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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]

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]

To maintain the optimal battery performance, it is essential to develop an efficient battery thermal management system for keeping the battery operation temperature within the appropriate range. In this work, a novel design of cold plate featuring airfoil fin channel is developed as a highly effective cooling module of a prismatic LiFePO 4 battery pack. The thermal performance of battery and the thermo-hydraulic performance of the cooling module for the cold plate featuring airfoil fin channel, U-type channel and serpentine channel are numerically investigated and compared to reveal the superiority of the novel cold plate. The results indicate that compared with the U-type channel and the serpentine channel, the airfoil fin channel can enhance the total heat dissipation amount by 3.47% and 4.64%, respectively. Besides, the airfoil fin channel can provide the smallest battery maximum temperature and temperature difference under the same coolant flow rate. The airfoil fin channel provides the smallest pressure loss and heat transfer coefficient but the largest overall thermo-hydraulic performance indictor in terms of j / f factor. Under the same requirement of battery cooling performance, the remarkably smaller power consumption is required for the airfoil fin channel compared with the U-type channel and serpentine channel. • A novel cold plate with airfoil fins is designed for cooling battery. • Performance of airfoil fin cold plate and two conventional cold plates is compared. • Airfoil fin cold plate is of the largest heat dissipation capacity. • Airfoil fin cold plate is of the best overall performance. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) is widely adopted to construct integrated battery thermal management systems (BTMSs) for all climates. However, integrated BTMSs in cylindrical battery modules remain arduous challenges due to the compact/massive cuboid-shaped PCM module and the curved surface of the cells. Herein, we propose a novel all-climate BTMS integrating units-assembled composite PCM (CPCM) module with force air convection. The CPCM module assembled by sleeve-like CPCM units provides developed airflow channels and enlarged heat transfer surface from 1.17 × 10−3 to 3.63 × 10−3 m2 for enhancing convective heat transfer. Consequently, compared to conventional cuboid-shaped module, the thermal resistance of the units-assembled module is remarkably reduced by 52.0% and 60.1%, and the heat flux is enhanced by 7 times under both cooling and preheating modes. In cooling tests, this BTMS demonstrates superior performance by controlling the temperature and temperature difference below 40.30 and 2.80 °C at 3-C discharge, respectively. In preheating tests, it effectively preheats the battery module from 0 to 10 °C in 302 s with a low temperature difference of 3.82 °C. Furthermore, this units-assembled CPCM module saves 53.8 wt% of the CPCM dosage, and thus the energy density of the battery module is increased from 75.6 to 94.4 Wh·kg−1. • All-climate BTMS integrates units-assembled CPCM module with force air convection. • Units-assembled CPCM module provides developed internal structure for heat transfer. • Thermal resistance of CPCM module is reduced, and heat flux is enhanced by 7 times. • BTMS shows superior cooling, preheating and heat-preservation performances. • BTMS reduces CPCM module weight, increasing the energy density of battery module. [ABSTRACT FROM AUTHOR]

The era of electric mobility has started, and petrol/diesel vehicles are being replaced by electric vehicles (EVs). The phase change material (PCM) is a trending field of research in its application of energy storage and thermal management. PCM-based thermal management method is found to be quite simple and effective for battery packs. However, its commercialization is difficult due to its low thermal conductivity and extra weight addition to the battery pack. Hence, the present research focuses on the battery performance with PCM. The experimental setup for a 48V, 25Ah battery pack is developed, and its performance is explored with and without PCM. The numerical model for same sized battery pack is developed, and validated with experimental results. The major objective of the present research is to find the optimal gap between two battery cells so that a sufficient amount of PCM can be filled inside the battery pack. Initially, inline and staggered cell arrangements are examined, and no significant difference in thermal performance is found. Further, cell spacing of 5 mm, 3 mm, and 1 mm are examined, and maximum temperature and temperature difference are compared along with the weight and volume of the battery pack. For a single charging process, 1 mm cell spacing is found sufficient, considering the weight of the battery pack and thermal performance. However, with 1 mm cell spacing, temperature increases significantly after each charging and discharging. At the same time, 3 mm and 5 mm are found as feasible solutions considering single and double charging-discharging cycles, respectively. 3 mm cell spacing is better option when weight is a critical issue, while 5 mm cell spacing is better when thermal performance is a critical issue. The current study offers guidance in the advancement of battery packs, particularly in cases where space constraints are a concern. • The research focuses on utilization of optimal amount of PCM. • The battery charging experiments are carried out on 48V, 25Ah battery pack. • PCM OM42 reduced battery temperature by 18 %. • The inline and staggered arrangements are found equally effective. • 3 mm cell spacing is found sufficient with limited weight increment. [ABSTRACT FROM AUTHOR]

