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In order to investigate the self-heating thermal runaway problem of ternary lithium-ion battery used in a certain forest plant protection machine, the structural composition of the battery cell, the heat generation mechanism of each side reaction and the three heat transfer modes of heat radiation, heat conduction and convective heat transfer between the battery cell, end plate, heat insulation pad, box body and the environment were first explored. Then based on the thermal runaway modeling method of the equivalent circuit model, the thermoelectric characteristic model of the 280 Ah large-capacity battery module was established in the Amesim one-dimensional simulation software by the physical parameters of the battery cell, the side reaction mechanism, and the exothermic heat transfer model. The heat transfer characteristics of the battery during self-heating thermal runaway and the path of thermal runaway propagation in the module were analyzed and simulated. Finally, according to the national standard GB 38031—2020, the self-heating experiment of the battery module was carried out to obtain the change of the cell temperature with time, and the specific position of the thermal runaway of the trigger cell was confirmed by CT scanning. The simulation and experimental results showed that the established model had high accuracy and reliable performance. The maximum error of the thermal runaway temperature of the cell was 11. 3%, and the maximum error of the thermal runaway trigger time was 4. 2%. It can provide technical reference for the design and development of battery thermal management, such as the prediction of thermal runaway temperature and the safety of preventing thermal diffusion of battery pack. [ABSTRACT FROM AUTHOR]

The thermal performance of a lithium-ion battery pack for an electric vehicle by adding straight rib turbulators in battery cooling plate channels has been numerically investigated in this paper and the numerical model of the battery pack has been validated by experimental data, which exhibits a satisfactory prediction accuracy. The effects of rib shapes, rib angles, rib spacings, and irregular gradient rib arrangement configurations on the flow and heat transfer behaviors of battery pack cooling plates have been thoroughly explored and analyzed in this paper. In addition, the thermal performance of the ribbed battery cooling plates was examined at actual high-speed climbing and low-temperature heating operating conditions. The results indicate that compared to the original smooth cooling plate, the square-ribbed battery cooling plate with a 60° angle and 5 mm spacing reduced the maximum battery temperature by 0.3 °C, but increased the cross-sectional temperature difference by 0.357 °C. To address this issue, a gradient rib arrangement was proposed, which slightly reduced the maximum battery temperature and lowered the cross-sectional temperature difference by 0.445 °C, significantly improving temperature uniformity. The thermal performance of the battery thermal management system with this gradient rib configuration meets the requirements for typical electric vehicle operating conditions, such as high-speed climbing and low-temperature heating conditions. [ABSTRACT FROM AUTHOR]

This paper reports on a novel hybrid thermal management strategy. It uses secondary coolants (air and liquid) to withdraw heat simultaneously from the composite phase change material, resulting in increased heat extraction capability of the composite phase change material and improved thermal environment of the battery module. The significance of this strategy is that the fluid used in the liquid cooling stays stationary. Comprehensive experimental and numerical studies are performed, and parametric studies are conducted to reduce the volume of the phase change material, size of the air duct, and airflow Reynolds number. The numerical results showed that the maximum temperature was limited to 27.8°C, and a high‐temperature uniformity of 0.4°C was obtained. Furthermore, the required volume of the composite phase change material is reduced by ~50%. Additionally, beyond a 6 mm height of the air duct, the reduction in maximum pressure drop is not significant enough, and it is considered the optimal height, and a Reynolds number of 1950 is considered the optimal airflow Reynolds number. Therefore, the proposed thermal management concept for the battery module can sustain the thermal environment needed for the effective operation of Lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

In the current era of energy conservation and emission reduction, the development of electric and other new energy vehicles is booming. With their various attributes, lithium batteries have become the ideal power source for new energy vehicles. However, lithium-ion batteries are highly sensitive to temperature changes. Excessive temperatures, either high or low, can lead to abnormal operation of the batteries, posing a threat to the safety of the entire vehicle. Therefore, developing a reliable and efficient Battery Thermal Management System (BTMS) that can monitor battery status and prevent thermal runaway is becoming increasingly important. In recent years, deep learning has gradually become widely applied in various fields as an efficient method, and it has also been applied to some extent in the development of BTMS. In this work, we discuss the basic principles of deep learning and related optimization principles and elaborate on the algorithmic principles, frameworks, and applications of various advanced deep learning methods in BTMS. We also discuss several emerging deep learning algorithms proposed in recent years, their principles, and their feasibility in BTMS applications. Finally, we discuss the obstacles faced by various deep learning algorithms in the development of BTMS and potential directions for development, proposing some ideas for progress. This paper aims to analyze the advanced deep learning technologies commonly used in BTMS and some emerging deep learning technologies and provide new insights into the current combination of deep learning technology in new energy trams to assist the development of BTMS. [ABSTRACT FROM AUTHOR]

Currently, the conventional heat pipe form and working fluid are not well suited for power batteries. Existing simulation studies on battery thermal management with coupled heat pipes often overlook the two-phase flow and heat transfer of working fluid within the heat pipe. Additionally, the temperature difference between electrode region and cell is neglected in thermal behaviour simulation of the battery. Aiming at these problems, this paper proposes the design of an L-shaped heat pipe, which aims to efficiently adapt to heat dissipation of square batteries and the spatial arrangement within the battery module. And the phase change, flow and heat transfer processes of working fluid inside heat pipe are simulated and reproduced using the VOF (volume of fluid) method. Additionally, a CFD (computational fluid dynamics) model of an 8S1P ternary lithium-ion battery module is established based on the NTGK (Newman, Tiedemann, Gu, and Kim) method. Focusing upon thermal behaviour properties of the 8S1P battery module at different discharge rates, we investigate and optimize the thermal management efficiency of L-shaped heat pipes coupled with air cooling. The analysis reveals that the battery module model provides a more accurate representation of the temperature field on the body of batteries and the temperature variation among them. The evaporation-condensation process of the working fluid inside the heat pipe can continue in dynamic equilibrium, and the heat transfer effect through phase transition is well. With battery discharge rates varying from 1C to 3.5C, the addition of forced air cooling and introduction of cold air from air conditioning allows efficient control of temperature and temperature difference of the module, resulting in an ideal cooling effect. This study further improves the accuracy of the design and simulation of BTM (battery thermal management) that coupled with heat pipes, which can provide certain reference for related research. [ABSTRACT FROM AUTHOR]

In this study, flow and thermal analyses of a liquid-cooled electric vehicle battery module were assessed via computational fluid dynamics (CFD) method. In CFD analyses, based on a validated model using battery heat generation data available in literature and obtained experimentally, the effect of contact resistance between the batteries and aluminum blocks and between aluminum blocks and water channels placed in battery module and cooling water flow rate were investigated for different working conditions. Findings revealed that at low discharge rate (C-rate) values, contact resistance could be disregarded, causing only a minor temperature difference of around 0.5°C. However, at high C-rate values, contact resistance became significant, resulting in a temperature difference of up to 2.5°C. Also, increasing the cooling liquid flow rate effectively lowered maximum temperature of battery module by approximately 8°C in high-heat scenarios. Conversely, in low-heat scenarios, excess cooling liquid flow rate led to unnecessary pump energy consumption, which could be reduced by approximately 1/8 while achieving a more homogeneous temperature distribution by choosing an appropriate cooling liquid flow rate. Also, the temperature difference between the batteries decreased and a more homogeneous temperature distribution was achieved in the module by increasing cooling flow rate. [ABSTRACT FROM AUTHOR]

