Search

• 3D-printed polymer-based battery thermal management system is proposed • Coolant flow architecture reduces the effect of polymer low thermal conductivity • Low coolant temperature raise leads to lower BTMS energy consumption The thermal performance of a novel battery thermal management system produced by additive manufacturing is investigated through simulations. The performance of 3D-printed polymer-based battery thermal management systems is investigated for heat-managing high power density Li-ion batteries for electric vehicles and stationary applications. The manufacturing of the battery packs through 3D-printing allows for greater complexity and novelty in the design of the coolant flow domains, in order to achieve a high heat transfer coefficient by the coolant. Having a high heat transfer coefficient at the coolant side allows the use of lower conductive materials in the body of the battery pack. The proposed system takes advantage of 3D-printing technology to embedded heat fins in the cooling channel. The simulations consider various discharging rates from 2C to a high of 3C to take the battery from a 100% to 20% state of charge in the discharging process. For the charging rates 2C and 3C, the maximum battery temperature within the pack reached 22.8°C and 24.5°C, respectively. However, the maximum temperature difference across a six-battery pack reached no more than 1.5°C and 4.5°C, respectively. A maximum temperature difference achieved by the proposed system shows the ability of the 3D-printed polymer-based system to achieve the required performance and demonstrates the potential of such systems that are equipped with the advantage of additive manufacturing. [ABSTRACT FROM AUTHOR]

The temperature control technology based on phase change material (PCM) demonstrates excellent performance in the field of battery thermal management. However, the compact and bulky structure of the traditional composite PCM (CPCM) module reduces the energy density of the battery pack greatly, and is unfavorable to the secondary heat dissipation. In this work, we develop a novel PCM cooling structure by substituting the common block-shaped CPCM (B-CPCM) module with serpentine CPCM (S-CPCM) plates. The S-CPCM plates with high shape stability provide a much larger surface area and many air flow channels in comparison to the B-CPCM module, thus endowing the module with outstanding secondary heat dissipation capability. For example, under the same fan power of forced air convection (5.2 W), the S-CPCM module delivers a much lower maximum temperature than the B-CPCM module (51.9 vs. 54.2 °C) during the repeated charge-discharge process. As highlighted here, on the basis of guaranteeing the cooling performance, the S-CPCM cooling structure also saves ~70% of the CPCM amount, and thereby the energy density of the battery module is increased by 13.8 Wh kg−1. Image 1 • Novel serpentine composite phase change material (S-CPCM) plates are designed. • The S-CPCM cooling structure saves 70% of the CPCM amount in the battery module. • The energy density of the module with S-CPCM cooling is increased by 13.8 Wh kg−1 • S-CPCM plates provide air flow channels and large surface area for heat dissipation. • The S-CPCM cooling structure shows much enhanced heat dissipation performance. [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]

• R134a AMFHP with 50% FR achieves the best performance among the three FRs. • The performance order of AMFHPs with 50% FR are ammonia > R134a > acetone. • Analysis is conducted about the liquid pool heat transfer of 3 fluids in AMFHPs. • The effect of air velocity on t e ¯ is obvious, however, its influence on λ eff is marginal. • Optimum air velocities for each AMFHP with different working fluids are presented. An experimental investigation is conducted to study the effect of the type of working fluid, liquid filling ratio (FR) and the cooling and heating conditions on the performance of air-cooled multi-port flat heat pipes (AMFHPs) designed for the thermal management of power battery. The results show that, under the same FR of 50%,the ammonia AMFHP owns the highest thermal performance, whose equivalent thermal conductivity is 2.21–3.30 times that of one filled with acetone and 1.05–1.31 times that of one using R134a as working substance. Evaporation thermal resistance of acetone AMFHP is significantly larger than those of the AMFHPs filled with ammonia and R134a, whereas their condensation thermal resistance values are comparative. Secondly, it is found that the equivalent thermal conductivity of the R134a AMFHP with 50% FR is 1.63–2.22 times that of one with 30% FR and 1.14–1.63 times that of one with 70% FR, respectively. Thirdly, result indicates that the effect of cooling air velocity on the equivalent thermal conductivity of AMFHP is insignificant, but the temperature of evaporation section is tightly connected to the cooling air velocity. There exists an economic air velocity for each AMFHP, the appropriate air velocities of the AMFHPs filled with R134a, acetone and ammonia at FR=50% are 3.5 m/s, 2.5 m/s and 3.5 m/s, respectively. In addition, analysis of heat transfer reveals that, the intensity of heat transfer mode of the AMFHPs in liquid pool ranges from R134a, ammonia and acetone, under the same working condition and filling ratio. The most direct conclusion is that the R134a AMFHP with appropriate FR is suitable to meet the thermal management requirements of lithium ion batteries for electric vehicles. [ABSTRACT FROM AUTHOR]

