Thermal Management Of Battery Pack Research Articles

Effect of turning conditions on the indirect liquid-cooled battery thermal management in the electric vehicle

There exist many kinds of turning situations for driving, and the turns would lead to additional forces on the liquid in the channel, which can affect the liquid-cooled battery pack thermal management of electric vehicles. However, few studies have investigated the cooling effect in battery packs during turns in electric vehicles. In view of this, the purpose of this paper is to study how the cooling effect of the battery pack varies under turning conditions and explain the mechanisms behind it. Based on an indirect liquid-cooled battery pack model and by applying turning conditions to the battery pack under different C-rate discharges, the cooling effect of the battery pack is investigated. It is found that the maximum temperature of the battery pack increases significantly under the turning motion condition and increases with vehicle speed. In addition, the temperature uniformity of the battery pack is also greatly deteriorated by the turning motion. Turning results in an increase of the inertial force, which acts on the cooling fluid and decreases the fluid mass flow, ultimately reducing the cooling effect of the battery pack.

Bidirectionally High Thermal Conductive Phase Change Materials with Arrayed Radially Oriented Boron Nitride Nanosheets for Battery Pack Thermal Management

Bidirectionally High Thermal Conductive Phase Change Materials with Arrayed Radially Oriented Boron Nitride Nanosheets for Battery Pack Thermal Management

Modeling and control strategy optimization of battery pack thermal management system considering aging and temperature inconsistency for fast charging

Maintaining the battery pack’s temperature in the desired range is crucial for fulfilling the thermal management requirements of a battery pack during fast charging. Furthermore, the temperature difference, temperature gradient, aging loss and energy consumption of the battery pack should be balanced to optimize its performance. This paper establishes the liquid cooling thermal management system model for an electric vehicle’s battery pack, which accurately characterizes the temperature distribution and electrical and aging characteristics of the battery pack. The discrepancies between the experimental and simulated results of battery’s fast charging-cooling suggest that maximum absolute temperature error is 2 °C, and the maximum relative voltage error is 1.5 %. Based on the non-dominated sorting genetic algorithm II algorithm, an optimization model with aging and temperature gradient of cells as objective functions is established. Three different thermal management strategies are created according to the optimization results. The comparison of these thermal management methods with the constant temperature cooling strategy demonstrates that the minimum temperature gradient strategy enhances the temperature consistency of the battery pack and reduces the maximum temperature gradient by 27 %. The minimum aging thermal management strategy depicts an aging loss of 0.091 %, reducing the charging time by 272 s and the maximum temperature gradient by 2.0 °C. The balanced thermal management strategy enables the battery pack to balance the temperature gradient and aging loss by optimizing the charging time, battery pack temperature difference, energy consumption and other indicators. The weight of each indicator is determined by its information entropy, which can be replaced according to the diverse needs to achieve different balanced thermal management strategies, providing a reference for the actual application of thermal management strategies.

Thermal modeling of porous medium integrated in PCM and its application in passive thermal management of electric vehicle battery pack

The integration of a composite of porous medium with phase change material (PCM) offers significant advantages in thermal management systems, enhancing heat transfer efficiency and addressing various thermal regulation challenges. This approach utilizes the PCM's latent heat absorption and the enhanced thermal conductivity provided by the porous medium, resulting in optimized system performance. Its applicability spans across electronics cooling and building insulation systems. However, predicting the thermal behavior of this composite material is challenging, necessitating computational tools to anticipate its response under different conditions and evaluate its influence on cooling strategies. The objective of this study is to create a computational tool specifically tailored to evaluate constitutive parameters of this composite material, thereby providing a comprehensive description of its thermal behavior. To achieve this goal, the multiscale homogenization principle is employed to assess the composite's effective thermophysical material properties using the representative volume element approach. The repeating unit cell of the aluminum lattice is incorporated into the PCM to define a representative volume element. The finite element method (FEM) is utilized to solve the three-dimensional homogenization problem, yielding an orthotropic effective thermal conductivity due to the inherent symmetry of the repeating material cell. Moreover, the study leverages the apparent heat capacity method to effectively manage the phase transitions within the PCM domain, utilizing smooth and temperature-dependent functions to accurately describe the thermophysical properties of the PCM. Integrating the composite into battery pack thermal management, this study thoroughly examines thermal dynamics by comparing outcomes with and without PCM integration. The transient thermal problem is accurately tackled using the FEM, employing the evaluated effective constitutive parameters of the homogenized composite to minimize computational effort. The results indicate a notable decline in the highest temperatures of the battery pack, leading to a reduction of about 14 °C at the specific moment when the phase change material fully transitions into its liquid form. The obtained results emphasize the effectiveness and practical feasibility of the proposed thermal management strategy. The modeling approach presented provides a robust tool with significant efficiency in reducing computational time for analyzing the thermal behavior of large models, as the utilization of the homogenization technique notably decreases the computational time.

