Design Of Battery Thermal Management System Research Articles

Research on battery heat generation characteristics and thermal management system applied to a typical eVTOL

Electric Vertical Takeoff and Landing (eVTOL) aircraft, as a highly promising future transportation mode, offers new possibilities for solving traffic congestion. Its unique flight mode and high power requirements present significant challenges for battery thermal management system design. Compared to electric vehicles, eVTOLs have totally different usage scenarios and operating conditions, leading to the fact that the thermal management system of conventional electric vehicles does not apply to eVTOLs. This paper proposes a battery thermal management design method for eVTOLs. The energy and power requirements for a short-distance eVTOL flight are determined through theoretical calculations. Additionally, experimental studies explore the thermal characteristics of a 61.5Ah lithium-ion battery under flight discharge conditions. Moreover, a battery thermal management system, which combines flat heat pipes and ram air, is analyzed through numerical simulations. Furthermore, this study investigates the effects of various air temperatures, air inlet mass flow rates, and fin spacing on the performance of the thermal management system. Finally, under the flight discharge cycle of a 61.5 Ah lithium-ion battery, with the environment temperature of 20 °C, the temperature can be controlled within 38.46 °C. The temperature difference can be cooled within 3.85 °C by the passive cooling system. Even at an extreme environment temperature of 40 °C, the battery temperature can still meet the standard. Meanwhile, comparing from multiple dimensions, this solution has a better overall performance than the traditional liquid cooling solution, which provides a foundation for designing a battery thermal management system for eVTOLs.

A Review of Thermal Management and Heat Transfer of Lithium-Ion Batteries

With the increasing demand for renewable energy worldwide, lithium-ion batteries are a major candidate for the energy shift due to their superior capabilities. However, the heat generated by these batteries during their operation can lead to serious safety issues and even fires and explosions if not managed effectively. Lithium-ion batteries also suffer from significant performance degradation at low temperatures, including reduced power output, a shorter cycle life, and reduced usable capacity. Deploying an effective battery thermal management system (BTMS) is crucial to address these obstacles and maintain stable battery operation within a safe temperature range. In this study, we review recent developments in the thermal management and heat transfer of Li-ion batteries to offer more effective, secure, and cost-effective solutions. We evaluate different technologies in BTMSs, such as air cooling, liquid cooling, phase change materials, heat pipes, external preheating, and internal preheating, discussing their advantages and disadvantages. Through comparative analyses of high-temperature cooling and low-temperature preheating, we highlight the research trends to inspire future researchers. According to the review of the literature, submerged liquid BTMS configurations show the greatest potential as a research focus to enhance thermal regulation in Li-ion batteries. In addition, there is considerable research potential in the innovation of air-based BTMSs, the optimization of liquid-based BTMSs, the coupling of heat pipes with PCMs, the integration of PCMs and liquid-cooled hybrid BTMSs, and the application of machine learning and topology optimization in BTMS design. The application of 3D printing in lithium-ion battery thermal management promises to enhance heat transfer efficiency and system adaptability through the design of innovative materials and structures, thereby improving the battery’s performance and safety.

Improving heat transfer in indirect liquid-based battery thermal management systems through turbulator-equipped conical flow paths

To guarantee the safe operation of Li-Ion Cells (LICs) in various applications, such as electric vehicles, an efficient Battery Thermal Management System (BTMS) is necessary. The design of BTMSs, as documented in the literature, typically involves the use of cooling channels with uniform and smooth configurations. However, these configurations encounter the challenge of temperature non-uniformity in the battery module, which stems from elevated coolant temperatures along the flow direction. In this study, a 3D numerical analysis is conducted to develop a novel indirect liquid-based cooling system for the BTMS of a module with cylindrical LICs. The study explores the effects of conical cooling channels, both with and without twisted turbulators, across various coolant mass flows during a 2C discharge process of LICs. Within the studied ranges, diverging cooling channels improve the overall thermal and hydraulic performance of the BTMS by an average of 40%, increasing the heat transfer coefficient by a maximum of 32.6%, and decreasing pressure drop by up to 35.1%. The application of turbulators proves effective in reducing the maximum temperature difference within the LICs, demonstrating a decrease of approximately 34.2% at the minimum mass flow rate and 74.4% at the maximum mass flow rate. This emphasizes the more substantial impact of turbulator utilization at higher coolant mass flow rates. An increased coolant flow rate leads to a significant enhancement of the heat transfer coefficient, ranging from 70.5% to 79.0% for the BTMS incorporating turbulators. Moreover, the study highlights a more pronounced impact of increasing mass flow rates in the BTMS designed with converging cooling channels compared to those designed with diverging channels. Finally, the results of this analysis demonstrate that the proposed system is capable of efficiently regulating the temperature of the entire battery module, ensuring that it consistently maintains a normal and safe operational range suitable for vehicular applications (below 40 °C).