AbstractThis study aims to enhance the performance of the air-cooled hybrid battery thermal management system (BTMS) by using fins under extreme discharge conditions such as 7C, 9C, and 11C. In this context, five different fin structures, Type-I (no fin), Type-II (rectangular), Type-III (extended), Type-IV (blade), and Type-V (triangular), were modeled, and numerical analyses of the developed BTMSs were performed using COMSOL Multiphysics software. In the numerical analysis, three different phase change materials (PCM-1, PCM-2, and PCM-3) with three different thicknesses (tPCM) of 4, 6, and 8 mm were considered, and the airflow was supplied to the system at three different Reynolds (Re) numbers of 100, 200, and 400. In this way, the effects of the BTMS types, tPCM, PCM types, and air velocity on the battery pack temperature distribution (ΔT), PCM melting uniformity (ΔF), and maximum battery cell temperature (Tmax) in the hybrid BTMS were investigated. As a result of the analyses, the maximum ΔT was found to be 5.58 °C for the case involving Type-II and PCM-1 with tPCM of 4 mm at 11C. PCM-2 exhibited the best performance for all BTMS types with a tPCM of 4 mm at 9C. However, at 11C, only the case involving PCM-3 with a tPCM of 6 mm and Type-V could maintain the Tmax under 60 °C. Moreover, the results obtained from the numerical analysis revealed that the use of fins significantly increased the PCM melting uniformity. [ABSTRACT FROM AUTHOR]

Electric mobility decarbonizes the transportation sector and effectively addresses sustainable development goals. A good battery thermal management system (BTMS) is essential for the safe working of electric vehicles with lithium‐ion batteries (LIBs) to address thermal runaway and associated catastrophic hazards effectively. However, PCMs suffer from low thermal conductivity issues, and hence, enhancement techniques include the use of fins, nano‐additives, extended graphite powder, and so forth. The use of composite phase change materials effectively addresses LIB thermal management widely used in electric vehicles while mitigating thermal runaway, besides providing flame retardancy, thermal/mechanical stability, and electrical insulation, and preventing leakage. It is noted that no single strategy of BTMS is brought down to a safe zone of temperature, and hybrid BTMSs are being employed, invariably involve phase change materials (PCMs) to a large extent. It is essential to utilize CPCMs to address the effects of low‐temperature environments and vibrations considering vehicle driving cycles and operating conditions. It is observed from the review that ultrasonic monitoring and early detection of internal short circuits are the steps towards mitigation of thermal runaway propagation. It is required to utilize optimization methods, machine learning and IoT tools for a feasible PCM based BTMS work. Present review briefly describes potential methods for effective utilization of PCMs, comparison among different methods, challenges associated and potential solutions. It is highly essential to develop compact and economical BTMS with effective CPCMs for better and safer LIB operation to attract large‐scale commercialization of electric vehicles. [ABSTRACT FROM AUTHOR]

The air-cooled system is one of the most widely used battery thermal management systems (BTMSs) for the safety of electric vehicles. In this study, an efficient design of air-cooled BTMSs is proposed for improving cooling performance and reducing pressure drop. Combining with a numerical calculation method, a strategy with a varied step length of adjustments (∆d) is developed to optimize the spacing distribution among battery cells for temperature uniformity improvement. The optimization results indicate that the developed strategy reduces the optimization time by about 50% compared with a strategy using identical ∆d values while maintaining good performance of the optimized system. Furthermore, the system's pressure drop does not increase after the spacing optimization. Based on this characteristic, a structural design strategy is proposed to improve the cooling performance and reduce the pressure drop simultaneously. First, the appropriate flow pattern is arranged and the secondary outlet is added to reduce the pressure drop of the system. The results show that the BTMS with U-type flow combined with a secondary outlet against the original outlet can effectively reduce the pressure drop of the system. Subsequently, this BTMS is further improved using the developed cell spacing optimization strategy with varied ∆d values while the pressure drop is fixed. It is found that the final optimized BTMS achieves a battery temperature difference below 1 K for different inlet airflow rates, with the pressure drop being reduced by at least 45% compared with the BTMS before the optimization. [ABSTRACT FROM AUTHOR]

Lithium battery temperatures will increase if the heat produced during the charging and discharging procedures is not promptly vented externally. Fewer investigations have been conducted on materials that can retain good flexibility at room temperature and shape stability at high temperatures under the existing thermal management system for phase change materials (PCM). In this study, a particular kind of flexible composite PCM (CPCM) at room temperature is created to address the issue of heat transfer between the PCM and the power battery. The characteristics of hardness, room-temperature flexibility, form stability at high temperature, and thermal conductivity are compared with those of three other thermally induced flexible CPCMs. The flexibility at room temperature of the new CPCM is demonstrated by the results, which makes assembly easier and helps further lower the contact thermal resistance. Charge–discharge test comparisons of the battery modules employing the chosen CPCM and thermally induced CPCM are performed to further evaluate their thermal management capabilities. The thermally induced CPCM exhibits larger maximum temperature profiles at the discharge rates of 1C, 2C, and 3C than the room-temperature flexible CPCM. The variations in maximum temperatures are 0.96, 1.48, and 2.08 °C. [ABSTRACT FROM AUTHOR]

In order to improve the energy efficiency of pure electric vehicles, the author proposes a thermal energy recovery and automation monitoring system for motor equipment based on new energy vehicles. Based on the analysis of the battery thermal management model, a series heat exchange model between the motor and the battery was established. An integrated thermal management system control strategy based on motor waste heat recovery was proposed for electric vehicles in low temperature environments, and simulation and validation were conducted at different environmental temperatures (-10~0 °C). The simulation results show that this configuration can shorten the heating time by 111-343 seconds compared to traditional battery thermal management systems during the heating stage. During the insulation stage, frequent activation of positive temperature coefficient thermistor can be avoided and the battery temperature can be maintained around 20 °C, which is not only conducive to extending the battery life but also reduces the comprehensive energy consumption by 4.39-7.70%. On the other hand, this configuration can reduce the impact of low temperature on comprehensive energy consumption from 9.77-2.07%. It is proved that heat recovery can effectively alleviate the range anxiety caused by ambient temperature. [ABSTRACT FROM AUTHOR]

Temperature uniformity and peak-temperature reduction of lithium-ion battery packs are critical for adequate battery performance, cycle life, and safety. In air-cooled battery packs that use conventional rectangular ducts for airflow, the insufficient cooling of cells near the duct outlet leads to temperature nonuniformity and a rise in peak temperature. This study proposes a simple method of using a converging, tapered airflow duct to attain temperature uniformity and reduce peak temperature in air-cooled lithium-ion battery packs. The conjugate forced convection heat transfer from the battery pack was investigated using computational fluid dynamics, and the computational model was validated using experimental results for a limiting case. The proposed converging taper provided to the airflow duct reduced the peak temperature rise and improved the temperature uniformity of the batteries. For the conventional duct, the boundary layer development and the increase in air temperature downstream resulted in hotspots on cells near the outlet. In contrast, for the proposed tapered duct, the flow velocity increased downstream, resulting in improved heat dissipation from the cells near the outlet. Furthermore, the study investigated the effects of taper angle, inlet velocity, and heat generation rate on the flow and thermal fields. Notably, with the increase in taper angle, owing to the increase in turbulent heat transfer near the exit, the location of peak temperature shifted from the exit region to the central region of the battery pack. The taper-induced improvement in cooling was evident over the entire range of inlet velocities and heat generation rates investigated in the study. The peak temperature rise and maximum temperature difference of the battery pack were reduced by up to 20% and 19%, respectively. The proposed method, being effective and simple, could find its application in the cooling arrangements for battery packs in electric vehicles. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive simulation study was carried out to obtain detailed battery temperature behaviors. The influences of air inlet temperature, air flow rate, C‐rate, and free stream temperature were investigated on the temperature uniformity and maximal battery temperature. Taguchi design is implemented to investigate the main effects of four control parameters in the battery thermal management process. Results indicated that as the free stream temperature (delta = 7.3366) was the most influential factor for the temperature uniformity, the air inlet temperature (delta = 0.2679) was the most efficient factor for the maximal battery temperature. The contribution of the air inlet temperature was 28% and 38% for temperature uniformity and maximal battery temperature, respectively. Additionally, the free stream temperature contributed 32% to temperature uniformity and 25% to the maximum battery temperature. The airflow rate was found to be the least effective factor for temperature uniformity (delta = 2.8672) and maximal battery temperature (delta = 0.0506). The results could be helpful in the design of a lithium‐ion battery thermal management process to improve temperature uniformity and maximal battery temperature. [ABSTRACT FROM AUTHOR]