The heat dissipation performance of batteries is crucial for electric vehicles, and unreasonable thermal management strategies may lead to reduced battery efficiency and safety issues. Therefore, this paper proposed an optimization strategy for battery thermal management systems (BTMS) based on linear time-varying model predictive control (LTMPC). To begin, based on the results of three-dimensional thermal flow analysis, a reduced order substitution model for the battery cooling system was established. Next, to address the issue of high computational complexity caused by the nonlinear model in the controller, a linearization method based on staged control was designed. Furthermore, the control parameters were optimized using the particle swarm optimization algorithm. Finally, a BTMS physical model based on SIMSCAPE was established for performance simulation. The performance of the logic threshold controller (LTC), linear model predictive controller (LMPC), and nonlinear model predictive controller (NMPC) was compared and analyzed. LTMPC was found to reduce the average temperature of the battery by up to 2.33 °C and 1.90 °C, and the cumulative temperature difference is reduced by 13.9% and 16.6% compared to LTC and NMPC, respectively. Compared to LMPC, LTMPC reduces thermal management energy consumption by 21.2%. • A complete mathematical model of the liquid cooling cycle circuit was derived through the order reduction method. • Reasonably incorporate future information into the controller to improve robustness of system. • Adopting a staged control strategy to segment the model, establishing a linear time-varying control model, greatly improving computational efficiency. • The upper controller uses the heat exchange between the coolant and the air conditioning system as the control variable, improving control efficiency. • The combination of particle swarm optimization algorithm and pareto curve fully exploits the optimization potential of parameters. [ABSTRACT FROM AUTHOR]

In order to improve the heat dissipation performance of lithium-ion batteries in hot climate, a coupled heat dissipation model including different air inlet and air outlet arrangements and PCM thicknesses was established by extracting cooling air from a vehicle air-conditioner. At the condition of the fixed PCM thickness, the effects of air inlet and air outlet arrangement on heat dissipation performance (HDP) of battery pack were researched, and the results indicate that case 5 is the optimal choice because of the low energy consumption and good HDP. The results of PCM thickness on HDP of battery pack be investigated through catastrophe theory analysis method. Thus, the results reveal that case 8 has highest evaluation value 0.97536 of the heat dissipation level of the battery pack among them. Based on the above results, four cases had been investigated to pursue the lower temperature difference of battery pack, and the results indicate that case 10 is the optimal choice, because of the lower energy consumption and temperature difference. • A coupled heat dissipation model including different air inlet and air outlet arrangements and PCM thicknesses was established. • Effects of different conditions on the heat dissipation of the battery pack is studied. • Catastrophe model was used to evaluate the heat dissipation level of the battery pack. [ABSTRACT FROM AUTHOR]

This paper describes a set of experimental tests carried out to better understand the thermal behavior of Lithium-ion batteries under load and the capability of various cooling fluids in maintaining the working conditions within a safe range for the cells. Despite several theoretical models are available in the literature, very few experimental data are reported. Different types of cells have been analyzed. The generation of hot spots has sometimes been registered, their occurrence being independent of cell geometry and size; instead, the battery's history and age, appeared the main factors in determining the onset of hot spots on the surface of the cell. Two experimental rigs have been set up to test the capability of different cooling fluids in removing the surplus heat generated in a Li-ion battery module, where the cells of interest have been replaced with electrically heated elements with the same thermal characteristics of the cells. It was thus possible to safely investigate "extreme" operating conditions, where the occurrence of a thermal runaway is possible. Among the tested fluids, air was unable to adequately limit the surface temperature increase, while a perfluorinated polyether, allowed to work within the optimal temperature range, even under severe operating conditions. • The thermal behavior of different types of Li-ion batteries has been experimentally investigated. • The cells have been tested under both ordinary and severe operating conditions. • Dangerous operating conditions of the batteries have been identified. • A reliable and dedicated experimental facility has been set up. • The cooling efficiency of a range of thermal fluids has been evaluated. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the thermal management based on phase change slurry (PCS) and mini channel cooling plate for the lithium-ion pouch battery module was proposed. The three-dimensional thermal model was established and the optimum structure of the cooling plate with mini channel was designed with the orthogonal matrix experimental method to balance the cooling performance and energy consumption. The simulation results showed that the cooling performance of PCS consisting of 20% n-octadecane microcapsules and 80% water was better than that of pure water, glycol solution and mineral oil, when the mass flow rate was less than 3 × 10−4 kg s−1. For different concentrations of PCS, if the mass flow rate exceeded the critical value, its cooling performance was worse than that of pure water. When the cooling target for battery maximum temperature was higher than 309 K, the PCS cooling with appropriate microcapsule concentration had the edge over in energy consumption compared with water cooling. At last, the dimensionless empirical formula was obtained to predict the effect of the PCS's physical parameters and flow characteristics on the heat transfer and cooling performance. The simulation results will be useful for the design of PCS based battery thermal management systems. Highlights • Battery thermal management based on the PCS and mini channel was proposed. • The cooling plate was designed to balance the cooling effect and energy consumption. • The management cooled battery effectively and performed better than water cooling. • The optimal mass flow rate for different concentrations of PCS was determined. • The dimensionless empirical formulas were obtained. [ABSTRACT FROM AUTHOR]