Influence of air-cooled heat dissipation on the thermal characteristics and thermal management of battery packs for electromechanical equipment under plateau environment

Influence of air-cooled heat dissipation on the thermal characteristics and thermal management of battery packs for electromechanical equipment under plateau environment

Theoretical and experimental investigations on liquid immersion cooling battery packs for electric vehicles based on analysis of battery heat generation characteristics

With the increasingly severe challenges of the thermal management of battery packs for electric vehicles, the liquid immersion cooling technology has gradually attracted more attention due to its superior characteristics such as high heat dissipation efficiency, well temperature uniformity and low risk of thermal runaway. To investigate the heat transfer characteristics of the liquid immersion cooling BTMSs, the 3D model of the 60-cell immersion cooling battery pack was established, and a well-established heat generation model that leveraged parameters derived from theoretical analysis and experiments was incorporated into the 3D simulation to analyze the thermal characteristics of battery pack. The simulation results showed that under the discharging rate of 2C, even with the lowest coolant flow rate in this work (0.2 L/min), no localized abnormal overheating within the battery pack was observed, and the highest temperature was 34.22 °C. The temperature uniformity within the battery pack improved with the increase of the coolant flow rate. It was recommended to maintain a flow rate above 0.5 L/min to ensure a temperature difference below 5 °C. The experimental apparatus of the immersion cooling battery pack was also developed to explore the heat dissipation and temperature uniformity at 2C discharge rate. The simulation results were in well agreement with the experimental results, with the deviation less than 0.43 °C when the flow rate exceeded 0.6 L/min. The effect of the localized high-rate discharge events (4.5C and 6.5C) at different battery pack locations on temperature distribution and uniformity was further discussed based on the verified 3D model. The results suggested that liquid immersion cooling systems offered promising potential for achieving both efficient heat dissipation and preventing thermal runaway in battery packs.

Lithium-ion battery pack thermal management under high ambient temperature and cyclic charging-discharging strategy design

To ensure the stable operation of lithium-ion battery under high ambient temperature with high discharge rate and long operating cycles, the phase change material (PCM) cooling with advantage in latent heat absorption and liquid cooling with advantage in heat removal are utilized and coupling optimized in this work. Based on the preferred hybrid cooling scheme, the two layers cold plates and fins are arranged, and the cold plate structure is redesigned to optimize cooling system. The coupling effects of composite PCM and water flow rate, as well as charging and discharging strategy, are numerically studied. The results show that the hybrid cooling is more suitable to high discharge rate of 5C and long-term cyclic operation at 40 °C. The two layers cold plate and fins arranged in hybrid cooling system can mitigate the temperature non-uniformity of batteries along the axis, and the maximum temperature Tmax and temperature difference ΔTmax are reduced by 4.44 °C and 4.17 °C, respectively. Also, the optimized cold plate can mitigate the temperature non-uniformity caused by battery dispersion, and the standard deviation of temperature of batteries is reduced from 0.48 to 0.37. Then, the composite PCM added with expanded graphite can further decrease the Tmax and ΔTmax by 2.18 °C and 1.79 °C, respectively. Lower charging rate offers more reliable cooling performance during continuous cyclic operations. In general, the designed fin-enhanced hybrid cooling system with composite PCM and two layers cold plate can control the Tmax and ΔTmax within 45.85 °C and 3.39 °C at 40 °C ambient temperature and 5C discharge respectively, and offers a reliable and desired cooling performance during continuous charging and discharging of 1C, 2C and 3C. During cyclic operation with 3C discharging and 1C charging, the Tmax and ΔTmax can be controlled below 44.39 °C and 2.64 °C, respectively.