Battery modeling and state estimation are critical to the battery safety and vehicle driving range. Currently, electrochemical mechanism based models require huge computation effort for solving partial differential equations, equivalent circuit models do not consider actual battery mechanism, while machine learning models are lack of generalization ability due to their data-driven nature. All these problems bring the challenges to guarantee the model effectiveness in wide temperature and large current conditions. To estimate the battery state of charge (SOC) and state of temperature (SOT) under these conditions, an electrochemical-thermal-neural-network (ETNN) model is formulated in this paper. Specifically, a simplified single particle model and a lumped thermal model are served as the sub-models of ETNN to predict core temperature and provide approximate terminal voltage. Then a neural network is incorporated to enhance the performance of sub-models. According to the extensive experiments, ETNN model is able to accurately estimate battery voltage and core temperature under the ambient temperatures of -10–40 °C and the discharge rate of 10-C. After that, an unscented Kalman filter (UKF) is integrated with ETNN to achieve reliable co-estimation of SOC-SOT. Experimental results illustrate that proposed ETNN-UKF can rapidly eliminate initial errors and provide satisfactory co-estimation performance. • Formulation of a hybrid battery electrochemical-thermal-neural-network model. • High model accuracy under large currents and wide range of ambient temperatures. • Accurate co-estimation of SOC and SOT by integrating the unscented Kalman filter. [ABSTRACT FROM AUTHOR]

The investigation and improvement of the cooling process of lithium-ion batteries (LIBs) used in battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs) are required in order to achieve better performance and longer lifespan. In this manuscript, the temperature and velocity profiles of cooling plates used to cool down the large prismatic Graphite/LiFePO4 battery are presented using both laboratory testing and modeling techniques. Computed tomography (CT) scanning was utilized for the cooling plate, Detroit Engineering Products (DEP) MeshWorks 8.0 was used for meshing of the cooling plate, and STAR CCM+ was used for simulation. The numerical investigation was conducted for higher C-rates of 3C and 4C with different ambient temperatures. For the experimental work, three heat flux sensors were attached to the battery surface. Water was used as a coolant inside the cooling plate to cool down the battery. The mass flow rate at each channel was 0.000277677 kg/s. The k-ε model was then utilized to simulate the turbulent behaviour of the fluid in the cooling plate, and the thermal behaviour under constant current (CC) discharge was studied and validated with the experimental data. This study provides insight into thermal and flow characteristics of the coolant inside a cooing plate, which can be used for designing more efficient cooling plates. [ABSTRACT FROM AUTHOR]

The effect of vibration on a passive battery thermal management (BTM) system is investigated. The BTM system includes phase change material (PCM) in an enclosure hosting a battery pack. Rubitherm® 35HC PCM is used in the current investigation with a goal to maintain the battery temperature within the range of 25 °C to 40 °C. The simulated batteries are made of aluminum cylinders containing ceramic cartridge heaters at their cores, which mimic 2300 mAh 18650 Lithium-ion batteries. A series of experimental tests have been carried out to study the transient thermal field behaviour of the battery pack under various discharge rates (i.e., 1C–5C). The ranges of applied frequency and amplitude during the experiments are 20–30 Hz and 30 mm/s to 50 mm/s, respectively, which are typically observed in plug-in hybrid electric vehicles (PHEV) on the road during normal operation. The temperature at the battery surface shows an increasing trend with increasing frequency and amplitude of vibration. However, the transient temperature variation pattern of batteries in the centre of the battery pack is slightly different than the batteries in the corners. • Effect of vibration on PCM based battery thermal management system was investigated. • Temperature profiles under vibration was characterized by four distinct regimes. • Battery surface temperature increases with increasing vibration frequencies. • Battery surface temperature increases with increasing discharge rates. [ABSTRACT FROM AUTHOR]

• Battery thermal management is carried out. • Free convection flow and heat transfer are analyzed. • Experimental rheological/thermal properties are measured. • The second law analysis is employed. • The lattice Boltzmann simulation is used. The growing demand of electric vehicles (EVs) attracts many researchers to work on the battery thermal management to maintain the temperature of battery package in the desired temperature. In this regard, the present work aims to use the numerical and experimental approaches in order to perform the battery thermal management. The lattice Boltzmann method is used to simulate the fluid flow and heat transfer during free convection in a rectangular cavity included with seven battery cylinders. The battery package and battery are simplified with rectangular cavity and circle cylinder, respectively. The top and bottom walls are kept at constant cold temperature with three different configurations (Smooth, Jagged and Zigzag). In addition, the cavity is filled with SLG (Single Layer Graphene)/water nanofluid which the thermal conductivity and dynamic viscosity are measured experimentally using modern devices. Furthermore, the second law analysis is carried out in order to find the influence of governing parameters including Rayleigh number, nanoparticle concentration (?? = 0.2, 0.4, 0.6, 0.8 and 1.0 mg/ml) and configuration of cavity on the local/total entropy generation. The flow structure, temperature field, local maps of heat transfer irreversibility and fluid friction irreversibility, volumetric magnitude of total entropy generation and average Nusselt number are presented. [ABSTRACT FROM AUTHOR]