Aiming at the problems of irreversible decay and shortened life of the battery caused by high temperature during the operation of power battery pack, a novel composite phase change material based on metal-organic framework (MOF) was proposed in this work. MIL-101-NH 2 , an amino functionalized MOF material, was grown in situ on expanded graphite (EG) to synthesize hierarchical structure-based loading material for efficient loading of phase change material lauric acid (LA). The microstructure and structure of the composite phase change materials, thermal properties such as phase change temperature and latent heat, thermal conductivity, thermal stability, thermal cycling properties, as well as thermal stability and thermal cycling properties were tested. The results show that amino functionalization of the loading materials is helpful to further improve the loading rate and latent heat of the composite phase change materials. LA/MIL-101-NH 2 and LA/EG@MIL-101-NH 2 can be loaded up to 70% and have high phase change latent heat (97.74 J/g and 94.55 J/g). When applied to battery thermal management, LA/EG@MIL-101-NH 2 can reduce the battery temperature by 4.5–22.3% under the discharge conditions of 1C, 2C, 3C, 4C and the cycle condition, and keep the safe temperature below 50 °C, which provides a new idea for passive thermal management of batteries. • A composite phase change material based on metal-organic skeleton is proposed. • Thermophysical parameters of composite phase change materials is tested. • A new idea for passive thermal management of batteries is provided. [ABSTRACT FROM AUTHOR]

A coupled battery thermal management (BTM) system based on novel quaternary phase change material plate (PCMP) is developed to balance the temperature in rectangular LiFePO 4 battery modules. Paraffin (PA), expanded graphite (EG), low-density polyethylene, and copper mesh were combined into a quaternary PCMP to strengthen the heat transfer. The thermal conductivity of the PCMP with double copper mesh (DCM-PCMP) was increased by 36.0% compared with that of PCMP composed of EG and PA. Accordingly, the DCM-PCMP reduced the maximum temperature and maximum temperature difference within the battery module to less than 52.8 and 3 °C, respectively, both the lowest among the four methods. The coupled system based on DCM-PCMP and forced air convection showed excellent thermal performance, which contributed to a stable temperature during the cycling process. Thermal simulations showed that the double outstretched copper mesh through the DCM-PCMP disturbed the air flow tempestuously, giving rise to a decrease in thermal resistance. Thus, the temperature distribution inside the battery and temperature uniformity within the battery module were both better optimized. The analysis of the power consumption of the DCM-PCMP method revealed that the optimal heat dissipation performance for the battery module is achieved at an air velocity of 6 m/s. [ABSTRACT FROM AUTHOR]

Driven by the development of electric vehicles, there is an unmet need to protect power battery from sharp temperature rise and thermal runaway. This study aims to design a new type of composite phase change material for thermal management of battery. By adsorption of lauric acid (LA), LA/EG@HPC composite phase change material with stable shape can be obtained. The BET surface area of the carrier is 15.9326 m2/g, and the pore size distribution is mainly mesoporous and macroporous. The three-dimensional structure of the carrier can provide a continuous layered heat transfer network channel for LA. The load rate of the composite phase change material can be up to 70%, and the thermal conductivity is 2.546 W/(m·K), 8.4 times that of pure LA. In addition, currently MOF materials used in phase change material carrier are synthesized by reaction kettle. The solvothermal method adopted in this study can greatly improve the single synthesis yield and is easy to operate. The composite phase change material shows excellent performance in the thermal management of batteries. In the discharge test of different rates, the maximum temperature of the battery pack is reduced by 13.4 °C compared with that of the battery pack without thermal management, the temperature difference of the battery is reduced by 1–1.5 °C, and the operating temperature is far lower than the safe temperature of 50 °C. During the cycle test, the temperature fluctuation of composite phase change material group is reduced by 45% under DST condition, and the temperature of the battery under constant high rate condition is maintained below the safe temperature, which has a remarkable thermal management effect. • LA/EG@HPC composite phase change material with stable shape was obtained. • Solvothermal method was used to improve the single synthesis yield. • Novel composite phase change material was used in the thermal management of batteries. [ABSTRACT FROM AUTHOR]