Investigation of multifactorial effects on the thermal performance of battery pack inserted with multi-layer phase change materials

The safe and efficient power battery thermal management system (BTMS) is a prerequisite for the effectiveness and long service life of electric vehicles. So, a BTMS with inserted multi-layer phase change materials (PCMs) is proposed to enhance the safety and working performance of battery pack. Effects of PCM settings and operating conditions on the thermal performance of battery pack are discussed and analyzed. The results reveal that PCM cooling plays a significant role in the thermal management of battery pack, where the maximum temperature value and temperature difference of BTMS with multi-layer PCM #C are respectively reduced by 13.61 °C and 2.54 °C compared to battery pack without PCM. Besides, the coupling effects of multiple factors, that is, PCM permutation, the thickness and height of PCMs, and ambient temperature, on the heat dissipation of battery pack are discussed via orthogonal results analysis. The optimized multi-layer PCMs are obtained for the BTMS, i.e., Ps = 121, h1 = 5 mm and L = 6 mm, which achieves the lowest values of Tmax = 43.02 °C and ΔT = 3.37 °C at Tamb = 20 °C. It provides insights for optimizing thermal control strategies for the advancement of thermal management in electric vehicles, ultimately enhancing safety, performance, and longevity.

Comparative Material Selection of Battery Pack Casing for an Electric Vehicle

Abstract: This paper discusses the battery pack thermal management components for electric vehicles that are necessary for the batteries to operate effectively in all weather. Due to their high energy density and long-life cycle, lithium-ion (Li-ion) battery cells are utilized in electric vehicles. Operating temperature affects the Li-ion battery's performance and lifespan. Moreover, this project aims to review materials for electric vehicles battery pack casing by incorporating proper thermal management required for efficient working of batteries in any climatic conditions. Lithium-ion (Li-ion) battery cells are being used for electric vehicles because they having high density of energy and long-life cycle. Higher operating temperatures lengthen battery life and boost capacity. The use of air, water and phase change materials (PCMs) as thermal management techniques are explored and contrasted. Following comparison, a useful battery pack casing for temperature management system is discussed. In this study, we explore the phenomena of heat generation and temperature problems of Li-ion batteries

Computational investigation of magnetohydrodynamic flow and melting process of phase change material in a battery pack using the lattice Boltzmann method

This study employs the lattice Boltzmann method to investigate the magnetohydrodynamic (MHD) flow and melting process of phase change material (PCM) in a battery pack. The inclusion of the MHD effect allows for an examination of its impact on PCM melting. We analyze fluid fraction diagrams, isothermal lines, and streamlines to assess how magnetic field strength (Ha number), battery heat generation, and MHD field angle influence PCM melting. The study considers a configuration with two batteries separated by PCM, presenting results for two scenarios: single-battery overheating and dual-battery overheating. Our findings reveal significant MHD-induced effects on flow dynamics and PCM melting, with implications for battery pack thermal management, performance, and safety. Increasing the Ha number results in a substantial, approximately 11 % reduction in the battery's maximum surface temperature when the Ha number increases from 0 to 100. Additionally, varying the MHD field angle can lead to a 5 % increase in the maximum temperature. Through a thorough examination of maximum temperature and a sensitivity analysis regarding the MHD field angle, we unequivocally establish the optimal orientation for MHD implementation as γ = 180. This research underscores the potential for leveraging MHD effects to enhance battery pack thermal management and performance. It provides valuable insights into controlling PCM melting, benefiting various battery system applications.