• Develop an efficient thermal network model for PCM thermal management systems. • The model has a high accuracy, high computation efficiency and high resolution. • The model optimizes the PCM properties for low temperature thermal management. • The model analyzes the long-term impacts of temperature field on battery life. This paper presents a simple 2D thermal network model for a battery thermal management system with phase change materials (PCMs). An equivalent electric circuit model is developed to solve heat transfer problems that include the processes of battery heat generation and PCM thermal storage. This thermal network model is compact and accurate. The simulation time is saved by 99% compared with a conventional numerical model, whereas the average prediction error of battery temperature is lower than 1 °C. This model is applied for the rapid optimization of the PCM properties to warm up a battery pack rapidly during cold starts. The results demonstrate that the PCM suitable for thermal management under low temperatures should have a melting point of approximately 40 °C, high thermal conductivity of over 5.4 W/m K, and a low latent heat storage density of less than 0.0145 kJ/m3. Utilizing its high computation efficiency and resolution for capturing the temperature distribution in 2D, the model can quantitatively assess the long-term effect of the thermal management system on the life of a battery module during a 10,000-hour charge–discharge cycle. A lifespan model that integrates a battery capacity fade model into the thermal network is developed and the simulation results verify that a lower temperature and temperature difference reduce the capacity loss in a multi-cell module. The thermal network model is efficient to design and optimize the thermal management system for a real-size battery pack, based on the assessment of its long-term impacts on battery performance. [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]

• A compact and lightweight liquid-cooled BTM solution is proposed. • The influences of the parameters on the performance of the TCS are investigated. • The structure of the TCS is designed for better performance and weight reduction. • Δ P , Δ T and m TCS after designing are reduced by 80%, 14% and 46%, respectively. • The system with parallel TCSs is designed to improve the cooling performance. Battery thermal management (BTM) is indispensable to the battery pack of electric vehicles (EVs) for safety. Among different types of BTM technologies, liquid cooling shows its superiority with high heat transfer coefficient and low power consumption. However, the previous works paid little attention to the compactness and weight ratio of liquid-cooled BTM system, which is vital to the specific energy of battery pack. In this study, a compact and lightweight liquid-cooled BTM system is presented to control the maximum temperature (T max) and the temperature difference (Δ T) of lithium-ion power battery pack. In this liquid-cooled solution, one thermal conductive structure (TCS) with three curved contact surfaces is developed to cool cylindrical battery. The influences of mass flow rate (m f), inner diameter (d), contact surface height (h) and contact surface angle (α) of the TCS are investigated through numerical study. It is found that for the 5C discharge rate process of battery, T max can be maintained within 313 K when m f is larger than 1 × 10−4 kg/s. A weight sensitive factor is defined to evaluate the influences of d , h and α on Δ T and the weight of TCS. It is found that d is the most important parameter that influences the weight. h is the secondary parameter, and α is the parameter with the minimal impact on the weight. Then the values of d , h , and α are designed to reduce the weight of TCS while maintaining its cooling performance. The designed TCS can control T max under 313 K with Δ T as 4.137 K. Compared to the original TCS, Δ P , Δ T and the weight are respectively reduced by 80%, 14% and 46% for the designed TCS. Furthermore, the performance of liquid-cooled system with parallel TCSs is discussed. The flow distribution among parallel TCSs is improved through designing the positions of the inlet and the outlet, which enables that T max and Δ T of battery pack is similar to the ones of a single battery. The present study facilitates the guideline for compact and lightweight design of liquid-cooled battery thermal management system. [ABSTRACT FROM AUTHOR]

• Branch-structured fins are designed for high temperature environment. • Thermal behaviors of modules under different ambient temperatures are compared. • How PCT influences the performance of PCM is investigated under high temperature. Battery modules with phase change material (PCM) cooling inevitably suffer from heat-storage saturation and poor secondary-heat dissipation, especially in high-temperature environments or hot regions. To optimize thermal management, this study firstly explores the thermal behaviors of PCMs with different phase change temperatures (PCTs) in a high-temperature environment. The experimental results show that a PCM with a PCT of 46 °C offers the best cooling effect at a high ambient temperature of 40 °C in this study. For example, the maximum temperature of a cell without PCM reaches 53.3 °C, whereas that of the cell with PCMs having PCTs 40, 46, and 55 °C, are 59.2, 51.6, and 57.5 °C, respectively, during the dynamic cycling process. Nevertheless, the application of above PCM is still unsatisfying because the maximum temperature of the battery in the PCM module exhibits obvious increasing trend with cycles in 40 °C environment. On this basis, several novel fins with multiple heat-flow channels (of V, Y and X shapes) are designed and introduced into the PCM module to enhance the secondary heat dissipation capability. These fins with innovative branch structures deliver excellent performance in alleviating the battery temperature than the traditional rectangular fins, which can be attributed to the ability of the branch structures to increase the heat transfer area by adding heat transfer channels. The results of this work show that the X-shape delivers the best performance in a high-temperature environment of 40 °C by maintaining the maximum temperature of the cell below 47 °C. [ABSTRACT FROM AUTHOR]