When an energy storage system (ESS) operates in cold conditions, the power and capacity of the battery critically fade. Therefore, an appropriate battery thermal management strategy (BTMS) is essential to prevent severe driving range loss at low ambient temperatures. However, none of existing studies considered the effect of BTMS on the driving range from a systematic perspective. Thus, we evaluated the trade-off between the performance enhancement by ESS heating and the additional energy consumption for ESS heating. We suggested and analyzed three BTMSs combined with a secondary heat pump: self-heating, active heating, and heat recovery. Active heating of the battery augmented the driving range of the EV by up to 18.8% over the self-heating strategy when the battery was used to full depletion, whereas the heat recovery strategy reduced the state-of-charge (SOC) decrease and thus increased EV driving range in nondepleted conditions. Furthermore, battery preheating with the heat pump achieved a temperature rise of 20 °C within an hour, consuming 38.4% less battery power than with conventional electric heater preheating. We expect this study contributes to the range extension of EV by suggesting the optimal BTMS depending on the driving conditions. • Experiments on the battery performance were conducted at low temperatures. • Battery thermal model was established and integrated with transient heat pump model. • Three strategies for battery thermal management were suggested. • Integrated thermal management model derived the optimal strategy under cold-start. [ABSTRACT FROM AUTHOR]

Thermal management of electric vehicles, especially battery thermal management, is critical to driving range and operational safety. To find a vehicle thermal management system with higher energy efficiency and environmental protection, an environmentally-friendly and efficient battery and cabin parallel cooling thermal management system was evaluated with CO 2 as the working fluid. First, different control strategies of the evaporation temperature were compared regarding the battery cooling performance. Then, the effect of the battery cooling evaporation temperature on the coefficient of performance (COP) was explored. It was found that the maximum COP increased by 8.38% as the evaporation temperature decreased from 17 to 5.8 °C. Besides, it was found that the optimal battery cooling evaporation temperature range is 10.2–11 °C when the battery heating power is 0.4 kW. The vapor quality at the cold plate outlet should be lower than 0.95. Finally, the battery cooling performance under variable operating conditions was investigated. The influence of operating parameters on the battery cooling evaporation temperature and CO 2 outlet vapor quality was also analyzed. Simulation results showed that the optimum evaporation temperature range varied significantly under different working conditions. The vapor quality at the cold plate outlet decreased slightly with the evaporation temperature. • A transcritical CO 2 battery direct cooling thermal management cycle is studied. • The temperature distribution characteristics of the battery surface are revealed. • The effects of CO 2 temperature and vapor quality on performance are researched. • Suggestions on optimal CO 2 temperature and vapor quality in BTM control are given. [ABSTRACT FROM AUTHOR]

In this study, a hybrid liquid cold plate design containing Z-type parallel cooling channel and PCM/aluminum foam composite, in conjunction with a novel delayed cooling strategy, is proposed to provide a compact, lightweight, and energy efficient solution for battery thermal management systems (BTMSs). A total of nine different cold plate designs, including one baseline cold plate without PCM composite and eight hybrid cold plates containing PCM composite, are analyzed systematically to demonstrate the superior cooling performance of the proposed cooling design. Specifically, the average temperature of battery surface and total power consumption performance of each design are analyzed and compared at a battery discharging rate of 1C under both continuous and delayed cooling schemes. Subsequently, two selected designs with superior cooling performance as well as the baseline cold plate are further investigated to discuss the effectiveness of hybrid liquid cold plates for cooling batteries at high discharge rates. The results show that the optimum hybrid cold plate design, which only weighs half of the baseline cold plate, can provide more than 50% reduction in the total pumping power while achieving the same cooling performance (i.e., with the average battery temperature controlled within 40 °C) compared with the baseline cold plate at battery discharging rates of 1C, 2C and 3C. These results can potentially provide important guidance to the design of advanced cooling systems for lithium-ion batteries. • A compact and lightweight battery thermal management system is proposed. • A delayed cooling strategy is proposed and analyzed. • Cooling performances were compared between different designs numerically. • Optimum cooling system allows >50% reduction in power consumption and weight. [ABSTRACT FROM AUTHOR]