Various coolants exert different effects on the cooling performance of liquid cold plates employed for EV battery cells. This research investigates the influence of utilizing CuO/water nanofluid on the liquid cold plate’s thermal and hydraulic performance. The present study uses 40 nm CuO nanoparticles with a 1% volume fraction, and the CuO/water nanofluid is prepared using a two-step method. Using CuO/water nanofluid achieves a lower surface temperature than water at different Reynolds numbers, with a maximum difference of 4.2% at Reynolds number 382. At Reynolds number 1530, the nanofluid achieved a surface temperature of approximately 35°C, well within the recommended operational range for Li-ion batteries. The heat absorption capacity of the nanofluid was enhanced by 3.21 J/s between Reynolds numbers 574 and 765, attributed to its higher thermal conductivity and specific heat capacity. The Nusselt number for the nanofluid surpassed that of water beyond Reynolds number 1147, indicating superior performance facilitated by improved fluid mixing. The maximum increase in pumping power consumption was 25.2% at a Reynolds number of 956. However, this penalty is small compared to the energy saved due to the better cooling performance of CuO/water nanofluid. [ABSTRACT FROM AUTHOR]

This study focused on the design of a battery pack cooling channel based on a Tesla Model S electric car. This study aimed to achieve a balance between cooling efficiency and pressure drop while maintaining safe and optimal operating temperatures for the batteries. A cooling channel design similar to the basic type employed in the Tesla Model S using 448 cylindrical Li-ion batteries was considered. Consequently, important parameters, such as the maximum temperature and temperature difference in the battery cells in a module, as well as the pressure drop of the coolant, were analyzed. In addition, the characteristics of the temperature changes in each cooling channel shape were investigated. The temperature limit for the battery in a module and the temperature limit difference were set to 40 °C and 5 °C, respectively, to evaluate the performance of the cooling system. Further, the effects of discharge rates (3C and 5C), cooling channel shapes (counter flow and parallel types), and coolant inlet velocities (0.1, 0.2, 0.3, and 0.4 m/s) on battery thermal management were analyzed. The results revealed that the parallel type channel yielded a lower pressure drop than the basic type channel; however, it was not as effective in removing heat from the battery. In contrast, the counter flow type channel effectively removed heat from the batteries with a higher coolant pressure drop in the channel. Therefore, a multi-counter flow type cooling channel combining the advantages of both these channels was proposed to decrease the pressure drop while maintaining appropriate operating temperatures for the battery module. The proposed cooling channel exhibited an excellent cooling performance with lower power consumption and better heat transfer characteristics. However, relatively minimal differences were confirmed for the maximum temperature and temperature difference in the battery module compared with the counter flow type. Therefore, the proposed cooling channel type can be implemented to ensure the optimal temperature operation of the battery module and to decrease system power consumption. [ABSTRACT FROM AUTHOR]

Composite phase change materials commonly exhibit drawbacks, such as low thermal conductivity, flammability, and potential leakage. This study focuses on the development of a novel flame-retardant phase change material (RPCM). The material's characteristics and its application in the thermal management of lithium-ion batteries are investigated. Polyethylene glycol (PEG) serves as the medium for phase change; expanded graphite (EG) and multi-walled carbon nanotubes (MWCNT) are incorporated. Moreover, an intumescent flame retardant (IFR) system based on ammonium polyphosphate (APP) is constructed, aided by the inclusion of bio-based flame-retardant chitosan (CS) and barium phytate (PA-Ba), which can improve the flame retardancy of the material. Experimental results demonstrate that the RPCM, containing 15% IFR content, exhibits outstanding flame retardancy, achieving a V-0 flame retardant rating in vertical combustion tests. Moreover, the material exhibits excellent thermomechanical properties and thermal stability. Notably, the material's thermal conductivity is 558% higher than that of pure PEG. After 2C and 3C high-rate discharge cycles, the highest temperature reached by the battery module cooled with RPCM is 18.71 °C lower than that of natural air-cooling; the material significantly reduces the temperature difference within the module by 62.7%, which achieves efficient and safe thermal management. [ABSTRACT FROM AUTHOR]

Performance of battery cells in an electric vehicle (EV) highly depends on environmental temperature. However, many studies do not consider its regional or seasonal characteristics. These characteristics can have a significant impact on the EV battery life in California, where there is a large variation of climate across the state. In some regions, the maximum ambient temperature can cause a rapid life degradation of the battery cells. In this study, we investigated the environmental temperature effects of six major cities in California on the capacity fade of the EV battery cells. A numerical model of an automotive battery pack and cycle-life model of a lithium-ion battery cell were implemented to predict the cell temperature and its corresponding capacity loss. The numerical results demonstrated the regional and seasonal effects of environmental temperature must be considered to prevent rapid life degradation in the automotive battery cells. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to explore the impact of integrating nano-additives on heat transfer enhancement within an LHTES (Latent Heat Thermal Energy Storage) system. Our findings revealed that introducing a minimal amount of nano-materials (less than 5.0 vol%) into the Phase Change Material (PCM) led to a remarkable alignment between experimental correlations and mixture models. Furthermore, employing the mixing model allowed for the accurate prediction of outcomes. In the current context of scientific research, there is a strong endorsement for the widespread adoption of Electric Vehicles (EVs) as a sustainable alternative to Internal Combustion Engines (ICEs), crucial for advancing decarbonization and mitigating climate-related crises. Lithium-ion batteries are the predominant choice for EVs and various electrical devices. However, the operational challenges posed by high temperatures, impacting their lifespan, charge/discharge cycles, and the risk of thermal runaway, necessitate effective thermal management systems. Given this background, our study focuses on simulating the heat dissipation of a single cylindrical Li-ion battery cell employing a Nano-enhanced Phase Change Material (NePCM)-based cooling system. We also introduce a novel fin design in this work. Through comprehensive analysis, we examine the performance of battery modules utilizing PCM and NePCM at different discharge rates, both with and without the newly proposed fin design. Our research demonstrates that the incorporation of fins and nanoparticles into PCM significantly enhances heat transfer and reduces the charging time compared to the base PCM. Notably, carbon-based nanoparticles outshine their metal-based counterparts in terms of melting rate and maintaining a uniform temperature profile within the battery. [ABSTRACT FROM AUTHOR]