Optimisation of a liquid cooling system for eVTOL aircraft: Impact of sizing mission and battery size

High-energy and -power density lithium-ion batteries (LiB) can enable viable electric vertical take-off and landing (eVTOL) aircraft for advanced air mobility provided that their battery thermal management system (BTMS) allows safe and efficient operations with acceptable weight penalties and capacity degradation. In this paper, we present the first optimisation of a liquid-cooled LiB BTMS for a notional tilt-wing reference eVTOL aircraft. Using an in-house developed BTMS sizing and battery degradation modelling algorithm, we investigate the effects of cruise altitude, hover duration, and battery pack oversizing on BTMS weight and battery lifetime. We minimise the BTMS weight, power, and battery temperature. The optimisation results reveal that varying cruise altitude has a negligible effect on BTMS design. While an extended hover duration does not adversely impact degradation, a considerably heavier BTMS is needed. The BTMS is about twice as heavy when the hover duration increases from one to seven minutes. Shortening the flight distance or oversizing the battery pack greatly impacts the battery lifespan. The battery capacity degradation rate halves when increasing the battery pack size by 20%.

A J-Type Air-Cooled Battery Thermal Management System Design and Optimization Based on the Electro-Thermal Coupled Model

Air-cooled battery thermal management system (BTMS) is a widely adopted temperature control strategy for lithium-ion batteries. However, a battery pack with this type of BTMS typically suffers from high temperatures and large temperature differences (∆T). To address this issue, this study conducted an electro-thermal coupled model to optimize the flow channel structure for reducing the maximum temperature (Tmax) and ∆T in a battery pack for a “J-type” air-cooled BTMS. The parameters required to predict battery heat generation were obtained from a single battery testing experiment. The flow and heat transfer model in a battery pack that had 24 18650 batteries was established by the Computational Fluid Dynamics software ANSYS Fluent 2020R2. The simulation results were validated by the measurement from the battery testing experiment. Using the proposed model, parameter analysis has been implemented. The flow channel structure was optimized in terms of the duct size, battery spacing, and battery arrangement for the air-cooled BTMS. The original BTMS was optimized to reduce Tmax and ∆T by 1.57 K and 0.80 K, respectively. This study may provide a valuable reference for designing air-cooled BTMS.

Thermal management of lithium-ion battery module using the phase change material

One of the significant challenges in the fast adoption of electric vehicles in the market is the thermal management of the battery pack. The current advancement in active and passive cooling techniques is helping resolve this issue in electric vehicles. The present work focuses on the use of passive cooling techniques, such as phase change material (PCM) and the heat sink, to maintain the battery module temperature within the thermal safety limit. The cartridge heaters were used as the mock-up cells. A 3 × 3 array of mock-up cells was formed with a cell-to-cell spacing of 6 mm. OM42 was used as a PCM with a melting point temperature of 44°C and latent heat of fusion, 199 kJ/kg. The experiments were conducted at different power settings of 10–40 W with an interval of 10 W. A heat sink was integrated into the bottom of the battery module. It was observed that increased power input reduces the time required to reach the operating temperature limit of 60°C. After incorporating the PCM, this time was extended by 100.8%, 35.5%, 24.7%, and 21.2% for the power input of 10, 20, 30, and 40 W, respectively. Cell-5 was found to be the most heat-affected cell in the battery module. At higher power inputs of 30 and 40 W, the temperature variation along the height of cell-5 was more than 5°C with and without the PCM. The present findings provide more insights into the heat dissipation at lower and higher power inputs, which may help designers to modify the existing battery thermal management system design efficiently.