As an important method for battery thermal management, traditional phase change material (PCM) technology is facing challenges due to the relatively low thermal conductivity, weak skeleton strength and/or leakage phenomenon of PCM. Herein we develop a copper mesh (CM)-enhanced paraffin (PA)/expanded graphite (EG) composite as a composite PCM for battery thermal management. EG with porous structure can absorb liquid phase PA, preventing PA leakage. CM acts as a skeleton to further enhance both the thermal conductivity and strength of the whole module. As a result, the as-constructed CM enhanced PCM of PA/EG plate (PCMP) presents much better heat dissipation performance and temperature uniformity compared to PCMP without CM, especially in harsh working conditions. Moreover, with forced air convection, copper fins exposed from the composite may play a crucial role in not only heat dissipation, but also disturbing the air flow, and thus further strengthen the heat transfer capability. [ABSTRACT FROM AUTHOR]

An efficient and safe thermal insulation structure design is critical in battery thermal management systems to prevent thermal runaway propagation. In this paper, using a common real-life overcharge as a trigger for battery runaway, we investigate the runaway response of the battery module without thermal insulation and with various thermal insulation materials. The experimental results indicate that the thermal insulation has the effect of stopping the thermal spread of the battery module and reducing the maximum temperature. By comparing the temperature change of the batteries, it is discovered that the fiber-based material has a temperature drop efficiency of 71.83%, while the aerogel materials are at least 13% more efficient in temperature reduction than fibrous materials. Meanwhile, it is demonstrated that by examining the capacity characteristics of the damaged battery and the characteristics of the insulation material, the pre-oxidized silk aerogel has the best thermal spread suppression effect and the TG (thermogravimetric) variation withstood high temperatures of up to 746 °C. SEM (scanning electron microscope) morphology for different insulation materials before and after combustion show that pre-oxidized silk aerogel maintains a strong thermal insulation capacity in the thermal spreading. It is expected to have a guidance for the design of thermal insulation in lithium-ion battery modules. • The greater the overcharge multiplier, the higher the temperature following thermal runaway. • The battery is highly susceptible to TR when the surface temperature exceed 200 °C. • The fiber material have a temperature drop efficiency of 71.83%. • The aerogel materials are at least 13% in temperature reduction than fibrous materials. • The pre-oxidized silk aerogel have the best thermal spread suppression effect. [ABSTRACT FROM AUTHOR]

Mini channeled cold plates (MCCP) are an impressive choice for electric vehicles with a liquid-based thermal management system to keep the battery temperature within the desired range and to achieve a homogeneous temperature distribution. This paper came up with an optimum solution for maximum battery temperature (MBT), maximum temperature difference on the battery surface (MTD) and pressure drops in the channels (ΔP), which are vital parameters. Multi-objective optimization of geometric parameters and coolant flow rate of a designed MCCP which is experimentally investigated is carried out using the Desirability Function Approach. Firstly, the design of experiments (DoE) is generated using response surface method after determining the input variables and their levels. Then, each sample of DoE are modeled and analyzed numerically. Furthermore, the regression equations of the objective functions (MBT, MTD and ΔP) depending on the design parameters are developed and their variance analyzes are performed. Prediction accuracies of model equations developed for MBT, MTD and ΔP are 97.75%, 95.49% and 97.15%, respectively. As a result, optimum values of design variables, namely channel width (mm), distance between branches (mm), channel depth (mm), number of crossovers in branches and coolant flow rate (l/min) are 5, 5, 10, 13 and 0.7061, respectively. • Multi-objective optimization of a mini channeled cold plate. • Simulation of temperature distribution on the battery surface for different cases. • Deriving regression equations for the optimization output variables. • Achieving a minimum prediction accuracy rate of 95.49% for the response parameters. [ABSTRACT FROM AUTHOR]

Liquid-cooled battery thermal management system with cold plate shows great potential for cooling battery packs in electric vehicles due to its merits of large heat transfer coefficient and good sealing performance. However, current design of cold plate leads to large temperature difference in battery packs, especially in the case with large battery packs. Besides, the pump energy consumption is usually high, which shortens the endurance of electric vehicles. In this paper, a parallel mini-channel cold plate (PMCP) for large battery packs is designed to reduce the temperature difference of the system. Numerical method is adopted to evaluate the performance of the PMCP, which is further demonstrated by experiment. Then a bidirectional symmetrical cold plate is designed to reduce both temperature difference and energy consumption. Positions of the outlets of the bidirectional symmetrical cold plates are adjusted to further improve the system performance. Finally, the designed cold plates are used for cooling large battery packs. Compared with systems equipped with traditional PMCP, the temperature difference in battery pack and the energy consumption of the system with designed PMCP are reduced by 77% and 82%, which shows that the designed PMCP significantly improves the system cooling and energy saving performance. • PMCP is used to cool large-scale battery packs at a high discharge rate. • Experiments are done to study the PMCP performance and verify the numerical method. • Performance of PMCP is improved by constructing bidirectional symmetrical system. • Influence of the outlet position on the performance of designed PMCP is studied. • Δ T avg-b and W P of designed BTMS are reduced by at least 76% and 81%, respectively. [ABSTRACT FROM AUTHOR]