• A dual-functional battery module was designed using aerogel felt coupled with PCM. • Thermal behaviors of the battery modules with PCM and aerogel were studied. • Evaluation of battery modules were conducted from two aspects simultaneously. In view of the flammability of phase change materials (PCMs), a safer structure design for thermal insulation protection is crucial in a PCM-based battery thermal management system. In this work, a series of experiments is performed on battery modules with and without PCM and/or aerogel to investigate their heat dissipation capability and thermal insulation capability in both thermal runaway tests and cycling tests. The results demonstrate that the PCM added with expandable graphite considerably inhibits the combustion flame and lowers the peak temperature of battery modules; however, it accelerates the thermal runaway propagation speed. In comparison, the aerogel felt exhibits excellent performance in delaying battery thermal runaway. Based on the foregoing, an optimized dual-functional battery module is proposed. The module combines the strengths of the PCM and aerogel, and its thermal behaviors are explored via proper analysis with experimental verification. [ABSTRACT FROM AUTHOR]

In order to improve cycle life and the working performance of the Li‐ion batteries and the reliability of battery thermal management (BTM) system, a composite matrix coupled with mini‐channel based BTM system is designed in this paper. The thermal performances of the BTM system at different discharge rates under the condition of air natural convection (ANC) and composite matrix (CM) are studied. The results show that the thermal conductivity of the PCMs/EG composites is about 28 times larger than the pure PCMs. Meanwhile, the latent heat is 134.28 J/g after adding EG. The batteries possess larger heat production both at larger state of charge (SOC) and lower SOC. Compared with ANC system, the highest temperature and the ΔTmax of the battery modules with CM system at the discharge rates of 3 C are 40.5°C and 2.4°C, respectively. When the battery modules coupled with mini‐channel, the 6 cooling channels with the inlet mass flow rate at 2 × 10−3 kg/s has the best cooling performance. The highest temperature of the packs could be controlled below 40.1°C and the ΔTmax is no more than 1.4°C during the cycle process at the discharge rate of 3 C(I = 30 Ah). [ABSTRACT FROM AUTHOR]

Recently, the use of electrical vehicles has abruptly increased due to environmental crises. The high energy density of lithium-ion batteries is their main advantage for use in electric vehicles (EVs). However, the thermal management of Li-ion batteries is a challenge due to the poor heat resistance of Lithium ions. The performance and lifetime of lithium ion batteries are strongly affected by the internal operating temperature. Thermal characterization of battery cells is very important to ensure the consistent operation of a Li-ion battery for its application. In the present study, the OHP (Oscillating Heat Pipe) system is proposed as a battery cooling module, and experimental verification was carried out. OHP is characterized by a long evaporator section, an extremely short condenser section, and almost no adiabatic section. Experimental investigations were conducted using various parameters such as the filling ratio, orientation, coolant temperature, and heat flux. Average temperature of the heater's surface was maintained at 56.4 °C using 14 W with 25 °C coolant water. The experimental results show that the present cooling technology basically meets the design goal of consistent operation. [ABSTRACT FROM AUTHOR]

Cooling the surface of large format batteries with solid conductive plates, or fins, has an inherent advantage of reducing the number of liquid seals relative to some mini-channel cold plate designs, as liquid is not passed through the numerous individual plates directly. This may reduce the overall pack leakage risk which is of utmost importance due to safety concerns associated with the possibility of a cell short circuit and thermal runaway event. However, fin cooling comes at a cost of an increased thermal resistance which can lead to higher cell temperatures and a poorer temperature uniformity under aggressive heat generation conditions. In this paper, a novel graphite-based fin material with an in-plane thermal conductivity 5 times greater than aluminium with the same weight is presented for advanced battery cooling. The thermal performance of the fin is benchmarked against conventional copper and aluminium fins in an experimental programme cycling real 53 Ah pouch cells. The results from the extensive experimental testing indicate that the new fin can reduce both the peak measured temperature and surface temperature gradient by up to 8 °C and 5 °C respectively, when compared to aluminium fins under an aggressive electric vehicle duty-cycle. [ABSTRACT FROM AUTHOR]