Electrification on transportation and electricity generation via renewable sources play a vital role to diminish the effects of energy usage on the environment. Transition from the conventional fuels to renewables for transportation and electricity generation demands the storage of electricity in great capacities with desired power densities and relatively high C-rate values. Yet, thermal and electrical characteristics vary greatly depending on the chemistry and structure of battery cells. At this point, lithium-ion (Li-ion) batteries are more suitable in most applications due to their superiorities such as long lifetime, high recyclability, and capacities. However, exothermic electrochemical reactions yield temperature to increase suddenly which affects the degradation in cells, ageing, and electrochemical reaction kinetics. Therefore, strict temperature control increases battery lifetime and eliminates undesired situations such as layer degradation and thermal runaway. In the literature, there are many distinct battery thermal management strategies to effectively control battery cell temperatures. These strategies vary based on the geometrical form, size, capacity, and chemistry of the battery cells. Here, we focus on proposed battery thermal management strategies and current applications in the electric vehicle (EV) industry. In this review, various battery thermal management strategies are documented and compared in detail with respect to geometry, thermal uniformity, coolant type and heat transfer methodology for Li-ion and post-lithium batteries. [ABSTRACT FROM AUTHOR]

The hybrid fuel cell/battery technology is an attractive option for a sustainable mobility with zero emissions. In fact, this solution owns system scalability features and high efficiency and, compared to battery electric solutions, it offers advantages in terms of flexibility of use and fast charging times. However, the thermal management for the battery in this type of powertrain is a crucial issue, since operating temperatures can significantly affect safety and performance. In this study, an innovative system aimed at providing high storage energy density and improving the battery pack performance of hybrid fuel cell/battery vehicles is investigated for use on-board of a plug-in fuel cell electric bike. The proposed system, developed by the authors in previous studies, integrates the battery pack with a hydrogen storage based on metal hydrides. The idea behind this solution is to exploit the endothermic desorption processes of hydrogen in metal hydrides to cool down the battery pack during operation. An experimental analysis is conducted to assess the thermal management capabilities of this system: by considering a typical duty cycle designed on the base of road test measurements, battery pack temperature profiles are evaluated and compared against those from a control experiment where no battery thermal management is enabled (i.e. no hydrogen desorption from the metal hydride tank). The results show that, beside enhancing the on-board stored energy capacity, the proposed system represents an effective solution to provide an efficient thermal management for the battery pack, with significant advantages in terms of attainable riding range. • Plug-in fuel cell electric bicycle with greater riding range than e-bike. • On-board storage system integrating metal hydrides tank and battery pack. • Enhanced volumetric and gravimetric on-board energy storage density. • Optimal thermal management of battery pack and metal hydride tank. [ABSTRACT FROM AUTHOR]

The accumulation of thermal energy in the form of latent heat of phase transition using phase change materials (PCMs) is one of the most attractive and studied research areas with huge application potential in both passive and active technical systems. The largest and most important group of PCMs for low-temperature applications are organic PCMs, mainly paraffins, fatty acids, fatty alcohols, and polymers. One of the major disadvantages of organic PCMs is their flammability. In many applications such as building, battery thermal management, and protective insulations, the crucial task is to reduce the fire risk of flammable PCMs. In the last decade, numerous research works have been performed to reduce the flammability of organic PCMs, without losing their thermal performance. In this review, the main groups of flame retardants, PCMs flame retardation methods as well as examples of flame-retarded PCMs and their application areas were described. [ABSTRACT FROM AUTHOR]

Adhering to the thermal management requirements of prismatic battery modules, an improved lightweight parallel liquid cooling structure with slender tubes and a thin heat-conducting plate is proposed. The multiobjective optimization of the structure, operating parameters of the thermal management system, and thermal characteristics of a battery module are carried out. The effects of the equivalent diameter of the square tubes and the inner diameter of the circular tubes on the maximum temperature, maximum temperature difference of the batteries, and coolant pressure drop of liquid cooling battery thermal management system (BTMS) are investigated. The more significant factors, selected as the design variables, are the equivalent diameter of the square tubes, the inner diameter of the circular tube, and the coolant inlet velocity. Combining the computational fluid dynamics (CFD) method with multiobjective optimization, the different conditions of heat management parameters obtained by Latin hypercube sampling are numerically calculated, and the optimization of these parameters is carried out by the second-generation Elitist Nondominated Sorting Genetic Algorithm (NSGA-II). Compared with the thermal characteristics of the battery module before optimization, the maximum temperature of the module after optimization is reduced by 9.3%, the maximum temperature difference is reduced by 20.7%, and the coolant pressure drop from inlet to outlet is reduced by 49.1%. [ABSTRACT FROM AUTHOR]

Paraffin phase change materials (PCMs) exhibit great potential in battery thermal management (BTM); nevertheless, their application has been hampered by the handicap of low thermal conductivity, leakage, and volume expansion during phase transition. In this work, ternary composite PCMs formed of paraffin, expanded graphite (EG), and low-density polyethylene (LDPE) were developed for application in BTM. The structure and properties of the composite PCMs were characterized via X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and thermal constant analysis. The result shows that EG can form a large-size graphite frame as heat conduction paths to improve the thermal conductivity of the composite PCM, and LDPE can form an interpenetrating network within the composite PCM to resist the internal stress of paraffin expansion and prevent deformation. The latent heat and thermal conductivity of the composite PCMs loaded with 10 wt% EG and 4 wt% LDPE can reach 172.06 J/g and 3.85 Wm−1K−1 with a relatively low leakage ratio of 6.2 wt%. Remarkably, the composite PCMs could reduce the temperature rise of the battery by 55.1%. In brief, this work provides a feasible route to develop high-performance PCMs for BTM. [ABSTRACT FROM AUTHOR]

Nanoencapsulated phase change materials (NePCMs) are promising thermal energy storage (TES) and heat transfer materials that show great potential in battery thermal management systems (BTMSs). In this work, nanocapsules with a paraffin core and silica shell were prepared using an optimized sol-gel method. The samples were characterized by different methods regarding chemical composition, thermal properties, etc. Then, the nanocapsules were used as the coolant by mixing with insulation oil in the immersion cooling of a simulative battery. The sample doped with Ag on the shell with a core-to-shell ratio of 1:1 showed the best performance. Compared to the sample without doping material, the thermal conductivity increased by 49%, while the supercooling degree was reduced by 35.6%. The average temperature of the simulative battery cooled by nanocapsule slurries decreased by up to 3.95 °C compared to the test performed with pure insulation oil as the coolant. These novel nanocapsules show great potential in the immersion cooling of a battery. [ABSTRACT FROM AUTHOR]

Refrigerant indirect contact phase-change cooling system flows refrigerant into a cold plate and utilizes the phase-change to exchange heat with the battery. However, R134a, commonly used, is being gradually restricted due to its environmental impact. A new kind of near azeotrope mixed refrigerant R1234yf/R152a (mass ratio 60.5:39.5) is proposed under environmental protection and safety. Based on the fluid-structure interaction model, the evaluation of different indirect contact phase-change cooling systems for battery thermal management (BTM) using R1234yf/R152a is investigated. After obtaining battery (150 Ah, 3.2 V LiFePO4) parameters, heat generation power, and main test conditions through experiments, the thermal properties are numerically studied by computational fluid dynamics (CFD). At 1 C discharge rate, the temperature gradient (TG) of single battery and the maximum temperature difference (TD) among batteries are analyzed for two cases: The maximum TD among batteries of Case_b is 6.5°C lower than that of Case_a. In addition, the effect of the mixed refrigerant and traditional liquid cooling on the battery temperature is studied at different evaporation temperatures (ETs) (20°C, 25°C) and different mass flow rates (MFRs) (0.02, 0.10, and 0.18 kg/s). The results show that both the increase of inlet MFR and the reduction of inlet ET may significantly improve the battery module cooling rate. Compared with 0.02 kg/s, as the MFR increases, the temperature drop slopes to 9.56 and 11.2 at 20°C. The battery module temperature uniformity is improved with the increase of ET. Overall, the mixed refrigerant has advantages in temperature uniformity and consistency. The new mixed refrigerant plays a positive role in controlling battery temperature. [ABSTRACT FROM AUTHOR]

