Vehicles ◽  
Internal Heat ◽  
Lithium Ion ◽  
Test Facility ◽  
Transportation Industry ◽  
Ambient Temperatures ◽  
Hybrid Electric

Development of electric and hybrid electric vehicles is of great interest to the transportation industry due to increased demand and cost of imported fuel, uncertainty in the steady supply of oil, and increased standards for reduced emissions. Lithium-ion batteries are considered as one of the leading types for the battery systems to be employed in electric vehicles (EVs) or hybrid electric vehicles (HEVs). Using a regenerative braking system and storing it in battery stacks and using it later for propulsion and acceleration can improve the overall efficiency and reduction of fuel consumption. The objective of this study is to evaluate experimentally the battery performance considering different discharge and charge rates, and investigate the thermal behavior and thermal management requirements of the batteries under a variety of environmental conditions. An experimental test facility has been developed to evaluate thermal performance during charging and discharging modes. Environmental temperatures were varied in environmental chamber to analyze their effects on the charging and discharging patterns of the battery by using the CADEX battery analyzer in order to find the temperature range for optimum battery performance. The batteries were monitored with thermal sensors and a thermal imaging camera while they were run through different load scenarios. In the present study, lithium-ion batteries have been tested and battery performance in terms of polarization curves and discharge capacity were measured using a computerized battery analyzer system for different discharge and charge rates, and over a range of ambient temperatures. Results indicate that at higher discharge and charge rates battery performance decreases due to increased polarization losses, which results in increased internal heat generation and temperature of the battery. Battery performance also depends strongly on the ambient temperature conditions.

scholarly journals Highly Anisotropic Thermal Transport in LiCoO2

2019 ◽  
Author(s):  
Hui Yang ◽  
Jia-Yue Yang ◽  
Christopher Savory ◽  
Jonathan Skelton ◽  
Benjamin Morgan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Lithium Ion Batteries ◽  
Phonon Dispersion ◽  
Lithium Ion ◽  
Boltzmann Transport ◽  
Heat Management ◽  
Positive Electrodes ◽  
Anharmonic Lattice ◽  
Anharmonic Interactions ◽  
The Impact

<div>LiCoO<sub>2</sub> is the prototype cathode in lithium ion batteries. It adopts a crystal structure with alternating Li<sup>+</sup> and CoO<sub>2</sub><sup>-</sup> layers along the hexagonal <0001> axis. It is well established that ionic and electronic conduction is highly anisotropic; however, little is known regarding heat transport. We analyse the phonon dispersion and lifetimes of LiCoO<sub>2</sub> using anharmonic lattice dynamics based on quantum chemical force constants. Around room temperature, the thermal conductivity in the hexagonal ab plane of the layered cathode is ≈ 6 times higher than that along the c axis based on the phonon Boltzmann transport. The low thermal conductivity (< 10Wm<sup>-1</sup>K<sup>-1</sup>) originates from a combination of short phonon lifetimes associated with anharmonic interactions between the octahedral face-sharing CoO<sub>2</sub><sup>-</sup> networks, as well as grain boundary scattering. The impact on heat management and thermal processes in lithium ion batteries based on layered positive electrodes is discussed.</div>

scholarly journals MATHEMATICAL MODELS OF HEAT TRANSFER IN ELEMENTS OF TURBO GENERATORS (CONTINUED)

2020 ◽  
Vol 2 (1) ◽  
pp. 21-28
Author(s):  
V. I. Havrysh ◽  
◽  
B. O. Bilinskyi ◽  
O. S. Korol ◽  
R. R. Shkrab ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Mathematical Models ◽  
Half Space ◽  
Analytical Solutions ◽  
Internal Heat ◽  
Normal Operation ◽  
Cylindrical Shape ◽  
Temperature Regimes

Previously developed [8] and presented new mathematical models for the analysis of temperature regimes in individual elements of turbo generators, which are geometrically described by isotropic half-space and space with an internal heat source of cylindrical shape. Cases are also considered for half-space, when the fuel-releasing cylinder is thin, and for space, when it is heat-sensitive. For this purpose, using the theory of generalized functions, the initial differential equations of thermal conductivity with boundary conditions are written in a convenient form. To solve the obtained boundary value problems of thermal conductivity, the integral Hankel transformation was used, and as a result, analytical solutions in the images were obtained. The inverse Hankel integral transformation was applied to these solutions, which made it possible to obtain the final analytical solutions of the initial problems. The obtained analytical solutions are presented in the form of improper convergent integrals. Computational programs have been developed to determine the numerical values ​​of temperature in the above structures, as well as to analyze the heat transfer in the elements of turbo generators due to different temperature regimes due to heating by internal heat sources concentrated in the cylinder volume. Using these programs, graphs are presented that show the behavior of curves constructed using numerical values ​​of the temperature distribution depending on the spatial radial and axial coordinates. The obtained numerical values ​​of temperature indicate the correspondence of the given mathematical models for determining the temperature distribution to the real physical process. The software also allows you to analyze media with internal heating, concentrated in the spatial figures of the correct geometric shape, in terms of their heat resistance. As a result, it becomes possible to increase it, to determine the allowable temperatures of normal operation of turbo generators, to protect them from overheating, which can cause the destruction of not only individual elements but also the entire structure.

scholarly journals Highly Anisotropic Thermal Transport in LiCoO2

2019 ◽  
Author(s):  
Hui Yang ◽  
Jia-Yue Yang ◽  
Christopher Savory ◽  
Jonathan Skelton ◽  
Benjamin Morgan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Lithium Ion Batteries ◽  
Phonon Dispersion ◽  
Lithium Ion ◽  
Boltzmann Transport ◽  
Heat Management ◽  
Positive Electrodes ◽  
Anharmonic Lattice ◽  
Anharmonic Interactions ◽  
The Impact

<div>LiCoO<sub>2</sub> is the prototype cathode in lithium ion batteries. It adopts a crystal structure with alternating Li<sup>+</sup> and CoO<sub>2</sub><sup>-</sup> layers along the hexagonal <0001> axis. It is well established that ionic and electronic conduction is highly anisotropic; however, little is known regarding heat transport. We analyse the phonon dispersion and lifetimes of LiCoO<sub>2</sub> using anharmonic lattice dynamics based on quantum chemical force constants. Around room temperature, the thermal conductivity in the hexagonal ab plane of the layered cathode is ≈ 6 times higher than that along the c axis based on the phonon Boltzmann transport. The low thermal conductivity (< 10Wm<sup>-1</sup>K<sup>-1</sup>) originates from a combination of short phonon lifetimes associated with anharmonic interactions between the octahedral face-sharing CoO<sub>2</sub><sup>-</sup> networks, as well as grain boundary scattering. The impact on heat management and thermal processes in lithium ion batteries based on layered positive electrodes is discussed.</div>

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