Majority existing organic composite phase change materials (CPCMs) are flammable that result in thermal hazards such as fire and explosions in battery modules. Furthermore, the performance of PCM-based battery modules in extreme conditions like thermal runaway has not been studied adequately. In this study, a tubular CPCM-cell structure is designed using physically flame-retardant-modified CPCMs, and a series of experiments on the CPCMs with/without real cells is conducted with calorimeter tests and SEM analysis on morphology structure. First, the calorimeter tests and comparison on the heat release rate (HRR) are conducted on the CPCMs with and without flame retardant additives. Results show that the addition of Al(OH) 3 reduced the HRR from 242.5 to 204.4 kW/m2 with 15 wt% additives. Besides, the analysis of the mitigating performances of structure-enhanced tubular module and traditional cuboid module with real batteries is conducted. A factor of safety (FOS) parameter is defined to evaluate the safety degree of thermal runaway domino with energy density. The FOS of blank, CPCM–0 C , and CPCM–15 C modules are 0, 3.59, and 16.67, respectively, while that of CPCM-15 T reaches 21.01, indicating a significant improvement on mitigating effects by structure enhancement compared to adding flame retardant additives. This study brings novelty in the design of PCM-based battery modules, particularly from the thermal safety prospect. • An optimized tubular module using modified CPCM is designed to reduce hazard risk. • Bottleneck issue is solved by structure enhancement without reducing energy density. • Effect of flame retardant additives on thermal hazards is tested with/without cells. • Mitigation of tubular unit with air-flow-channel on heat propagation is tested. • Evaluation of battery modules are conducted from two aspects simultaneously. [ABSTRACT FROM AUTHOR]

Serious performance loss of lithium-ion batteries at subzero temperatures is the major obstacle to promoting battery system in cold regions. This paper proposes a novel heating strategy to heat battery from extremely cold temperatures based on a battery-powered external heating structure. The strategy contains two stages: preheating process for battery cold-start, and temperature holding process for battery temperature control after preheating. The strategy switches from the preheating to the temperature holding according to the power capability of battery pack. Both the electrical and thermal behaviors of battery pack are described based on equivalent circuit models, and the state-of-charge and state-of-power of battery pack are co-estimated online to support the implementation of the strategy. Systematic battery-in-the-loop tests are conducted for a series-connected battery pack to verify the effectiveness of the strategy at – 40 °C. Experimental results show that the battery pack can not only be heated from −41.4 °C to −14.0 °C in 371 s by consuming 6.1% of nominal capacity without being over-discharged, but also output 64.81% and 66.59% of nominal energy for loading the modified dynamic stress test cycles and the modified federal urban driving schedule cycles respectively after preheating. [ABSTRACT FROM AUTHOR]

The battery thermal management system (BTMS) is important to ensure the lithium-ion battery life, performance, and safety. A novel inclined U-shaped flat microheat pipe array (FMHPA) is used for BTMS to achieve high efficiency and space-saving in this study. The thermal control performance is experimentally studied and compared with the module without FMHPAs. Results show that the equivalent thermal conductivity of the inclined U-shaped FMHPA is approximately 4350 W m−1 K−1, and plays the role of core heat transfer element. The maximum temperature and temperature difference of the module with FMHPAs are reduced by 16% and 60%, respectively, compared with those of the module without FMHPAs; FMHPAs keep the module in a suitable temperature range for most of the time in the ambient temperature of 25 °C during the 1C charge–2C discharge cycle. Moreover, the temperature difference at cell and module level are maintained within 5 °C in ambient temperature of 25 °C and 40 °C. The heating rate of the module with FMHPAs reaches 0.61 °C/min under the temperature difference of less than 5 °C; variable power heating (from large to small) will increase the temperature rise rate of the battery by 0.19 °C/min. • Inclined U-shaped flat microheat pipe array is used in battery module. • The module with inclined U-shaped FMHPAs is compact in structure and saves space. • The separation of the coolant and batteries improves safety. • Module is kept in suitable temperature in 1C charge–2 C discharge cycle. • Temperature difference at cell and module level are maintained within 5 °C. [ABSTRACT FROM AUTHOR]