This work investigates on the performance of a hybrid energy storage system made of a metal hydride tank for hydrogen storage and a lithium-ion battery pack, specifically conceived to replace the conventional battery pack in a plug-in fuel cell electric scooter. The concept behind this solution is to take advantage of the endothermic hydrogen desorption in metal hydrides to provide cooling to the battery pack during operation. The analysis is conducted numerically by means of a finite element model developed in order to assess the thermal management capabilities of the proposed solution under realistic operating conditions. The results show that the hybrid energy storage system is effectively capable of passively controlling the temperature of the battery pack, while enhancing at the same time the on-board storage energy density. The maximum temperature rise experienced by the battery pack is around 12 °C when the thermal management is provided by the hydrogen desorption in metal hydrides, against a value above 30 °C obtained for the same case without thermal management. Moreover, the hybrid energy storage system provides the 16% of the total mass of hydrogen requested by the fuel cell stack during operation, which corresponds to a significant enhancement of the hydrogen storage capability on-board of the vehicle. • Hybrid energy storage system for plug-in fuel cell electric scooter • Numerical modelling of metal hydride tank integrated with battery pack • Passive, self-sustained thermal management of metal hydride tank and battery pack • Enhanced on-board energy density and improved vehicle driving range [ABSTRACT FROM AUTHOR]

Liquid fuel has been the main source of energy in internal combustion engines (ICE) for decades. However, lithium-ion batteries (LIB) have replaced ICE for environmentally friendly vehicles and reducing fossil fuel dependence. This paper focuses on the comparative analysis of battery thermal management system (BTMS) to maintain a working temperature in the range 15–35 °C and prevent thermal runaway and high temperature gradient, consequently increasing LIB lifecycle and performance. The proposed approach is to use biodiesel as the engine feed and coolant. A 3S2P LIB module is simulated using Ansys-Fluent CFD software tool. Four selective dielectric biodiesels are used as coolants, namely palm, karanja, jatropha, and mahua oils. In comparison to the conventional coolants in BTMS, mainly air and 3M Novec, biodiesel fuels have been proven as coolants to maintain LIB temperature within the optimum working range. For instance, the use of palm biodiesel can lightweight the BTMS by 43%, compared with 3M Novec, and likewise maintain BTMS performance. [ABSTRACT FROM AUTHOR]

In a battery cooling system, by adopting a cooling optimization control strategy, the battery temperature under different external environments and load currents can be adjusted to ensure performance and safety. In this study, two modes of the thermal management system are established for the 6s4p (six serial and four parallel batteries in a stage) battery pack. A single particle model, considering battery aging, is adopted for the battery. Furthermore, a cooling optimization control strategy for the battery is proposed based on the triple-step nonlinear method, and then the optimization effect is validated under two C-rate charge–discharge cycles, NEDC cycles, and US06 cycles. Moreover, an extended PID control strategy is constructed and compared with the triple-step nonlinear method. A comparison of pump power, thermal behavior, and aging performance indicate parallel cooling is more advantageous. This verifies the validity of the triple-step nonlinear method and shows its advantages over the extended PID method. The present study provides a method to investigate the thermal behavior and aging performance of a battery pack in a BTM system, and fills in the research gaps in the cooling optimization control strategy for battery packs. [ABSTRACT FROM AUTHOR]

[Display omitted] • The thermal application of carbon nanotube from waste plastic was firstly studied. • The thermal conductivity of phase change composite material increased by 104%. • Latent heat capacity of phase change composite material retains 90.7%. • The produced carbon nanotube shows similar potential as commercial carbon nanotube. • This phase change nanocomposite is promising for battery thermal management. Carbon nanotube (CNT), has been demonstrated as a promising high-value product from thermal chemical conversion of waste plastics and securing new applications is an important prerequisite for large-scale production of CNT from waste-plastic recycling. In this study, CNT, produced from waste plastic through chemical vapor deposition (pCNT), was applied as a nanofiller in phase change material (PCM), affording pCNT-PCM composites. Compared with pure PCM, the addition of 5.0 wt% pCNT rendered the peak melting temperature increase by 1.3 ℃, latent heat retain by 90.7%, and thermal conductivity increase by 104%. The results of morphological analysis and leakage testing confirmed that pCNT has similar PCM encapsulation performance and shape stability to those of commercial CNT. The formation of uniform pCNT cluster networks allowed for a large CNT loading into the PCM on the premise of free phase change, responsible for the high thermal conductivity inside the homogeneous phase. Thus, the resulting capillary forces retained a high latent heat capacity and suitable melting temperature and prohibited PCM leakage from the matrix to the outside during re-melting as the pCNT loading ratio increased. Therefore, the as-prepared pCNT-PCM composite is believed to have similar potential to cCNT and shows prominent performance as a flowable conductive filler for battery thermal management systems. [ABSTRACT FROM AUTHOR]

Lithium batteries in the electric vehicles (EVs) reveal that the operating temperature and temperature uniformity within the battery pack significantly affect its performance. An efficient thermal management system is urgently needed to protect the battery module within suitable temperature range. In this study, the composite silica gel (CSG), coupled with cross-structure mini-channel cold plate (MCP) as the cooling system, has been proposed and applied in a battery module, which can provide a reliable method of controlling battery temperature with low energy consumption. The experimental and simulation results reveal that a composite silica gel-based liquid system can control the temperature below 45 °C and maintain the temperature difference within 2 °C at a 3C discharge rate. Besides, the CSG, coupled with the structure of reciprocal chiasma channels for the battery module, presents an optimum temperature-controlling performance among various cooling structures during the charge and discharge cycling process. This research is expected to provide significant insights into the designing and optimization of thermal management systems. [ABSTRACT FROM AUTHOR]

The trend of transition from fossil fuel to electrification in transportation is a result of no carbon emission produced by electric vehicles (EVs) during their daily operations. Furthermore, the global carbon footprint of EVs can be minimized if the electricity is generated from renewable sources such as wind and solar. On the other hand, there are some drawbacks of these vehicles such as charging time being very long and the mileage range of vehicles not at the desired level. Battery cells are being charged at relatively high C‐rates to eliminate these problems, yet high current rates accelerate the aging of batteries and capacity losses due to the generated heat. Generated heat causes overheating, and excess temperature triggers degradation and thermal runaway risks. This paper uncovers how the battery pack temperature uniformity and strict thermal control can be achieved with heat transfer enhancement by conduction (cold plates) and convection (vascular channels). We aimed to reduce the energy consumption of the EV battery pack system while increasing the thermal performance. The impact of the thermal contact resistance is also considered for many realistic scenarios. The results indicate that an integrated system with cold plates and vascular channels satisfies the temperature uniformity requirement (over 81%) with comparatively less pumping power (∼72%) of advanced electric vehicles for relatively high C‐rates. Furthermore, findings show the temperature level can increase up to 4°C as thermal contact resistance increases. The proposed cooling technique, which has low cost, easy application, and lower energy consumption superiorities, can be implemented in palpable EV battery packs. [ABSTRACT FROM AUTHOR]