Multi-objective optimization design and experimental investigation for a parallel liquid cooling-based Lithium-ion battery module under fast charging

• Parallel liquid cooling system is proposed for a battery module under fast charging. • Sensitivity analysis proves mini-channel depth as the most influential parameter. • Thermal control and energy cost can be enhanced by multi-objective optimization. • Volume energy density gets enhanced by 9.0% after optimization. • Accuracy of the numerical model and optimization is validated by experiments. Enhancing the charging rate capability is beneficial for the driving convenience of electric vehicles. However, high current rate charging causes inevitable severe heat generation, thermal inconsistency, and even thermal runaway. This study proposes a parallel liquid cooling system for a prismatic battery module to achieve the shortest charging interval and thermal safety under fast charging. Furthermore, a surrogate model with the objectives of the thermal performance and energy cost is constructed, the impact of some influential design parameters is explored through sensitivity analysis and response surface analysis. Moreover, a multi-objective optimization design is conducted for the optimal design selection. Finally, the optimal design is validated by experiments under 2.5C fast charging. Results demonstrate that mini-channel depth is the most influential design parameter on the cooling effect (70.8%), the temperature distribution uniformity (75.7%), and the energy cost (86.1%). Volume energy density, maximum temperature ( T max ), temperature standard deviation ( TSD ), and the energy cost ( W ) of the system are enhanced by 9.0%, 2.1%, 23.7% and 26.9%, respectively. Experimental validation proves that T max , TSD , and W of the battery module can be maintained within 33.1℃, 0.9℃, and 17.29 J, respectively. This study guides for the battery thermal management system design with enhanced efficiency and energy cost, especially during harsh operations.

Advanced Engineering Materials for Enhancing Thermal Management and Thermal Safety of Lithium-Ion Batteries: A Review

Lithium-ion batteries (LiBs) are the key power source for electric vehicles (EVs). Battery thermal management system (BTMS) is essential to ensure safety and extend service life of LIBs. This paper reviews the various refrigeration materials used in the BTMS in EVs, including liquid coolant, phase change material (PCM). The thermal properties of these refrigerant materials are summarized and the innovative ways to improve the cooling efficiency of the BTMS are analyzed. The various ways to enhance the battery’s thermal performance by modifying the materials of the electrode, separator, and electrolyte are also reviewed. Finally, the research prospect in area of BTMS is summarized. This review will inspire new BTMS design and further improvement in battery safety and performance with the aid of advanced intelligent technologies.

Experimental study on the cell-jet temperatures of abused prismatic Ni-rich automotive batteries under medium and high states of charge

• The temperature distribution of battery jet was revealed. • The variation of battery jet temperature with the state of charge was provided. • The battery jet temperature can reach a value of 701 °C. • The battery jet temperature rising rate can reach a value of 173 °C/s。 The temperature of the battery jet is one of the key basic parameters for the design of battery thermal management system (BTMS) for vehicles, with sufficient results under combustion conditions in the presence of air. However, the original temperature distribution of battery jet in an inert atmosphere and its variation with the state of charge are not very clear for prismatic Ni-rich automotive batteries. This is closer to the real inside environment of the battery pack. In this work, a 50 Ah commercial prismatic cell with a Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 cathode is triggered to thermal runaway using external heating in a sealed chamber with a nitrogen atmosphere to avoid combustion caused by oxygen from the outside. The results show that the farther away from the safety valve, the lower the temperature of the jet. The jet temperature and its rise rate show an increasing trend with the maximum value of 701 °C and 173 °C/s detected with increasing states of charge. Therefore, the BTMS design needs to take into account the high thermal load and high thermal shock caused by thermal runaway even in the absence of external air to participate in the combustion.

Modelling of battery thermal management: A new concept of cooling using fuel

Battery thermal management system (BTMS) design is crucial for its performance, which can be associated with extra costs and system complexity. Most of the current studies are focused on the BTMS design but with a little focus on the improvement of coolants. In this work, the feasibility of using combustion engine fuel for the LIB thermal management of hybrid electric vehicles is investigated. N-heptane is used as a dielectric hydrocarbon coolant in the introduced system. The thermal performance of the proposed system is investigated numerically using the CFD software ANSYS-Fluent. To benchmark and validate the system performance, a comparative study is made among other common approaches, including the use of air and 3M-Novec 7200. A variety of input parameters are accounted for, including inlet velocities and discharge rates. The results show that air cooling is the least effective method to control the battery module temperature uniformity and the Li-ion battery safety limit. At the same time, n-heptane and 3M-Novec 7200 have shown good control of the module temperature range (20 °C–40 °C) at various discharge rates and different inlet velocities. However, using n-heptane is a considerable improvement to the cost of the system and reduction in its weight and maximum temperature, compared to that using 3M-Novec 7200 coolant. For instance, at 0.1 m·s-1, n-heptane has reduced the Li-ion battery maximum temperature at 1C and 2C discharge rates by more than 7.9 °C (2.6%) and 17.9 °C (5.65%), respectively, compared to those predicted using the same battery module without cooling.