It is becoming increasingly apparent that wide application of electric vehicles (EVs) are subject to significant improvements in battery technology. Temperature sensitivity is a major issue adversely affecting battery performance and requiring a robust thermal control. Yet, this is challenged by the large variety of temporal scenarios though which heat is generated in a battery pack, demanding dynamic tools to predict the thermal evolution of batteries. Classical transfer functions provide a low-cost and effective predictive tool. However, they are limited to linear systems, while nonlinear predictive tools can become impractical for EV applications. Therefore, this study provides a methodology to assess the dynamics of battery cooling. This is achieved through conduction of high fidelity modelling of battery cooling exposed to different temporal disturbances on the internal heat generation. The results are then post-processed to evaluate the extent of linearity. A quantitative measure of non-linearity is further applied to clearly determine the degree of nonlinearity in the heat transfer response. It is shown that battery cooling system can be approximated as a linear dynamical system as long as the disturbances are of short duration and relatively low amplitude. Conversely, long and large amplitude temporal disturbances can render strongly nonlinear thermal responses. • A novel measure of nonlinearity of battery cooling process is introduced. • Cooling process remains nearly linear at low load modulation amplitudes (10%). • Long duration temporal disturbances of the battery load generate strong nonlinearity. • For linear conditions, transfer function of Nu is like a low-pass filter. [ABSTRACT FROM AUTHOR]

The large-format lithium-ion cells are growing in popularity as high-energy-density power sources in mobile applications, which calls for efficient and compact passive thermal management systems. Hydrogel, capable of absorbing and holding extremely large amounts of water, emerges as a new type of heat sink material. Herein, we presented a systematic study on the passive thermal management systems employing hydrogel for the 20 Ah large-format lithium-ion cell with emphasis on regulating the temperature homogeneity and temperature spike. Four types of configurations were designed and experimentally explored to achieve optimal cooling performance. It showed that introducing heat conducting plate between hydrogel and battery surface can effectively improve the temperature homogeneity, and the highest temperature and largest temperature difference were controlled to be only 40.5 °C and 2.5 °C even under a high discharge rate of 4C, which were about 2.5 °C and 2.3 °C lower than the pure hydrogel system. In addition, heat dissipation fins and copper foam were also employed to further accelerate the heat transfer process within the hydrogel. It showed that the fin-hydrogel system held the best performance and delivered a maximum surface temperature and a largest temperature difference of 32.6 °C and 1.4 °C over eight 3C/1C discharge/charge cycles. • Four hydrogel-based cooling architectures are explored for large-format batteries. • Temperature homogeneity is enhanced by the indirect-contact structure. • Fin-hydrogel system affords the best cooling performance. • Temperature spike and temperature gradient are well controlled even at 4C. • Sustainable cooling capability of the hydrogel systems is validated over cycles. [ABSTRACT FROM AUTHOR]

A battery thermal management system that effectively maintains its temperature is highly desired. However, the promising cooling method utilizing phase change materials (PCM) has challenges of low thermal conductivity and sharp temperature growth after complete melting. To address the problems, a hybrid system that couples PCM/copper foam with helical liquid channels is proposed and the effects of the influencing factors are investigated numerically. Results showed that the hybrid system achieved more than 30 K temperature drop than the natural convection case. The maximum temperatures with the helical pitch of 10 mm and 40 mm were 332.28 K and 332.88 K, respectively, compared to 334.17 K for the straight-channel system. The increments of helical diameter and tube number improved the battery temperature but raised the power consumption. The flow velocity growth could significantly reduce the battery temperature, but beyond 0.05 m/s the temperature became relatively stable. In the studied ranges, the temperature reached the optimum at the foam porosity of 0.92 and was reduced with the increasing pore density. The maximum temperature with the melting point of 28 °C was around 4 K and 8 K lower than that of PCM35HC and PCM44HC cases. The conclusions in this study could provide insights into the design of hybrid battery thermal management systems. • A hybrid battery thermal management system is studied. • Novel helical channels are employed. • Parameters from perspectives of the liquid channel, porous structure and PCM are investigated. • Nonequilibrium thermal model for the PCM/copper foam composite is used. [ABSTRACT FROM AUTHOR]