The Thermal Management System (TMS) of the battery is one of the most significant systems in the building of an electric vehicle, with the goal of improving the battery's performance and life. The benefits and drawbacks of the proposed Battery Thermal Management System (BTMS) solutions are thoroughly examined, as well as the adaptability of these systems. The purpose of this paper is to critically evaluate previous studies and research on the types, designs, and operating principles of BTMSs used in the building of various‐shaped lithium‐ion batteries, with a focus on cooling methods. The information thus compiled provides necessary and valuable information to people interested in this area, as well as future research directions, which may be utilized to improve the effectiveness of the BTMSs and hence the overall efficiency of the electric car. Details of various TMSs, such as air, Phase Change Material (PCM), Heat Pipe (HP), liquid, and immersion cooling, are addressed and contrasted with the goal of enhancing exterior heat dissipation. The major drawback of PCM‐ and HP‐based systems is the efficient change of state is not achieved, which results in a poor cooling effect of the battery pack. Liquid cooling is suggested as the most suitable method for large‐scale battery packs charged/discharged at higher charge rates (C‐rates) and in high‐temperature environments and it is suggested as the most suitable method for large‐scale battery packs charged/discharged at higher C‐rates and in high‐temperature environments. [ABSTRACT FROM AUTHOR]

Fast charging and discharging are keen focus areas of electric vehicles (EVs) in order to reduce vehicle down time and support the variable load requirement. In EVs, mainly lithium batteries with various chemistry such as NCA (nickel cobalt aluminum oxides), LTO (lithium titanate oxide), LFP (lithium iron phosphate), LNO (lithium nickel oxide) and NMC (nickel manganese cobalt oxides) are used as energy storage system. Performance of lithium batteries varies with the chemistry and temperature of batteries along with surrounding conditions. More heat is generated during fast charging and discharging of batteries which lead to high temperature rise and further impact the performance, life and safety of batteries. Thus, it's essential to study the thermal behaviour for fast charging and discharging of various lithium batteries to provide desired thermal management system for safety and better performance. In this paper, the thermal characteristics of various 18650 lithium batteries including NCA, NMC and LFP are investigated experimentally and numerically from slow charging and discharging loading rate of 0.5C to fast charging and discharging loading rates of 1.5C and 2.5C at different surrounding temperature of 27°C and 45°C. In the numerical investigation, the internal resistance of the batteries is first measured experimentally at various SOCs and battery temperatures, and then the battery surface temperature is determined using an appropriate numerical method for solving the energy balance equation. From slow to fast loading rates at varying ambient temperatures, the numerical study approach presented in this work estimates the battery surface temperature with at least 90% accuracy for the whole duration of the load cycle. The thermal assessment of NCA, NMC, and LFP batteries in this work can help to determine battery management system operating strategies and, ultimately, to develop an appropriate thermal management system. [ABSTRACT FROM AUTHOR]

The thermal management system of batteries plays a significant role in the operation of electric vehicles (EVs). The purpose of this study is to survey various parameters enhancing the performance of a heat pipe-based battery thermal management system (HP-BTMS) for cooling the lithium-ion batteries (LIBs), including the ambient temperature, coolant temperature, coolant flow rate, heat generation rate, start-up time, inclination angle of the heat pipe, and length of the condenser/evaporator section. This review provides knowledge on the HP-BTMS that can guarantee achievement of the optimum performance of an EV LIB at a high charge/discharge rate. [ABSTRACT FROM AUTHOR]

The pumped two-phase cooling method is a practical way to dissipate heat from the battery module. The operating parameters of the cooling system should be investigated thoroughly to improve the performance of the battery thermal management system (BTMS). However, the previous BTMS designs only explored the thermal performance and ignored the electrical performance in the battery module. This study designed a pumped two-phase cooling BTMS with the refrigerant of R1233zd. An electrothermal coupled model was established for a series-connected battery module to predict thermal and electrical behavior. The results showed that the pumped two-phase cooling system could obtain excellent cooling performance with low system pressure under 2C discharging condition. The average temperature of the module and the temperature difference among cells could be maintained under 40 °C and 5 K under a 2C discharging rate. A lower saturation temperature, higher mass flux, and higher subcooling degree could enhance heat dissipation for the cooling system based on R1233zd. An increase in the saturation temperature and a decrease in the subcooling degree could enhance the temperature uniformity within the module. The battery consistency was mainly dominated by the temperature difference and deteriorated with a lower average temperature in the pack. The research outcome of this paper can guide the design and optimization of the pumped two-phase cooling BTMS. [ABSTRACT FROM AUTHOR]

Electric vehicles (EVs) are booming all over the world for a low carbon emission and greener environment. The fast charging is an urgent demand for consumers. However, the dramatic temperature rising during high-power charging has a high risk of trigging thermal runaway and other safety issues. This article proposes an external liquid cooling method for lithium-ion battery module with cooling plates and circulating cool equipment. A comprehensive experiment study is carried out on a battery module with up to 4C fast charging, the results show that the three-side cooling plates layout with low coolant temperature provides better temperature control effect, while the coolant velocity and type have very weak impact. Then the simulation model with high precision is built for ultra-fast charging, and a safe charging range under 5C charging is proposed. The safe charging range under 5C can be increased by 50.1%. The environment close to the room temperature demonstrates the best effects of external cooling. For actual applications in the EVs, the circulating cooling equipment outside EVs can be integrated with high-power charging infrastructure and provide a 117 km improvement in mileage under 5C safe charging which indicates a tremendous application prospect. [ABSTRACT FROM AUTHOR]

The battery thermal management system with phase change material coupled cold plates was investigated with the numerical simulation method. The results show that, the temperature and temperature difference of the battery pack decreases with the increase of the flow rates of the cold plate in the system, while the power consumption of the cold plate significantly increases, which leads to poor efficiency of the system. To improve the efficiency of the coupled thermal management system, an adjusting strategy was introduced to optimize the thickness distribution of phase change materials with the system volume fixed. The optimized results of typical cases show that, the optimal phase change material thickness distribution can be obtained by only 5 adjusting steps. Compared with the original system, the maximum temperature of the battery pack drops by 1.1 K and the temperature difference narrows down by 29% after the optimization. To achieve the same temperature difference in the battery pack, the power consumption of the optimized system lowers down by 64% compared with that of the original system. [ABSTRACT FROM AUTHOR]

Highlights: The phase change materials possess conformable configuration to the structure of Li-ion batteries in macro-scale and multidirectional thermal pathways for rapid and uniform heat transfer in micro-scale. Hierarchically structured phase change materials achieve dual-mode thermal management ability for heating and cooling Li-ion batteries. Excellent practical battery thermal management performance was verified by 18,650 Li-ion batteries in both cold and hot environments. Phase change materials (PCMs) are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries (LIBs) according to real-time thermal conditions, guaranteeing the reliable operation of LIBs in both cold and hot environments. Herein, we report a liquid metal (LM) modified polyethylene glycol/LM/boron nitride PCM, capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction. Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB's structure and heat-conduction characteristic. Typically, soft and deformable LMs are modified on the boron nitride surface, serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m−1 K−1 in the vertical and in-plane directions, respectively. In addition, LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system. As a proof-of-concept, this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10 °C at high charging/discharging rate, opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway. [ABSTRACT FROM AUTHOR]