A new approach for battery thermal management system design based on Grey Relational Analysis and Latin Hypercube Sampling

A liquid cooling system is an effective type of battery cooling system on which many studies are presented nowadays. In this research, the effects of the mass flow rate and number of channels on the maximum temperature and pressure drop are investigated for multi-channel serpentine cooling plates. A new approach with LHS and GRA is used to obtain the optimum ranges of design parameters to minimize the pressure drop, maximum temperature and to maximize the convective heat transfer coefficient. In this study, the values of the parameters for the numerical modeling are obtained by the experiments. The width and height of the serpentine channel and mass flow rate are chosen as input parameters and the pressure drop, convective heat transfer coefficient and maximum temperature are selected as output parameters. Comparing with the base design, the optimized design provided up to 40.3% decrease in the pressure drop with a penalty of 11.3% decrease in the convective heat transfer coefficient with a slight decrease in the maximum temperature. The proposed approach can be used to design better cooling plates to keep the batteries in safe temperature ranges and to reduce the power consumption by optimizing the pressure drop and maximum temperature values.

Effects of Structure Parameters on the Thermal Performance of a Ternary Lithium-Ion Battery under Fast Charging Conditions

The heat generated by a lithium-ion battery (LIB) under fast charging conditions can influence the charging efficiency, lifetime, and security of the battery. Considering the Joule heat generation of the tabs during the fast charging process, the electrochemical–thermal coupling model of a ternary LIB is built. The voltage and temperature of the battery are calculated during the constant current charging processes of 1 C, 3 C, and 6 C. By comparing the calculation results with the experiment results, the effectiveness of the model is verified. The electrochemical performance and thermal performance of the battery under fast charging conditions are obtained and analyzed through the model. The effects of the structure parameters such as the positive electrode thickness, N/P ratio, separator thickness, tab size, and arrangement on the average volume heat generation rate and temperature rise of the battery are investigated at charging rates of 3 C and 6 C. The conclusions obtained can provide references for the battery structure design and battery thermal management system design oriented to fast charging applications.

Battery space optimization to limit heat transfer in a lithium-ion battery using adaptive elephant herding optimization

Pure electric vehicles have a variety of benefits such as energy efficiency, zero environmental emissions, elimination in air pollution, and decreased carbon dioxide emissions. While it offers major benefits, it suffers from numerous battery-related issues, and, among them, heat dissipation is considered to be a major challenge, leading to significant performance degradation if not handled properly. In this present work, a battery thermal management system design is presented using ANSYS Fluent and adaptive elephant herding optimization algorithm for optimizing the battery spacing, reducing the heat dissipation, and ensuring a proper battery temperature in the lithium-ion battery pack. The adaptive elephant herding optimization algorithm provides an optimal battery spacing of (17, 23, 21, 0.23, 0.23, 0.174, 0.174), and the maximum temperature, minimum temperature, and temperature difference values observed are 298.3112 K, 292.9874 K, and 5.47 K, respectively. The research findings show that the adaptive elephant herding optimization algorithm works as an appropriate cost-effective strategy for depicting the influence of the battery spacing towards the battery temperature and results in a uniform cooling of the entire battery pack.

A computational multi-node electro-thermal model for large prismatic lithium-ion batteries

During operation of large prismatic lithium-ion batteries, temperature heterogeneities are aggravated which affect the performance, lifetime and safety of the cells and packs. Therefore, an accurate model to predict the evolution of temperature profiles in a cell is essential for effective thermal management. In this paper, a pseudo 3D coupled multi-node electro-thermal model is presented for real-time prediction of the heterogeneous temperature field evolution on the surface and inside the battery. The model consists of two parts: a heat generation model based on a second-order equivalent-circuit model and a multi-node heat transfer model based on the battery geometry. Three types of nodes are adopted to describe the thermal characteristics of various components of the cell. Simulation results show that the proposed model has a great consistency with finite element method, and its computational cost is reduced by 90%. The validity of the coupled electrical and thermal model is also demonstrated experimentally for a 105 Ah prismatic cell applying wide ranges of temperature and SOC. The maximum error is less than 2 K throughout the cycles. The proposed model holds a great potential for online temperature estimation in advanced lithium-ion battery thermal management system design.