Numerical analysis of topology-optimized cold plates for thermal management of battery packs

Thermal management is important for battery packs and liquid cooling is one method which gains more attentions. However, for the battery cold plate, ensuring the uniformity of the battery temperature and reducing the pressure drop is the issue that needs to be addressed. In order to solve this problem, this paper uses the method of topology optimization to design two novel cold plates (TOPA and TOPB)with different functional focuses. An experimentally derived dynamic simulated heat source is used to model the performance of a cold plate in combination with a high-capacity battery. Then their performance are compared with that of conventional cold plates(RP and SP) by numerical simulation. The results indicate that these new cold plates are able to guarantee the dual requirements of temperature uniformity and low flow resistance. Under the condition of 0.1 m/s inlet velocity, TOPA and TOPB have 1.6 % and 1.7 % lower maximum battery temperatures compared to RP, TOPA and TOPB have 46.7 % and 42.3 % better battery temperature uniformity compared to SP cold plate, and both have about 70 % lower pressure drop than SP. Appropriately increasing the inlet velocity of the cold plate also reduces the maximum battery temperature and temperature difference. Moreover, the values of pressure drops for TOPA and TOPB are very close to RP under all inlet velocity conditions. At the same input power, the heat transfer coefficient of the TOPA cold plate is 69 % and 33 % higher than that of RP and SP cold plates, respectively. As a result, this new cold plate is more suitable for use in BTMS than conventional cold plates.

Thermal assessment of lithium-ion battery pack system with heat pipe assisted passive cooling using Simulink

This study explores a novel application of heat pipes as passive cooling devices, addressing complex electric resistance behaviors in lithium-ion batteries, which lead to manufacturing and thermal safety issues. The aim is to effectively manage battery temperatures, thereby reducing manufacturing and operational costs. An innovative heat generation model was designed based on the Equivalent Circuit Model, leveraging Simulink and MATLAB to predict battery pack power. This intricate electrochemical calculation process is integrated and validated with system-level thermal modeling to compare the viability of heat pipe specifications and to forecast cooling availability via simulation. This research presents both numerical and experimental validations for voltage, state of charge, and cell temperatures. Crucially, we found that in high power output scenarios, such as at rates from 4C to 8C, the use of a heat pipe can reduce the temperature deviation between the cell and the ambient environment to less than three degrees. Furthermore, this paper discusses battery pack system configurations to compare thermal resistance between active and passive cooling systems. This study's novelty lies in its integrated approach to thermal management using heat pipes in the context of lithium-ion batteries, an aspect that has not been extensively explored in previous literature yet. It points to a new direction for future passive cooling strategies in battery pack thermal management.

Effects of heating film and phase change material on preheating performance of the lithium-ion battery pack with large capacity under low temperature environment

In this work, a preheating management system for large-capacity ternary lithium battery is designed, where a novel coupling preheating method of heating film and phase change material (PCM) is employed to preheat. In order to make the preheating system meet the preheating requirements of the battery pack, effects of four influencing factors (heating film power, heating film power difference, cell spacing and PCM thickness) on preheating of the battery pack are studied numerically. Then, the relationship between four factors and preheating time and temperature difference is found, and the optimum parameters in the coupled preheating management system are obtained based on simulation. Finally, the preheating schemes of conventional preheating and rapid preheating under low ambient temperature are determined and investigated. The results show that rapid preheating takes much less preheating time than conventional preheating, where the temperature difference is about 1.48 K and the time consumption is 602 s, 518 s and 394 s under the low temperatures of 253.15 K, 263.15 K and 273.15 K, respectively. In addition, this preheating scheme also prove the feasibility of the designed battery pack thermal management system, which can meet the actual use of electric vehicles.