Application of refrigerant-cooled multi-channel evaporators (MCEs) is a promising solution to cool electric vehicle batteries because the non-uniformly distributed heat from a battery can be efficiently dissipated by suitable arrangement of the multi-channels in an MCE. In order to provide a simulation tool for the design of an MCE, a distributed parameter model for quickly predicting the performance of an MCE at various channel arrangements and non-uniformly distributed heating conditions is useful, and thus it is developed in this study. In the model, heat and mass transfer in multiple flow paths in an MCE are separately described; the uneven mass flow distribution among these channels is predicted based on the pressure balance; each flow path is divided into multiple control volumes to reflect the non-uniformly distributed heating conditions; and the mass flow distribution among flow paths and the heat transfer in all the control volumes are jointly solved by a combined iteration algorithm of pressure drop and heat transfer. The proposed model is validated by experiments under the condition of battery heat flux ranging from 500 to 1500 W m−2. The results show that the prediction deviations of the average temperature and the highest temperature on the MCE surface from the experimental ones are 1.5 °C and 1.6 °C, respectively, which indicates that the proposed model can well predict the thermal performance of MCE under non-uniformly distributed battery heat. • A distributed parameter model of refrigerant-cooled MCE for power battery is developed. • Refrigerant flow among multi-channels is modeled as uneven flow with fix direction. • Arbitrary heat flux input can be calculated by the model. • The average deviation of temperature predictions is less than 3.0 °C. [ABSTRACT FROM AUTHOR]

The in-depth research on the heat exchanger for lithium-ion batteries is of significant importance due to its crucial role in ensuring the safe operation of electric vehicle (EV) power systems. To enhance the thermal and flow characteristic of the heat exchangers, the novel heat exchangers for 18650-cylinderical lithium-ion batteries have been proposed by topology optimization with the minimization of pressure drop and the lowest average temperature (∏ 1) and the minimization of pressure drop and the lowest temperature difference (∏ 2) as two different optimal goals. The topology optimization based on the variable density method is utilized to get two-dimensional (2D) optimal channels, and then the optimized results are extended to three-dimensional (3D) heat exchangers. The 3D heat exchangers are named TOHE-1 which is gotten by stretching the topology channels with ∏ 1 as optimal goal and TOHE-2 which is gotten by that with ∏ 2 as optimal goal. Subsequently, a detailed thermodynamic analysis is performed to assess the effect of the type of heat exchangers, channel heights, weight factor of topology optimization function, mass flow rates and discharge rates on the cooling effect of the batteries. The results show that compared with the traditional channel heat exchangers, the heat transfer coefficient of topological heat exchangers have increased by 49.92%, while reducing pressure drop by 27.81%. Meanwhile, compared to TOHE-1, heat transfer coefficient of TOHE-2 is increased by 9.70%, while pressure drop is saved by 4.70%. Other studies have indicated that for a 4 C discharge of the battery, a topological heat exchanger with a channel height of 1.5 mm, a thermal performance weight factor of 0.1, and a mass flow with 3.3 × 10−3 kg s−1 is the optimum heat dissipation scheme. Finally, the numerical studies are verified by conducting the convective heat transfer experimental tests. [Display omitted] • The topology optimization heat dissipation scheme for cylindrical lithium batteries is proposed. • The performance of topological heat exchangers is studied numerically and verified experimentally. • The performance of different functional types of topological heat exchangers is compared. • The ratio of heat dissipation scheme to battery weight is considered in cooling scheme design. [ABSTRACT FROM AUTHOR]

• Design for hybrid battery pack with high energy density and high safety. • Thermal Management Optimization Layout Design for Hybrid Battery Packs. • The P2D model is used to study electrochemical properties of single battery. • Multiphysics coupling analysis of electro-thermal behavior. • The SOC estimation method for hybrid battery pack. As traditional battery systems, lithium iron phosphate (LFP) batteries have better safety but lower energy density and nickel manganese cobalt oxide (NMC) batteries have higher energy density but poorer safety. In this work, we design a hybrid battery pack that has both higher energy density and higher battery safety. By analyzing the thermal properties of battery packs with aligned, staggered, and staggered arrangements, it can be concluded that the aligned arrangement has superior cooling efficiency and space-efficient optimization compared to the other arrangements, which have shorter flow paths to minimize air energy loss and reduce pressure drop. Notably, we design the optimal arrangement to avoid placing the NMC cells near the air outlet, to avoid NMC concentration, and to decentralize the LFP cells to reduce the relatively high maximum temperature and temperature difference. This hybrid battery pack is expected to give a boost to lithium-ion battery applications. [ABSTRACT FROM AUTHOR]

To maintain the optimal operating temperature range for the power batteries of new energy vehicles, this paper proposes a novel tree-structured channel cold plate. An orthogonal experimental approach was employed to investigate the effects of inlet flow rate m, inlet channel quantity n, channel width d, and hierarchy ratio α on battery temperatures T max , standard temperature difference T σ , and pressure drop Δ P. Non-dominated sorting genetic algorithm II (NSGA-II) was utilized to obtain an optimized solution set. The results reveal that the tree-like cold plate configuration including m = 15 g/s, n = 7 and 8, d = 3 mm, and α = 1:2:1 demonstrates superior performance. Thus, the developed cold plate was further compared with the conventional straight-through cold plate design. The results indicate that the proposed tree-like cold plate exhibits the maximum decreases of 13.94% in T max , 52.94% in T σ , and 61.5% in Δ P. The most significant improvement in the composite indicator PEC was 89%. In conclusion, the tree-like channel cold plate developed in this study provides excellent heat dissipation capability for power batteries, offering valuable insights for the thermal design of battery liquid cooling systems. [ABSTRACT FROM AUTHOR]

Electric autonomous underwater vehicles (AUVs) are facing more urgent battery thermal management (BTM) demands than electric cars, as their battery compartment design is constrained by limited volume, airtightness and impact loads. In this paper, a novel hybrid battery thermal management strategy of metal foam/paraffin composite combined with thermal bridges is proposed for the AUVs' BTM. A three-dimensional model considering the non-thermal equilibrium effect for AUVs' battery module was developed. Gradient PCMs and gradient foam porosity were introduced to improve the temperature and melting behaviors in various regions of AUVs' battery pack. The trade-off between performance and weight of metal foam/PCM composite on AUVs' battery thermal management was also quantitatively analyzed. The results showed that the temperature in the top region of the battery pack was higher than that in the bottom region due to the natural convection of the liquid PCM. The positive gradient porosity of metal foam has the advantages of large porosity increasing the heat storage and small porosity improving the thermal conductivity, both benefit to reduce the maximum temperature of the battery module. The positive gradient latent heat and melting point hybrid strategy of PCM demonstrates the best thermal management performance when compared with constant parameter cases, and the maximum temperature of battery modules is more sensitive to the melting point of PCM. When the metal foam/PCM composite was introduced, the weight of the battery module increased by 27.1%, while the maximum temperature and temperature difference of the battery module decreased by 44.27 K and 11.1 K, respectively. The safe working time of the battery module was extended by 105.7%, and the mass-energy density that can be utilized was increased by 61.9%. The findings can help AUVs to achieve the goals of high speed and long range. • The metal foam/paraffin composite was innovatively used for AUVs' BTM. • A 3D model was established considering non-thermal-equilibrium effect. • The thermal and melting behaviors of battery module were discussed in depth. • The performance of metal foam/paraffin with gradient parameters was compared. • The trade-off between performance and weight of metal foam/paraffin was evaluated. [ABSTRACT FROM AUTHOR]