A heat pipe (HP) heat dissipation model of a lithium-ion-battery pack is established for the climate in the central and southern regions in China, and the heat transfer effects of various fins with different spacing and thickness are investigated. According to the change of heat dissipation, inlet and outlet pressure difference and average heat transfer coefficient with fin spacing and thickness, the relatively optimal heat dissipation fin structure parameters are determined, and the battery temperature distribution and temperature change under different discharge rates of the battery pack in a high temperature environment, and the characteristics of the HP heat dissipation battery thermal management system(BTMS) are analyzed and the effects of HP-based BTMS on battery startup heating in low temperature are evaluated. The results show that the optimal parameters are that the fin spacing is 5 mm, the thickness is 2 mm, the air flow velocity varies from 4 to 16 m/s, and the average heat transfer coefficient is 7.6–11.9 W/(m·K). The battery pack using the HP can reach the proper temperature of 288.15 K in 682s, 615s, and 375 s at 1C, 2C, and 4C discharge rates respectively. [Display omitted] • A heat pipe heat dissipation model of a twelve-lithium-ion-battery module is established. • Relatively optimal heat dissipation fin structure parameters are obtained. • Effect of HP-based BTMS on battery startup heating in low temperature is evaluated. [ABSTRACT FROM AUTHOR]

The degraded performance of lithium-ion batteries at low temperatures is a key obstacle to the development of battery energy storage system applied in extremely cold environment. Therefore, this paper proposes a heating method based on model prediction to support the low-temperature operation of battery pack without additional power sources. Battery pack model is developed based on Thevenin equivalent circuit model. A co-estimator is established to update model parameters and state-of-charge online using adaptive recursive least squares and extended Kalman filter. The permissible discharging current of pack is predicted based on multiple constraints to prevent over-discharge. Then, the battery-powered heating structure, control circuit, and heating strategy are designed. The strategy contains a preheating process for cold-start and a holding process for stabilizing cell temperature. The method is verified experimentally through systematic battery-in-the-loop tests at the environmental temperature of – 40 °C. Results show that the method can uniformly preheat all in-pack cells from − 40 °C to − 20 °C in 330 s consuming 4.7% of nominal capacity. In holding process, it is energy-efficient to raise cell temperature continuously and then maintain at 5 °C, which makes 68.3% of nominal capacity available when loading a modified federal urban driving schedule. • Propose a battery-powered heating method for the battery pack working at – 40 °C. • Utilize the limited battery power to heat battery pack efficiently. • Develop model-based estimation and prediction to evaluate battery power capability. • Design the heating structure, control circuit, and strategy for heating control. • Conduct battery-in-the-loop tests for experimental verification and investigation. [ABSTRACT FROM AUTHOR]

The heat dissipation from the battery surface significantly affects battery performance and lifetime. This study proposes a new and an alternative method to predict the thermal performance of the battery operation according to the surface temperature gradients and heat & exergy losses by using a data-driven dynamic mode decomposition method, which is new for thermal flows. To predict the thermal gradients, a 10 min long experiment is performed via an infrared thermographic camera for a commercial Li-polymer battery of a smartphone. The camera collects the thermal images on the battery surface along 1 min as the data training period at first; then, the proposed method predicts the surface temperature gradients for the rest of the experimental period, 5 min. The temperature gradients on the battery surface are well predicted with less than 1% error whereas the heat dissipation and the exergy loss are predicted with the maximum error values of 2.75% and 5.30%, respectively. According to the error probability distribution plots, the vast majority of the occurred error is less than ±5%. The results prove the fast prediction ability of the proposed technique and show promising outcomes for further improvement studies. Image 1 • A novel data-driven technique is developed for heat loss from batteries. • Training periods of 30 and 60 s-periods achieve well-prediction. • The method is verified via experimental results with less than 5% errors. • Data visualization is shown for 5 min-long battery charging. [ABSTRACT FROM AUTHOR]

In this paper, the thermal performance of thermoelectric cooler (TEC) in thermal management of a cylindrical battery module is investigated. The battery module consisted of 18650 test batteries in 3 × 5 array embedded in the copper foam impregnated with organic phase change material (PCM) for heat transfer enhancement. In the experimental test, the transient and steady-state thermal performances were examined base on the thermoelectric cooling in comparison with the natural convection and liquid cooling conditions. The characteristic PCM melting stages were identified to correlate with the maximum temperature and temperature difference in the battery module. In comparison, the thermoelectric cooling reduced the battery temperature and prolonged the working time significantly. The optimal current was experimentally obtained to be about 6.0–6.5 A based on the highest cooling power or lowest battery temperature, which is close to the optimal range based on the steady-state theoretical analysis. Further analysis shows that the optimal current is affected markedly by the hot-side thermal resistance, but little by the cold-side thermal resistance. Increasing the number of TEC thermoelectric arms by reducing the spacing has a favorable effect in improving the coefficient of performance (COP) of the TEC module. • Battery thermal management based on the TEC cooling with impregnated PCM composite investigated. • TEC cooling reduced the maximum battery temperature and prolonged working time. • Characteristic PCM melting processes with TEC cooling identified for battery module. • Agreement is found between theoretical analysis and experimental measurements. [ABSTRACT FROM AUTHOR]