Multi-Objective Optimization with PCM integration and delayed cooling strategy for high-rate discharge applications

The thermal safety of lithium-ion batteries has been a significant concern in the industry, prompting a pressing need for research to ensure efficient and energy-saving operation of energy storage battery's thermal management system. This study focuses on addressing the multi-objective optimization problem of heat dissipation coupling energy consumption in battery packs under high discharge rate with a maximum temperature (Tmax), a maximum temperature difference (ΔT) and the pump energy consumption (P) as objectives. The Kriging interpolation and CRITIC weighting method are used for multi-objective optimization to determine the optimum solution objectively. The results indicate that increasing the diameter of the liquid cooling pipe (X) and the coolant inlet velocity (vin) both contribute to reducing the maximum temperature of system. However, these changes have negative impacts on temperature uniformity within the battery pack and the energy consumption of the water pump. The above rule is reversed when considering the impact of initiation time of coolant flow (T), which in addition can lead to exhaustion of latent heat of CPCM and insufficient cooling capacity and thus potential overheating of the battery pack. According to the CRITIC weighting method analysis, the index weights of Tmax, ΔT and P are 40.21%, 32.01% and 27.79%, respectively. Further analysis reveals that the optimal comprehensive performance of the battery pack thermal management system is achieved when X = 3.875 mm, vin = 0.4 m/s, and T = 537.5 s, corresponding the P of 2.53 J, Tmax of 309.32 K and ΔT of 2.41 K, both falling within the specified technical requirements at a discharge of 4 C . The latent heat of the phase change material in the battery pack has been recovered at this stage, providing sufficient cooling capacity for the next cycle of charging and discharging.

Cold plate enabling air and liquid cooling simultaneously: Experimental study for battery pack thermal management and electronic cooling

The temperature of cells varies greatly during dis/charge while their performance and lifetime are greatly affected by this fluctuation. Elevated temperatures may yield battery fire due to thermal runaway as well they accelerate ageing and capacity fade of cells. Thermal management systems are a necessity for electric vehicles to extend the lifetime of battery cells and eliminate any fire risks, especially for fast dis/charging applications. Here, we document a hybrid cold plate with a working fluid(s) of sole air or liquid as well as both of them. Hybridization of air and liquid cooling promises to minimize energy consumption requirements during a charge/discharge cycle by combining the benefits of both thermal management strategies if energy management is controlled accordingly. The temperature of each cell can be kept below 30°C with the proposed hybrid cooling heat exchanger, and the temperature difference between the cells is reduced by 30 % relative to liquid cooling. The maximum temperatures are decreased by 18 % and 3 % in hybrid cooling when compared to air and water cooling, respectively. Furthermore, a step function combining various discharge rates (1C and 3C) was employed in experiments to mimic a realistic situation, i.e. variable C-rate rather than constant. The results show that the temperature of the battery cells can be kept below 30°C with air cooling for variable discharge rate and the effect of contact resistance should not be overlooked for liquid cooling. Furthermore, the possible use of the proposed hybrid cold plates is surveyed in the cooling of electronic devices which produce more and continuous heat than cells. Therefore, three resistance heaters with a capacity of 50W are used in experiments as well. The results show that the proposed cold plates could be used in both electronics cooling and battery thermal management with a control algorithm to switch between sole working fluid and combination modes which could be developed based on the results of this paper.

An air-cooled system with a control strategy for efficient battery thermal management

Air-cooled systems are widely used in electric vehicles for the thermal management of battery packs. Due to the low specific heat capacity of air, design of air-cooled systems is required to improve the temperature uniformity of battery packs. However, structural design of the system cannot meet the requirement of battery thermal management under varying operating conditions. In this study, a parallel air-cooled system with a control strategy is developed for efficient cooling of battery packs under varying operating conditions. The performance of the air-cooled systems with different single flow types is investigated numerically, with the results verified by experiments. A control strategy based on the temperature difference among battery cells is proposed for the system with J-type flow, and the mechanism by which traditional systems fail in temperature difference control is revealed. To address this issue, an efficient thermal management system that integrates different flow types is proposed and relevant control strategy is developed, with decreased widths of the parallel channels on both ends. The proposed system with the control strategy reduces the temperature difference among battery cells by switching the flow type on demand and guiding more cooling air to the battery cell with high temperature. The numerical results of the cases with high current discharge rate and with varying random operating conditions show that the developed system enables the temperature difference to be controlled below 0.5 K after several switches of flow type. The average temperature difference among the battery cells in the developed system is reduced by more than 67% compared to that with J-type flow alone. The proposed system with the relevant control strategy is efficient for thermal management of battery packs under varying operating conditions.