Efficient battery thermal management system design to ensure fast charging in extreme cold conditions

In extreme cold conditions, there are negative consequences on battery life due to extremely slower rate of chemical reactions, resulting in lower charging rates. Therefore, an efficient battery thermal management system is required to ensure temperature optimization is low which may also result in charging. In best of authors understanding, there is hardly any research being carried out in this direction. In this paper, an Intelligent Optimization framework combined with computational fluid dynamics (CFD) shall be proposed to optimize the heating method accuracy so as to maintain the uniform and desired temperature across the battery for ensuring smooth and quick charging. Battery pack model shall be designed in CFD platform and the thermal analysis shall be carried for given set of conditions (such as constant heat source, air flow rate, air temperature). Based on the obtained set of analysis samples, a model shall be formulated illustrating relationship between the minimum temperature output and the inputs (air flow rate, air temperature, etc.). The minimum temperature output shall be maximized using NSGA II so as to determine the optimum set of input conditions (air flow rate, air temperature, etc.). The battery pack simulation revealed that thermal system utilizing a liquid medium is more effective than air medium. Future research directions shall be discussed in the end.

Battery Thermal Management System Design: Role of Influence of Nanofluids, Flow Directions, and Channels

Abstract Lithium-ion batteries are currently being produced and used in large quantities in the automobile sector as a clean alternative to fossil fuels. The thermal behavior of the battery pack is a very important criterion, which is not only essential for safety but also has an equally important role in the capacity and life cycle of the batteries. The liquid battery thermal management system is a very efficient type of thermal management system, and mini-channel-based liquid cooling systems are one of the most popular type of the battery thermal management system and have been researched extensively. This paper mainly intends to study the effects of tapering, the addition of grooves to the channel, the use of different nanofluids, and the flow direction of coolant on the thermal performance of the battery pack using a three-dimensional computational fluid dynamics model. The results suggest that converging channels can be used to control the temperature rise, while diverging channels can be used to control the temperature deviation. The addition of grooves and the use of nanofluids were beneficial in reducing the temperature rise. The final setups were able to reduce the maximum temperature rise by 2.267 K with a substantial pressure drop increase and by 1.513 K with an increase in pressure drop of only 19.92%.

A set strategy approach for multidisciplinary robust design optimization under interval uncertainty

Uncertainties widely exist in complex engineering systems. Robust design is one of the most used method for designing under uncertainty and has been gaining more attention. For the wide range of uncertainties, this article proposes a multidisciplinary robust design optimization method based on the set strategy. In this method, a robust design model that utilizes the maximum variation analysis is developed for uncertainty analysis. Then, a set strategy–based approach is employed to build a system optimization model, which is used to coordinate the coupling variables between full autonomy subsystems and obtains a new design space. Finally, the system robust optimal solution and the optimal robust design space are obtained through the sequential optimization, which provide a direction for the subsequent analysis. Two mathematics examples and the speed reducer design problem are taken to verify the validity and accuracy of the proposed method. A practical engineering problem, namely, air cooling battery thermal management system design problem, is successfully solved by the proposed method.

Multi-objective optimal design of lithium-ion battery packs based on evolutionary algorithms

Lithium-battery energy storage systems (LiBESS) are increasingly being used on electric mobility and stationary applications. Despite its increasing use and improvements of the technology there are still challenges associated with cost reduction, increasing lifetime and capacity, and higher safety. A correct battery thermal management system (BTMS) design is critical to achieve these goals. In this paper, a general framework for obtaining optimal BTMS designs is proposed. Due to the trade-off between the BTMS's design goals and the complex modeling of thermal response inside the battery pack, this paper proposes to solve this problem using a novel Multi-Objective Particle Swarm Optimization (MOPSO) approach. A theoretical case of a module with 6 cells and a real case of a pack used in a Solar Race Car are presented. The results show the capabilities of the proposal methodology, in which improved designs for battery packs are obtained.