An optimization workflow combining Latin hypercube sampling (LHS), surrogate models and multi-objective optimization is explored and applied to augment the effectiveness of a hexagonal mini-channelled cooling plate proposed previously in mitigating the overheating issues of 20Ah pouch batteries. Three design parameters are selected and deliberately randomized to explore a range of geometric configurations that might not be readily apparent through traditional intuition. Alongside, two thermo-fluidic parameters are varied with an optimization objective to minimize maximum battery temperature, pressure drop and enhance heat transfer performance simultaneously. Initially, 160 sample points are generated using LHS, followed by simulations conducted using COMSOL Multiphysics for a fixed discharge rate of 3C and an ambient temperature of 35 °C. Then, Multi linear regression, Response surface approximation, Support vector machine, and Kriging model are considered in search of the best surrogate. Results highlighted that the Kriging model could make predictions more accurately and is used further. Later, a Pareto analysis is performed using non-dominated sorting genetic algorithm II to generate 100 optimal solutions influencing the three conflicting objectives. Finally, the best compromise solutions are obtained using a K-means clustering algorithm and are numerically validated. The case with a side length of 18.99 mm, a channel width of 4.99 mm, a branching angle of 91.51° and a coolant temperature of 25 °C is ideal. This aided in reducing the pressure drop by 62.32% and enhancing heat transfer coefficient by 64.41%, with a minimal change in maximum temperature compared to that of the initial design under the same mass flow rate limit of 0.003 kg s−1. In addition, the SHapley Additive exPlanations technique is employed to unravel the design and operating variable's impact on the objective functions. Overall, the proposed framework could be a valuable contribution to optimizing the cooling channel design and potentially boosting the battery lifespan. [Display omitted] • Performed multi-objective optimization of hexagonal cold plate design for Li-ion battery. • Identified Kriging as the superior model with a higher R2 value for different cases. • Implemented NSGA II to get optimal design, forming a balance amid conflicting goals. • SHAP insights in assessing the feature impact in the machine learning prediction. [ABSTRACT FROM AUTHOR]

Efficient cooling during rapid battery charging/discharging necessitates forced circulating flow in immersion cooling systems. However, under forced flow immersion cooling (FFIC), the comprehensive impact on the electrical and thermal performance of battery modules remains inadequately explored. This study constructs an immersion-cooled battery module test platform for experimental research on the evolution of electrical and thermal characteristics. The results show that under FFIC, when the depth of discharge (DOD) during 2C and 3C discharges is below 85 %, the voltage deviation of module (δ U,t) remains stable within 1 % and 2 %, respectively. At DOD of 100 %, the maximum δ U,t for 2C and 3C are 10 % and 24.5 %, respectively. Furthermore, the analysis of Pearson correlation coefficient under FFIC reveals that the δ U,t exhibits a very strong positive correlation with temperature difference of battery module and cell, with correlation coefficients of +0.94 and + 0.87, respectively. Higher flow rates accelerate the recovery of module temperature and facilitate voltage distribution equalization after discharge. Additionally, to elucidate the influence of flow rate on FFIC, module-scale heat transfer characteristics during battery discharge are theoretically analyzed, establishing a fitting relationship between C-rates, flow rates, and the Nusselt number (Nu). This study provides a comprehensive understanding of integrated electro-thermal performance and external heat transfer capability for flow regulation in immersion cooling. [Display omitted] • Immersion-cooled battery platform was developed for electro-thermal performance. • Evolution of module electro-thermal performance was analyzed at varied Re and C-rates. • Interaction and strength between electrical and thermal parameters were revealed. • Heat transfer characteristics during discharging were theoretically analyzed. • The relationships between discharge C-rate, Re and Nu were established. [ABSTRACT FROM AUTHOR]

In order to improve the low thermal conductivity of phase change materials for battery thermal management, paraffin-expanded graphite composite phase change materials with various contents were prepared. In the phase change energy storage unit, PA-EG composite phase change materials are used to wrap the heat source and the heat pipe is coupled to enhance its heat dissipation capacity. A square heating source is used to simulate the heating of a high-density energy battery, and the thermal management performance of the PA-EG composite phase change materials coupled heat pipe with different EG content is explored under different heating powers. The experimental results show that when the heating power is low, the thermal management performance of each phase change material is equivalent. When the heating power is higher, the higher EG content will bring higher thermal conductivity and better thermal management effect. When the EG content is 5%, the thermal conductivity can be increased to 6.36 times that of paraffin. The maximum cooling rate in the experiment can reach 7.6%, and the peak temperature difference in the phase change energy storage unit is 37.7% of that in the paraffin system. When the content of EG is low, the thermal conductivity of PA-EG composite phase change material is isotropic when it is not melted, but when the PA is melted, the strong natural convection heat exchange will cause uneven temperature distribution in the energy storage unit. It will easily lead to uneven temperature on the battery surface to produce stress, so the EG content should not be less than 5%. [ABSTRACT FROM AUTHOR]

In this work, we develop a hybrid battery thermal management (BTM) system for a 7 × 7 large battery module by coupling an epoxy resin (ER)-enhanced phase change material (PCM) module with internal liquid cooling (LC) tubes. The supporting material of ER greatly enhances the thermal stability and prevents PCM leakage under high-temperature environments. In addition, the other two components of paraffin and expanded graphite contribute a large latent heat of 189 J g−1 and a high thermal conductivity of 2.2 W m−1 K−1 to the PCM module, respectively. The LC tubes can dissipate extra heat under severe operating conditions, demonstrating effective secondary heat dissipation and avoiding heat storage saturation of the module. Consequently, during the charge-discharge tests under a 40 °C ambient temperature, the temperature of the PCM-LC battery module could be maintained below 40.48, 43.56, 45.38 and 47.61 °C with the inlet water temperature of 20, 25, 30 and 35 °C, respectively. During the continuous charge-discharge cycles, the temperature could be maintained below ~48 °C. We believe that this work contributes a guidance for designing PCM-LC-based BTM systems with high stability and reliability towards large-scale battery modules. [ABSTRACT FROM AUTHOR]

In advanced battery thermal management systems for electric vehicles, liquid cooling (LC) is typically coupled with a phase-change material (PCM) cooling for secondary heat dissipation. However, a continuous LC consumes a considerable amount of energy without considering the operating conditions. In this study, the thermal behaviors of tubular PCMs were examined under different liquid temperatures (25, 45, and 65 °C) to simulate the complex operating conditions of battery modules. In addition, a thermal management module coupling the PCM and copper pipe (CP) with LC was assembled to enhance the secondary heat dissipation of PCM cooling, particularly in a high-temperature environment. The experimental results confirmed the superior cooling effect of the PCM–CP module, even at high temperatures. Moreover, a dynamic LC (DLC) mode was proposed to reduce the energy consumption caused by LC, where LC operates intermittently. The effects of the LC activation time on the cooling behavior were explored. A coefficient illustrating the energy efficiency ratio (EER) was defined to evaluate the cooling performance and energy consumption of the two DLC modes with varying working times. The results proved that DLC-2 performed better than DLC-1 with E E R ¯ j values of 0.35 and 0.24, respectively. These results are expected to provide insights into the development of advanced energy-saving thermal management systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Different battery thermal management (BTM) for a 18650 cylindrical Li-ion battery pack were simulated based on the lumped model. Phase change material (PCM) was introduced for its benefits: high latent heat and uniform melting temperature. However, the heat absorbed into the PCM was not dissipated to the environment. Thus, an additional cooling mechanism was required to reach satisfying temperature limits (45 °C for lifespan and 50 °C for safety). These include natural convection cooling, forced convection cooling, finned-natural convection cooling, PCM cooling, and PCM cooling coupled with liquid cooling channels. The temperature of the battery pack using natural convection, finned-natural convection, and PCM cooling reached 62.1 °C, 55 °C, and 50 °C, which were equal or over (50 °C), while it decreased to 49 °C using forced convection, which was over (45 °C). However, PCM coupled with liquid cooling channels satisfied the requirements, and the temperature was reduced to 42 °C using this system. [ABSTRACT FROM AUTHOR]