Design of Cold Plate for a Battery Pack, it’s Experimental Analysis and Simulation.

The battery is the heart of the Electric Vehicle. Electric vehicles have become popular due to their high tank-to-wheels efficiency and zero-emission. The Electric Vehicles batteries generate heat during operation, and this heat generated must be reduced (cooled) to ensure the safety and long life of the vehicle. Thermal management systems (TMS) are essential for the proper functioning of EV battery pack. This research focuses on the development of cold plate for a battery pack, its experimental and simulation analysis. The battery pack used in this research has a capacity of 250 Wh and the cold plate is designed to dissipate heat from the battery cells to maintain their temperature within a safe operating range (20 – 40°C). The experimental analysis involves testing of the cold plate under different operating conditions, including varying coolant flow rates, discharge C rates and ambient temperatures. The ANSYS Fluent software is used to develop the digital twin (simulational model) to model the fluid flow and heat transfer characteristics of the cold plate being used in battery pack. The simulation results are to be validated against the experimental results. The main objective of this research is to match the simulation result with the experimental result, thus validating the results of digital twin as an effective tool for cold plate design optimization in battery pack thermal management system. The digital twin can be used to make battery pack of bigger scale with cooling system.[2]

Axial and radial thermal conductivity measurement of 18,650 Lithium-ion battery

Thermal conductivities of lithium-ion batteries are critical for the thermal management of battery packs. In this work, a novel method and experimental apparatuses are developed to measure the axial and radial thermal conductivities of the 18,650 LiNiCoAlO2 (NCA) lithium-ion battery. For the axial conductivity measurement, the one-dimensional steady conduction principle considering uniform heat loss is used, while the combined method of experiment and computational fluid dynamics (CFD) simulation is used for the radial conductivity measurement. By measuring the conductivity of the stainless steel cylinder, the errors are estimated to be less than 1.45 % and 1.37 % for the axial and radial measurement methods respectively. The axial and radial conductivities of the battery are measured at different open circuit voltage (OCV) and temperatures. Under the experimental conditions, the axial conductivity of the battery ranges from 10.26 to 14.20 W/m/K, and the axial conductivity generally increases with OCV and temperature. The radial conductivity ranges from 2.14 to 2.87 W/m/K if the battery core and the steel shell are considered as a whole; and the radial conductivity of the core ranges from 1.84 to 2.55 W/m/K if the core and the shell are considered separately. In the normal OCV range, there is no obvious relationship among the radial conductivity, temperature and OCV, whether the core and the shell are treated separately or not. This work may contribute towards improved thermal simulation of Li-ion cells.

Experimental investigation on hybrid cooled lithium‐ion battery pack with 3S4P cell configuration using OM 48 as phase change material and heat pipe

AbstractBecause of their high energy capacity and power density, lithium‐ion batteries are an essential component of electric and hybrid vehicles; however, they frequently experience excessive temperature rise because of heat creation inside the batteries. The charge state and charge/discharge rate play a major role in this heat generation. Due to its high latent heat, compact design and lightweight nature without requiring any external power, passive techniques like phase change material (PCM) and heat pipe (HP) cooling have gained widespread popularity. Therefore, this work focussed on hybrid BTMS integrating Heat Pipe with PCM for better thermal management of battery pack supported by a heat pipe that is used to analyse the thermal performance of a battery module having three and four lithium‐ion batteries placed in series and parallel. The objective of maintaining temperature gradient of less than 5°C between the adjacent cells and maintaining the overall battery temperature in the range of 25°C–45°C has been successfully achieved. The results of experiments at various discharge rates showed that a heat pipe was crucial to quickly transferring heat and maintaining temperature homogeneity for PCM‐based battery modules. It can be concluded that the data presented above can offer views for creating and improving battery heat management systems.

A manifold channel liquid cooling system with low-cost and high temperature uniformity for lithium-ion battery pack thermal management

A manifold channel liquid cooling system with low-cost and high temperature uniformity for lithium-ion battery pack thermal management